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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "base/threading/platform_thread.h"
      6 
      7 #include "base/debug/alias.h"
      8 #include "base/debug/profiler.h"
      9 #include "base/logging.h"
     10 #include "base/threading/thread_id_name_manager.h"
     11 #include "base/threading/thread_restrictions.h"
     12 #include "base/tracked_objects.h"
     13 
     14 #include "base/win/windows_version.h"
     15 
     16 namespace base {
     17 
     18 namespace {
     19 
     20 // The information on how to set the thread name comes from
     21 // a MSDN article: http://msdn2.microsoft.com/en-us/library/xcb2z8hs.aspx
     22 const DWORD kVCThreadNameException = 0x406D1388;
     23 
     24 typedef struct tagTHREADNAME_INFO {
     25   DWORD dwType;  // Must be 0x1000.
     26   LPCSTR szName;  // Pointer to name (in user addr space).
     27   DWORD dwThreadID;  // Thread ID (-1=caller thread).
     28   DWORD dwFlags;  // Reserved for future use, must be zero.
     29 } THREADNAME_INFO;
     30 
     31 // This function has try handling, so it is separated out of its caller.
     32 void SetNameInternal(PlatformThreadId thread_id, const char* name) {
     33   THREADNAME_INFO info;
     34   info.dwType = 0x1000;
     35   info.szName = name;
     36   info.dwThreadID = thread_id;
     37   info.dwFlags = 0;
     38 
     39   __try {
     40     RaiseException(kVCThreadNameException, 0, sizeof(info)/sizeof(DWORD),
     41                    reinterpret_cast<DWORD_PTR*>(&info));
     42   } __except(EXCEPTION_CONTINUE_EXECUTION) {
     43   }
     44 }
     45 
     46 struct ThreadParams {
     47   PlatformThread::Delegate* delegate;
     48   bool joinable;
     49 };
     50 
     51 DWORD __stdcall ThreadFunc(void* params) {
     52   ThreadParams* thread_params = static_cast<ThreadParams*>(params);
     53   PlatformThread::Delegate* delegate = thread_params->delegate;
     54   if (!thread_params->joinable)
     55     base::ThreadRestrictions::SetSingletonAllowed(false);
     56 
     57   /* Retrieve a copy of the thread handle to use as the key in the
     58    * thread name mapping. */
     59   PlatformThreadHandle::Handle platform_handle;
     60   DuplicateHandle(
     61       GetCurrentProcess(),
     62       GetCurrentThread(),
     63       GetCurrentProcess(),
     64       &platform_handle,
     65       0,
     66       FALSE,
     67       DUPLICATE_SAME_ACCESS);
     68 
     69   ThreadIdNameManager::GetInstance()->RegisterThread(
     70       platform_handle,
     71       PlatformThread::CurrentId());
     72 
     73   delete thread_params;
     74   delegate->ThreadMain();
     75 
     76   ThreadIdNameManager::GetInstance()->RemoveName(
     77       platform_handle,
     78       PlatformThread::CurrentId());
     79   return NULL;
     80 }
     81 
     82 // CreateThreadInternal() matches PlatformThread::Create(), except that
     83 // |out_thread_handle| may be NULL, in which case a non-joinable thread is
     84 // created.
     85 bool CreateThreadInternal(size_t stack_size,
     86                           PlatformThread::Delegate* delegate,
     87                           PlatformThreadHandle* out_thread_handle) {
     88   unsigned int flags = 0;
     89   if (stack_size > 0 && base::win::GetVersion() >= base::win::VERSION_XP) {
     90     flags = STACK_SIZE_PARAM_IS_A_RESERVATION;
     91   } else {
     92     stack_size = 0;
     93   }
     94 
     95   ThreadParams* params = new ThreadParams;
     96   params->delegate = delegate;
     97   params->joinable = out_thread_handle != NULL;
     98 
     99   // Using CreateThread here vs _beginthreadex makes thread creation a bit
    100   // faster and doesn't require the loader lock to be available.  Our code will
    101   // have to work running on CreateThread() threads anyway, since we run code
    102   // on the Windows thread pool, etc.  For some background on the difference:
    103   //   http://www.microsoft.com/msj/1099/win32/win321099.aspx
    104   void* thread_handle = CreateThread(
    105       NULL, stack_size, ThreadFunc, params, flags, NULL);
    106   if (!thread_handle) {
    107     delete params;
    108     return false;
    109   }
    110 
    111   if (out_thread_handle)
    112     *out_thread_handle = PlatformThreadHandle(thread_handle);
    113   else
    114     CloseHandle(thread_handle);
    115   return true;
    116 }
    117 
    118 }  // namespace
    119 
    120 // static
    121 PlatformThreadId PlatformThread::CurrentId() {
    122   return GetCurrentThreadId();
    123 }
    124 
    125 // static
    126 PlatformThreadHandle PlatformThread::CurrentHandle() {
    127   NOTIMPLEMENTED(); // See OpenThread()
    128   return PlatformThreadHandle();
    129 }
    130 
    131 // static
    132 void PlatformThread::YieldCurrentThread() {
    133   ::Sleep(0);
    134 }
    135 
    136 // static
    137 void PlatformThread::Sleep(TimeDelta duration) {
    138   // When measured with a high resolution clock, Sleep() sometimes returns much
    139   // too early. We may need to call it repeatedly to get the desired duration.
    140   TimeTicks end = TimeTicks::Now() + duration;
    141   TimeTicks now;
    142   while ((now = TimeTicks::Now()) < end)
    143     ::Sleep((end - now).InMillisecondsRoundedUp());
    144 }
    145 
    146 // static
    147 void PlatformThread::SetName(const char* name) {
    148   ThreadIdNameManager::GetInstance()->SetName(CurrentId(), name);
    149 
    150   // On Windows only, we don't need to tell the profiler about the "BrokerEvent"
    151   // thread, as it exists only in the chrome.exe image, and never spawns or runs
    152   // tasks (items which could be profiled).  This test avoids the notification,
    153   // which would also (as a side effect) initialize the profiler in this unused
    154   // context, including setting up thread local storage, etc.  The performance
    155   // impact is not terrible, but there is no reason to do initialize it.
    156   if (0 != strcmp(name, "BrokerEvent"))
    157     tracked_objects::ThreadData::InitializeThreadContext(name);
    158 
    159   // The debugger needs to be around to catch the name in the exception.  If
    160   // there isn't a debugger, we are just needlessly throwing an exception.
    161   // If this image file is instrumented, we raise the exception anyway
    162   // to provide the profiler with human-readable thread names.
    163   if (!::IsDebuggerPresent() && !base::debug::IsBinaryInstrumented())
    164     return;
    165 
    166   SetNameInternal(CurrentId(), name);
    167 }
    168 
    169 // static
    170 const char* PlatformThread::GetName() {
    171   return ThreadIdNameManager::GetInstance()->GetName(CurrentId());
    172 }
    173 
    174 // static
    175 bool PlatformThread::Create(size_t stack_size, Delegate* delegate,
    176                             PlatformThreadHandle* thread_handle) {
    177   DCHECK(thread_handle);
    178   return CreateThreadInternal(stack_size, delegate, thread_handle);
    179 }
    180 
    181 // static
    182 bool PlatformThread::CreateWithPriority(size_t stack_size, Delegate* delegate,
    183                                         PlatformThreadHandle* thread_handle,
    184                                         ThreadPriority priority) {
    185   bool result = Create(stack_size, delegate, thread_handle);
    186   if (result)
    187     SetThreadPriority(*thread_handle, priority);
    188   return result;
    189 }
    190 
    191 // static
    192 bool PlatformThread::CreateNonJoinable(size_t stack_size, Delegate* delegate) {
    193   return CreateThreadInternal(stack_size, delegate, NULL);
    194 }
    195 
    196 // static
    197 void PlatformThread::Join(PlatformThreadHandle thread_handle) {
    198   DCHECK(thread_handle.handle_);
    199   // TODO(willchan): Enable this check once I can get it to work for Windows
    200   // shutdown.
    201   // Joining another thread may block the current thread for a long time, since
    202   // the thread referred to by |thread_handle| may still be running long-lived /
    203   // blocking tasks.
    204 #if 0
    205   base::ThreadRestrictions::AssertIOAllowed();
    206 #endif
    207 
    208   // Wait for the thread to exit.  It should already have terminated but make
    209   // sure this assumption is valid.
    210   DWORD result = WaitForSingleObject(thread_handle.handle_, INFINITE);
    211   if (result != WAIT_OBJECT_0) {
    212     // Debug info for bug 127931.
    213     DWORD error = GetLastError();
    214     debug::Alias(&error);
    215     debug::Alias(&result);
    216     debug::Alias(&thread_handle.handle_);
    217     CHECK(false);
    218   }
    219 
    220   CloseHandle(thread_handle.handle_);
    221 }
    222 
    223 // static
    224 void PlatformThread::SetThreadPriority(PlatformThreadHandle handle,
    225                                        ThreadPriority priority) {
    226   switch (priority) {
    227     case kThreadPriority_Normal:
    228       ::SetThreadPriority(handle.handle_, THREAD_PRIORITY_NORMAL);
    229       break;
    230     case kThreadPriority_RealtimeAudio:
    231       ::SetThreadPriority(handle.handle_, THREAD_PRIORITY_TIME_CRITICAL);
    232       break;
    233     default:
    234       NOTREACHED() << "Unknown priority.";
    235       break;
    236   }
    237 }
    238 
    239 }  // namespace base
    240