Making TCPSocket.new "Happy"!

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def self.tcp(host, port, ...) # ... state = :start loop
do case state when :start then Start hostname resolution when :v4w then Wait for 50ms for IPv6 name resolution when :v6c, :v4c, :v46c then Start a new connection attempt when :v46w then Wait for the connection state to be confirmed and name resolution to complete when :success then Return the successfully connected socket when :failure then Raise an exception when :timeout then Raise a timeout exception end end end 5IFJNQMFNFOUBUJPOPG4PDLFUUDQ )FSFJTBCSJFGPWFSWJFXPG4PDLFUUDQXJUI)&W JNQMFNFOUBUJPO

5IFTUBUFUSBOTJUJPO def self.tcp(host, port, ...) # ... state = :start
loop do case state when :start then Start hostname resolution when :v4w then Wait for 50ms for IPv6 name resolution when :v6c, :v4c, :v46c then Start a new connection attempt when :v46w then Wait for the connection state to be confirmed and name resolution to complete when :success then Return the successfully connected socket when :failure then Raise an exception when :timeout then Raise a timeout exception end end end WD GBJMVSF TVDDFTT TUBSU WX UJNFPVU WX WD WD 5IFTUBUFUSBOTJUJPOEJBHSBNJTSFQSFTFOUFE CZDBMMJOHBDBTFTUBUFNFOUJOTJEF,FSOFMMPPQ

do case state when :start then Start hostname resolution when :v4w then Wait for 50ms for IPv6 name resolution when :v6c, :v4c, :v46c then Start a new connection attempt when :v46w then Wait for the connection state to be confirmed and name resolution to complete when :success then Return the successfully connected socket when :failure then Raise an exception when :timeout then Raise a timeout exception end end end 5IFDVSSFOUTUBUFJTTUPSFEJOBWBSJBCMFTUBUF TUBUF"WBSJBCMFUPTUPSFUIFDVSSFOUTUBUF 5IFDVSSFOUTUBUF 5IFTUBUFUSBOTJUJPO

do case state when :start then Start hostname resolution when :v4w then Wait for 50ms for IPv6 name resolution when :v6c, :v4c, :v46c then Start a new connection attempt when :v46w then Wait for the connection state to be confirmed and name resolution to complete when :success then Return the successfully connected socket when :failure then Raise an exception when :timeout then Raise a timeout exception end end end 5IFQSPDFTTPQFSBUFTBTGPMMPXT &YFDVUFUIFQSFEF fi OFEQSPDFTTJOHGPSUIFDVSSFOUTUBUF ➡︎ 4FUUIFOFYUTUBUF ➡︎ 1SPDFFEUPUIFOFYUMPPQJUFSBUJPO 5IFBDUJPOTQFSGPSNFEGPSFBDITUBUF TUBUF"WBSJBCMFUPTUPSFUIFDVSSFOUTUBUF 5IFDVSSFOUTUBUF 5IFTUBUFUSBOTJUJPO

5IFTUBUFUSBOTJUJPO def self.tcp(host, port, ...) # ... state = :start
loop do case state when :start then Start hostname resolution when :v4w then Wait for 50ms for IPv6 name resolution when :v6c, :v4c, :v46c then Start a new connection attempt when :v46w then Wait for the connection state to be confirmed and name resolution to complete when :success then Return the successfully connected socket when :failure then Raise an exception when :timeout then Raise a timeout exception end end end "UUIFTUBSUPGUIFNFUIPE UIFWBSJBCMFTUBUFJT JOJUJBMJ[FEXJUIUIFJOJUJBMTUBUFTUBSU TUBSUBTBJOJUJBMTUBUF

5IFTUBUFTUBSU def self.tcp(host, port, ...) # ... state = :start
loop do case state when :start then Start hostname resolution when :v4w then Wait for 50ms for IPv6 name resolution when :v6c, :v4c, :v46c then Start a new connection attempt when :v46w then Wait for the connection state to be confirmed and name resolution to complete when :success then Return the successfully connected socket when :failure then Raise an exception when :timeout then Raise a timeout exception end end end WD GBJMVSF TVDDFTT TUBSU WX UJNFPVU WX WD WD *OUIF fi STUJUFSBUJPOPGUIFMPPQ UIFQSPDFTTPGTUBSUJTFYFDVUFE

case state when :start # ... TUBSU'JSTU DSFBUFBOPCKFDUXJUI BQBJSPGQJQF SFUVSOWBMVFPG*0QJQF
BOEBRVFVF SFUVSOWBMVFPG2VFVFOFX hostname_resolution_queue = HostnameResolutionQueue.new(resolving_family_names.size) 4UBSUIPTUOBNFSFTPMVUJPO def initialize(size) # ... @rpipe, @wpipe = IO.pipe @queue = Queue.new @mutex = Mutex.new end 5IFTUBUFTUBSU

case state when :start # ... hostname_resolution_threads.concat( resolving_family_names.map { |family|
thread_args = [family, *hostname_resolution_args] thread = Thread.new(*thread_args) { |*thread_args| hostname_resolution(*thread_args) } Thread.pass thread } ) # ... TUBSU4QBXOBUISFBEGPSFBDIBEESFTTGBNJMZ #ZDBMMJOHUIFOBNFSFTPMVUJPONFUIPEJOFBDIDIJME UISFBE *1WBOE*1WOBNFSFTPMVUJPOTUBSUJOQBSBMMFM 5IFOBNFSFTPMVUJPONFUIPE 4QBXOBUISFBE 4UBSUIPTUOBNFSFTPMVUJPO hostname_resolution_queue = HostnameResolutionQueue.new(resolving_family_names.size) hostname_resolution_waiting = hostname_resolution_queue.waiting_pipe hostname_resolution_args = [host, port, hostname_resolution_queue] 5IFTUBUFTUBSU

case state when :start # ... hostname_resolution_threads.concat( resolving_family_names.map { |family|
thread_args = [family, *hostname_resolution_args] thread = Thread.new(*thread_args) { |*thread_args| hostname_resolution(*thread_args) } Thread.pass thread } ) # ... 4UBSUIPTUOBNFSFTPMVUJPO hostname_resolution_queue = HostnameResolutionQueue.new(resolving_family_names.size) hostname_resolution_waiting = hostname_resolution_queue.waiting_pipe hostname_resolution_args = [host, port, hostname_resolution_queue] TUBSU1BTTUIFPCKFDUDSFBUFEFBSMJFSUIBUIPMETUIFQJQF BOEUIFRVFVF BMPOHXJUIPUIFSFMFNFOUTOFDFTTBSZGPS OBNFSFTPMVUJPOUPUIFNFUIPE BTBSHVNFOUT 5IFTUBUFTUBSU

def self.hostname_resolution(family, host, port, hostname_resolution_queue) begin resolved_addrinfos = Addrinfo.getaddrinfo(host, port,
ADDRESS_FAMILIES[family], :STREAM) hostname_resolution_queue.add_resolved(family, resolved_addrinfos) rescue => e # ... end end TUBSU)FSFJTUIFJNQMFNFOUBUJPOPG UIFOBNFSFTPMVUJPONFUIPE 5IFTUBUFTUBSU

ADDRESS_FAMILIES[family], :STREAM) hostname_resolution_queue.add_resolved(family, resolved_addrinfos) rescue => e # ... end end TUBSU$BMM"EESJOGPHFUBEESJOGPXIJDIQFSGPSNT IPTUOBNFSFTPMVUJPO 'PSIPTUOBNFSFTPMVUJPO 5IFTUBUFTUBSU

ADDRESS_FAMILIES[family], :STREAM) hostname_resolution_queue.add_resolved(family, resolved_addrinfos) rescue => e # ... end end TUBSU0ODFIPTUOBNFSFTPMVUJPOJTDPNQMFUF QVTIUIFPCUBJOFEBEESFTTFTJOUPUIFRVFVFTIBSFE CFUXFFOUIFDIJMEUISFBETBOEUIFNBJOUISFBE def add_resolved(family, resolved_addrinfos) @mutex.synchronize do @queue.push [family, resolved_addrinfos] @wpipe.putc HOSTNAME_RESOLUTION_QUEUE_UPDATED end end 5IFTUBUFTUBSU

ADDRESS_FAMILIES[family], :STREAM) hostname_resolution_queue.add_resolved(family, resolved_addrinfos) rescue => e # ... end end TUBSU"OEJUJTOFDFTTBSZUPOPUJGZUIFNBJOUISFBE UIBUOBNFSFTPMVUJPOIBTDPNQMFUFEJOUIFDIJMEUISFBE def add_resolved(family, resolved_addrinfos) @mutex.synchronize do @queue.push [family, resolved_addrinfos] @wpipe.putc HOSTNAME_RESOLUTION_QUEUE_UPDATED end end 5IFTUBUFTUBSU

ADDRESS_FAMILIES[family], :STREAM) hostname_resolution_queue.add_resolved(family, resolved_addrinfos) rescue => e # ... end end TUBSU5PEPUIJT XSJUFUIFOPUJ fi DBUJPOUPUIFXSJUFFOE PGBQJQFUIBUJTBMTPTIBSFEXJUIUIFNBJOUISFBE def add_resolved(family, resolved_addrinfos) @mutex.synchronize do @queue.push [family, resolved_addrinfos] @wpipe.putc HOSTNAME_RESOLUTION_QUEUE_UPDATED end end 5IFTUBUFTUBSU

case state when :start # Create child threads and call
Socket.hostname_resolution hostname_resolved, _, = IO.select( # ... (hostname_resolution_waiting, nil, nil, nil) TUBSU*OUIFNBJOUISFBE *0TFMFDUJTDBMMFE BGUFSTQBXOJOHUIFDIJMEUISFBET 4UBSUIPTUOBNFSFTPMVUJPO 5IFTUBUFTUBSU

Socket.hostname_resolution hostname_resolved, _, = IO.select( # ... (hostname_resolution_waiting, nil, nil, nil) TUBSU5IFSFBEFOEPGUIFQJQFTIBSFEXJUI UIFDIJMEUISFBEJTQBTTFEBTBOBSHVNFOUUP*0TFMFDU 4UBSUIPTUOBNFSFTPMVUJPO 5IFTUBUFTUBSU 5IFSFBEFOEPGUIFQJQF

Socket.hostname_resolution hostname_resolved, _, = IO.select( # ... (hostname_resolution_waiting, nil, nil, nil) TUBSU8IFOFJUIFSUIF*1WPS*1WOBNFSFTPMVUJPO DPNQMFUFTJOUIFDIJMEUISFBE BOPUJ fi DBUJPOJTTFOU UISPVHIUIJTQJQF6OUJMUIBUOPUJ fi DBUJPOBSSJWFT *0TFMFDUXJMMCMPDLJOEF fi OJUFMZ #MPDLQSPDFTTJOH 4UBSUIPTUOBNFSFTPMVUJPO 5IFTUBUFTUBSU 5IFOPUJ fi DBUJPOGSPNUIFDIJMEUISFBEBSSJWFTIFSF

Socket.hostname_resolution hostname_resolved, _, = IO.select( # ... family_name, res = hostname_resolution_queue.get # ... state = case family_name when :ipv6 then :v6c when :ipv4 then :v4w end selectable_addrinfos.add(family_name, res) # ... next TUBSU8IFOBOPUJ fi DBUJPOBSSJWFTUISPVHIUIFQJQF BOE*0TFMFDUVOCMPDLT UIFOSFUSJFWFUIFSFTPMWFE BEESFTTFT (FUUIFSFTVMUPGUIFIPTUOBNFSFTPMVUJPO 4UBSUIPTUOBNFSFTPMVUJPO 5IFTUBUFTUBSU (hostname_resolution_waiting, nil, nil, nil)

Socket.hostname_resolution hostname_resolved, _, = IO.select( # ... family_name, res = hostname_resolution_queue.get # ... state = case family_name when :ipv6 then :v6c when :ipv4 then :v4w end selectable_addrinfos.add(family_name, res) # ... next TUBSU*GUIFSFTPMWFEBEESFTTFTBSF*1W USBOTJUJPOUPWX*GJUJT*1W USBOTJUJPOUPWD %FUFSNJOFUIFOFYUTUBUF (POFYU 4UBSUIPTUOBNFSFTPMVUJPO 5IFTUBUFTUBSU (hostname_resolution_waiting, nil, nil, nil)

5IFTUBUFWX def self.tcp(host, port, ...) # ... state = :start
loop do case state when :start then Start hostname resolution when :v4w then Wait for 50ms for IPv6 name resolution when :v6c, :v4c, :v46c then Start a new connection attempt when :v46w then Wait for the connection state to be confirmed and name resolution to complete when :success then Return the successfully connected socket when :failure then Raise an exception when :timeout then Raise a timeout exception end end end WD GBJMVSF TVDDFTT TUBSU WX UJNFPVU WX WD WD WXJTTUBUFGPS3FTPMVUJPO%FMBZ XIJDIXBJUTVQUPNTGPSPOMZ*1WOBNFSFTPMVUJPO

case state when :v4w ipv6_resolved, _, = IO.select( # ...
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case state when :v4w ipv6_resolved, _, = IO.select( # ...
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case state when :v4w ipv6_resolved, _, = IO.select( if ipv6_resolved
family_name, res = hostname_resolution_queue.get selectable_addrinfos.add(family_name, res) unless res.is_a? E state = :v46c else state = :v4c end next WX"GUFS*0TFMFDUVOCMPDLTBOEJG*1WJTSFTPMWFE XJUIJONT USBOTJUJPOUPWD *GOPU USBOTJUJPOUPWD (hostname_resolution_waiting, nil, nil, RESOLUTION_DELAY) Exception (POFYU %FUFSNJOFUIFOFYUTUBUF 5IFTUBUFWX 8BJUGPSNTGPS*1WOBNFSFTPMVUJPO

5IFTUBUFWDWDWD def self.tcp(host, port, ...) # ... state = :start
loop do case state when :start then Start hostname resolution when :v4w then Wait for 50ms for IPv6 name resolution when :v6c, :v4c, :v46c then Start a new connection attempt when :v46w then Wait for the connection state to be confirmed and name resolution to complete when :success then Return the successfully connected socket when :failure then Raise an exception when :timeout then Raise a timeout exception end end end WD GBJMVSF TVDDFTT TUBSU WX UJNFPVU WX WD WD WD WD BOEWDBSFUIFTUBUF UPTUBSUBOFXDPOOFDUJPOBUUFNQU

case state when :v6c, :v4c, v46c # ... addrinfo =
selectable_addrinfos.get # ... socket = Socket.new( # ... result = socket.connect_nonblock(addrinfo, exception: false) # ... (addrinfo.pfamily, addrinfo.socktype, addrinfo.protocol) WDWDWD3FUSJFWFPOFPGBWBJMBCMFBEESFTTFT GPSUIFDPOOFDUJPOBOETUBSUBOPOCMPDLJOHDPOOFDUJPO 4UBSUBOFXDPOOFDUJPOBUUFNQU 3FUSJFWFBOBWBJMBCMFBEESFTT 4UBSUBDPOOFDUJPOBUUFNQU 5IFTUBUFWDWDWD

case state when :v6c, :v4c, v46c # ... addrinfo =
selectable_addrinfos.get # ... socket = Socket.new( # ... result = socket.connect_nonblock(addrinfo, exception: false) # ... connecting_sockets.add(socket, addrinfo) state = :v46w # ... next (addrinfo.pfamily, addrinfo.socktype, addrinfo.protocol) WDWDWD5IFOTUPSFUIFTPDLFUVTFEGPS UIFDPOOFDUJPOBUUFNQU BOEUSBOTJUJPOUPWX (POFYU 4FUUIFOFYUTUBUF 4UPSFUIFTPDLFU 4UBSUBOFXDPOOFDUJPOBUUFNQU 5IFTUBUFWDWDWD

do case state when :start then Start hostname resolution when :v4w then Wait for 50ms for IPv6 name resolution when :v6c, :v4c, :v46c then Start a new connection attempt when :v46w then Wait for the connection state to be confirmed and name resolution to complete when :success then Return the successfully connected socket when :failure then Raise an exception when :timeout then Raise a timeout exception end end end WD GBJMVSF TVDDFTT TUBSU WX UJNFPVU WX WD WD *OWX UIFQSPDFTTXBJUTGPSUIFDPOOFDUJPOUPCF FTUBCMJTIFE0S JGUIFPUIFSBEESFTTGBNJMZJTTUJMMSFTPMWJOH BUUIJTQPJOU JUBMTPXBJUTGPSUIBUSFTPMVUJPOUPDPNQMFUF 5IFTUBUFWX

case state when :v46w # ... hostname_resolved, connectable_sockets, = IO.select(
# ... (hostname_resolution_waiting, connecting_sockets.all, nil, remaining) WX5IFQSPDFTTJOHJTCMPDLFEXJUI*0TFMFDUBHBJO 5IJT*0TFMFDUNPOJUPSTCPUIUIFSFBEFOEPGUIFQJQF BOEBMMUIFTPDLFUTDVSSFOUMZBUUFNQUJOHUPDPOOFDU 8BJUGPSUIFDPOOFDUJPOTUBUFUPCFDPO fi SNFEBOEOBNFSFTPMVUJPOUPDPNQMFUF 5IFTUBUFWX 5IFTPDLFUTBUUFNQUJOHUPDPOOFDU 5IFSFBEFOEPGUIFQJQF #MPDLQSPDFTTJOH

# ... (hostname_resolution_waiting, connecting_sockets.all, nil, remaining) 8BJUGPSUIFDPOOFDUJPOTUBUFUPCFDPO fi SNFEBOEOBNFSFTPMVUJPOUPDPNQMFUF #MPDLQSPDFTTJOH WX5IFUJNFPVUBSHVNFOUJTTFUUPNT 5IJTSFQSFTFOUT$POOFDUJPO"UUFNQU%FMBZ UIFXBJUJOHUJNFCFUXFFOTUBSUJOHUIFQSFWJPVT DPOOFDUJPOBUUFNQUBOETUBSUJOHUIFOFYUPOF NTGPS$POOFDUJPO"UUFNQU%FMBZ 5IFTPDLFUTBUUFNQUJOHUPDPOOFDU 5IFSFBEFOEPGUIFQJQF 5IFTUBUFWX

5IFTUBUFWX case state when :v46w # ... hostname_resolved, connectable_sockets, =
IO.select( # ... (hostname_resolution_waiting, connecting_sockets.all, nil, remaining) 8BJUGPSUIFDPOOFDUJPOTUBUFUPCFDPO fi SNFEBOEOBNFSFTPMVUJPOUPDPNQMFUF #MPDLQSPDFTTJOH NTGPS$POOFDUJPO"UUFNQU%FMBZ 5IFTPDLFUTBUUFNQUJOHUPDPOOFDU 5IFSFBEFOEPGUIFQJQF WX*0TFMFDUVOCMPDLTXIFOFJUIFSBOBNFSFTPMVUJPO DPNQMFUJPOOPUJ fi DBUJPOBSSJWFTPOUIFSFBEFOEPGUIFQJQF BOZPGUIFTPDLFUTDVSSFOUMZBUUFNQUJOHUPDPOOFDUCFDPNF XSJUBCMF PSUIFNTUJNFPVUFMBQTFT

# ... if connectable_sockets&.any? # ... elsif hostname_resolved&.any? # ... else # ... end # ... next (hostname_resolution_waiting, connecting_sockets.all, nil, remaining) WX0ODF*0TFMFDUVOCMPDLT UIFOFYUTUBUFJT EFUFSNJOFECBTFEPOUIFSFBTPOJUXBTVOCMPDLFE (POFYU %FUFSNJOFUIFOFYUTUBUF 5IFJNQMFNFOUBUJPOPG4PDLFUUDQ WX 8BJUGPSUIFDPOOFDUJPOTUBUFUPCFDPO fi SNFEBOEOBNFSFTPMVUJPOUPDPNQMFUF *GUIF$POOFDUJPO"UUFNQU%FMBZUJNFTPVU

5IFJNQMFNFOUBUJPOPG4PDLFUUDQ def self.tcp(host, port, ...) # ... state = :start
loop do case state when :start then Start hostname resolution when :v4w then Wait for 50ms for IPv6 name resolution when :v6c, :v4c, :v46c then Start a new connection attempt when :v46w then Wait for the connection state to be confirmed and name resolution to complete when :success then Return the successfully connected socket when :failure then Raise an exception when :timeout then Raise a timeout exception end end end WD GBJMVSF TVDDFTT TUBSU WX UJNFPVU WX WD WD &WFOUVBMMZ POFPGUIFUFSNJOBMTUBUFT TVDDFTT GBJMVSF PSUJNFPVU JTSFBDIFE5IFO4PDLFUUDQ fi OJTIFTCZ FJUIFSSFUVSOJOHUIFDPOOFDUFETPDLFUPSSBJTJOH BOFYDFQUJPO EFQFOEJOHPOUIFTJUVBUJPO

do case state when :start then Start hostname resolution when :v4w then Wait for 50ms for IPv6 name resolution when :v6c, :v4c, :v46c then Start a new connection attempt when :v46w then Wait for the connection state to be confirmed and name resolution to complete when :success then Return the successfully connected socket when :failure then Raise an exception when :timeout then Raise a timeout exception end end end WD GBJMVSF TVDDFTT TUBSU WX UJNFPVU WX WD WD 5IFJNQMFNFOUBUJPOPG4PDLFUUDQXJUI)&W JTOPXDPNQMFUF 5IFJNQMFNFOUBUJPOPG4PDLFUUDQ

5IJTDIBOHFXBTNFSHFEJOUP3VCZNBTUFSPO'FC 5IJTJTUIFTUPSZ*JOUSPEVDFEBU3VCZ,BJHJMBTUZFBS .FSHFE IUUQTHJUIVCDPNSVCZSVCZQVMM 5IJTXSBQTVQPVSSFWJFXPG"O"EWFOUVSFPG)BQQZ&ZFCBMMT

.BLJOH5$14PDLFUOFX)BQQZ /PX MFUTJOUSPEVDF)BQQZ&ZFCBMMT7FSTJPO JOUP5$14PDLFUOFX JNQMFNFOUFEJO$ VTJOHUIF4PDLFUUDQJNQMFNFOUBUJPOBTBSFGFSFODF

)PXFWFS

"DPODFSOSBJTFECZ!BLS .BZ

"DPODFSOSBJTFECZ!BLS 5IFJNQMFNFOUBUJPOMPPLT FYDFTTJWFMZMJLFBTUBUFUSBOTJUJPO !BLS

"OFYBNQMFTPGUIFFYDFTTJWFMZBTUBUFUSBOTJUJPOMJLFJNQM case state when :start # ... hostname_resolved, _, =
IO.select( # ... family_name, res = hostname_resolution_queue.get # ... state = case family_name when :ipv6 then :v6c when :ipv4 then :v4w end selectable_addrinfos.add(family_name, res) # ... next (hostname_resolution_waiting, nil, nil, remaining) -FUTSFWJFXTUBSUBHBJO GPDVTJOHPOXIBUIBQQFOT BGUFS*0TFMFDUVOCMPDLTUIBUJT BGUFSFJUIFSUIF*1W PS*1WSFTPMVUJPODPNQMFUFT 4UBSUIPTUOBNFSFTPMVUJPO

case state when :start # ... hostname_resolved, _, = IO.select(
# ... family_name, res = hostname_resolution_queue.get # ... state = case family_name when :ipv6 then :v6c when :ipv4 then :v4w end selectable_addrinfos.add(family_name, res) # ... next (hostname_resolution_waiting, nil, nil, remaining) 5IFOFYUTUBUFJTEFUFSNJOFECBTFEPOXIFUIFS UIFBEESFTTSFUSJFWFGSPNUIFRVFVFJT*1WPS*1W 4UBSUIPTUOBNFSFTPMVUJPO (FUUIFSFTVMU "OFYBNQMFTPGUIFFYDFTTJWFMZBTUBUFUSBOTJUJPOMJLFJNQM %FUFSNJOFUIFOFYUTUBUF

# ... family_name, res = hostname_resolution_queue.get # ... state = case family_name when :ipv6 then :v6c when :ipv4 then :v4w end selectable_addrinfos.add(family_name, res) # ... next (hostname_resolution_waiting, nil, nil, remaining) 8IBUIBQQFOTJGCPUI*1WBOE*1WIBWF BMSFBEZDPNQMFUFEOBNFSFTPMVUJPOBUUIJTQPJOU 4UBSUIPTUOBNFSFTPMVUJPO "OFYBNQMFTPGUIFFYDFTTJWFMZBTUBUFUSBOTJUJPOMJLFJNQM

# ... family_name, res = hostname_resolution_queue.get # ... state = case family_name when :ipv6 then :v6c when :ipv4 then :v4w end selectable_addrinfos.add(family_name, res) # ... next 4UBSUIPTUOBNFSFTPMVUJPO *1W *OUIJTDBTF UIFRVFVFIBT CPUI*1WBOE*1WBEESFTTFT (hostname_resolution_waiting, nil, nil, remaining) "OFYBNQMFTPGUIFFYDFTTJWFMZBTUBUFUSBOTJUJPOMJLFJNQM *1W 5IFRVFVF

# ... family_name, res = hostname_resolution_queue.get # ... state = case family_name when :ipv6 then :v6c when :ipv4 then :v4w end selectable_addrinfos.add(family_name, res) # ... next 4UBSUIPTUOBNFSFTPMVUJPO 'PSFYBNQMF JGUIF*1WBEESFTTFTBSFSFUSJFWFEGSPNUIFRVFVF (hostname_resolution_waiting, nil, nil, remaining) "OFYBNQMFTPGUIFFYDFTTJWFMZBTUBUFUSBOTJUJPOMJLFJNQM *1W *1W 5IFRVFVF 3FUSJFWF*1WBEESFTTPOMZ

# ... family_name, res = hostname_resolution_queue.get # ... state = case family_name when :ipv6 then :v6c when :ipv4 then :v4w end selectable_addrinfos.add(family_name, res) # ... next 4UBSUIPTUOBNFSFTPMVUJPO %FUFSNJOFUIBU*1WXBTSFTPMWFE fi STU BOEUIFQSPDFTTUSBOTJUJPOTUPWX UPXBJUGPS*1WOBNFSFTPMVUJPO (hostname_resolution_waiting, nil, nil, remaining) %FUFSNJOFUIFOFYUTUBUFBTWX "OFYBNQMFTPGUIFFYDFTTJWFMZBTUBUFUSBOTJUJPOMJLFJNQM 3FUSJFWF*1WBEESFTTPOMZ

case state when :v4w ipv6_resolved, _, = IO.select( if ipv6_resolved
family_name, res = hostname_resolution_queue.get # ... state = :v46c else state = :v4c end next *OWX *0TFMFDUJTDBMMFEUPXBJUGPS*1WOBNF SFTPMVUJPO FWFOUIPVHI*1WIBTBMSFBEZCFFOSFTPMWFE "OVOOFDFTTBSZ*0TFMFDUDBMMJTPDDVSSJOH &WFOUIPVHI*1WIBTBMSFBEZCFFOJOUIFRVFVF (hostname_resolution_waiting, nil, nil, RESOLUTION_DELAY) "OFYBNQMFTPGUIFFYDFTTJWFMZBTUBUFUSBOTJUJPOMJLFJNQM 8BJUGPSNTGPS*1WOBNFSFTPMVUJPO *1W 3FUSJFWF*1WBEESFTT 5IFRVFVF

8IBU`TUIFQSPCMFN 1SFNJTF ɾ5IFDVSSFOUTUBUFJTNBOBHFEEVSJOHFYFDVUJPO ɾ&BDITUBUFIBTQSFEF fi OFEBDUJPOTBOE ɹDPOEJUJPOTGPSUSBOTJUJPOJOHUPUIFOFYUTUBUF

8IBU`TUIFQSPCMFN &WFOJGDPOEJUJPO"GPSUSBOTJUJPOJOHUPTUBUF"BOE DPOEJUJPO#GPSUSBOTJUJPOJOHUPTUBUF#BSFVOJOUFOUJPOBMMZTBUJT fi FE BUUIFTBNFUJNF # " TUBSU TBUJT
fi FE TBUJT fi FE

8IBU`TUIFQSPCMFN &WFOJGDPOEJUJPO"GPSUSBOTJUJPOJOHUPTUBUF"BOE DPOEJUJPO#GPSUSBOTJUJPOJOHUPTUBUF#BSFVOJOUFOUJPOBMMZTBUJT fi FE BUUIFTBNFUJNF POMZPOFPGUIFUXPFJUIFSTUBUF"PSTUBUF#XJMMCFTFMFDUFE BTUIFOFYUTUBUF "
TUBSU TBUJT fi FEBOETFMFDUFE TBUJT fi FEBOEOPUTFMFDUFE #

8IBU`TUIFQSPCMFN "TBSFTVMU UIFSFJTBSJTLUIBUQSPDFTTJOHXIJDITIPVMEOPUIBWFCFFO QFSGPSNFEXJMMCFFYFDVUFEJOUIFTFMFDUFETUBUF BOEQSPDFTTJOHXIJDITIPVMEIBWFCFFOQFSGPSNFEXJMMCFTLJQQFEJO UIFVOTFMFDUFETUBUF " TUBSU
TBUJT fi FEBOETFMFDUFE &YFDVUFXIBUTIPVMEOPUEP $BOUFYFDVUFXIBUTIPVMEEP TBUJT fi FEBOEOPUTFMFDUFE #

5IJTJTTVFDBOCFBWPJEFECZJOUSPEVDJOHBOFXTUBUF$UIBU SFQSFTFOUTUIFDBTFXIFSFCPUIDPOEJUJPO"BOE#BSFTBUJT fi FE 5IBUJT JGXFBSFXJMMJOHUPBDDFQUUIFJODSFBTFEDPNQMFYJUZJOCPUI UIFTQFDJ fi DBUJPOBOEUIFJNQMFNFOUBUJPOUIBUDPNFTXJUI NBOBHJOHNPSFTUBUFT
8IBU`TUIFQSPCMFN " TUBSU $ # TBUJT fi FEBOETFMFDUFE

5IJTJTTVFDBOCFBWPJEFECZJOUSPEVDJOHBOFXTUBUF$UIBU SFQSFTFOUTUIFDBTFXIFSFCPUIDPOEJUJPO"BOE#BSFTBUJT fi FE 5IBUJT JGXFBSFXJMMJOHUPBDDFQUUIFJODSFBTFEDPNQMFYJUZJOCPUI UIFTQFDJ fi DBUJPOBOEUIFJNQMFNFOUBUJPOUIBUDPNFTXJUI NBOBHJOHNPSFTUBUFT
8IBU`TUIFQSPCMFN " TUBSU $ # "the excessively a state-transition-like impl"

#FGPSFXPSLJOHPO5$14PDLFUOFX -FUTSFJNQMFNFOU4PDLFUUDQ

$PODFQUPGUIFUIFJNQSPWFEWFSTJPOPG4PDLFUUDQ ɾ&MJNJOBUFDVSSFOUTUBUFNBOBHFNFOU ɾ&YFDVUFBMMQSPDFTTJOHUIBUDBOCFQFSGPSNFE ɹBUUIBUNPNFOU JOTUFBEPGFYFDVUJOHPOMZUIFQSPDFTTJOH ɹQSFEF fi OFEGPSFBDITUBUF 5IFJNQSPWFEWFSTJPOPG4PDLFUUDQ

5IFPWFSWJFXPGUIFJNQSPWFEWFSTJPOPG4PDLFUUDQ def self.tcp(host, port, ...) <Initialization of the timeout variables>
<Start hostname resolution in child threads> loop do if <The condition to start a connection> then <Start a connection> timeout = <Calculate the timeout value> IO.select(<name resolution>, <connections>, nil, <timeout>) if <Sockets are confirmed connected> then <Verify the connection> if <A name resolution is complete> then <Save the resolved IP addresses> if <The next loop cannot proceed> then <Raise an exception> end end -FUTSFWJFXUIFDIBOHFT

def self.tcp(host, port, ...) <Initialization of the timeout variables> <Start
hostname resolution in child threads> loop do # Processes in this loop end end 5IFPWFSWJFXPGUIFJNQSPWFEWFSTJPOPG4PDLFUUDQ 'JSTU UIFJOJUJBMJ[BUJPOPGWBSJBCMFTGPSNBOBHJOH UJNFPVUT TVDIBT3FTPMVUJPO%FMBZBOE $POOFDUJPO"UUFNQU%FMBZ BSFOFXMZBEEFE "EEFE

*OJUJBMJ[BUJPOPGUIFUJNFPVUWBSJBCMFT def self.tcp(host, port, ...) # Other initialization processes resolution_delay_expires_at
= nil connection_attempt_delay_expires_at = nil <Start hostname resolution in child threads> loop do # Processes in this loop end end SFTPMVUJPO@EFMBZ@FYQJSFT@BUJTBWBSJBCMFUIBUTUPSFT UIFEFBEMJOFGPSXBJUJOHPO*1WOBNFSFTPMVUJPO BTQBSUPGUIF3FTPMVUJPO%FMBZ *OJUJBMJ[BUJPOPGUIFUJNFPVUWBSJBCMFT

= nil connection_attempt_delay_expires_at = nil <Start hostname resolution in child threads> loop do # Processes in this loop end end DPOOFDUJPO@BUUFNQU@EFMBZ@FYQJSFT@BUJTBWBSJBCMF UIBUTUPSFTUIFUJNFBUXIJDIUIFOFYUDPOOFDUJPO BUUFNQUDBOCFHJOBGUFSUIFQSFWJPVTPOFIBTTUBSUFE BTQBSUPG$POOFDUJPO"UUFNQU%FMBZ *OJUJBMJ[BUJPOPGUIFUJNFPVUWBSJBCMFT

= nil connection_attempt_delay_expires_at = nil <Start hostname resolution in child threads> loop do # Processes in this loop end end 5IFTFWBSJBCMFTBSFJOJUJBMMZTFUUPOJM 5IFWBMVFTXJMMCFTFUMBUFS XIFOXBJUJOHCFDPNFT OFDFTTBSZ *OJUJBMJ[FXJUIOJM

def self.tcp(host, port, ...) # Other initialization processes resolution_delay_expires_at =
nil connection_attempt_delay_expires_at = nil <Start hostname resolution in child threads> loop do # Processes in this loop end end 4UBSUIPTUOBNFSFTPMVUJPOJODIJMEUISFBET /FYU UIFNFUIPEGPSOBNFSFTPMVUJPOJTDBMMFE 5IFJNQMFNFOUBUJPOBOEJOWPDBUJPOPGUIJTNFUIPEBSF NPTUMZUIFTBNFBTQSFWJPVTJNQMFNFOUBUJPO &YFDVUFUIFOBNFSFTPMVUJPONFUIPE

def self.tcp(host, port, ...) # Other initialization processes resolution_delay_expires_at =
nil connection_attempt_delay_expires_at = nil <Start hostname resolution in child threads> loop do # Processes in this loop end end 4UBSUBMPPQ 4UBSUBMPPQ

loop do if <The condition to start a connection> then
<Start a connection> timeout = <Calculate the timeout value> IO.select(<name resolution>, <connections>, nil, <timeout>) if <Sockets are confirmed connected> then <Verify the connection> if <A name resolution is complete> then <Save the resolved IP addresses> if <The next loop cannot proceed> then <Raise an exception> end 5IFPWFSWJFXPGUIFQSPDFTTFTJOUIJTMPPQ 5IFDBTFTUBUFNFOUJOUIFQSFWJPVTJNQMFNFOUBUJPO XIJDIEJSFDUFEQSPDFTTJOHCBTFEPOUIFDVSSFOUTUBUF IBTCFFOSFQMBDFEXJUIJGTUBUFNFOUTJOTJEFUIFMPPQ 3FQMBDFDBTFXJUIJGT

<Start a connection> timeout = <Calculate the timeout value> IO.select(<name resolution>, <connections>, nil, <timeout>) if <Sockets are confirmed connected> then <Verify the connection> if <A name resolution is complete> then <Save the resolved IP addresses> if <The next loop cannot proceed> then <Raise an exception> end 5IFPWFSWJFXPGUIFQSPDFTTFTJOUIJTMPPQ 0OFBDIMPPQJUFSBUJPO DPOEJUJPOTBSFDIFDLFEBOE UIFOFDFTTBSZQSPDFTTJOHJTQFSGPSNFE 3FQMBDFDBTFXJUIJGT

<Start a connection> timeout = <Calculate the timeout value> IO.select(<name resolution>, <connections>, nil, <timeout>) if <Sockets are confirmed connected> then <Verify the connection> if <A name resolution is complete> then <Save the resolved IP addresses> if <The next loop cannot proceed> then <Raise an exception> end 5IF fi STUDPOEJUJPO 5IF fi STUDPOEJUJPODIFDLT XIFUIFSBOFXDPOOFDUJPOBUUFNQUDBOCFTUBSUFE 5IFSFRVJSFNFOUTGPSTUBSUJOHBOBUUFNQUBSF

if resolution_store.any_addrinfos? && !resolution_delay_expires_at && !connection_attempt_delay_expires_at # ... end 5IFDPOEJUJPOUPTUBSUBDPOOFDUJPO
5IFDPOEJUJPOUPTUBSUBDPOOFDUJPO

if resolution_store.any_addrinfos? && !resolution_delay_expires_at && !connection_attempt_delay_expires_at # ... end 5IFDPOEJUJPOUPTUBSUBDPOOFDUJPO
"UMFBTUPOFBEESFTTGBNJMZIBTDPNQMFUFEOBNF SFTPMVUJPO BOEUIFSFBSFBWBJMBCMFDBOEJEBUF BEESFTTFTUPDPOOFDUUP 5IFDPOEJUJPOUPTUBSUBDPOOFDUJPO

if resolution_store.any_addrinfos? && !resolution_delay_expires_at && !connection_attempt_delay_expires_at # ... end SFTPMVUJPO@EFMBZ@FYQJSFT@BUJTOJM
NFBOJOHJUJTOPUEVSJOH3FTPMVUJPO%FMBZ 5IFDPOEJUJPOUPTUBSUBDPOOFDUJPO 5IFDPOEJUJPOUPTUBSUBDPOOFDUJPO

if resolution_store.any_addrinfos? && !resolution_delay_expires_at && !connection_attempt_delay_expires_at # ... end DPOOFDUJPO@BUUFNQU@EFMBZ@FYQJSFT@BUJTOJM
NFBOJOHJUJTOPUEVSJOH$POOFDUJPO"UUFNQU%FMBZ 5IFDPOEJUJPOUPTUBSUBDPOOFDUJPO 5IFDPOEJUJPOUPTUBSUBDPOOFDUJPO

if resolution_store.any_addrinfos? && !resolution_delay_expires_at && !connection_attempt_delay_expires_at while (addrinfo = resolution_store.get_addrinfo)
# ... socket = Socket.new(addrinfo.pfamily, addrinfo.socktype, addrinfo.protocol) socket.bind(local_addrinfo) if local_addrinfo result = socket.connect_nonblock(addrinfo, exception: false) if result == :wait_writable # ... # ... connecting_sockets[socket] = addrinfo # ... end end end *GBMMUIFTFDPOEJUJPOTBSFNFU POFEFTUJOBUJPOBEESFTTJT3FUSJFWF BOETUBSUBDPOOFDUJPOBUUFNQUJOOPOCMPDLJOHNPEF 3FUSJFWFBOBEESFTT 4UBSUBOPOCMPDLJOHDPOOFDU 5IFDPOEJUJPOUPTUBSUBDPOOFDUJPO

# ... socket = Socket.new(addrinfo.pfamily, addrinfo.socktype, addrinfo.protocol) socket.bind(local_addrinfo) if local_addrinfo result = socket.connect_nonblock(addrinfo, exception: false) if result == :wait_writable connection_attempt_delay_expires_at = now + CONNECTION_ATTEMPT_DELAY # ... end end end DPOOFDUJPO@BUUFNQU@EFMBZ@FYQJSFT@BUJTTFUUP UIFDVSSFOUUJNF NT5IJTSFQSFTFOUTUIFUJNFBU XIJDIUIFOFYUDPOOFDUJPOBUUFNQUDBOCFHJO 5IFDVSSFOUUJNF NT 5IFDPOEJUJPOUPTUBSUBDPOOFDUJPO

# ... socket = Socket.new(addrinfo.pfamily, addrinfo.socktype, addrinfo.protocol) socket.bind(local_addrinfo) if local_addrinfo result = socket.connect_nonblock(addrinfo, exception: false) if result == :wait_writable connection_attempt_delay_expires_at = now + CONNECTION_ATTEMPT_DELAY # ... connecting_sockets[socket] = addrinfo # ... end end end 5IFOTUPSFUIFTPDLFUVTFEGPSUIFDPOOFDUJPOBUUFNQU FYJUUIJTJGTUBUFNFOU 4UPSFUIFTPDLFU 5IFDPOEJUJPOUPTUBSUBDPOOFDUJPO

<Start a connection> timeout = <Calculate the timeout value> IO.select(<name resolution>, <connections>, nil, <timeout>) if <Sockets are confirmed connected> then <Verify the connection> if <A name resolution is complete> then <Save the resolved IP addresses> if <The next loop cannot proceed> then <Raise an exception> end "GUFSUIF fi STUDPOEJUJPO 5IFOFYUTUFQJTUPDBMM*0TFMFDU

<Start a connection> timeout = <Calculate the timeout value> IO.select(<name resolution>, <connections>, nil, <timeout>) if <Sockets are confirmed connected> then <Verify the connection> if <A name resolution is complete> then <Save the resolved IP addresses> if <The next loop cannot proceed> then <Raise an exception> end $BMM*0TFMFDUUPXBJU *OUIFQSFWJPVTJNQMFNFOUBUJPO *0TFMFDUXBTDBMMFEJO UISFFEJ ff FSFOUTUBUFTTUBSU WX BOEWXUPXBJU GPSFJUIFSBDPOOFDUJPOPSOBNFSFTPMVUJPOUPDPNQMFUF

<Start a connection> timeout = <Calculate the timeout value> IO.select(<name resolution>, <connections>, nil, <timeout>) if <Sockets are confirmed connected> then <Verify the connection> if <A name resolution is complete> then <Save the resolved IP addresses> if <The next loop cannot proceed> then <Raise an exception> end $BMM*0TFMFDUUPXBJU *OUIFOFXJNQMFNFOUBUJPO JUJTDPOTPMJEBUFEJOUP BTJOHMFMPDBUJPO XIFSFJUXBJUTGPSFJUIFSBDPOOFDUJPO PSOBNFSFTPMVUJPOUPDPNQMFUF

<Start a connection> timeout = <Calculate the timeout value> IO.select(<name resolution>, <connections>, nil, <timeout>) if <Sockets are confirmed connected> then <Verify the connection> if <A name resolution is complete> then <Save the resolved IP addresses> if <The next loop cannot proceed> then <Raise an exception> end 5PTVQQPSUUIJT MPHJDIBTCFFOBEEFEUPDBMDVMBUF UIFBQQSPQSJBUFUJNFPVUWBMVFUPQBTTUP*0TFMFDU CBTFEPOUIFDVSSFOUTJUVBUJPO $BMM*0TFMFDUUPXBJU

$BMDVMBUFUIFUJNFPVUWBMVF ends_at = if resolution_store.any_addrinfos? resolution_delay_expires_at || connection_attempt_delay_expires_at else [user_specified_resolv_timeout_at,
user_specified_connect_timeout_at].compact.max end )FSFJUJT

ends_at = if resolution_store.any_addrinfos? resolution_delay_expires_at || connection_attempt_delay_expires_at else [user_specified_resolv_timeout_at, user_specified_connect_timeout_at].compact.max
end *GUIFSFBSFDBOEJEBUFBEESFTTFTBWBJMBCMFBUUIJTQPJOU $BMDVMBUFUIFUJNFPVUWBMVF

end BOE3FTPMVUJPO%FMBZJTJOQSPHSFTT SFTPMVUJPO@EFMBZ@FYQJSFT@BUXJMMIBWFBWBMVF BOEUIBUWBMVFJTSFUVSOFE $BMDVMBUFUIFUJNFPVUWBMVF

user_specified_connect_timeout_at].compact.max end *G3FTPMVUJPO%FMBZJTOPUJOQSPHSFTT UIFWBMVFTFU DPOOFDUJPO@BUUFNQU@EFMBZ@FYQJSFT@BUJTSFUVSOFE JOTUFBE

user_specified_connect_timeout_at].compact.max end *GUIFSFBSFOPBWBJMBCMFDBOEJEBUFBEESFTTFT 5IJTNFBOTFJUIFSOPOBNFSFTPMVUJPOIBTCFFO DPNQMFUFEZFU PSDPOOFDUJPOBUUFNQUTIBWFBMSFBEZ CFFOTUBSUFEGPSBMMSFTPMWFEBEESFTTFTBUUIJTQPJOU

user_specified_connect_timeout_at].compact.max end *OUIJTDBTF JGTPNFVTFSTQFDJ fi FEUJNFPVUWBMVFT BSFQSPWJEFEBTBOBSHVNFOUUP4PDLFUUDQ UIFMBSHFSWBMVFJTVTFE

end *GOPVTFSTQFDJ fi FEUJNFPVUJTHJWFO BXPSLBSPVOEJTBQQMJFEUPSFUVSOBWBMVFUIBU F ff FDUJWFMZXBJUTJOEF fi OJUFMZ EFUBJMTPNJUUFEIFSF $BMDVMBUFUIFUJNFPVUWBMVF

end hostname_resolved, writable_sockets, except_sockets = IO.select( hostname_resolution_notifier, connecting_sockets.keys, is_windows_environment ? connecting_sockets.keys : nil, second_to_timeout(current_clock_time, ends_at), ) $BMM*0TFMFDUXJUIUIFUJNFPVUWBMVFDBMDVMBUFEGSPN UIFSFUVSOWBMVFPGUIJTMPHJD $BMM*0TFMFDUXJUIUIFUJNFPVUWBMVF "DUVBMUJNFPVUWBMVF

end hostname_resolved, writable_sockets, except_sockets = IO.select( hostname_resolution_notifier, connecting_sockets.keys, is_windows_environment ? connecting_sockets.keys : nil, second_to_timeout(current_clock_time, ends_at), ) "TWXJOUIFQSFWJPVTJNQMFNFOUBUJPO UIFBSHVNFOUTPUIFSUIBOUIFUJNFPVUBSF ɾ5IFQJQFXBJUJOHGPSOBNFSFTPMVUJPOOPUJ fi DBUJPOT ɾ5IFTPDLFUTDVSSFOUMZBUUFNQUJOHUPDPOOFDU $BMM*0TFMFDUXJUIUIFUJNFPVUWBMVF 5IFQJQFXBJUJOHGPSOBNFSFTPMVUJPOOPUJ fi DBUJPO 5IFTPDLFUTBUUFNQUJOHUPDPOOFDU

"GUFS*0TFMFDU hostname_resolved, writable_sockets, except_sockets = IO.select( hostname_resolution_notifier, connecting_sockets.keys, is_windows_environment ?
connecting_sockets.keys : nil, second_to_timeout(current_clock_time, ends_at), ) now = current_clock_time if expired?(now, resolution_delay_expires_at) resolution_delay_expires_at = nil end if expired?(now, connection_attempt_delay_expires_at) connection_attempt_delay_expires_at = nil end 0ODF*0TFMFDUVOCMPDLT UIF fi STUTUFQJTUP DIFDLUIFWBMVFTPGUIFUJNFPVUWBSJBCMFT SFTPMVUJPO@EFMBZ@FYQJSFT@BUJTQBTU DPOOFDUJPO@BUUFNQU@EFMBZ@FYQJSFT@BUJTQBTU

hostname_resolved, writable_sockets, except_sockets = IO.select( hostname_resolution_notifier, connecting_sockets.keys, is_windows_environment ? connecting_sockets.keys
: nil, second_to_timeout(current_clock_time, ends_at), ) now = current_clock_time if expired?(now, resolution_delay_expires_at) resolution_delay_expires_at = nil end if expired?(now, connection_attempt_delay_expires_at) connection_attempt_delay_expires_at = nil end 3FTFU "GUFS*0TFMFDU *GBOZTUPSFEUJNFIBTBMSFBEZQBTTFEBUUIJTQPJOU JUJTSFTFUUPOJM 3FTFU

<Start a connection> timeout = <Calculate the timeout value> IO.select(<name resolution>, <connections>, nil, <timeout>) if <Sockets are confirmed connected> then <Verify the connection> if <A name resolution is complete> then <Save the resolved IP addresses> if <The next loop cannot proceed> then <Raise an exception> end $IFDLUIFSFTVMUPG*0TFMFDU /FYU CBTFEPOUIFSFTVMUPG*0TFMFDU DIFDLXIFUIFS ɾ0OFPSNPSFXSJUBCMFTPDLFUTBSFBWBJMBCMF ɾ"OBNFSFTPMVUJPOOPUJ fi DBUJPOIBTBSSJWFEPOUIFQJQF $IFDLUIFSFTVMU

0OFPSNPSFXSJUBCMFTPDLFUTBSFBWBJMBCMF if writable_sockets&.any? while (writable_socket = writable_sockets.pop) is_connected = is_windows_environment
|| ( sockopt = writable_socket.getsockopt(Socket::SOL_SOCKET, Socket::SO_ERROR) sockopt.int.zero? ) if is_connected connecting_sockets.delete writable_socket return writable_socket else # ... end end end *GUIFSFBSFXSJUBCMFTPDLFUT DIFDLUIFJSDPOOFDUJPO TUBUVT*GUIFDPOOFDUJPOJTTVDDFTTGVM SFUVSOUIFTPDLFUBOEFYJU4PDLFUUDQ *TUIFDPOOFDUJPOTVDDFTTGVM 3FUVSOUIFTVDDFTTGVMMZDPOOFDUFETPDLFU $IFDLUIFDPOOFDUJPOTUBUVT

if hostname_resolved&.any? while (family_and_result = hostname_resolution_result.get) family_name, result = family_and_result
if result.is_a? Exception # ... else resolution_store.add_resolved(family_name, result) end end # ... end *GBOBNFSFTPMVUJPOOPUJ fi DBUJPOIBTBSSJWFEPO UIFQJQF SFUSJFWFUIFSFTPMWFEBEESFTTFT BOETUPSFUIFN "OBNFSFTPMVUJPOOPUJ fi DBUJPOIBTBSSJWFE 0CUBJOSFTPMWFEBEESFTTFT 4UPSFUIFPCUBJOFEBEESFTTFT

if hostname_resolved&.any? while (family_and_result = hostname_resolution_result.get) # ... end if
resolution_store.resolved?(:ipv4) if resolution_store.resolved?(:ipv6) hostname_resolution_notifier = nil resolution_delay_expires_at = nil user_specified_resolv_timeout_at = nil elsif resolution_store.resolved_successfully?(:ipv4) resolution_delay_expires_at = now + RESOLUTION_DELAY end end end *GPOMZ*1WJTSFTPMWFEBOE*1WJTTUJMMVOSFTPMWFE TFU SFTPMVUJPO@EFMBZ@FYQJSFT@BUUPUIFDVSSFOUUJNF NTUPXBJUGPS*1WSFTPMVUJPOJOUIFOFYUMPPQ "OBNFSFTPMVUJPOOPUJ fi DBUJPOIBTBSSJWFE 4FUSFTPMVUJPO@EFMBZ@FYQJSFT@BU *1WIBTCFFOSFTPMWFE *1WIBTOPUCFFOSFTPMWFE

<Start a connection> timeout = <Calculate the timeout value> IO.select(<name resolution>, <connections>, nil, <timeout>) if <Sockets are confirmed connected> then <Verify the connection> if <A name resolution is complete> then <Save the resolved IP addresses> if <The next loop cannot proceed> then <Raise an exception> end "UUIFFOEPGUIFMPPQ "UUIFFOEPGUIFMPPQ UIFSFJTBDIFDLUPEFUFSNJOF XIFUIFSUIFOFYUMPPQJUFSBUJPODBOQSPDFFE

loop do # ... if resolution_store.empty_addrinfos? if connecting_sockets.empty? && resolution_store.resolved_all_families?
raise last_error end if (expired?(now, user_specified_resolv_timeout_at) || ...) && (expired?(now, user_specified_connect_timeout_at) || ...) raise Errno::ETIMEDOUT, 'user specified timeout' end end end ɾ*GUIFSFBSFOPBWBJMBCMFBEESFTTDBOEJEBUFT ɾ"OEUIFSFBSFOPTPDLFUTDVSSFOUMZDPOOFDUJOH ɾ"OEBMMOBNFSFTPMVUJPOTIBWFDPNQMFUFE UIFOOPGVSUIFSQSPDFTTJOHDBOCFQFSGPSNFE TPBOFYDFQUJPOJTSBJTFE 8IFUIFSUIFOFYUMPPQJUFSBUJPODBOQSPDFFE 3BJTFBOFYDFQUJPO

raise last_error end if (expired?(now, user_specified_resolv_timeout_at) || ...) && (expired?(now, user_specified_connect_timeout_at) || ...) raise Errno::ETIMEDOUT, 'user specified timeout' end end end *GUIFVTFSTQFDJ fi FEUJNFPVUTIBWFCFFOFYDFFEFE SBJTFBUJNFPVUFYDFQUJPO 8IFUIFSUIFOFYUMPPQJUFSBUJPODBOQSPDFFE 3BJTFBUJNFPVUFYDFQUJPO

raise last_error end if (expired?(now, user_specified_resolv_timeout_at) || ...) && (expired?(now, user_specified_connect_timeout_at) || ...) raise Errno::ETIMEDOUT, 'user specified timeout' end end end 0UIFSXJTF TJODFUIFSFBSFTUJMMFYFDVUBCMFQSPDFTTFT SFNBJOJOH QSPDFFEUPUIFOFYUMPPQJUFSBUJPO 8IFUIFSUIFOFYUMPPQJUFSBUJPODBOQSPDFFE 5PCFDPOUJOVFE ⬇︎

hostname resolution in child threads> loop do if <The condition to start a connection> then <Start a connection> timeout = <Calculate the timeout value> IO.select(<name resolution>, <connections>, nil, <timeout>) if <Sockets are confirmed connected> then <Verify the connection> if <A name resolution is complete> then <Save the resolved IP addresses> if <The next loop cannot proceed> then <Raise an exception> end end 5IJTSFQFBUTVOUJM4PDLFUUDQSFUVSOTBTVDDFTTGVMMZ DPOOFDUFETPDLFU 8IFUIFSUIFOFYUMPPQJUFSBUJPODBOQSPDFFE

hostname resolution in child threads> loop do if <The condition to start a connection> then <Start a connection> timeout = <Calculate the timeout value> IO.select(<name resolution>, <connections>, nil, <timeout>) if <Sockets are confirmed connected> then <Verify the connection> if <A name resolution is complete> then <Save the resolved IP addresses> if <The next loop cannot proceed> then <Raise an exception> end end 5IFJNQSPWFEWFSTJPOPG4PDLFUUDQ 5IFJNQSPWFEWFSTJPOPG4PDLFUUDQJTOPXDPNQMFUF

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begin resolved_addrinfos = Addrinfo.getaddrinfo(...) hostname_resolution_queue.add_resolved(...) rescue => e # ... end

1SFSFRVJTJUF 6OUJM3VCZ UIFTFNFUIPETIBEBMJNJUBUJPO UIFZDPVMEO`UCFJOUFSSVQUFEPODFFYFDVUJPOIBETUBSUFE 5IJTXBTCFDBVTFUIFZJOUFSOBMMZSFMJFEPOUIF$MJCSBSZ GVODUJPOHFUBEESJOGP XIJDIJTBCMPDLJOHGVODUJPO UIBUJT PODFDBMMFE
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DBMM@HFUBEESJOGP ɹɹ ➡︎ STPDL@HFUBEESJOGP ɹɹ ➡︎ SC@HFUBEESJOGP *OUFSSVQUJCMFHFUBEESJOGP*NQMFNFOUBUJPO BTPG3VCZ Attention! *OBOFOWJSPONFOUXIFSFUIFQUISFBEMJCSBSZJTBWBJMBCMF

static int rb_getaddrinfo(...) { // ... pthread_t th; if (do_pthread_create(&th,
do_getaddrinfo, arg) != 0) { free_getaddrinfo_arg(arg); return EAI_AGAIN; } pthread_detach(th); // ... } *OUFSSVQUJCMFHFUBEESJOGP*NQMFNFOUBUJPO BTPG3VCZ IUUQTHJUIVCDPNSVCZSVCZCMPCSVCZ@@FYUTPDLFUSBEESJOGPD BOEEFUBDIJU 4QBXOBOFXDIJMEUISFBE *OBOFOWJSPONFOUXIFSFUIFQUISFBEMJCSBSZJTBWBJMBCMF *OTJEFSC@HFUBEESJOGP BOFXDIJMEUISFBEJTTQBXOFEBOEEFUBDIFE GSPNUIFNBJOUISFBE

do_getaddrinfo, arg) != 0) { free_getaddrinfo_arg(arg); return EAI_AGAIN; } pthread_detach(th); // ... } *OUFSSVQUJCMFHFUBEESJOGP*NQMFNFOUBUJPO BTPG3VCZ static void *do_getaddrinfo(void *ptr) { // ... int err, gai_errno; err = getaddrinfo(...); // ... } $BMMHFUBEESJOGP IUUQTHJUIVCDPNSVCZSVCZCMPCSVCZ@@FYUTPDLFUSBEESJOGPD *OBOFOWJSPONFOUXIFSFUIFQUISFBEMJCSBSZJTBWBJMBCMF *OUIFEFUBDIFEDIJMEUISFBE HFUBEESJOGP JTDBMMFE

do_getaddrinfo, arg) != 0) { free_getaddrinfo_arg(arg); return EAI_AGAIN; } pthread_detach(th); // ... } *OUFSSVQUJCMFHFUBEESJOGP*NQMFNFOUBUJPO BTPG3VCZ static void *do_getaddrinfo(void *ptr) { // ... arg->done = 1; rb_native_cond_signal(&arg->cond); // ... } 4JHOBMUPUIFNBJOUISFBE IUUQTHJUIVCDPNSVCZSVCZCMPCSVCZ@@FYUTPDLFUSBEESJOGPD *OBOFOWJSPONFOUXIFSFUIFQUISFBEMJCSBSZJTBWBJMBCMF 0ODFOBNFSFTPMVUJPOXJUIHFUBEESJOGP JTDPNQMFUF OPUJGZJUUPUIFNBJOUISFBEVTJOHBDPOEJUJPOWBSJBCMF

do_getaddrinfo, arg) != 0) { free_getaddrinfo_arg(arg); return EAI_AGAIN; } pthread_detach(th); rb_thread_call_without_gvl2(wait_getaddrinfo, arg, cancel_getaddrinfo, arg); // ... } *OUFSSVQUJCMFHFUBEESJOGP*NQMFNFOUBUJPO BTPG3VCZ IUUQTHJUIVCDPNSVCZSVCZCMPCSVCZ@@FYUTPDLFUSBEESJOGPD *OBOFOWJSPONFOUXIFSFUIFQUISFBEMJCSBSZJTBWBJMBCMF *OUIFNBJOUISFBE JUXBJUTVOUJMBOPUJ fi DBUJPOBSSJWFT POUIFDPOEJUJPOWBSJBCMF 8BJUGPSOPUJ fi DBUJPOUPUIFDPOEJUJPOWBSJBCMF

do_getaddrinfo, arg) != 0) { free_getaddrinfo_arg(arg); return EAI_AGAIN; } pthread_detach(th); rb_thread_call_without_gvl2(wait_getaddrinfo, arg, cancel_getaddrinfo, arg); // ... } *OUFSSVQUJCMFHFUBEESJOGP*NQMFNFOUBUJPO BTPG3VCZ IUUQTHJUIVCDPNSVCZSVCZCMPCSVCZ@@FYUTPDLFUSBEESJOGPD *OBOFOWJSPONFOUXIFSFUIFQUISFBEMJCSBSZJTBWBJMBCMF %FUFDUTBDPNQMFUJPOPGOBNFSFTPMVUJPO %FUFDUTBOJOUFSSVQUJPO 5IJTDPOEJUJPOWBSJBCMFJTOPUJ fi FEOPUPOMZ XIFOOBNFSFTPMVUJPODPNQMFUFTJOBDIJMEUISFBE CVUBMTPXIFOUIFNFUIPEJTJOUFSSVQUFE

do_getaddrinfo, arg) != 0) { free_getaddrinfo_arg(arg); return EAI_AGAIN; } pthread_detach(th); rb_thread_call_without_gvl2(wait_getaddrinfo, arg, cancel_getaddrinfo, arg); // ... } *OUFSSVQUJCMFHFUBEESJOGP*NQMFNFOUBUJPO BTPG3VCZ IUUQTHJUIVCDPNSVCZSVCZCMPCSVCZ@@FYUTPDLFUSBEESJOGPD *OBOFOWJSPONFOUXIFSFUIFQUISFBEMJCSBSZJTBWBJMBCMF 5PCFDPOUJOVFE ⬇︎ 0ODFUIFOPUJ fi DBUJPOBSSJWFT UIFXBJUJTMJGUFE BOEUIFTVCTFRVFOUQSPDFTTJOHJTDBSSJFEPVU CBTFEPOUIFSFBTPOUIBUUSJHHFSFEUIFOPUJ fi DBUJPO

do_getaddrinfo, arg) != 0) { free_getaddrinfo_arg(arg); return EAI_AGAIN; } pthread_detach(th); rb_thread_call_without_gvl2(wait_getaddrinfo, arg, cancel_getaddrinfo, arg); // ... } *OUFSSVQUJCMFHFUBEESJOGP*NQMFNFOUBUJPO BTPG3VCZ IUUQTHJUIVCDPNSVCZSVCZCMPCSVCZ@@FYUTPDLFUSBEESJOGPD *OBOFOWJSPONFOUXIFSFUIFQUISFBEMJCSBSZJTBWBJMBCMF 5PCFDPOUJOVFE ⬇︎ 8JUIUIBUJONJOE MFUTHFUCBDLUPUIFNBJOUPQJD

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*OUIFNBJOUISFBE static VALUE init_fast_fallback_inetsock_internal(VALUE v) { // ... if (raddrinfo_pthread_create(...,
do_fast_fallback_getaddrinfo, ...) != 0) { rsock_raise_resolution_error("getaddrinfo(3)", EAI_AGAIN); } pthread_detach(threads[i]); // ... } *OTJEFJOJU@GBTU@GBMMCBDL@JOFUTPDL@JOUFSOBM BOFXUISFBEJTDSFBUFEBOEEFUBDIFE GPSFBDIBEESFTTGBNJMZ "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM BOEEFUBDIJU $SFBUFBOFXUISFBE

do_fast_fallback_getaddrinfo, ...) != 0) { // ... } pthread_detach(threads[i]); // ... } *OTJEFFBDIPGUIFEFUBDIFEDIJMEUISFBET HFUBEESJOGP JTDBMMFE $BMMJOUIFUISFBE "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM void *do_fast_fallback_getaddrinfo(void *ptr) { // ... int err, gai_errno; err = getaddrinfo(...); // ... } $BMMHFUBEESJOGP

do_fast_fallback_getaddrinfo, ...) != 0) { // ... } pthread_detach(threads[i]); // ... } 0ODFOBNFSFTPMVUJPOJTDPNQMFUF BOPUJ fi DBUJPOJTTFOUUPUIFQJQFTIBSFEXJUI UIFNBJOUISFBE $BMMJOUIFUISFBE "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM void *do_fast_fallback_getaddrinfo(void *ptr) { // ... write(shared->notify, &notification, strlen(&notification)); // ... } 8SJUFUIFOPUJGZUPUIFQJQF

do_fast_fallback_getaddrinfo, ...) != 0) { rsock_raise_resolution_error("getaddrinfo(3)", EAI_AGAIN); } pthread_detach(threads[i]); // ... rb_thread_call_without_gvl2( wait_fast_fallback, &wait_arg, cancel_fast_fallback, arg->getaddrinfo_shared ); // ... } .FBOXIJMF JOUIFNBJOUISFBE DBMMBGVODUJPOUPXBJU GPSCPUIOBNFSFTPMVUJPOPSBDPOOFDUJPOUPDPNQMFUF 8BJUGPSCPUIDPOOFDUJPODPNQMFUJPO BOEOBNFSFTPMVUJPO 5PCFDPOUJOVFE ⬇︎ "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM

8BJUJOHGPSCPUIDPOOFDUJPOBOEOBNFSFTPMVUJPO static void * wait_fast_fallback(void *ptr) { struct wait_fast_fallback_arg *arg
= (struct wait_fast_fallback_arg *)ptr; int status; status = select(arg->nfds, arg->readfds, arg->writefds, NULL, arg->delay); arg->status = status; if (errno == EINTR) *arg->cancelled = true; return 0; } *OUIFXBJUJOHGVODUJPO DBMMTFMFDU UPNPOJUPSCPUI UIFQJQFXBJUJOHGPSOBNFSFTPMVUJPOOPUJ fi DBUJPOBOE UIFTPDLFUTDVSSFOUMZBUUFNQUJOHUPDPOOFDU "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM

static void * wait_fast_fallback(void *ptr) { struct wait_fast_fallback_arg *arg =
(struct wait_fast_fallback_arg *)ptr; int status; status = select(arg->nfds, arg->readfds, arg->writefds, NULL, arg->delay); arg->status = status; if (errno == EINTR) *arg->cancelled = true; return 0; } TFMFDU VOCMPDLTXIFOFJUIFSBOBNFSFTPMVUJPO DPNQMFUJPOOPUJ fi DBUJPOBSSJWFTPOUIFQJQF BOZPGUIF TPDLFUTDVSSFOUMZBUUFNQUJOHUPDPOOFDUCFDPNF XSJUBCMF PSUIFXBJUUJNFFYDFFETUIFUJNFPVU "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM 8BJUJOHGPSCPUIDPOOFDUJPOBOEOBNFSFTPMVUJPO *ODMVEFTUIFQJQF *ODMVEFTUIFTPDLFUTBUUFNQUJOHUPDPOOFDU

(struct wait_fast_fallback_arg *)ptr; int status; status = select(arg->nfds, arg->readfds, arg->writefds, NULL, arg->delay); arg->status = status; if (errno == EINTR) *arg->cancelled = true; return 0; } *OTIPSU UIJTTFMFDU QFSGPSNTUIFTBNFSPMFBTUIF *0TFMFDUJOUIF4PDLFUUDQJNQMFNFOUBUJPO "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM 8BJUJOHGPSCPUIDPOOFDUJPOBOEOBNFSFTPMVUJPO

➡︎ SBEESJOGP@QUISFBE@DSFBUF ➡︎ EP@GBTU@GBMMCBDL@HFUBEESJOGPɹ ➡︎ SC@UISFBE@DBMM@XJUIPVU@HWM ➡︎ XBJU@GBTU@GBMMCBDLDBODFM@GBTU@GBMMCBDL ➡︎ $BMM4UBDLPG5$14PDLFUOFXXJUI)&W "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM "OBNFSFTPMVUJPOGVODUJPO JOUIFDIJMEUISFBE 4QBXOBOFXDIJMEUISFBE 8BJUJOUIFNBJOUISFBE 5IJTJNQMFNFOUBUJPOBMTPSFRVJSFTUIFQUISFBEMJCSBSZ 5$14PDLFUOFXXJUI)&WJTPOMZJOFOWJSPONFOUT XIFSFQUISFBEJTBWBJMBCMFBOECFIBWFTBTJUBMXBZT IBTPOQMBUGPSNTMJLF8JOEPXT

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/PWFNCFS

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/PWFNCFS

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/PWFNCFS "GUFS fi OJTIJOHUIF fi YFTCBTFEPOUIFSFWJFX

/PWFNCFS .FSHFE13JOUPNBTUFS

15 of 29 CIs failed!! /PWFNCFS

8IJDIUFTUTXFSFGBJMJOHPO$* 0SUFTUTTJNJMBSUPUIFTFBSFJODMVEFEJOUIFUFTUTGPS /FU)551 > 1) Failure: > TestNetHTTP_v1_2_chunked#test_timeout_during_HTTP_session_write > [/.../ruby/test/net/http/test_http.rb:572]:
> [Net::WriteTimeout] exception expected, > not #<Net::OpenTimeout: Failed to open TCP connection to ...>.

5FTU/FU)551@W@@DIVOLFEUFTU@UJNFPVU@EVSJOH@)551@TFTTJPO@XSJUF def test_timeout_during_HTTP_session_write th = nil TCPServer.open('localhost', 0) {|server| port
= server.addr[1] conn = Net::HTTP.new('localhost', port) conn.write_timeout = EnvUtil.apply_timeout_scale(0.01) conn.open_timeout = EnvUtil.apply_timeout_scale(0.1) th = Thread.new do assert_raise(Net::WriteTimeout) do assert_warning(/Content-Type did not set/) do conn.post('/', "a"*50_000_000) end end end assert th.join(EnvUtil.apply_timeout_scale(10)) } # ... end UFTUOFUIUUQUFTU@IUUQSC "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM 5IF8JOEPXTTQFDJ fi DQBSUTBSFPNJUUFE

= server.addr[1] conn = Net::HTTP.new('localhost', port) conn.write_timeout = EnvUtil.apply_timeout_scale(0.01) conn.open_timeout = EnvUtil.apply_timeout_scale(0.1) th = Thread.new do assert_raise(Net::WriteTimeout) do assert_warning(/Content-Type did not set/) do conn.post('/', "a"*50_000_000) end end end assert th.join(EnvUtil.apply_timeout_scale(10)) } # ... end *OUIJTUFTU BTFSWFSJT fi STUTUBSUFEPOMPDBMIPTU 4UBSUB5$1TFSWFS UFTUOFUIUUQUFTU@IUUQSC "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM 5IF8JOEPXTTQFDJ fi DQBSUTBSFPNJUUFE

= server.addr[1] conn = Net::HTTP.new('localhost', port) conn.write_timeout = EnvUtil.apply_timeout_scale(0.01) conn.open_timeout = EnvUtil.apply_timeout_scale(0.1) th = Thread.new do assert_raise(Net::WriteTimeout) do assert_warning(/Content-Type did not set/) do conn.post('/', "a"*50_000_000) end end end assert th.join(EnvUtil.apply_timeout_scale(10)) } # ... end 5IFO UIFDMJFOUTUJNFPVUWBMVFTBSFTFU BXSJUFUJNFPVUPGNT BOEBDPOOFDUUJNFPVUPGNT XSJUFUJNFPVUNT DPOOFDUUJNFPVUNT UFTUOFUIUUQUFTU@IUUQSC "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM 5IF8JOEPXTTQFDJ fi DQBSUTBSFPNJUUFE

= server.addr[1] conn = Net::HTTP.new('localhost', port) conn.write_timeout = EnvUtil.apply_timeout_scale(0.01) conn.open_timeout = EnvUtil.apply_timeout_scale(0.1) th = Thread.new do assert_raise(Net::WriteTimeout) do assert_warning(/Content-Type did not set/) do conn.post('/', "a"*50_000_000) end end end assert th.join(EnvUtil.apply_timeout_scale(10)) } # ... end 5IFDMJFOUUIFOTUBSUTBDPOOFDUJPOUPUIFTFSWFS 4UBSUBOFXDPOOFDUJPO UFTUOFUIUUQUFTU@IUUQSC "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM 5IF8JOEPXTTQFDJ fi DQBSUTBSFPNJUUFE

def test_timeout_during_HTTP_session_write th = nil TCPServer.open('localhost', 0) {|server| port =
server.addr[1] conn = Net::HTTP.new('localhost', port) conn.write_timeout = EnvUtil.apply_timeout_scale(0.01) conn.open_timeout = EnvUtil.apply_timeout_scale(0.1) th = Thread.new do assert_raise(Net::WriteTimeout) do assert_warning(/Content-Type did not set/) do conn.post('/', "a"*50_000_000) end end end assert th.join(EnvUtil.apply_timeout_scale(10)) } # ... end 5FTU/FU)551@W@@DIVOLFEUFTU@UJNFPVU@EVSJOH@)551@TFTTJPO@XSJUF 4FOEBWFSZMPOHTUSJOH *GUIFDPOOFDUJPOJTTVDDFTTGVM JUBUUFNQUTUPTFOEBWFSZMPOHTUSJOH BTBSFRVFTUNFTTBHFUPUIFTFSWFS UFTUOFUIUUQUFTU@IUUQSC "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM 5IF8JOEPXTTQFDJ fi DQBSUTBSFPNJUUFE

= server.addr[1] conn = Net::HTTP.new('localhost', port) conn.write_timeout = EnvUtil.apply_timeout_scale(0.01) conn.open_timeout = EnvUtil.apply_timeout_scale(0.1) th = Thread.new do assert_raise(Net::WriteTimeout) do assert_warning(/Content-Type did not set/) do conn.post('/', "a"*50_000_000) end end end assert th.join(EnvUtil.apply_timeout_scale(10)) } # ... end 5IFFYQFDUBUJPOJTUIBUEVSJOHUIFTFOE NTXJMM QBTTBOE/FU8SJUF5JNFPVUBTBXSJUFUJNFPVU XJMMCFSBJTFE UFTUOFUIUUQUFTU@IUUQSC "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM 5IF8JOEPXTTQFDJ fi DQBSUTBSFPNJUUFE

/PU/FU8SJUF5JNFPVU CVU/FU0QFO5JNFPVU *OUIFGBJMJOHUFTU /FU0QFO5JNFPVUPDDVSTXIFSF/FU8SJUF5JNFPVUJTFYQFDUFE 5IJTJOEJDBUFTUIBUUIFUJNFPVUJTIBQQFOJOHEVSJOHUIFDPOOFDUJPO BUUFNQU CFGPSFUIFXSJUFFWFOCFHJOT > 1)
Failure: > TestNetHTTP_v1_2_chunked#test_timeout_during_HTTP_session_write > [/.../ruby/test/net/http/test_http.rb:572]: > [Net::WriteTimeout] exception expected, > not #<Net::OpenTimeout: Failed to open TCP connection to ...>.

/FU)551DPOOFDU def connect # ... s = Timeout.timeout(@open_timeout, Net::OpenTimeout) {
begin TCPSocket.open(conn_addr, conn_port, @local_host, @local_port) rescue => e # ... end } # ... end private :connect MJCOFUIUUQSC "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM -FUTUBLFBMPPLBU/FU)551 5IFNFUIPESFTQPOTJCMFGPSBUUFNQUJOH B5$1DPOOFDUJPOJT/FU)551DPOOFDU 5$14PDLFUPQFO BOBMJBTGPS5$14PDLFUOFXTUBSUTBDPOOFDUJPO

begin TCPSocket.open(conn_addr, conn_port, @local_host, @local_port) rescue => e # ... end } # ... end private :connect )FSF UJNFPVUHFNJTVTFEUPNBOBHFUIFDPOOFDUJPO UJNFPVU*GUIFUJNFUBLFOGPSUIFDPOOFDUJPOBUUFNQU FYDFFETUIFTQFDJ fi FEUJNFPVUWBMVF /FU0QFO5JNFPVUJTSBJTFE .BOBHFUJNFPVU /FU0QFO5JNFPVUXJUIDPOOFDUUJNFPVU MJCOFUIUUQSC "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM

begin TCPSocket.open(conn_addr, conn_port, @local_host, @local_port) rescue => e # ... end } # ... end private :connect 5IJTDPEFBOEUIFUFTUXFSFXPSLJOHBTFYQFDUFE CFGPSF)&WXBTJOUSPEVDFE4PXIBU`THPJOHPOOPX def test_timeout_during_HTTP_session_write th = nil TCPServer.open('localhost', 0) {|server| # ... conn.open_timeout = EnvUtil.apply_timeout_scale(0.1) # ... } # ... end UFTUOFUIUUQUFTU@IUUQSC MJCOFUIUUQSC "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM

server.addr[1] conn = Net::HTTP.new('localhost', port) conn.write_timeout = EnvUtil.apply_timeout_scale(0.01) conn.open_timeout = EnvUtil.apply_timeout_scale(0.1) th = Thread.new do assert_raise(Net::WriteTimeout) do assert_warning(/Content-Type did not set/) do conn.post('/', "a"*50_000_000) end end end assert th.join(EnvUtil.apply_timeout_scale(10)) } # ... end "OTXFSJOHUIFRVFTUJPO8IZJTUIFUFTUGBJMJOH -FU`TUBLFMPPLBUUIFUFTUDPEFBHBJO 5IFTFSWFSJTTUBSUFECZQBTTJOHMPDBMIPTU UP5$14FSWFSOFX 4UBSUB5$1TFSWFS XJUIIPTUOBNFMPDBMIPTU UFTUOFUIUUQUFTU@IUUQSC "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM 5IF8JOEPXTTQFDJ fi DQBSUTBSFPNJUUFE

server.addr[1] conn = Net::HTTP.new('localhost', port) conn.write_timeout = EnvUtil.apply_timeout_scale(0.01) conn.open_timeout = EnvUtil.apply_timeout_scale(0.1) th = Thread.new do assert_raise(Net::WriteTimeout) do assert_warning(/Content-Type did not set/) do conn.post('/', "a"*50_000_000) end end end assert th.join(EnvUtil.apply_timeout_scale(10)) } # ... end *OUIFCBDLHSPVOE UIFTFSWFSSFTPMWFTUIFIPTUOBNF MPDBMIPTUBOECJOETJUTMJTUFOJOHTPDLFU UPPOFPGUIFSFTPMWFEBEESFTTFT CJOE 0OFPGUIFSFTPMWFEBEESFTTFT "MJTUFOJOHTPDLFU 4FSWFS "OTXFSJOHUIFRVFTUJPO8IZJTUIFUFTUGBJMJOH UFTUOFUIUUQUFTU@IUUQSC "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM 5IF8JOEPXTTQFDJ fi DQBSUTBSFPNJUUFE

server.addr[1] conn = Net::HTTP.new('localhost', port) conn.write_timeout = EnvUtil.apply_timeout_scale(0.01) conn.open_timeout = EnvUtil.apply_timeout_scale(0.1) th = Thread.new do assert_raise(Net::WriteTimeout) do assert_warning(/Content-Type did not set/) do conn.post('/', "a"*50_000_000) end end end assert th.join(EnvUtil.apply_timeout_scale(10)) } # ... end 0OBEVBMTUBDLIPTU UIFTFSWFSCJOETUP FJUIFS *1W PS *1W EFQFOEJOHPOXIJDIPOFJTSFTPMWFE fi STU "MJTUFOJOHTPDLFU 4FSWFS PS 8IJDIFWFSSFTPMWFT fi STU CJOE 8IFUIFS*1WPS*1WHFUTSFTPMWFE fi STU EFQFOETPOUIF04BOEOFUXPSLTFUUJOHT "OTXFSJOHUIFRVFTUJPO8IZJTUIFUFTUGBJMJOH UFTUOFUIUUQUFTU@IUUQSC "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM 5IF8JOEPXTTQFDJ fi DQBSUTBSFPNJUUFE

server.addr[1] conn = Net::HTTP.new('localhost', port) conn.write_timeout = EnvUtil.apply_timeout_scale(0.01) conn.open_timeout = EnvUtil.apply_timeout_scale(0.1) th = Thread.new do assert_raise(Net::WriteTimeout) do assert_warning(/Content-Type did not set/) do conn.post('/', "a"*50_000_000) end end end assert th.join(EnvUtil.apply_timeout_scale(10)) } # ... end *OUIFFOWJSPONFOUXIFSFUIFUFTUXBTGBJMJOH UIFTFSWFSFOEFEVQCJOEJOHUP *1W "MJTUFOJOHTPDLFU 4FSWFS *OUIFFOWJSPONFOU XIFSFUIFUFTUXBTGBJMJOH CJOE "OTXFSJOHUIFRVFTUJPO8IZJTUIFUFTUGBJMJOH UFTUOFUIUUQUFTU@IUUQSC "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM 5IF8JOEPXTTQFDJ fi DQBSUTBSFPNJUUFE

0OUIFPUIFSTJEF JGUIFDMJFOUTVDDFTTGVMMZSFTPMWFTCPUI *1WBOE*1WBEESFTTFT JUGPMMPXTUIF)&WTQFDJ fi DBUJPOBOEQSJPSJUJ[FTDPOOFDUJOH UPUIF*1WBEESFTT 4FSWFS 4UBSUBDPOOFDUJPOBUUFNQUUP
5$14PDLFUOFX "OTXFSJOHUIFRVFTUJPO8IZJTUIFUFTUGBJMJOH 3FTPMWFECPUI BOE

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)PXFWFS JOSFBMJUZ $POOFDUJPO"UUFNQU%FMBZTUBSUTBUUIJTQPJOU BOEJUJTBCPVUUPXBJUNTCFGPSFBUUFNQUJOHUIF DPOOFDUJPOUPUIF*1WBEESFTT 4UBSUBDPOOFDUJPOBUUFNQUUP 5$14PDLFUOFX 5IFBUUFNQUGBJMT
4FSWFS "OTXFSJOHUIFRVFTUJPO8IZJTUIFUFTUGBJMJOH 8BJUNT

server.addr[1] conn = Net::HTTP.new('localhost', port) conn.write_timeout = EnvUtil.apply_timeout_scale(0.01) conn.open_timeout = EnvUtil.apply_timeout_scale(0.1) th = Thread.new do assert_raise(Net::WriteTimeout) do assert_warning(/Content-Type did not set/) do conn.post('/', "a"*50_000_000) end end end assert th.join(EnvUtil.apply_timeout_scale(10)) } # ... end UFTUOFUIUUQUFTU@IUUQSC "TPG13IUUQTHJUIVCDPNSVCZSVCZQVMM 5IJTNFBOTUIBUXIJMFXBJUJOHGPSUIFNT $POOFDUJPO"UUFNQU%FMBZ UIFNT DPOOFDUUJNFPVUXBTCFJOHUSJHHFSFE DPOOFDUUJNFPVUNT "OTXFSJOHUIFRVFTUJPO8IZJTUIFUFTUGBJMJOH 5IFNTUJNFPVUFYQJSFTEVSJOHUIFNTXBJU 5IF8JOEPXTTQFDJ fi DQBSUTBSFPNJUUFE

3FTPMWJOHUIFUJNFPVUJTTVF if (status > 0) { /* check for connection
*/ if (in_progress_fds(arg->connection_attempt_fds_size)) { for (/* If there are sockets with a confirmed connection state */) { // Check for connection } if (connected_fd >= 0) break; if (!in_progress_fds(arg->connection_attempt_fds_size)) { if (/* No address candidates available and finished name resolution */) { // Raise an error and exit } connection_attempt_delay_expires_at = NULL; user_specified_connect_timeout_at = NULL; } } // ... FYUTPDLFUJQTPDLFUD 4P *SFTFUDPOOFDUJPO@BUUFNQU@EFMBZ@BUXIFOBMM QSFWJPVTDPOOFDUJPOBUUFNQUTIBWFGBJMFE BMMPXJOHUIF OFYUDPOOFDUJPOUPTUBSUXJUIPVUXBJUJOHNT 3FTFUDPOOFDUJPO@BUUFNQU@EFMBZ@FYQJSFT@BU 5IFSFJTOPTVDDFTTGVMMZDPOOFDUFETPDLFU BOEOPTPDLFUDVSSFOUMZBUUFNQUJOHUPDPOOFDU

.FSHFE13 XIJDIJODMVEFTUIJT fi Y IUUQTHJUIVCDPNSVCZSVCZQVMM /PWFNCFS

.FSHFE13 XIJDIBMTPJODMVEFTUIJT fi Y /PWFNCFS IUUQTHJUIVCDPNSVCZSVCZQVMM

3VCZ$*HPUJOOFSQFBDF All CIs passed

.FSHFE13 UPTPMWFTBNFQSPCMFNJO4PDLFUUDQ IUUQTHJUIVCDPNSVCZSVCZQVMM

%FDFNCFS

"OJTTVFSFQPSUFECZ!KIBXUIPSO %FDFNCFS

"OJTTVFSFQPSUFECZ!KIBXUIPSO 4PDLFUGBTU@GBMMCBDLTFHGBVMUTXIFO GETBSF'%@4&54*;& IUUQTCVHTSVCZMBOHPSHJTTVFT

"OJTTVFSFQPSUFECZ!KIBXUIPSO 4PDLFUGBTU@GBMMCBDLTFHGBVMUTXIFO GETBSF'%@4&54*;& *GUIFOVNCFSPG fi MFEFTDSJQUPS GE PQFOFECZ5$14PDLFUOFXFYDFFET'%@4&54*;& BTFHNFOUBUJPOGBVMUXJMMPDDVS
5IF fi MFEFTDSJQUPS GE MJNJUTFUCZUIFIPTU

"OJTTVFSFQPSUFECZ!KIBXUIPSO require "socket" open_fds = [] loop do file =
open(__FILE__) open_fds << file break if file.fileno >= 1010 end TCPServer.open("localhost", 0) do |server| port = server.addr[1] sockets = [] 50.times do |i| socket = TCPSocket.open("localhost", port) p socket sockets << socket end end IUUQTCVHTSVCZMBOHPSHJTTVFT 3FQSPEVDUJPODPEFCZ!KIBXUIPSO

open(__FILE__) open_fds << file break if file.fileno >= 1010 end TCPServer.open("localhost", 0) do |server| port = server.addr[1] sockets = [] 50.times do |i| socket = TCPSocket.open("localhost", port) p socket sockets << socket end end IUUQTCVHTSVCZMBOHPSHJTTVFT 3FQSPEVDUJPODPEFCZ!KIBXUIPSO 0QFOFOPVHI fi MFTJOBEWBODFTPUIBU UIFUPUBMOVNCFSPGGETDPNFTDMPTF UPUIFTZTUFN`T'%@4&54*;&MJNJU

open(__FILE__) open_fds << file break if file.fileno >= 1010 end TCPServer.open("localhost", 0) do |server| port = server.addr[1] sockets = [] 50.times do |i| socket = TCPSocket.open("localhost", port) p socket sockets << socket end end IUUQTCVHTSVCZMBOHPSHJTTVFT 3FQSPEVDUJPODPEFCZ!KIBXUIPSO 4UBSUBTFSWFS

open(__FILE__) open_fds << file break if file.fileno >= 1010 end TCPServer.open("localhost", 0) do |server| port = server.addr[1] sockets = [] 50.times do |i| socket = TCPSocket.open("localhost", port) p socket sockets << socket end end IUUQTCVHTSVCZMBOHPSHJTTVFT 3FQSPEVDUJPODPEFCZ!KIBXUIPSO 4UBSUTFWFSBMOFXDPOOFDUJPOTUP UIFTFSWFSVTJOH5$14PDLFUPQFO 5$14PDLFUOFX

open(__FILE__) open_fds << file break if file.fileno >= 1010 end TCPServer.open("localhost", 0) do |server| port = server.addr[1] sockets = [] 50.times do |i| socket = TCPSocket.open("localhost", port) p socket sockets << socket end end IUUQTCVHTSVCZMBOHPSHJTTVFT 3FQSPEVDUJPODPEFCZ!KIBXUIPSO 8IFOUIFUPUBMOVNCFSPG BMSFBEZPQFOFE fi MFT UIFTPDLFUT PQFOFECZ5$14PDLFUOFX SFBDIFTFYDFFET'%@4&54*;& 4UBSUTFWFSBMOFXDPOOFDUJPOTUP UIFTFSWFSVTJOH5$14PDLFUPQFO 5$14PDLFUOFX

"OJTTVFSFQPSUFECZ!KIBXUIPSO $ ulimit -n 2048 $ ruby test.rb #<TCPSocket:fd 1015,
AF_INET6, ::1, 40622> #<TCPSocket:fd 1014, AF_INET6, ::1, 40628> #<TCPSocket:fd 1016, AF_INET6, ::1, 40630> ... ================================================================= ==3180778==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ae35aadc580 at pc 0x7ae35b1b7449 bp 0x7fffc9af1af0 sp 0x7fffc9af1ae8 READ of size 8 at 0x7ae35aadc580 thread T0 #0 0x7ae35b1b7448 in init_fast_fallback_inetsock_internal /.../ruby/ext/socket/ipsocket.c:912:17 #1 0x60462ff14879 in rb_ensure /.../ruby/eval.c:1053:18 #2 0x7ae35b1b41b9 in rsock_init_inetsock /.../ruby/ext/socket/ipsocket.c:1315:20 #3 0x7ae35b1bae9a in tcp_init /.../ruby/ext/socket/tcpsocket.c:91:12 ... IUUQTCVHTSVCZMBOHPSHJTTVFT A segmentation fault occurs!!

"GVODUJPOPGUIFDBVTFPGUIFQSPCMFN static void * wait_fast_fallback(void *ptr) { struct wait_fast_fallback_arg *arg
= (struct wait_fast_fallback_arg *)ptr; int status; status = select(arg->nfds, arg->readfds, arg->writefds, NULL, arg->delay); arg->status = status; if (errno == EINTR) *arg->cancelled = true; return 0; } 5IFDBVTFPGUIJTJTTVFXBT UIFGVODUJPOQSFWJPVTMZJOUSPEVDFE

"GVODUJPOPGUIFDBVTFPGUIFQSPCMFN static void * wait_fast_fallback(void *ptr) { struct wait_fast_fallback_arg *arg
= (struct wait_fast_fallback_arg *)ptr; int status; status = select(arg->nfds, arg->readfds, arg->writefds, NULL, arg->delay); arg->status = status; if (errno == EINTR) *arg->cancelled = true; return 0; } *OTJEFUIJTGVODUJPO DBMMTFMFDU XBJUGPSFJUIFS OBNFSFTPMVUJPOPSBDPOOFDUJPOUPDPNQMFUF CZ NPOJUPSJOHCPUIUIFQJQFXBJUJOHGPSOBNFSFTPMVUJPO OPUJ fi DBUJPOTBOEUIFTPDLFUTBUUFNQUJOHUPDPOOFDU 5IFQJQFXBJUJOHGPSOBNFSFTPMVUJPOOPUJ fi DBUJPOT 5IFTPDLFUTXBJUJOHUPDPOOFDU

(struct wait_fast_fallback_arg *)ptr; int status; status = select(arg->nfds, arg->readfds, arg->writefds, NULL, arg->delay); arg->status = status; if (errno == EINTR) *arg->cancelled = true; return 0; } "GVODUJPOPGUIFDBVTFPGUIFQSPCMFN *OBTFOTF TFMFDU JTUIFNPTUJNQPSUBOUTZTUFNDBMM XIFOJUDPNFTUPJNQMFNFOUJOHUIF)&WTQFDJ fi DBUJPO 5IFNPTUJNQPSUBOUTZTUFNDBMMGPS)&W

(struct wait_fast_fallback_arg *)ptr; int status; status = select(arg->nfds, arg->readfds, arg->writefds, NULL, arg->delay); arg->status = status; if (errno == EINTR) *arg->cancelled = true; return 0; } "GVODUJPOPGUIFDBVTFPGUIFQSPCMFN 5IFQSPCMFNJTUIBUTFMFDU DBOOPUNPOJUPS GETOVNCFSHSFBUFSUIBO'%@4&54*;& /PUTVQQPSUFECFZPOE'%@4&54*;&

TFMFDU -JOVYNBOVBMQBHF IUUQTNBOPSHMJOVYNBOQBHFTNBOTFMFDUIUNM 5IJTMJNJUBUJPOJTBDUVBMMZEPDVNFOUFEJOUIFNBOVBM GPSTFMFDU 'PSFYBNQMF IFSF`TUIFSFMFWBOUTFDUJPO GSPNUIFNBOPG-JOVY
DESCRIPTION WARNING: select() can monitor only fi le descriptors numbers that are less than FD_SETSIZE (1024)—an unreasonably low limit for many modern applications—and this limitation will not change. All modern applications should instead use poll(2) or epoll(7), which do not su ff er this limitation.

TFMFDU -JOVYNBOVBMQBHF IUUQTNBOPSHMJOVYNBOQBHFTNBOTFMFDUIUNM DESCRIPTION WARNING: select() can monitor only
fi le descriptors numbers that are less than FD_SETSIZE (1024)—an unreasonably low limit for many modern applications—and this limitation will not change. All modern applications should instead use poll(2) or epoll(7), which do not su ff er this limitation.

TFMFDU -JOVYNBOVBMQBHF IUUQTNBOPSHMJOVYNBOQBHFTNBOTFMFDUIUNM NOTES The following header also provides
the fd_set type: <sys/time.h>. An fd_set is a fi xed size bu ff er. Executing FD_CLR() or FD_SET() with a value of fd that is negative or is equal to or larger than FD_SETSIZE will result in unde fi ned behavior. Moreover, POSIX requires fd to be a valid fi le descriptor. '%@$-3 BOE'%@4&5 BSFNBDSPT UIBUBSFFYFDVUFECFGPSFDBMMJOHTFMFDU

TFMFDU -JOVYNBOVBMQBHF IUUQTNBOPSHMJOVYNBOQBHFTNBOTFMFDUIUNM NOTES The following header also provides
the fd_set type: <sys/time.h>. An fd_set is a fi xed size bu ff er. Executing FD_CLR() or FD_SET() with a value of fd that is negative or is equal to or larger than FD_SETSIZE will result in unde fi ned behavior. Moreover, POSIX requires fd to be a valid fi le descriptor. 5IJTJTBQSPCMFN

5IFTFMFDU QSPCMFN 5PTPMWFUIJTJTTVF XFOFFEUPQFSGPSNUIFQSPDFTTJOHDVSSFOUMZEPOF CZTFMFDU VTJOHBXBZPUIFSUIBOTFMFDU

TFMFDU -JOVYNBOVBMQBHF IUUQTNBOPSHMJOVYNBOQBHFTNBOTFMFDUIUNM 5IFNBOPG-JOVYSFDPNNFOETVTJOH FJUIFSQPMM PSFQPMM GPSUIJTQVSQPTF
DESCRIPTION WARNING: select() can monitor only fi le descriptors numbers that are less than FD_SETSIZE (1024)—an unreasonably low limit for many modern applications—and this limitation will not change. All modern applications should instead use poll(2) or epoll(7), which do not su ff er this limitation.

TFMFDU -JOVYNBOVBMQBHF DESCRIPTION WARNING: select() can monitor only fi
le descriptors numbers that are less than FD_SETSIZE (1024)—an unreasonably low limit for many modern applications—and this limitation will not change. All modern applications should instead use poll(2) or epoll(7), which do not su ff er this limitation. IUUQTNBOPSHMJOVYNBOQBHFTNBOTFMFDUIUNM FQPMM JTBO"1*TQFDJ fi DUP-JOVYFOWJSPONFOUT 4JODF5$14PDLFUOFXXJUI)&WJTJOUFOEFEUPXPSLPO BMMFOWJSPONFOUTXIFSFQUISFBETBSFBWBJMBCMF DIPPTJOH QPMM JTUIFNPSFSFBTPOBCMFPQUJPOJOUIJTDBTF

4PMWJOHUIFTFMFDU QSPCMFN *MPPLFEJOUPXIFUIFS TFMFDU DPVMECFSFQMBDFEXJUIQPMM CZFYBNJOJOH UIFEJ
ff FSFODFTCFUXFFOUIFTFTZTUFNDBMMT "TBSFTVMU *GPVOEUIBUUIFJSEJ ff FSFODFTBSFBTGPMMPXT

5IFEJ ff FSFODFTCFUXFFOTFMFDU BOEQPMM 'VODUJPOTJHOBUVSFT int poll( struct
pollfd *fds, nfds_t nfds, int timeout ); int select( int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *utimeout );

5IFEJ ff FSFODFTCFUXFFOTFMFDU BOEQPMM 5ZQFTPGUBSHFUTUIFZDBONPOJUPS int poll( struct
pollfd *fds, nfds_t nfds, int timeout ); int select( int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *utimeout ); +VTUTPNFGE@TFUT struct pollfd { int fd; short events; short revents:  };

5IFEJ ff FSFODFTCFUXFFOTFMFDU BOEQPMM 5ZQFTPGFWFOUTUIFZDBONPOJUPS ɾPOLLIN ɾPOLLOUT ɾPOLLERR
ɾPOLLHUP ɾPOLNVAL ɾreadfds ɾwritefds ɾexceptfds int poll( struct pollfd *fds, nfds_t nfds, int timeout ); int select( int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *utimeout );

5IFEJ ff FSFODFTCFUXFFOTFMFDU BOEQPMM )PXUPTQFDJGZUIFGETUPNPOJUPS int fd; fd_set
set; FD_ZERO(&set); FD_SET(fd, &set); int fd; struct pollfd fds[1]; fds[0].fd = fd; fds[0].events = POLLIN | POLLOUT; int poll( struct pollfd *fds, nfds_t nfds, int timeout ); int select( int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *utimeout );

5IFEJ ff FSFODFTCFUXFFOTFMFDU BOEQPMM 5JNFPVUSFTPMVUJPO NJMMJTFDPOET struct timeval
{ time_t tv_sec; suseconds_t tv_usec  }; int poll( struct pollfd *fds, nfds_t nfds, int timeout ); int select( int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *utimeout );

5IFEJ ff FSFODFTCFUXFFOTFMFDU BOEQPMM $PODMVTJPO 1SFUUZNVDIFWFSZUIJOHJTEJ ff FSFOU

5IFEJ ff FSFODFTCFUXFFOTFMFDU BOEQPMM $PODMVTJPO 1SFUUZNVDIFWFSZUIJOHJTEJ ff FSFOU
➡︎ 4JHOJ fi DBOUBNPVOUPGDPEFXJMMOFFEUPCFSFXSJUUFO ɹ5IFQSPCMFNJT JU`TBMSFBEZ%FDFNCFSUI ɹ -FTTUIBOEBZTMFGUVOUJMUIFSFMFBTFPG3VCZ *`EMJLFUPIBWFUIFDIBOHFTNFSHFEBOEUIFOMFU3VCZ$* SVOGPSBEFDFOUBNPVOUPGUJNFUPNPOJUPSUIFSFTVMUT

5IJTJTTVFEPFTOPUPDDVSXJUI4PDLFUUDQ BTJNQMFNFOUFEJO3VCZ )PXJTJUIBOEMFEJO4PDLFUUDQ

class Socket # ... def self.tcp(...) # ... hostname_resolved, writable_sockets,
except_sockets = IO.select( hostname_resolution_notifier, connecting_sockets.keys, is_windows_environment ? connecting_sockets.keys : nil, second_to_timeout(current_clock_time, ends_at), ) # ... end # ... end *O4PDLFUUDQ *0TFMFDUJTVTFEUPXBJUGPS OBNFSFTPMVUJPOBOEDPOOFDUJPODPNQMFUJPO 4PIPXJTJUIBOEMFEJO4PDLFUUDQ )PXJTJUIBOEMFEJO4PDLFUUDQ

void Init_IO(void) { // ... rb_cIO = rb_define_class("IO", rb_cObject); //
... rb_define_singleton_method(rb_cIO, "select", rb_f_select, -1); // ... } 5IFJOUFSOBMJNQMFNFOUBUJPOPG*0TFMFDU JPD *GPVOEUIBU*0TFMFDUJTJNQMFNFOUFEJOUFSOBMMZ JO3VCZBTSC@G@TFMFDU %F fi OFSC@G@TFMFDUBT*0TFMFDU %F fi OF*0DMBTT

$BMM4UBDLPG*0TFMFDU *0TFMFDU ➡︎ SC@G@TFMFDU ➡︎ SC@FOTVSF ➡︎
TFMFDU@DBMM ➡︎ TFMFDU@JOUFSOBM ➡︎ SC@UISFBE@GE@TFMFDU ➡︎ TFMFDU@FOE 5IFJOUFSOBMJNQMFNFOUBUJPOPG*0TFMFDU 5IJTGVODUJPODBMMTSC@UISFBE@GE@TFMFDU BOJOUFSOBM3VCZGVODUJPO

int rb_thread_fd_select(int max, rb_fdset_t * read, rb_fdset_t * write, rb_fdset_t
* except, struct timeval *timeout) { // ... BLOCKING_REGION(set->th, { struct timeval tv; if (!RUBY_VM_INTERRUPTED(set->th->ec)) { result = native_fd_select(set->max, set->rset, set->wset, set->eset, rb_hrtime2timeval(&tv, to), set->th); if (result < 0) lerrno = errno; } }, ubf_select, set->th, TRUE); // ... } SC@UISFBE@GE@TFMFDUUIFODBMMTOBUJWF@GE@TFMFDU 5IFJOUFSOBMJNQMFNFOUBUJPOPG*0TFMFDU

5IFJOUFSOBMJNQMFNFOUBUJPOPG*0TFMFDU ɾUISFBE@QUISFBED 5IFEF fi OJUJPOPGOBUJWF@GE@TFMFDUEJ ff FST EFQFOEJOHPOXIFUIFSUIFFOWJSPONFOUTVQQPSUT QUISFBETPSJTSVOOJOHPO8JOEPXT static
int native_fd_select(int n, rb_fdset_t *readfds, rb_fdset_t *writefds, rb_fdset_t *exceptfds, struct timeval *timeout, rb_thread_t *th) static int native_fd_select(int n, rb_fdset_t *readfds, rb_fdset_t *writefds, rb_fdset_t *exceptfds, struct timeval *timeout, rb_thread_t *th) ɾUISFBE@XJOD

5IFJOUFSOBMJNQMFNFOUBUJPOPG*0TFMFDU static int native_fd_select(int n, rb_fdset_t *readfds, rb_fdset_t *writefds, rb_fdset_t
*exceptfds, struct timeval *timeout, rb_thread_t *th) { return rb_fd_select(n, readfds, writefds, exceptfds, timeout); } UISFBE@QUISFBED *OFOWJSPONFOUTXJUIQUISFBET JUJOUFSOBMMZDBMMTSC@GE@TFMFDU

ɾJODMVEFSVCZJOUFSOBMJOUFSOTFMFDUMBSHFTJ[FI 5IFJOUFSOBMJNQMFNFOUBUJPOPG*0TFMFDU SC@GE@TFMFDUBMTPIBTEJ ff FSFOUEF fi OJUJPOTEFQFOEJOH PO04'PSDFSUBJOWFSTJPOTPG04 JUJTEF fi
OFEJO MBSHFTJ[FIGPSPUIFST JUJTEF fi OFEJOQPTJYI int rb_fd_select(int nfds, rb_fdset_t *rfds, rb_fdset_t *wfds, rb_fdset_t *efds, struct timeval *timeout) #define rb_fd_select select ɾJODMVEFSVCZJOUFSOBMJOUFSOTFMFDUQPTJYI

5BSHFU04WFSTJPOTGPSMBSHFTJ[FI /** * ... * * - Linux 2.2.12 (?)
* * - NetBSD 1.2 (src/sys/kern/sys_generic.c:1.25) * ... * - FreeBSD 2.2 (src/sys/kern/sys_generic.c:1.19) * * - OpenBSD 2.0 (src/sys/kern/sys_generic.c:1.4) * ... * - Solaris 8 has `select_large_fdset` * * - Mac OS X 10.7 (Lion) * ... */ )FSFBSFUIFMJTUPG04WFSTJPOT XIFSFUIFMBSHFTJ[FIEF fi OJUJPOJTVTFE JODMVEFSVCZJOUFSOBMJOUFSOTFMFDUMBSHFTJ[FI

/** * ... * * - Linux 2.2.12 (?) *
* - NetBSD 1.2 (src/sys/kern/sys_generic.c:1.25) * ... * - FreeBSD 2.2 (src/sys/kern/sys_generic.c:1.19) * * - OpenBSD 2.0 (src/sys/kern/sys_generic.c:1.4) * ... * - Solaris 8 has `select_large_fdset` * * - Mac OS X 10.7 (Lion) * ... */ 'PSNPTUNPEFSO DPNNPOMZVTFE04WFSTJPOT UIFEF fi OJUJPOJOMBSHFTJ[FIJTUIFPOFUIBUHFUTVTFE 5BSHFU04WFSTJPOTGPSMBSHFTJ[FI JODMVEFSVCZJOUFSOBMJOUFSOTFMFDUMBSHFTJ[FI

/** * ... * * Several Unix platforms support file
descriptors bigger than FD_SETSIZE in * `select(2)` system call. * * ... (The target OS versions) ... * * When `fd_set` is not big enough to hold big file descriptors, it should be * allocated dynamically. Note that this assumes `fd_set` is structured as * bitmap. * * `rb_fd_init` allocates the memory. * `rb_fd_term` frees the memory. * `rb_fd_set` may re-allocate bitmap. * * So `rb_fd_set` doesn't reject file descriptors bigger than `FD_SETSIZE`. */ 8IBUMBSHFTJ[FIUFMMT )FSF`TXIBU`TXSJUUFOJOMBSHFTJ[FI JODMVEFSVCZJOUFSOBMJOUFSOTFMFDUMBSHFTJ[FI

descriptors bigger than FD_SETSIZE in * `select(2)` system call. * * ... (The target OS versions) ... * * When `fd_set` is not big enough to hold big file descriptors, it should be * allocated dynamically. Note that this assumes `fd_set` is structured as * bitmap. * * `rb_fd_init` allocates the memory. * `rb_fd_term` frees the memory. * `rb_fd_set` may re-allocate bitmap. * * So `rb_fd_set` doesn't reject file descriptors bigger than `FD_SETSIZE`. */ 8IBUMBSHFTJ[FIUFMMT JODMVEFSVCZJOUFSOBMJOUFSOTFMFDUMBSHFTJ[FI

descriptors bigger than FD_SETSIZE in * `select(2)` system call. * * ... (The target OS versions) ... * * When `fd_set` is not big enough to hold big file descriptors, it should be * allocated dynamically. Note that this assumes `fd_set` is structured as * bitmap. * * `rb_fd_init` allocates the memory. * `rb_fd_term` frees the memory. * `rb_fd_set` may re-allocate bitmap. * * So `rb_fd_set` doesn't reject file descriptors bigger than `FD_SETSIZE`. */ JODMVEFSVCZJOUFSOBMJOUFSOTFMFDUMBSHFTJ[FI 8IBUMBSHFTJ[FIUFMMT GE@TFUTUPSFTUIF fi MFEFTDSJQUPSTUPCFNPOJUPSFE

5IFJNQMFNFOUBUJPOPGSC@GE@TFMFDU int rb_fd_select(int n, rb_fdset_t *readfds, rb_fdset_t *writefds, rb_fdset_t *exceptfds,
struct timeval *timeout) { fd_set *r = NULL, *w = NULL, *e = NULL; if (readfds) { rb_fd_resize(n - 1, readfds); r = rb_fd_ptr(readfds); } if (writefds) { rb_fd_resize(n - 1, writefds); w = rb_fd_ptr(writefds); } if (exceptfds) { rb_fd_resize(n - 1, exceptfds); e = rb_fd_ptr(exceptfds); } return select(n, r, w, e, timeout); } UISFBED

int rb_fd_select(int n, rb_fdset_t *readfds, rb_fdset_t *writefds, rb_fdset_t *exceptfds, struct
timeval *timeout) { fd_set *r = NULL, *w = NULL, *e = NULL; if (readfds) { rb_fd_resize(n - 1, readfds); r = rb_fd_ptr(readfds); } if (writefds) { rb_fd_resize(n - 1, writefds); w = rb_fd_ptr(writefds); } if (exceptfds) { rb_fd_resize(n - 1, exceptfds); e = rb_fd_ptr(exceptfds); } return select(n, r, w, e, timeout); } 5IJTGVODUJPONBLFTVTFPGUIFTUSVDUSC@GETFU@U 5IFJNQMFNFOUBUJPOPGSC@GE@TFMFDU TUSVDUSC@GETFU@UTBSFVTFE UISFBED

TUSVDUSC@GETFU@U /** * The data structure which wraps the fd_set
bitmap used by select(2). This * allows Ruby to use FD sets larger than that allowed by historic limitations * on modern platforms. */ typedef struct { int maxfd; /**< Maximum allowed number of FDs. */ fd_set *fdset; /**< File descriptors buffer */ } rb_fdset_t; JODMVEFSVCZJOUFSOBMJOUFSOTFMFDUMBSHFTJ[FI

/** * The data structure which wraps the fd_set bitmap
used by select(2). This * allows Ruby to use FD sets larger than that allowed by historic limitations * on modern platforms. */ typedef struct { int maxfd; /**< Maximum allowed number of FDs. */ fd_set *fdset; /**< File descriptors buffer */ } rb_fdset_t; TUSVDUSC@GETFU@U TUSVDUSC@GETFU@UXSBQTUIFGE@TFU UPCFQBTTFEUPTFMFDU 5IFGE@TFUUPCFQBTTFEUPTFMFDU JODMVEFSVCZJOUFSOBMJOUFSOTFMFDUMBSHFTJ[FI

/** * The data structure which wraps the fd_set bitmap
used by select(2). This * allows Ruby to use FD sets larger than that allowed by historic limitations * on modern platforms. */ typedef struct { int maxfd; /**< Maximum allowed number of FDs. */ fd_set *fdset; /**< File descriptors buffer */ } rb_fdset_t; "OEJUIBTBDPNNFOU JODMVEFSVCZJOUFSOBMJOUFSOTFMFDUMBSHFTJ[FI TUSVDUSC@GETFU@U

struct timeval *timeout) { fd_set *r = NULL, *w = NULL, *e = NULL; if (readfds) { rb_fd_resize(n - 1, readfds); r = rb_fd_ptr(readfds); } if (writefds) { rb_fd_resize(n - 1, writefds); w = rb_fd_ptr(writefds); } if (exceptfds) { rb_fd_resize(n - 1, exceptfds); e = rb_fd_ptr(exceptfds); } return select(n, r, w, e, timeout); } SC@GE@TFMFDUEZOBNJDBMMZBMMPDBUFTPSFYQBOETUIF CJUNBQSFHJPOTGPSUIFNPOJUPSFEGE@TFU BDDPSEJOHUPUIFNBYJNVNGEOVNCFS UISFBED

struct timeval *timeout) { fd_set *r = NULL, *w = NULL, *e = NULL; if (readfds) { rb_fd_resize(n - 1, readfds); r = rb_fd_ptr(readfds); } if (writefds) { rb_fd_resize(n - 1, writefds); w = rb_fd_ptr(writefds); } if (exceptfds) { rb_fd_resize(n - 1, exceptfds); e = rb_fd_ptr(exceptfds); } return select(n, r, w, e, timeout); } BOEQBTTFTQPJOUFSTUPUIFTFSFHJPOTUPTFMFDU UIFSFCZFOBCMJOHTVQQPSUGPS fi MFEFTDSJQUPST UIBUFYDFFE'%@4&54*;& $BMMTFMFDU XJUIUIFQPJOUFST UISFBED

$BMM4UBDLPG*0TFMFDU *0TFMFDU ➡︎ SC@G@TFMFDU ➡︎ SC@FOTVSF ➡︎
TFMFDU@DBMM ➡︎ TFMFDU@JOUFSOBM ➡︎ SC@UISFBE@GE@TFMFDU ➡︎ OBUJWF@GE@TFMFDU ➡︎ SC@GE@TFMFDU ➡︎ TFMFDU@FOE 4P EPFTO`UUIBUNFBO5$14PDLFUOFXDPVMEKVTUDBMM SC@GE@TFMFDUJOTUFBEPGDBMMJOHTFMFDU EJSFDUMZ This seems like a good fit!

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5IFMBTU%FW.FFUJOHJOUIFZFBS "TBSFTVMUPGUIFEJTDVTTJPO XFEFDJEFEUPQSPWJEFUIFGPMMPXJOHXBZTUPDPOUSPMJU ɾ"OBSHVNFOUUPUIFNFUIPE ɾ"OBDDFTTPSNFUIPEPOUIF4PDLFUDMBTT ɾ"OFOWJSPONFOUWBSJBCMF Socket.tcp(host, port, fast_fallback:
false) # Disable TCPSocket.new(host, port, fast_fallback: false) # Disable Socket.tcp_fast_fallback = false # Disable TCP_NO_FAST_FALLBACK = 1 # Disable

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5IFPVUDPNFPGJOUSPEVDJOH)&W require "rubydns" RubyDNS.run_server([[:udp, "0.0.0.0", 53], [:udp, "::", 53]]) do
match("example.com", Resolv::DNS::Resource::IN::A) do |tx| tx.respond!("127.0.0.1") end match("example.com", Resolv::DNS::Resource::IN::AAAA) do |tx| sleep Float::INFINITY tx.respond!("::1") end otherwise do |query| tx.fail!(:NXDomain) end end *QSFQBSFEB%/4TFSWFSUIBUOFWFSSFUVSOTBOZ*1W BEESFTTFT CVUSFTQPOETJNNFEJBUFMZXJUIBO*1W BEESFTT /FWFSSFUVSOTBO*1WBEESFTT 3FUVSOTBO*1WBEESFTTJNNFEJBUFMZ

$ time ruby -rsocket -e " > p TCPSocket.new('example.com', 4567,
fast_fallback: false) > " 5IFPVUDPNFPGJOUSPEVDJOH)&W 8JUIUIJT%/4TFSWFSQSPDFTTSVOOJOH fi STUSVO5$14PDLFUOFXXJUI)&WEJTBCMFE *OUIJTDBTF 3VCZPO6CVOUV

fast_fallback: false) > " #<TCPSocket:fd 5, AF_INET, 127.0.0.1, 48004> 0.06s user 0.01s system 0% cpu 15.086 total 5IFPVUDPNFPGJOUSPEVDJOH)&W JUUBLFTBCPVUTFDPOETGPSUIFNFUIPEUPDPNQMFUF 3VCZPO6CVOUV

fast_fallback: false) > " #<TCPSocket:fd 5, AF_INET, 127.0.0.1, 48004> 0.06s user 0.01s system 0% cpu 15.086 total $ time ruby -rsocket -e " > p TCPSocket.new('example.com', 4567, fast_fallback: true) > " 5IFPVUDPNFPGJOUSPEVDJOH)&W 0OUIFPUIFSIBOE XIFO)&WJTFOBCMFE 3VCZPO6CVOUV

fast_fallback: false) > " #<TCPSocket:fd 5, AF_INET, 127.0.0.1, 48004> 0.06s user 0.01s system 0% cpu 15.086 total $ time ruby -rsocket -e " > p TCPSocket.new('example.com', 4567, fast_fallback: true) > " #<TCPSocket:fd 7, AF_INET, 127.0.0.1, 54768> 0.05s user 0.01s system 52% cpu 0.114 total 5IFPVUDPNFPGJOUSPEVDJOH)&W UIFSFTVMUJTSFUVSOFEJOBCPVUTFDPOET *OBXPSTUDBTFTDFOBSJPMJLFUIJT FOBCMJOH)&W NBLFTUIFDPOOFDUJPOSPVHIMZUJNFTGBTUFS 132.3x faster! 3VCZPO6CVOUV

*NQBDUPOQFSGPSNBODF require "socket" require "benchmark" hostname = "www.ruby-lang.org" port =
80 Benchmark.bmbm do |x| x.report("fast_fallback: false") do 100.times { TCPSocket.new(hostname, port, fast_fallback: false).close } end x.report("fast_fallback: true") do 100.times { TCPSocket.new(hostname, port, fast_fallback: true).close } end end 0OUIFPUIFSIBOE SFHBSEJOHUIFJNQBDUPOQFSGPSNBODF SVOBCFODINBSLPWFSFYFDVUJPOT

*NQBDUPOQFSGPSNBODF $ time ruby benchmark.rb Rehearsal -------------------------------------------------------- fast_fallback: false 0.014033
0.078984 0.093017 ( 1.413951) fast_fallback: true 0.017588 0.097045 0.114633 ( 1.460664) ----------------------------------------------- total: 0.207650sec user system total real fast_fallback: false 0.018392 0.110852 0.129244 ( 1.466014) fast_fallback: true 0.020891 0.124054 0.144945 ( 1.473816) 'PSFYBNQMF XIFODPOOFDUJOHUPSVCZMBOHPSH UIFBWFSBHFFYFDVUJPOUJNFXBTTFDPOET XJUI)&WEJTBCMFE BOETFDPOETXJUIJUFOBCMFE 3VCZPO6CVOUV

0UIFS$POTJEFSBUJPOT#FZPOE1FSGPSNBODF "TJEFGSPNQFSGPSNBODF UIFSFNBZBMTPCFDBTFTXIFSF)&WJTOPUTVJUBCMF GPSDFSUBJOFOWJSPONFOUTPSVTFDBTFT FH ɾ8IFOUIFEFTUJOBUJPOTFSWFSMJNJUTNVMUJQMFTJNVMUBOFPVT ɹDPOOFDUJPOTGSPNUIFTBNF*1BEESFTT ɾ8IFOUIFDMJFOUIPTUIBTTUSJDUMJNJUTPOUIF ɹOVNCFSPGBWBJMBCMF
fi MFEFTDSJQUPST

0UIFS$POTJEFSBUJPOT#FZPOE1FSGPSNBODF *OTVDIDBTFT QMFBTFDPOTJEFSVTJOHUIFPQUJPOUPEJTBCMF)&W ɾ"OBSHVNFOUUPUIFNFUIPE ɾ"OBDDFTTPSNFUIPEPOUIF4PDLFUDMBTT ɾ"OFOWJSPONFOUWBSJBCMF Socket.tcp(host, port, fast_fallback:
false) # Disable TCPSocket.new(host, port, fast_fallback: false) # Disable Socket.tcp_fast_fallback = false # Disable TCP_NO_FAST_FALLBACK = 1 # Disable

BOEUIFZBMMMJWFEIBQQJMZFWFSBGUFS

BOEUIFZBMMMJWFEIBQQJMZFWFSBGUFS ➡︎ /PURVJUF 4PNFJTTVFTIBWFCFFOSFQPSUFEBGUFSUIFSFMFBTF TPNFPGUIFN* fi YFENZTFMG BOEPUIFSTXFSF fi
YFECZGFMMPX3VCZJTUT

)BQQZ&ZFCBMMT7FSTJPOJTBMSFBEZ BQBSUPG3VCZ *IPQFUIBUBTJUDPOUJOVFTUPJNQSPWF XJUIJOUIFDPNNVOJUZ JUXJMMDPOUSJCVUF UPUIFGVSUIFSFWPMVUJPOPG3VCZ

0WFSUIFQBTUZFBS UIF3VCZDPNNVOJUZIBWFUVSOFENF B3VCZJTUXJUIBOJOUFSFTUJOOFUXPSLJOH JOUPB3VCZDPNNJUUFS

"TBNFNCFSPGUIFDPNNVOJUZ *`ECFIBQQZJGTPNFPOFMJTUFOJOHUPUIJTUBML FOETVQCFDPNJOHBGVUVSFUFBNNBUF XPSLJOHUPHFUIFSPODIBMMFOHFTMJLFUIFTF

.BLJOH5$14PDLFUOFX)BQQZ 4QFDJBMUIBOLTUP !BLS !OBSVTF !KIBXUIPSO !ZVJLOL !HBDIBDPNQMFUF !ITCU !LBLVUBOJBOE3VCZDPNNJUUFST

Making TCPSocket.new "Happy"!

Making TCPSocket.new "Happy"!

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