Make it possible to remove an Awakable with a specific "context" from a Dispatcher.

mojo/edk/system/awakable_list_unittest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // NOTE(vtl): Some of these tests are inherently flaky (e.g., if run on a
 // heavily-loaded system). Sorry. |test::EpsilonTimeout()| may be increased to
 // increase tolerance and reduce observed flakiness (though doing so reduces the
 // meaningfulness of the test).
 
 #include "mojo/edk/system/awakable_list.h"
@@ skipping 267 matching lines @@
   EXPECT_EQ(MOJO_RESULT_OK, result1);
   EXPECT_EQ(7u, context1);
   EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION, result2);
   EXPECT_EQ(8u, context2);
   EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION, result3);
   EXPECT_EQ(9u, context3);
   EXPECT_EQ(MOJO_RESULT_CANCELLED, result4);
   EXPECT_EQ(10u, context4);
 }
 
+TEST(AwakableListTest, RemoveWithContext) {
+  MojoResult result;
+  uint64_t context;
+
+  {
+    AwakableList awakable_list;
+    test::SimpleWaiterThread thread(&result, &context);
+    awakable_list.Add(thread.waiter(), MOJO_HANDLE_SIGNAL_READABLE, 1);
+    awakable_list.Add(thread.waiter(), MOJO_HANDLE_SIGNAL_READABLE, 2);
+    thread.Start();
+    awakable_list.RemoveWithContext(thread.waiter(), 2);
+    awakable_list.AwakeForStateChange(HandleSignalsState(
+        MOJO_HANDLE_SIGNAL_READABLE,
+        MOJO_HANDLE_SIGNAL_READABLE | MOJO_HANDLE_SIGNAL_WRITABLE));
+    awakable_list.RemoveWithContext(thread.waiter(), 1);
+    // Double-remove okay:
+    awakable_list.RemoveWithContext(thread.waiter(), 1);
+  }  // Join |thread|.
+  EXPECT_EQ(MOJO_RESULT_OK, result);
+  EXPECT_EQ(1u, context);
+
+  // Try the same thing, but remove "1" before the awake instead.
+  {
+    AwakableList awakable_list;
+    test::SimpleWaiterThread thread(&result, &context);
+    awakable_list.Add(thread.waiter(), MOJO_HANDLE_SIGNAL_READABLE, 1);
+    awakable_list.Add(thread.waiter(), MOJO_HANDLE_SIGNAL_READABLE, 2);
+    thread.Start();
+    awakable_list.RemoveWithContext(thread.waiter(), 1);
+    awakable_list.AwakeForStateChange(HandleSignalsState(
+        MOJO_HANDLE_SIGNAL_READABLE,
+        MOJO_HANDLE_SIGNAL_READABLE | MOJO_HANDLE_SIGNAL_WRITABLE));
+    awakable_list.RemoveWithContext(thread.waiter(), 2);
+  }  // Join |thread|.
+  EXPECT_EQ(MOJO_RESULT_OK, result);
+  EXPECT_EQ(2u, context);
+}
+
 class KeepAwakable : public Awakable {
  public:
   KeepAwakable() : awake_count(0) {}
 
   bool Awake(MojoResult result, uint64_t context) override {
     awake_count++;
     return true;
   }
 
   int awake_count;
@@ skipping 52 matching lines @@
   EXPECT_EQ(keep1.awake_count, 2);
   EXPECT_EQ(remove2.awake_count, 1);
 
   remove_first.Remove(&keep0);
   remove_first.Remove(&keep1);
 }
 
 }  // namespace
 }  // namespace system
 }  // namespace mojo