1 // Copyright (c) 2011 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 #ifndef BASE_SYNCHRONIZATION_LOCK_IMPL_H_ 6 #define BASE_SYNCHRONIZATION_LOCK_IMPL_H_ 7 8 #include "base/base_export.h" 9 #include "base/logging.h" 10 #include "base/macros.h" 11 #include "build/build_config.h" 12 13 #if defined(OS_WIN) 14 #include "base/win/windows_types.h" 15 #elif defined(OS_POSIX) || defined(OS_FUCHSIA) 16 #include <errno.h> 17 #include <pthread.h> 18 #endif 19 20 namespace base { 21 namespace internal { 22 23 // This class implements the underlying platform-specific spin-lock mechanism 24 // used for the Lock class. Most users should not use LockImpl directly, but 25 // should instead use Lock. 26 class BASE_EXPORT LockImpl { 27 public: 28 #if defined(OS_WIN) 29 using NativeHandle = CHROME_SRWLOCK; 30 #elif defined(OS_POSIX) || defined(OS_FUCHSIA) 31 using NativeHandle = pthread_mutex_t; 32 #endif 33 34 LockImpl(); 35 ~LockImpl(); 36 37 // If the lock is not held, take it and return true. If the lock is already 38 // held by something else, immediately return false. 39 bool Try(); 40 41 // Take the lock, blocking until it is available if necessary. 42 void Lock(); 43 44 // Release the lock. This must only be called by the lock's holder: after 45 // a successful call to Try, or a call to Lock. 46 inline void Unlock(); 47 48 // Return the native underlying lock. 49 // TODO(awalker): refactor lock and condition variables so that this is 50 // unnecessary. native_handle()51 NativeHandle* native_handle() { return &native_handle_; } 52 53 #if defined(OS_POSIX) || defined(OS_FUCHSIA) 54 // Whether this lock will attempt to use priority inheritance. 55 static bool PriorityInheritanceAvailable(); 56 #endif 57 58 private: 59 NativeHandle native_handle_; 60 61 DISALLOW_COPY_AND_ASSIGN(LockImpl); 62 }; 63 64 #if defined(OS_WIN) Unlock()65void LockImpl::Unlock() { 66 ::ReleaseSRWLockExclusive(reinterpret_cast<PSRWLOCK>(&native_handle_)); 67 } 68 #elif defined(OS_POSIX) || defined(OS_FUCHSIA) Unlock()69void LockImpl::Unlock() { 70 int rv = pthread_mutex_unlock(&native_handle_); 71 DCHECK_EQ(rv, 0) << ". " << strerror(rv); 72 } 73 #endif 74 75 } // namespace internal 76 } // namespace base 77 78 #endif // BASE_SYNCHRONIZATION_LOCK_IMPL_H_ 79