base/threading: restrict to set only current thread priority

base/threading/platform_thread_posix.cc

 // 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.
 
 #include "base/threading/platform_thread.h"
 
 #include <errno.h>
 #include <pthread.h>
 #include <sched.h>
 #include <sys/resource.h>
@@ skipping 41 matching lines @@
 
 void* ThreadFunc(void* params) {
   base::InitOnThread();
   ThreadParams* thread_params = static_cast<ThreadParams*>(params);
 
   PlatformThread::Delegate* delegate = thread_params->delegate;
   if (!thread_params->joinable)
     base::ThreadRestrictions::SetSingletonAllowed(false);
 
   if (thread_params->priority != ThreadPriority::NORMAL) {
-    PlatformThread::SetThreadPriority(PlatformThread::CurrentHandle(),
-                                      thread_params->priority);
+    PlatformThread::SetCurrentThreadPriority(thread_params->priority);
   }
 
   // Stash the id in the handle so the calling thread has a complete
   // handle, and unblock the parent thread.
   *(thread_params->handle) = PlatformThreadHandle(pthread_self(),
                                                   PlatformThread::CurrentId());
   thread_params->handle_set.Signal();
 
   ThreadIdNameManager::GetInstance()->RegisterThread(
       PlatformThread::CurrentHandle().platform_handle(),
@@ skipping 150 matching lines @@
 
 // static
 void PlatformThread::Join(PlatformThreadHandle thread_handle) {
   // Joining another thread may block the current thread for a long time, since
   // the thread referred to by |thread_handle| may still be running long-lived /
   // blocking tasks.
   base::ThreadRestrictions::AssertIOAllowed();
   CHECK_EQ(0, pthread_join(thread_handle.platform_handle(), NULL));
 }
 
-// Mac has its own Set/GetThreadPriority() implementations.
+// Mac has its own Set/GetCurrentThreadPriority() implementations.
 #if !defined(OS_MACOSX)
 
 // static
-void PlatformThread::SetThreadPriority(PlatformThreadHandle handle,
-                                       ThreadPriority priority) {
+void PlatformThread::SetCurrentThreadPriority(ThreadPriority priority) {
 #if defined(OS_NACL)
   NOTIMPLEMENTED();
 #else
-  if (internal::SetThreadPriorityForPlatform(handle, priority))
+  if (internal::SetCurrentThreadPriorityForPlatform(priority))
     return;
 
   // setpriority(2) should change the whole thread group's (i.e. process)
   // priority. However, as stated in the bugs section of
   // http://man7.org/linux/man-pages/man2/getpriority.2.html: "under the current
   // Linux/NPTL implementation of POSIX threads, the nice value is a per-thread
   // attribute". Also, 0 is prefered to the current thread id since it is
   // equivalent but makes sandboxing easier (https://crbug.com/399473).
-  DCHECK_NE(handle.id(), kInvalidThreadId);
   const int nice_setting = internal::ThreadPriorityToNiceValue(priority);
-  const PlatformThreadId current_id = PlatformThread::CurrentId();
-  if (setpriority(PRIO_PROCESS, handle.id() == current_id ? 0 : handle.id(),
-                  nice_setting)) {
-    DVPLOG(1) << "Failed to set nice value of thread (" << handle.id()
+  if (setpriority(PRIO_PROCESS, 0, nice_setting)) {
+    DVPLOG(1) << "Failed to set nice value of thread ("
+              << PlatformThread::CurrentHandle().id()

[gab, 2015/06/23 17:01:32]

If I'm not mistaken this is the only use of PlatformHandle::id() after this CL;
if so, and especially if the only use case is logging now, we should remove it
and log PlatformThread::CurrentId() instead.

I never liked the fact that the id() property as it's not cross-platform (not
set on Windows) and am excited to get rid of it if we can :-).

(this could in this CL or as a follow-up CL with a TODO in this one, I'm fine
either way)

[Takashi Toyoshima, 2015/06/24 04:15:39]

Thread::thread_id() still calls it, so it isn't as simple as I do it in this
patch.

But it is needed for one of my goal,
https://codereview.chromium.org/1150563002/.
I tried to achieve it without removing it, but it caused tricky issues. So, I'm
also happy if I can remove it. I'd add TODO in the header file.

               << ") to " << nice_setting;
   }
 #endif  // defined(OS_NACL)
 }
 
 // static
-ThreadPriority PlatformThread::GetThreadPriority(PlatformThreadHandle handle) {
+ThreadPriority PlatformThread::GetCurrentThreadPriority() {
 #if defined(OS_NACL)
   NOTIMPLEMENTED();
   return ThreadPriority::NORMAL;
 #else
-  // Mirrors SetThreadPriority()'s implementation.
+  // Mirrors SetCurrentThreadPriority()'s implementation.
   ThreadPriority platform_specific_priority;
-  if (internal::GetThreadPriorityForPlatform(handle,
-                                             &platform_specific_priority)) {
+  if (internal::GetCurrentThreadPriorityForPlatform(
+      &platform_specific_priority)) {
     return platform_specific_priority;
   }
 
-  DCHECK_NE(handle.id(), kInvalidThreadId);
-  const PlatformThreadId current_id = PlatformThread::CurrentId();
   // Need to clear errno before calling getpriority():
   // http://man7.org/linux/man-pages/man2/getpriority.2.html
   errno = 0;
-  int nice_value =
-      getpriority(PRIO_PROCESS, handle.id() == current_id ? 0 : handle.id());
+  int nice_value = getpriority(PRIO_PROCESS, 0);
   if (errno != 0) {
-    DVPLOG(1) << "Failed to get nice value of thread (" << handle.id() << ")";
+    DVPLOG(1) << "Failed to get nice value of thread ("
+              << PlatformThread::CurrentHandle().id()
+              << ")";
     return ThreadPriority::NORMAL;
   }
 
   return internal::NiceValueToThreadPriority(nice_value);
 #endif  // !defined(OS_NACL)
 }
 
 #endif  // !defined(OS_MACOSX)
 
 }  // namespace base