Use a semaphore to signal message availability

The Event hack was too much of a hack: on actually thinking about it,
there's a rather obvious race.

1 files changed, 8 insertions, 7 deletions

diff --git a/actioncable/test/client_test.rb b/actioncable/test/client_test.rb
index d30c381131..26629216e5 100644
--- a/actioncable/test/client_test.rb
+++ b/actioncable/test/client_test.rb
@@ -54,7 +54,7 @@ class ClientTest < ActionCable::TestCase
       @ws = Faye::WebSocket::Client.new("ws://127.0.0.1:#{port}/")
       @messages = Queue.new
       @closed = Concurrent::Event.new
-      @has_messages = Concurrent::Event.new
+      @has_messages = Concurrent::Semaphore.new(0)
       @pings = 0
 
       open = Concurrent::Event.new
@@ -79,7 +79,7 @@ class ClientTest < ActionCable::TestCase
           @pings += 1
         else
           @messages << hash
-          @has_messages.set
+          @has_messages.release
         end
       end
 
@@ -92,8 +92,7 @@ class ClientTest < ActionCable::TestCase
     end
 
     def read_message
-      @has_messages.wait(WAIT_WHEN_EXPECTING_EVENT) if @messages.empty?
-      @has_messages.reset if @messages.size < 2
+      @has_messages.try_acquire(1, WAIT_WHEN_EXPECTING_EVENT)
 
       msg = @messages.pop(true)
       raise msg if msg.is_a?(Exception)
@@ -104,9 +103,11 @@ class ClientTest < ActionCable::TestCase
     def read_messages(expected_size = 0)
       list = []
       loop do
-        @has_messages.wait(list.size < expected_size ? WAIT_WHEN_EXPECTING_EVENT : WAIT_WHEN_NOT_EXPECTING_EVENT)
-        if @has_messages.set?
-          list << read_message
+        if @has_messages.try_acquire(1, list.size < expected_size ? WAIT_WHEN_EXPECTING_EVENT : WAIT_WHEN_NOT_EXPECTING_EVENT)
+          msg = @messages.pop(true)
+          raise msg if msg.is_a?(Exception)
+
+          list << msg
         else
           break
         end