VRMutex.h

/* -*- mode: c++; indent-tabs-mode: nil -*- */
/*
    VRMutex.h
 
    recursive lock object
 
    Qore Programming Language
 
    Copyright (C) 2003 - 2023 Qore Technologies, s.r.o.
 
    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
    to deal in the Software without restriction, including without limitation
    the rights to use, copy, modify, merge, publish, distribute, sublicense,
    and/or sell copies of the Software, and to permit persons to whom the
    Software is furnished to do so, subject to the following conditions:
 
    The above copyright notice and this permission notice shall be included in
    all copies or substantial portions of the Software.
 
    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
    DEALINGS IN THE SOFTWARE.
 
    Note that the Qore library is released under a choice of three open-source
    licenses: MIT (as above), LGPL 2+, or GPL 2+; see README-LICENSE for more
    information.
*/
 
#ifndef _QORE_VRMUTEX_H
 
#define _QORE_VRMUTEX_H
 
#include "qore/intern/AbstractSmartLock.h"
#include "qore/intern/VLock.h"
 
// reentrant thread lock using tiered locking and deadlock detection infrastructure
class VRMutex : public AbstractSmartLock {
public:
    DLLLOCAL VRMutex();
 
    // grabs the lock recursively, returns >= 0 for OK, -1 for error
    DLLLOCAL int enter(ExceptionSink *xsink);
 
    // releases the lock, returns 0 if the lock is unlocked, -1 if there are still more calls to exit
    DLLLOCAL int exit();
 
    DLLLOCAL virtual const char* getName() const { return "VRMutex"; }
 
    DLLLOCAL int get_count() const {
        return count;
    }
 
private:
    int count = 0;
 
    DLLLOCAL virtual int releaseImpl();
    DLLLOCAL virtual int releaseImpl(ExceptionSink *xsink);
    DLLLOCAL virtual int grabImpl(int mtid, VLock *nvl, ExceptionSink *xsink, int64 timeout_ms = 0);
    DLLLOCAL virtual int tryGrabImpl(int mtid, VLock *nvl);
    DLLLOCAL virtual int cleanupImpl();
};
 
class VRMutexOptionalLockHelper {
public:
    DLLLOCAL VRMutexOptionalLockHelper(VRMutex* vm, ExceptionSink* xsink) : m(vm && vm->enter(xsink) >= 0 ? vm : 0) {
        //printd(5, "VRMutexOptionalLockHelper::VRMutexOptionalLockHelper() vm: %p m: %p\n", vm, m);
    }
 
    DLLLOCAL ~VRMutexOptionalLockHelper() {
        if (m)
            m->exit();
    }
 
protected:
    VRMutex* m;
};
 
#endif