[Mac] In PlatformThread::CurrentId(), use pthread_self() instead of mach_thread_self().

BUG=105513
TEST=none


Review URL: http://codereview.chromium.org/9281011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@118780 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 19 insertions, 17 deletions

diff --git a/base/threading/platform_thread.h b/base/threading/platform_thread.h
index f958ef6..3aa3879 100644
--- a/base/threading/platform_thread.h
+++ b/base/threading/platform_thread.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 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.
 
@@ -19,12 +19,8 @@
 #include <windows.h>
 #elif defined(OS_POSIX)
 #include <pthread.h>
-#if defined(OS_MACOSX)
-#include <mach/mach.h>
-#else  // OS_POSIX && !OS_MACOSX
 #include <unistd.h>
 #endif
-#endif
 
 namespace base {
 
@@ -39,12 +35,8 @@ const PlatformThreadHandle kNullThreadHandle = NULL;
 #elif defined(OS_POSIX)
 typedef pthread_t PlatformThreadHandle;
 const PlatformThreadHandle kNullThreadHandle = 0;
-#if defined(OS_MACOSX)
-typedef mach_port_t PlatformThreadId;
-#else  // OS_POSIX && !OS_MACOSX
 typedef pid_t PlatformThreadId;
 #endif
-#endif
 
 const PlatformThreadId kInvalidThreadId = 0;
 
diff --git a/base/threading/platform_thread_posix.cc b/base/threading/platform_thread_posix.cc
index 7eda4e9..27e666a 100644
--- a/base/threading/platform_thread_posix.cc
+++ b/base/threading/platform_thread_posix.cc
@@ -16,7 +16,6 @@
 #include "base/tracked_objects.h"
 
 #if defined(OS_MACOSX)
-#include <mach/mach.h>
 #include <sys/resource.h>
 #include <algorithm>
 #endif
@@ -132,11 +131,7 @@ bool CreateThread(size_t stack_size, bool joinable,
 PlatformThreadId PlatformThread::CurrentId() {
   // Pthreads doesn't have the concept of a thread ID, so we have to reach down
   // into the kernel.
-#if defined(OS_MACOSX)
-  mach_port_t port = mach_thread_self();
-  mach_port_deallocate(mach_task_self(), port);
-  return port;
-#elif defined(OS_LINUX)
+#if defined(OS_LINUX)
   return syscall(__NR_gettid);
 #elif defined(OS_ANDROID)
   return gettid();
diff --git a/base/threading/worker_pool_posix_unittest.cc b/base/threading/worker_pool_posix_unittest.cc
index 1b700e1..a8d9218 100644
--- a/base/threading/worker_pool_posix_unittest.cc
+++ b/base/threading/worker_pool_posix_unittest.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 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.
 
@@ -231,7 +231,22 @@ TEST_F(PosixDynamicThreadPoolTest, Complex) {
   pool_->PostTask(FROM_HERE, CreateNewIncrementingTaskCallback());
   WaitForIdleThreads(1);
 
-  EXPECT_EQ(3U, unique_threads_.size());
+  // The POSIX implementation of PlatformThread::CurrentId() uses pthread_self()
+  // which is not guaranteed to be unique after a thread joins. The OS X
+  // implemntation of pthread_self() returns the address of the pthread_t, which
+  // is merely a malloc()ed pointer stored in the first TLS slot. When a thread
+  // joins and that structure is freed, the block of memory can be put on the
+  // OS free list, meaning the same address could be reused in a subsequent
+  // allocation. This in fact happens when allocating in a loop as this test
+  // does.
+  //
+  // Because there are two concurrent threads, there's at least the guarantee
+  // of having two unique thread IDs in the set. But after those two threads are
+  // joined, the next-created thread can get a re-used ID if the allocation of
+  // the pthread_t structure is taken from the free list. Therefore, there can
+  // be either 2 or 3 unique thread IDs in the set at this stage in the test.
+  EXPECT_TRUE(unique_threads_.size() >= 2 && unique_threads_.size() <= 3)
+      << "unique_threads_.size() = " << unique_threads_.size();
   EXPECT_EQ(1, peer_.num_idle_threads());
   EXPECT_EQ(4, counter_);
 }