New plugin hooks around fetching gems and git sources

bundler/lib/bundler/plugin/events.rb

@@ -45,6 +45,30 @@ def self.defined_event?(event)
       #   GEM_AFTER_INSTALL = "after-install"
       define :GEM_AFTER_INSTALL,  "after-install"
 
+      # @!parse
+      #   A hook called before each individual gem is fetched for installation.
+      #   Includes a Bundler::ParallelInstaller::SpecInstallation and a source reference.
+      #   GEM_BEFORE_FETCH = "before-fetch"
+      define :GEM_BEFORE_FETCH, "before-fetch"
+
+      # @!parse
+      #   A hook called after each individual gem is fetched for installation.
+      #   Includes a Bundler::ParallelInstaller::SpecInstallation and a source reference.
+      #   GEM_AFTER_FETCH = "after-fetch"
+      define :GEM_AFTER_FETCH, "after-fetch"
+
+      # @!parse
+      #   A hook called before a git source is fetched.
+      #   Includes a Bundler::Source::Git reference.
+      #   GIT_GEM_BEFORE_FETCH = "git-before-fetch"
+      define :GIT_BEFORE_FETCH, "git-before-fetch"
+
+      # @!parse
+      #   A hook called after a git source is fetched.
+      #   Includes a Bundler::Source::Git reference.
+      #   GEM_AFTER_FETCH = "git-after-fetch"
+      define :GIT_AFTER_FETCH, "git-after-fetch"
+
       # @!parse
       #   A hook called before any gems install
       #   Includes an Array of Bundler::Dependency objects

bundler/lib/bundler/source/git.rb

@@ -191,8 +191,10 @@ def specs(*)
         set_cache_path!(app_cache_path) if use_app_cache?
 
         if requires_checkout? && !@copied
+          Plugin.hook(Plugin::Events::GIT_BEFORE_FETCH, self)
           fetch unless use_app_cache?
           checkout
+          Plugin.hook(Plugin::Events::GIT_AFTER_FETCH, self)
         end
 
         local_specs
@@ -205,7 +207,9 @@ def install(spec, options = {})
         print_using_message "Using #{version_message(spec, options[:previous_spec])} from #{self}"
 
         if (requires_checkout? && !@copied) || force
+          Plugin.hook(Plugin::Events::GEM_BEFORE_FETCH, spec, self)
           checkout
+          Plugin.hook(Plugin::Events::GEM_AFTER_FETCH, spec, self)
         end
 
         generate_bin_options = { disable_extensions: !spec.missing_extensions?, build_args: options[:build_args] }

bundler/lib/bundler/source/rubygems.rb

@@ -431,11 +431,14 @@ def fetch_names(fetchers, dependency_names, index)
       end
 
       def fetch_gem_if_possible(spec, previous_spec = nil)
-        if spec.remote
+        Plugin.hook(Plugin::Events::GEM_BEFORE_FETCH, spec, self)
+        gem_path = if spec.remote
           fetch_gem(spec, previous_spec)
         else
           cached_gem(spec)
         end
+        Plugin.hook(Plugin::Events::GEM_AFTER_FETCH, spec, self)
+        gem_path
       end
 
       def fetch_gem(spec, previous_spec = nil)

bundler/spec/plugins/hook_spec.rb

@@ -1,6 +1,79 @@
 # frozen_string_literal: true
 
 RSpec.describe "hook plugins" do
+
+  context "before-and-after-fetch hooks" do
+    before do
+      build_repo2 do
+        build_plugin "fetch-timing-timing-plugin" do |s|
+          s.write "plugins.rb", <<-RUBY
+            @timing_start = nil
+            Bundler::Plugin::API.hook Bundler::Plugin::Events::GEM_BEFORE_FETCH do |spec_install|
+              @timing_start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+              puts "gem \#{spec_install.name} started fetch at \#{@timing_start}"
+            end
+            Bundler::Plugin::API.hook Bundler::Plugin::Events::GEM_AFTER_FETCH do |spec_install|
+              timing_end = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+              puts "gem \#{spec_install.name} took \#{timing_end - @timing_start} to fetch"
+              @timing_start  = nil
+            end
+          RUBY
+        end
+      end
+
+      bundle "plugin install fetch-timing-timing-plugin --source https://gem.repo2"
+    end
+
+    it "runs before and after each rubygem is installed" do
+      install_gemfile <<-G
+        source "https://gem.repo1"
+        gem "rake"
+        gem "myrack"
+      G
+
+      expect(out).to include "gem rake started fetch at"
+      expect(out).to match /gem rake took \d+\.\d+ to fetch/
+      expect(out).to include "gem myrack started fetch at"
+      expect(out).to match /gem myrack took \d+\.\d+ to fetch/
+    end
+  end
+
+  context "before-and-after-git hooks" do
+    before do
+      build_repo2 do
+        build_plugin "fetch-timing-timing-plugin" do |s|
+          s.write "plugins.rb", <<-RUBY
+            @timing_start = nil
+            Bundler::Plugin::API.hook Bundler::Plugin::Events::GIT_BEFORE_FETCH do |spec_install|
+              @timing_start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+              puts "gem \#{spec_install.name} started git fetch/checkout at \#{@timing_start}"
+            end
+            Bundler::Plugin::API.hook Bundler::Plugin::Events::GIT_AFTER_FETCH do |spec_install|
+              timing_end = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+              puts "gem \#{spec_install.name} took \#{timing_end - @timing_start} to fetch"
+              @timing_start  = nil
+            end
+          RUBY
+        end
+      end
+
+      bundle "plugin install fetch-timing-timing-plugin --source https://gem.repo2"
+    end
+
+    it "runs before and after each git source rubygem is installed" do
+      build_git "foo", "1.0", path: lib_path("foo")
+
+      relative_path = lib_path("foo").relative_path_from(bundled_app)
+      install_gemfile <<-G, verbose: true
+        source "https://gem.repo1"
+        gem "foo", :git => "#{relative_path}"
+      G
+
+      expect(out).to include "gem foo started git fetch/checkout at"
+      expect(out).to match /gem foo took \d+\.\d+ to fetch/
+    end
+  end
+
   context "before-install-all hook" do
     before do
       build_repo2 do