Wow Code, Such Read!

Abstract:
An exploration of improving at the skill of reading source code.

This talk was presented at the New Relic afterparty for RailsConf 2016 in Kansas City, MO.
Blog post: http://kwugirl.blogspot.com/2016/05/wow-code-such-read.html

Transcript

1. @kwugirl Wow Code, Such Read! KWu Ruby Agent Engineer amaze understand so power
2. @kwugirl This document and the information herein (including any information that may be incorporated by reference) is provided for informational purposes only and should not be construed as an offer, commitment, promise or obligation on behalf of New Relic, Inc. (“New Relic”) to sell securities or deliver any product, material, code, functionality, or other feature. Any information provided hereby is proprietary to New Relic and may not be replicated or disclosed without New Relic’s express written permission. Such information may contain forward-looking statements within the meaning of federal securities laws. Any statement that is not a historical fact or refers to expectations, projections, future plans, objectives, estimates, goals, or other characterizations of future events is a forward-looking statement. These forward-looking statements can often be identified as such because the context of the statement will include words such as “believes,” “anticipates,” “expects” or words of similar import. Actual results may differ materially from those expressed in these forward-looking statements, which speak only as of the date hereof, and are subject to change at any time without notice. Existing and prospective investors, customers and other third parties transacting business with New Relic are cautioned not to place undue reliance on this forward-looking information. The achievement or success of the matters covered by such forward-looking statements are based on New Relic’s current assumptions, expectations, and beliefs and are subject to substantial risks, uncertainties, assumptions, and changes in circumstances that may cause the actual results, performance, or achievements to differ materially from those expressed or implied in any forward-looking statement. Further information on factors that could affect such forward-looking statements is included in the filings we make with the SEC from time to time. Copies of these documents may be obtained by visiting New Relic’s Investor Relations website at ir.newrelic.com or the SEC’s website at www.sec.gov. New Relic assumes no obligation and does not intend to update these forward-looking statements, except as required by law. New Relic makes no warranties, expressed or implied, in this document or otherwise, with respect to the information provided.
3. @kwugirl the goal: get better at reading code
4. be fearless in diving into code you don’t know Edmond Lau theeffectiveengineer.com
5. @kwugirl 2. remember your question 3. enlist help 1. see the code
6. @kwugirl the problem
7. @kwugirl the problem connection.execute("EXPLAIN #{query}")
8. @kwugirl the problem connection.execute("EXPLAIN #{query}") SELECT "blogs".* FROM "blogs" WHERE "blogs"."id" = $1 LIMIT 1 with
9. @kwugirl the problem connection.execute("EXPLAIN #{query}") SELECT "blogs".* FROM "blogs" WHERE "blogs"."id" = $1 LIMIT 1 with
10. @kwugirl { :sql=>
 "SELECT \"blogs\".* FROM \"blogs\" WHERE \"blogs\".\"id \" = $1 LIMIT 1", … :binds=> [[#<ActiveRecord::ConnectionAdapters::PostgreSQLColumn: 0x007fd13a879e58 @array=false, @cast_type=#<ActiveRecord::ConnectionAdapters::PostgreS QL::OID::Integer:0x007fd13a87afd8 @limit=nil, @precision=nil, @range=-2147483648...2147483648, @scale=nil>,…,42]] } ActiveSupport::Notifications.subscribe 'sql.active_record'
11. @kwugirl { :sql=>
 "SELECT \"blogs\".* FROM \"blogs\" WHERE \"blogs\".\"id \" = $1 LIMIT 1", … :binds=> [[#<ActiveRecord::ConnectionAdapters::PostgreSQLColumn: 0x007fd13a879e58 @array=false, @cast_type=#<ActiveRecord::ConnectionAdapters::PostgreS QL::OID::Integer:0x007fd13a87afd8 @limit=nil, @precision=nil, @range=-2147483648...2147483648, @scale=nil>,…,42]] } ActiveSupport::Notifications.subscribe 'sql.active_record'
12. @kwugirl 2. remember your question 3. enlist help 1. see the code
13. @kwugirl
14. @kwugirl $ cd src/
15. @kwugirl $ cd src/ $ git clone git@github.com:rails/rails.git
 $ cd rails/
16. @kwugirl $ cd src/ $ git clone git@github.com:rails/rails.git
 $ cd rails/ $ git checkout v4.2.0
17. @kwugirl # Gemfile gem 'rails', '4.2.0'
18. @kwugirl # Gemfile # gem 'rails', '4.2.0' gem 'rails', :path => '../../src/rails'
19. @kwugirl @instrumenter.instrument( "sql.active_record", :sql => sql, :name => name, :connection_id => object_id, :statement_name => statement_name, :binds => binds) { yield } def log(sql, name = "SQL", binds = [], statement_name = nil) # active_record/connection_adapters/abstract_adapter.rb
20. @kwugirl @instrumenter.instrument( "sql.active_record", :sql => sql, :name => name, :connection_id => object_id, :statement_name => statement_name, :binds => binds) { yield } def log(sql, name = "SQL", binds = [], statement_name = nil) # active_record/connection_adapters/abstract_adapter.rb
21. @kwugirl @instrumenter.instrument( "sql.active_record", :sql => sql, :name => name, :connection_id => object_id, :statement_name => statement_name, :binds => binds) { yield } def log(sql, name = "SQL", binds = [], statement_name = nil) # active_record/connection_adapters/abstract_adapter.rb
22. @kwugirl def log(sql, name = "SQL", binds = [], statement_name = nil) @instrumenter.instrument( "sql.active_record", :sql => sql, :name => name, :connection_id => object_id, :statement_name => statement_name, :binds => binds) { yield } puts "====== HELLO IS IT ME YOU'RE LOOKING FOR?!!?? ======" # active_record/connection_adapters/abstract_adapter.rb
23. @kwugirl git blame (can be) your friend
24. @kwugirl 2. remember your question 3. enlist help 1. see the code
25. @kwugirl don’t get lost
26. @kwugirl don’t get lost learn one thing at a time
27. @kwugirl don’t get lost learn one thing at a time what are your unknowns?
28. @kwugirl the problem connection.execute("EXPLAIN #{query}") SELECT "blogs".* FROM "blogs" WHERE "blogs"."id" = $1 LIMIT 1 with
29. @kwugirl the problem connection.execute("EXPLAIN #{query}") SELECT "blogs".* FROM "blogs" WHERE "blogs"."id" = $1 LIMIT 1 with
30. @kwugirl the problem connection.execute("EXPLAIN #{query}") SELECT "blogs".* FROM "blogs" WHERE "blogs"."id" = $1 LIMIT 1 with
31. @kwugirl 2. remember your question 3. enlist help 1. see the code
32. @kwugirl pair programming
33. @kwugirl pair programming ?????????? ?????????? ??????????
34. @kwugirl
35. @kwugirl What are you looking for?
36. @kwugirl What are you looking for? Why?
37. @kwugirl What are you looking for? Why? How did you know to look there?
38. @kwugirl Kernel#caller
39. @kwugirl active_record/connection_adapters/postgresql_adapter.rb:601:in `exec_cache' active_record/connection_adapters/postgresql_adapter.rb:585:in `execute_and_clear' active_record/connection_adapters/postgresql/database_statements.rb:161:in `exec_query' active_record/connection_adapters/abstract/database_statements.rb:341:in `select' active_record/connection_adapters/abstract/database_statements.rb:37:in `select_all' active_record/connection_adapters/abstract/query_cache.rb:70:in `select_all' active_record/querying.rb:39:in `find_by_sql' active_record/relation.rb:639:in `exec_queries' active_record/relation.rb:514:in `load' active_record/relation.rb:243:in `to_a' active_record/relation.rb:617:in `pretty_print' Kernel#caller
40. @kwugirl Method#source_location
41. @kwugirl Method#source_location $ bundle exec rails console
42. @kwugirl Method#source_location $ bundle exec rails console irb(main):001:0> method(:try).source_location
43. @kwugirl Method#source_location $ bundle exec rails console irb(main):001:0> method(:try).source_location => ["/…/active_support/core_ext/object/try.rb", 62]
44. @kwugirl the solution connection.exec_query("EXPLAIN #{statement.sql}", "Explain #{statement.name}", statement.binds) wow beauty wonder
45. @kwugirl the solution connection.exec_query("EXPLAIN #{statement.sql}", "Explain #{statement.name}", statement.binds) wow beauty wonder
46. @kwugirl the solution connection.exec_query("EXPLAIN #{statement.sql}", "Explain #{statement.name}", statement.binds) wow beauty wonder
47. @kwugirl success!!1!one!!
48. @kwugirl success!!1!one!! $1
49. @kwugirl success!!1!one!! $1 }Explain plan
50. @kwugirl success!!1!one!! released last week in 3.15.2 $1 }Explain plan
51. @kwugirl 2. remember your question 3. enlist help 1. see the code
52. @kwugirl resources
53. @kwugirl resources readingcodegood.com
54. @kwugirl resources readingcodegood.com schneems' talk “Dissecting Ruby with Ruby”
55. @kwugirl resources readingcodegood.com schneems' talk “Dissecting Ruby with Ruby” schneems.com/2016/01/25/ruby-debugging-magic- cheat-sheet.html
 tenderlovemaking.com/2016/02/05/i-am-a-puts- debuggerer.html
56. @kwugirl appendix
57. @kwugirl doge The White Rabbit, Alice in Wonderland sad Keanu pear/pair programming Lionel Richie + Where’s Waldo !!1!one!! the “!1” phenomenon breadfish Slurms MacKenzie, Futurama