RUBY-2869 Do not use mutexes in finalizers

Author: comandeo-mongo

lib/mongo/cluster/reapers/cursor_reaper.rb

@@ -44,6 +44,7 @@ def initialize(cluster)
         @to_kill = {}
         @active_cursor_ids = Set.new
         @mutex = Mutex.new
+        @pipe_read, @pipe_write = IO.pipe
       end
 
       attr_reader :cluster
@@ -56,12 +57,14 @@ def initialize(cluster)
       #
       # @api private
       def schedule_kill_cursor(kill_spec, server)
-        @mutex.synchronize do
-          if @active_cursor_ids.include?(kill_spec.cursor_id)
-            @to_kill[server.address.seed] ||= Set.new
-            @to_kill[server.address.seed] << kill_spec
-          end
-        end
+        msg = [
+          server.address.seed,
+          kill_spec.cursor_id,
+          kill_spec.coll_name,
+          kill_spec.db_name,
+          kill_spec.service_id
+        ].join("\t")
+        @pipe_write.puts(msg)
       end
 
       # Register a cursor id as active.
@@ -110,6 +113,25 @@ def unregister_cursor(id)
         end
       end
 
+      def read_scheduled_kill_specs
+        while readable_io = IO.select([@pipe_read], nil, nil, 0.1)
+          msg = readable_io.first[0].gets.strip
+          seed, cursor_id, coll_name, db_name, service_id = msg.split("\t")
+          kill_spec = Cursor::KillSpec.new(
+            cursor_id: cursor_id.to_i,
+            coll_name: coll_name,
+            db_name: db_name,
+            service_id: service_id
+          )
+          @mutex.synchronize do
+            if @active_cursor_ids.include?(kill_spec.cursor_id)
+              @to_kill[seed] ||= Set.new
+              @to_kill[seed] << kill_spec
+            end
+          end
+        end
+      end
+
       # Execute all pending kill cursors operations.
       #
       # @example Execute pending kill cursors operations.

lib/mongo/cursor/kill_spec.rb

@@ -33,6 +33,18 @@ def initialize(cursor_id:, coll_name:, db_name:, service_id:)
       end
 
       attr_reader :cursor_id, :coll_name, :db_name, :service_id
+
+      def ==(other)
+        cursor_id == other.cursor_id && coll_name == other.coll_name && db_name == other.db_name && service_id == other.service_id
+      end
+
+      def eql?(other)
+        self.==(other)
+      end
+
+      def hash
+        [cursor_id, coll_name, db_name, service_id].compact.hash
+      end
     end
   end
 end

spec/mongo/cluster/cursor_reaper_spec.rb

@@ -61,19 +61,22 @@
 
         before do
           reaper.schedule_kill_cursor(cursor_kill_spec_1, server)
+          reaper.read_scheduled_kill_specs
         end
 
         it 'initializes the list of op specs to a set' do
           expect(to_kill.keys).to eq([ address.seed ])
-          expect(to_kill[address.seed]).to eq(Set.new([cursor_kill_spec_1]))
+          expect(to_kill[address.seed]).to contain_exactly(cursor_kill_spec_1)
         end
       end
 
       context 'when there is a list of ops already for the server' do
 
         before do
           reaper.schedule_kill_cursor(cursor_kill_spec_1, server)
+          reaper.read_scheduled_kill_specs
           reaper.schedule_kill_cursor(cursor_kill_spec_2, server)
+          reaper.read_scheduled_kill_specs
         end
 
         it 'adds the op to the server list' do
@@ -85,6 +88,7 @@
 
           before do
             reaper.schedule_kill_cursor(cursor_kill_spec_2, server)
+            reaper.read_scheduled_kill_specs
           end
 
           it 'does not allow duplicates ops for a server' do