(maint) Do not recurse into recursive globbed exclusions when purging

When we purge at the environment level we create recurse globs of our
Puppetfile managed directories, eg "<environment>/modules/**/*".

Previous to this patch we would collect a list of all content in the
environment and then match them against this recursive glob using
`File.fnmatch?`. This means we could be doing fnmatches against hundreds
of thousands of then-filtered results which can become prohibitively
slow.

This patch removes the usage of Dir.glob to retrieve all files and
instead manually recurses into child directories if set to recurse and
the child does not match either the purge_exclusions or whitelist globs.
However, because we match using a glob something like
"<environment>/modules/**/*" won't match "<environment>/modules", but
instead will filter each module within "<environment>/modules". In large
deployments this may mean filtering over a thousand child files, but
will prevent us from recursing into any of the modules themselves.

This maintains the post-recursion filtering of "desired_contents" as
this is how git-backed, environment maintained files are cleaned.

lib/r10k/util/purgeable.rb

@@ -38,16 +38,16 @@ def current_contents(recurse)
         end
       end
 
+      # @deprecated Unused helper function
       # @return [Array<String>] Directory contents that are expected but not present
       def pending_contents(recurse)
         desired_contents - current_contents(recurse)
       end
 
-      # @return [Array<String>] Directory contents that are present but not expected
-      def stale_contents(recurse, exclusions, whitelist)
-        fn_match_opts = File::FNM_PATHNAME | File::FNM_DOTMATCH
+      def potentially_purgeable(dir, exclusions, whitelist, recurse, fn_match_opts)
+        children = Pathname.new(dir).children.reject do |item|
+          item = item.to_s
 
-        (current_contents(recurse) - desired_contents).reject do |item|
           if exclusion_match = exclusions.find { |ex_item| (ex_item == item) || File.fnmatch?(ex_item, item, fn_match_opts) }
             logger.debug2 _("Not purging %{item} due to internal exclusion match: %{exclusion_match}") % {item: item, exclusion_match: exclusion_match}
           elsif whitelist_match = whitelist.find { |wl_item| (wl_item == item) || File.fnmatch?(wl_item, item, fn_match_opts) }
@@ -56,6 +56,29 @@ def stale_contents(recurse, exclusions, whitelist)
 
           !!exclusion_match || !!whitelist_match
         end
+
+        children.flat_map do |child|
+          if File.directory?(child) && recurse
+            potentially_purgeable(child, exclusions, whitelist, recurse, fn_match_opts)
+          else
+            child.to_s
+          end
+        end.compact
+      end
+
+      # @return [Array<String>] Directory contents that are present but not expected
+      def stale_contents(recurse, exclusions, whitelist)
+        dirs = self.managed_directories
+        desired = self.desired_contents
+        fn_match_opts = File::FNM_PATHNAME | File::FNM_DOTMATCH
+
+        initial_purgelist = dirs.flat_map do |dir|
+          potentially_purgeable(dir, exclusions, whitelist, recurse, fn_match_opts)
+        end
+
+        initial_purgelist.reject do |item|
+          !!desired.find { |des_item| (des_item == item) || File.fnmatch?(des_item, item, fn_match_opts) }
+        end
       end
 
       # Forcibly remove all unmanaged content in `self.managed_directories`

spec/unit/util/purgeable_spec.rb

@@ -98,7 +98,12 @@
 
     describe '#current_contents' do
       it 'collects contents of all managed directories recursively' do
-        expect(subject.current_contents(recurse)).to contain_exactly(/\/expected_1/, /\/expected_2/, /\/unmanaged_1/, /\/unmanaged_2/, /\/managed_subdir_1/, /\/subdir_expected_1/, /\/subdir_unmanaged_1/)
+        expect(subject.current_contents(recurse)).
+          to contain_exactly(/\/expected_1/, /\/expected_2/,
+                             /\/unmanaged_1/, /\/unmanaged_2/,
+                             /\/managed_subdir_1/,
+                             /\/subdir_expected_1/, /\/subdir_unmanaged_1/,
+                             /\/managed_subdir_2/, /\/ignored_1/)
       end
     end
 
@@ -114,7 +119,8 @@
         let(:whitelist) { [] }
 
         it 'collects current_contents that should not exist recursively' do
-          expect(subject.stale_contents(recurse, exclusions, whitelist)).to contain_exactly(/\/unmanaged_1/, /\/unmanaged_2/, /\/subdir_unmanaged_1/)
+          expect(subject.stale_contents(recurse, exclusions, whitelist)).
+            to contain_exactly(/\/unmanaged_1/, /\/unmanaged_2/, /\/subdir_unmanaged_1/, /\/ignored_1/)
         end
       end
 
@@ -124,7 +130,17 @@
 
         it 'collects current_contents that should not exist except whitelisted items' do
           expect(subject.logger).to receive(:debug).with(/unmanaged_1.*whitelist match/i)
-          expect(subject.stale_contents(recurse, exclusions, whitelist)).to contain_exactly(/\/unmanaged_2/, /\/subdir_unmanaged_1/)
+
+          expect(subject.stale_contents(recurse, exclusions, whitelist)).
+            to contain_exactly(/\/unmanaged_2/, /\/subdir_unmanaged_1/, /\/ignored_1/)
+        end
+
+        it 'does not collect contents that match recursive globbed whitelist items as intermediate values' do
+          recursive_whitelist = ['**/managed_subdir_1/**/*']
+          expect(subject.logger).not_to receive(:debug).with(/ignored_1/)
+
+          expect(subject.stale_contents(recurse, exclusions, recursive_whitelist)).
+            to contain_exactly(/\/unmanaged_2/, /\/managed_one\/unmanaged_1/)
         end
       end
 
@@ -134,7 +150,17 @@
 
         it 'collects current_contents that should not exist except excluded items' do
           expect(subject.logger).to receive(:debug2).with(/unmanaged_2.*internal exclusion match/i)
-          expect(subject.stale_contents(recurse, exclusions, whitelist)).to contain_exactly(/\/unmanaged_1/, /\/subdir_unmanaged_1/)
+
+          expect(subject.stale_contents(recurse, exclusions, whitelist)).
+            to contain_exactly(/\/unmanaged_1/, /\/subdir_unmanaged_1/, /\/ignored_1/)
+        end
+
+        it 'does not collect contents that match recursive globbed exclusion items as intermediate values' do
+          recursive_exclusions = ['**/managed_subdir_1/**/*']
+          expect(subject.logger).not_to receive(:debug).with(/ignored_1/)
+
+          expect(subject.stale_contents(recurse, recursive_exclusions, whitelist)).
+            to contain_exactly(/\/unmanaged_2/, /\/managed_one\/unmanaged_1/)
         end
       end
     end
@@ -179,7 +205,11 @@
     end
 
     context "recursive whitelist glob" do
-      let(:whitelist) { managed_directories.collect { |dir| File.join(dir, "**", "*unmanaged*") } }
+      let(:whitelist) do
+        managed_directories.flat_map do |dir|
+          [File.join(dir, "**", "*unmanaged*"), File.join(dir, "**", "managed_subdir_2")]
+        end
+      end
       let(:purge_opts) { { recurse: true, whitelist: whitelist } }
 
       describe '#purge!' do
@@ -214,7 +244,7 @@
     context "when class does not implement #purge_exclusions" do
       describe '#purge!' do
         it 'purges normally' do
-          expect(FileUtils).to receive(:rm_r).at_least(3).times
+          expect(FileUtils).to receive(:rm_r).at_least(4).times
 
           subject.purge!(purge_opts)
         end