Perf fix: use symbols instead of strings for const/ivar access methods
From pull request: https://github.com/ruby/ruby/pull/195
Fixes a number of places where literal, non-dynamic strings are used as the first argument for constant and instance variable get, set, and defined? methods. This reduces object overhead in all cases.
- Setting @originalfilename and @contenttype in read_multipart (cgi/core.rb). This is called for every multipart read.
- Setting @uri and @ref in DrbObject.new_with (drb/drb.rb). Called for every "with" instantiation of a DrbObject.
- Setting BINDING_QUEUE in IRB::Workspace#initialize (irb/workspace.rb). Called for every new IRB workspace.
- Getting @mon_mutex in ConditionVariable#wait (monitor.rb). Called for every #wait. This fix makes the method require zero object allocation (other than imposed by the runtime).
The other fixes are rarely called, but fixed for consistency.
make test-all passes the same with or without this patch.