base: Support setting thread priorities generically.

base/threading/platform_thread_posix.cc

Index: base/threading/platform_thread_posix.cc
diff --git a/base/threading/platform_thread_posix.cc b/base/threading/platform_thread_posix.cc
index 43e58b73375a0c3273422d9c28e10150d3835197..8b0eda27a75130e253ff78ba6f9e46b48e2e98f5 100644
--- a/base/threading/platform_thread_posix.cc
+++ b/base/threading/platform_thread_posix.cc
@@ -11,6 +11,7 @@
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/safe_strerror_posix.h"
+#include "base/synchronization/waitable_event.h"
 #include "base/threading/thread_id_name_manager.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/tracked_objects.h"
@@ -28,17 +29,18 @@
 #include <unistd.h>
 #endif
 
-#if defined(OS_ANDROID)
-#include <sys/resource.h>
-#include "base/android/thread_utils.h"
-#include "jni/ThreadUtils_jni.h"
-#endif
-
 namespace base {
 
-#if defined(OS_MACOSX)
 void InitThreading();
-#endif
+void InitOnThread();
+void TerminateOnThread();
+size_t GetDefaultThreadStackSize(const pthread_attr_t& attributes);
+
+std::ostream& operator<< (std::ostream &out,

[jar (doing other things), 2013/05/15 02:18:36]

Why do we need this?

[epennerAtGoogle, 2013/05/15 05:09:08]

Looks like I can get rid of it completely.

+                          const PlatformThreadHandle& handle) {
+  out << handle.handle;
+  return out;
+}
 
 namespace {
 
@@ -46,56 +48,34 @@ struct ThreadParams {
   PlatformThread::Delegate* delegate;
   bool joinable;
   ThreadPriority priority;
-};
-
-void SetCurrentThreadPriority(ThreadPriority priority) {
-#if defined(OS_LINUX) || defined(OS_ANDROID)
-  switch (priority) {
-    case kThreadPriority_Normal:
-      NOTREACHED() << "Don't reset priority as not all processes can.";
-      break;
-    case kThreadPriority_RealtimeAudio:
-#if defined(OS_LINUX)
-      const int kNiceSetting = -10;
-      // Linux isn't posix compliant with setpriority(2), it will set a thread
-      // priority if it is passed a tid, not affecting the rest of the threads
-      // in the process.  Setting this priority will only succeed if the user
-      // has been granted permission to adjust nice values on the system.
-      if (setpriority(PRIO_PROCESS, PlatformThread::CurrentId(), kNiceSetting))
-        DVLOG(1) << "Failed to set nice value of thread to " << kNiceSetting;
-#elif defined(OS_ANDROID)
-      JNIEnv* env = base::android::AttachCurrentThread();
-      Java_ThreadUtils_setThreadPriorityAudio(env, PlatformThread::CurrentId());
-#endif  // defined(OS_LINUX)
-      break;
+  PlatformThreadHandle* handle;
+  WaitableEvent thread_id_set;
+  ThreadParams()

[jar (doing other things), 2013/05/15 02:18:36]

nit: Constructors come before members.

[epennerAtGoogle, 2013/05/15 05:09:08]

Done.

+    : thread_id_set(false, false) {

[jar (doing other things), 2013/05/15 02:18:36]

nit: indent colon by 4.

Where are initializers for the other POD members?

[epennerAtGoogle, 2013/05/15 05:09:08]

Done.

   }
-#else  // !defined(OS_LINUX) && !defined(OS_ANDROID)
-  PlatformThread::SetThreadPriority(pthread_self(), priority);
-#endif
-}
+};
 
 void* ThreadFunc(void* params) {
-#if defined(OS_ANDROID)
-  // Threads on linux/android may inherit their priority from the thread
-  // where they were created. This sets all threads to the default.
-  // TODO(epenner): Move thread priorities to base. (crbug.com/170549)
-  if (setpriority(PRIO_PROCESS, PlatformThread::CurrentId(), 0))
-    DVLOG(1) << "Failed to reset initial thread nice value to zero.";
-#endif
+  base::InitOnThread();
   ThreadParams* thread_params = static_cast<ThreadParams*>(params);
+
   PlatformThread::Delegate* delegate = thread_params->delegate;
   if (!thread_params->joinable)
     base::ThreadRestrictions::SetSingletonAllowed(false);
 
-  // If there is a non-default priority for this thread, set it now.
-  if (thread_params->priority != kThreadPriority_Normal)
-    SetCurrentThreadPriority(thread_params->priority);
+  if (thread_params->priority != kThreadPriority_Normal) {
+    PlatformThread::SetThreadPriority(PlatformThread::CurrentHandle(),
+                                      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->id = PlatformThread::CurrentId();
+  thread_params->thread_id_set.Signal();
 
-  delete thread_params;
   delegate->ThreadMain();
-#if defined(OS_ANDROID)
-  base::android::DetachFromVM();
-#endif
+
+  base::TerminateOnThread();
   return NULL;
 }
 
@@ -103,60 +83,35 @@ bool CreateThread(size_t stack_size, bool joinable,
                   PlatformThread::Delegate* delegate,
                   PlatformThreadHandle* thread_handle,
                   ThreadPriority priority) {
-#if defined(OS_MACOSX)
   base::InitThreading();
-#endif  // OS_MACOSX
 
   bool success = false;
   pthread_attr_t attributes;
   pthread_attr_init(&attributes);
 
-  // Pthreads are joinable by default, so only specify the detached attribute if
-  // the thread should be non-joinable.
+  // Pthreads are joinable by default, so only specify the detached
+  // attribute if the thread should be non-joinable.
   if (!joinable) {
     pthread_attr_setdetachstate(&attributes, PTHREAD_CREATE_DETACHED);
   }
 
-#if defined(OS_MACOSX) && !defined(OS_IOS)
-  // The Mac OS X default for a pthread stack size is 512kB.
-  // Libc-594.1.4/pthreads/pthread.c's pthread_attr_init uses
-  // DEFAULT_STACK_SIZE for this purpose.
-  //
-  // 512kB isn't quite generous enough for some deeply recursive threads that
-  // otherwise request the default stack size by specifying 0. Here, adopt
-  // glibc's behavior as on Linux, which is to use the current stack size
-  // limit (ulimit -s) as the default stack size. See
-  // glibc-2.11.1/nptl/nptl-init.c's __pthread_initialize_minimal_internal. To
-  // avoid setting the limit below the Mac OS X default or the minimum usable
-  // stack size, these values are also considered. If any of these values
-  // can't be determined, or if stack size is unlimited (ulimit -s unlimited),
-  // stack_size is left at 0 to get the system default.
-  //
-  // Mac OS X normally only applies ulimit -s to the main thread stack. On
-  // contemporary OS X and Linux systems alike, this value is generally 8MB
-  // or in that neighborhood.
-  if (stack_size == 0) {
-    size_t default_stack_size;
-    struct rlimit stack_rlimit;
-    if (pthread_attr_getstacksize(&attributes, &default_stack_size) == 0 &&
-        getrlimit(RLIMIT_STACK, &stack_rlimit) == 0 &&
-        stack_rlimit.rlim_cur != RLIM_INFINITY) {
-      stack_size = std::max(std::max(default_stack_size,
-                                     static_cast<size_t>(PTHREAD_STACK_MIN)),
-                            static_cast<size_t>(stack_rlimit.rlim_cur));
-    }
-  }
-#endif  // OS_MACOSX && !OS_IOS
+  // Get a better default if available.
+  if (stack_size == 0)
+    stack_size = base::GetDefaultThreadStackSize(attributes);
 
   if (stack_size > 0)
     pthread_attr_setstacksize(&attributes, stack_size);
 
-  ThreadParams* params = new ThreadParams;
-  params->delegate = delegate;
-  params->joinable = joinable;
-  params->priority = priority;
+  ThreadParams params;
+  params.delegate = delegate;
+  params.joinable = joinable;
+  params.priority = priority;
+  params.handle = thread_handle;
 
-  int err = pthread_create(thread_handle, &attributes, ThreadFunc, params);
+  int err = pthread_create(&thread_handle->handle,
+                           &attributes,
+                           ThreadFunc,
+                           &params);
   success = !err;
   if (!success) {
     errno = err;
@@ -164,8 +119,12 @@ bool CreateThread(size_t stack_size, bool joinable,
   }
 
   pthread_attr_destroy(&attributes);
-  if (!success)
-    delete params;
+
+  // Don't let this call complete until the thread id
+  // is set in the handle.
+  if (success)
+    params.thread_id_set.Wait();
+
   return success;
 }
 
@@ -193,6 +152,11 @@ PlatformThreadId PlatformThread::CurrentId() {
 #endif
 }
 
+//static
+PlatformThreadHandle PlatformThread::CurrentHandle() {
+  return PlatformThreadHandle(pthread_self(), CurrentId());
+}
+
 // static
 void PlatformThread::YieldCurrentThread() {
   sched_yield();
@@ -213,42 +177,6 @@ void PlatformThread::Sleep(TimeDelta duration) {
     sleep_time = remaining;
 }
 
-#if defined(OS_LINUX)
-// static
-void PlatformThread::SetName(const char* name) {
-  ThreadIdNameManager::GetInstance()->SetName(CurrentId(), name);
-  tracked_objects::ThreadData::InitializeThreadContext(name);
-
-  // On linux we can get the thread names to show up in the debugger by setting
-  // the process name for the LWP.  We don't want to do this for the main
-  // thread because that would rename the process, causing tools like killall
-  // to stop working.
-  if (PlatformThread::CurrentId() == getpid())
-    return;
-
-  // http://0pointer.de/blog/projects/name-your-threads.html
-  // Set the name for the LWP (which gets truncated to 15 characters).
-  // Note that glibc also has a 'pthread_setname_np' api, but it may not be
-  // available everywhere and it's only benefit over using prctl directly is
-  // that it can set the name of threads other than the current thread.
-  int err = prctl(PR_SET_NAME, name);
-  // We expect EPERM failures in sandboxed processes, just ignore those.
-  if (err < 0 && errno != EPERM)
-    DPLOG(ERROR) << "prctl(PR_SET_NAME)";
-}
-#elif defined(OS_MACOSX)
-// Mac is implemented in platform_thread_mac.mm.
-#else
-// static
-void PlatformThread::SetName(const char* name) {
-  ThreadIdNameManager::GetInstance()->SetName(CurrentId(), name);
-  tracked_objects::ThreadData::InitializeThreadContext(name);
-
-  // (This should be relatively simple to implement for the BSDs; I
-  // just don't have one handy to test the code on.)
-}
-#endif  // defined(OS_LINUX)
-
 // static
 const char* PlatformThread::GetName() {
   return ThreadIdNameManager::GetInstance()->GetName(CurrentId());
@@ -257,6 +185,7 @@ const char* PlatformThread::GetName() {
 // static
 bool PlatformThread::Create(size_t stack_size, Delegate* delegate,
                             PlatformThreadHandle* thread_handle) {
+  base::ThreadRestrictions::ScopedAllowWait allow_wait;
   return CreateThread(stack_size, true /* joinable thread */,
                       delegate, thread_handle, kThreadPriority_Normal);
 }
@@ -265,6 +194,7 @@ bool PlatformThread::Create(size_t stack_size, Delegate* delegate,
 bool PlatformThread::CreateWithPriority(size_t stack_size, Delegate* delegate,
                                         PlatformThreadHandle* thread_handle,
                                         ThreadPriority priority) {
+  base::ThreadRestrictions::ScopedAllowWait allow_wait;
   return CreateThread(stack_size, true,  // joinable thread
                       delegate, thread_handle, priority);
 }
@@ -273,6 +203,7 @@ bool PlatformThread::CreateWithPriority(size_t stack_size, Delegate* delegate,
 bool PlatformThread::CreateNonJoinable(size_t stack_size, Delegate* delegate) {
   PlatformThreadHandle unused;
 
+  base::ThreadRestrictions::ScopedAllowWait allow_wait;
   bool result = CreateThread(stack_size, false /* non-joinable thread */,
                              delegate, &unused, kThreadPriority_Normal);
   return result;
@@ -284,21 +215,7 @@ void PlatformThread::Join(PlatformThreadHandle thread_handle) {
   // the thread referred to by |thread_handle| may still be running long-lived /
   // blocking tasks.
   base::ThreadRestrictions::AssertIOAllowed();
-  pthread_join(thread_handle, NULL);
-}
-
-#if !defined(OS_MACOSX) && !defined(OS_ANDROID)
-// Mac OS X uses lower-level mach APIs and Android uses Java APIs.
-// static
-void PlatformThread::SetThreadPriority(PlatformThreadHandle, ThreadPriority) {
-  // TODO(crogers): Implement, see http://crbug.com/116172
-}
-#endif
-
-#if defined(OS_ANDROID)
-bool RegisterThreadUtils(JNIEnv* env) {
-  return RegisterNativesImpl(env);
+  pthread_join(thread_handle.handle, NULL);
 }
-#endif  // defined(OS_ANDROID)
 
 }  // namespace base