VLock.h

/* -*- mode: c++; indent-tabs-mode: nil -*- */
/*
    VLock.h
 
    Qore Programming Language
 
    Copyright (C) 2003 - 2023 David Nichols
 
    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
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    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_VLOCK_H
 
#define _QORE_VLOCK_H
 
#include <qore/Qore.h>
#include "qore/intern/AbstractSmartLock.h"
 
#include <vector>
#include <map>
#include <atomic>
 
typedef std::map<int, class VLock*> vlock_map_t;
 
// testing shows that a vector is slightly faster than a deque for this usage
// and must faster than a list
typedef std::vector<AbstractSmartLock*> abstract_lock_list_t;
 
// forward references
class QoreCondition;
 
// for tracking locks per thread and detecting deadlocks
class VLock : protected abstract_lock_list_t {
public:
    DLLLOCAL VLock(int tid);
 
    DLLLOCAL ~VLock() {
        //printd(5, "VLock::~VLock() this=%p\n", this);
        assert(begin() == end());
    }
 
    DLLLOCAL void push(AbstractSmartLock* g);
    DLLLOCAL int pop(AbstractSmartLock* asl);
    DLLLOCAL void del();
    DLLLOCAL AbstractSmartLock* find(AbstractSmartLock* g) const;
 
    // for blocking smart locks with deadlock detection
    DLLLOCAL int waitOn(AbstractSmartLock* asl, VLock* vl, ExceptionSink* xsink, int timeout_ms = 0);
    // for smart locks using an alternate condition variable
    DLLLOCAL int waitOn(AbstractSmartLock* asl, QoreCondition* cond, VLock* vl, ExceptionSink* xsink, int timeout_ms = 0);
    // for smart locks that can be held by more than one thread
    DLLLOCAL int waitOn(AbstractSmartLock* asl, vlock_map_t& vmap, ExceptionSink* xsink, int timeout_ms = 0);
    DLLLOCAL int getTID() const { return tid; }
 
#ifdef DEBUG
    DLLLOCAL void show(class VLock* nvl) const;
#endif
 
private:
    std::atomic<AbstractSmartLock*> waiting_on;   // the lock this object is waiting on
    int tid;
 
    // not implemented
    VLock(const VLock&);
    VLock& operator=(const VLock&);
};
 
#endif