Add and use SkSemaphore

src/utils/SkCondVar.h

-/*
- * Copyright 2012 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#ifndef SkCondVar_DEFINED
-#define SkCondVar_DEFINED
-
-#include "SkTypes.h"
-
-#ifdef SK_BUILD_FOR_WIN32
-    #include <windows.h>
-#else
-    #include <pthread.h>
-#endif
-
-/**
- * Condition variable for blocking access to shared data from other threads and
- * controlling which threads are awake.
- *
- * Currently only supported on platforms with posix threads and Windows Vista and above.
- */
-class SkCondVar {
-public:
-    /** Returns true if it makes sense to create and use SkCondVars.
-     *  You _MUST_ call this method and it must return true before creating any SkCondVars.
-     */
-    static bool Supported();
-
-    SkCondVar();
-    ~SkCondVar();
-
-    /**
-     * Lock a mutex. Must be done before calling the other functions on this object.
-     */
-    void lock();
-
-    /**
-     * Unlock the mutex.
-     */
-    void unlock();
-
-    /**
-     * Pause the calling thread. Will be awoken when signal() or broadcast() is called.
-     * Must be called while lock() is held (but gives it up while waiting). Once awoken,
-     * the calling thread will hold the lock once again.
-     */
-    void wait();
-
-    /**
-     * Wake one thread waiting on this condition. Must be called while lock()
-     * is held.
-     */
-    void signal();
-
-    /**
-     * Wake all threads waiting on this condition. Must be called while lock()
-     * is held.
-     */
-    void broadcast();
-
-private:
-#ifdef SK_BUILD_FOR_WIN32
-    CRITICAL_SECTION   fCriticalSection;
-    CONDITION_VARIABLE fCondition;
-#else
-    pthread_mutex_t  fMutex;
-    pthread_cond_t   fCond;
-#endif
-};
-
-#endif