Line data    Source code

       1             : /*
       2             :  * Copyright 2011 Google Inc. All Rights Reserved.
       3             :  *
       4             :  * Licensed under the Apache License, Version 2.0 (the "License");
       5             :  * you may not use this file except in compliance with the License.
       6             :  * You may obtain a copy of the License at
       7             :  *
       8             :  *      http://www.apache.org/licenses/LICENSE-2.0
       9             :  *
      10             :  * Unless required by applicable law or agreed to in writing, software
      11             :  * distributed under the License is distributed on an "AS IS" BASIS,
      12             :  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      13             :  * See the License for the specific language governing permissions and
      14             :  * limitations under the License.
      15             :  */
      16             : 
      17             : #ifndef SFNTLY_CPP_SRC_SFNTLY_PORT_LOCK_H_
      18             : #define SFNTLY_CPP_SRC_SFNTLY_PORT_LOCK_H_
      19             : 
      20             : #if defined (WIN32)
      21             : #include <windows.h>
      22             : #else  // Assume pthread.
      23             : #include <pthread.h>
      24             : #include <errno.h>
      25             : #endif
      26             : 
      27             : #include "sfntly/port/type.h"
      28             : 
      29             : namespace sfntly {
      30             : 
      31             : #if defined (WIN32)
      32             :   typedef CRITICAL_SECTION OSLockType;
      33             : #else  // Assume pthread.
      34             :   typedef pthread_mutex_t OSLockType;
      35             : #endif
      36             : 
      37             : class Lock {
      38             :  public:
      39             :   Lock();
      40             :   ~Lock();
      41             : 
      42             :   // If the lock is not held, take it and return true.  If the lock is already
      43             :   // held by something else, immediately return false.
      44             :   bool Try();
      45             : 
      46             :   // Take the lock, blocking until it is available if necessary.
      47             :   void Acquire();
      48             : 
      49             :   // Release the lock.  This must only be called by the lock's holder: after
      50             :   // a successful call to Try, or a call to Lock.
      51             :   void Unlock();
      52             : 
      53             :  private:
      54             :   OSLockType os_lock_;
      55             :   NO_COPY_AND_ASSIGN(Lock);
      56             : };
      57             : 
      58             : // A helper class that acquires the given Lock while the AutoLock is in scope.
      59             : class AutoLock {
      60             :  public:
      61           0 :   explicit AutoLock(Lock& lock) : lock_(lock) {
      62           0 :     lock_.Acquire();
      63           0 :   }
      64             : 
      65           0 :   ~AutoLock() {
      66           0 :     lock_.Unlock();
      67           0 :   }
      68             : 
      69             :  private:
      70             :   Lock& lock_;
      71             :   NO_COPY_AND_ASSIGN(AutoLock);
      72             : };
      73             : 
      74             : }  // namespace sfntly
      75             : 
      76             : #endif  // SFNTLY_CPP_SRC_SFNTLY_PORT_LOCK_H_