[rubygems/rubygems] (Further) Improve Bundler::Settings#[] performance and memory usage

I previously identified and improved this method over in https://github.com/rubygems/rubygems/pull/6884
but while reviewing another memory_profiler profile, I realized another
gain we can eek out.

This method keeps comes up in part because `configs` is allocating a new
Hash every time. My last change took advantage of that by using `map!`
on it. `configs` is called quite often, including in this `[]` method,
so there's a benefit to memoizing it.

Back in `[]`, logically we are trying to find the first Hash in `configs`
that has a value for the given key. Currently, we end up `map` and
`compact` to just get that value.

Instead, we can use a loop over `configs`, and break when we find the
value for the key.

https://github.com/rubygems/rubygems/commit/b913cfc87b

1 files changed, 8 insertions, 5 deletions

diff --git a/lib/bundler/settings.rb b/lib/bundler/settings.rb
index f5999481a8..e31f207d90 100644
--- a/lib/bundler/settings.rb
+++ b/lib/bundler/settings.rb
@@ -102,10 +102,13 @@ module Bundler
     def [](name)
       key = key_for(name)
 
-      values = configs.values
-      values.map! {|config| config[key] }
-      values.compact!
-      value = values.first
+      value = nil
+      configs.each do |_, config|
+        if config[key]
+          value = config[key]
+          break
+        end
+      end
 
       converted_value(value, name)
     end
@@ -316,7 +319,7 @@ module Bundler
     private
 
     def configs
-      {
+      @configs ||= {
         :temporary => @temporary,
         :local => @local_config,
         :env => @env_config,