UT_Lock.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * NAME:        UT_Lock.h ( UT Library, C++)
 *
 * COMMENTS:
 *      Locking class
 */

#ifndef __UT_Lock_h__
#define __UT_Lock_h__

#include "UT_API.h"
#include "UT_Assert.h"
#include "UT_LockUtil.h"
#include "UT_NonCopyable.h"
#include "UT_String.h"
#include <SYS/SYS_Types.h>

class UT_Condition;

#if defined(LINUX) || defined(MBSD)
#define HAVE_PLATFORM_LOCK
#include <pthread.h>
#elif defined(WIN32)
#define HAVE_PLATFORM_LOCK
#endif

#ifdef HAVE_PLATFORM_LOCK

// Enable a printout of the number of calls to lock() along with a
// backtrace showing where the lock was first called.  Currently only
// available on linux/mac.
//#define DEBUG_LOCK_CALLERS

class UT_API UT_Lock : UT_NonCopyable
{
    friend class UT_Condition;
public:
    // thread_lock *must* be true
    explicit UT_Lock(bool initially_locked = false);
    ~UT_Lock();

    // tries the lock once, returns true if the lock was obtained.
    bool        tryLock();

    // blocks until the lock is obtained.  lock() is inlined for speed.
#if defined(WIN32) || defined(DEBUG_LOCK_CALLERS)
    void        lock();
#elif defined(LINUX) || defined(MBSD)
    void        lock()
    {
        UT_VERIFY(pthread_mutex_lock(&myLock) == 0);

        // NOTE: pthread_mutex_lock does a memory fence as appropriate.
        //       See POSIX.1-2008 Section 4.11 Memory Synchronization.
        //       If it didn't, we would need at least a SYSloadFence() here,
        //       after acquiring the lock.
    }
#endif

    bool        safeLock() { lock(); return true; }

    // tries for N ms to get the lock, returns true if the lock was obtained.
    bool        lock(int ms);

    // release the lock.  unlock() is inlined for speed.
#if defined(LINUX) || defined(MBSD)
    void        unlock()
    {
        // NOTE: pthread_mutex_unlock does a memory fence as appropriate.
        //       See POSIX.1-2008 Section 4.11 Memory Synchronization.
        //       If it didn't, we would need at least a SYSstoreFence() here,
        //       before releasing the lock.
    #if (UT_ASSERT_LEVEL > UT_ASSERT_LEVEL_NONE)
        int result = pthread_mutex_unlock(&myLock);
        UT_ASSERT(result == 0);
    #else
        (void) pthread_mutex_unlock(&myLock);
    #endif
    }
#elif defined(WIN32)
    void        unlock();
#endif

    bool        isLocked();
    int         getCollisions() { return 0; }

    int64       getMemoryUsage(bool inclusive) const;

    /// Class for auto-unlocking
    typedef UT_LockScopeType<UT_Lock> Scope;

private:
#if defined(LINUX) || defined(MBSD)
    pthread_mutex_t      myLock;
    pthread_mutexattr_t  myLockAttributes;
#elif defined(WIN32)
    struct Impl         // Actually a Windows SRWLOCK
    {
        uint8            myBuffer[16];

        struct Data;
        Data *cast();
    };
    void                 sleep(void *cond_var);

    Impl                 myLock;
#endif

#if defined(DEBUG_LOCK_CALLERS)
    int                  myLockCount;
    UT_String            myBacktrace;
#endif
};

#else // HAVE_PLATFORM_LOCK

#include "UT_SpinLock.h"
typedef UT_RecursiveSpinLock UT_Lock;

#endif

typedef UT_AutoLockType<UT_Lock>        UT_AutoLock;
typedef UT_DebugLockType<UT_Lock>       UT_DebugLock;
typedef UT_ObjLockType<UT_Lock>         UT_ObjLock;
typedef UT_AutoObjLockType<UT_Lock>     UT_AutoObjLock;

#endif