QoreRWLock.h

/* -*- mode: c++; indent-tabs-mode: nil -*- */
/*
  QoreRWLock.h
 
  simple pthreads-based read-write lock
 
  Qore Programming Language
 
  Copyright (C) 2003 - 2024 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_QORERWLOCK_H
#define _QORE_QORERWLOCK_H
 
#include <pthread.h>
 
#ifdef DEBUG
extern int q_gettid() noexcept;
#endif
 
 
class QoreRWLock {
public:
    DLLLOCAL QoreRWLock() {
#ifndef NDEBUG
        int rc =
#endif
        pthread_rwlock_init(&m, 0);
        assert(!rc);
    }
 
    DLLLOCAL ~QoreRWLock() {
#ifndef NDEBUG
        int rc =
#endif
        pthread_rwlock_destroy(&m);
        assert(!rc);
    }
 
    DLLLOCAL int wrlock() {
#ifndef NDEBUG
        int rc = pthread_rwlock_wrlock(&m);
        if (!rc) {
            wr_tid = q_gettid();
        }
        return rc;
#else
        return pthread_rwlock_wrlock(&m);
#endif
    }
 
    DLLLOCAL int trywrlock() {
#ifndef NDEBUG
        int rc = pthread_rwlock_trywrlock(&m);
        if (!rc) {
            wr_tid = q_gettid();
        }
        return rc;
#else
        return pthread_rwlock_trywrlock(&m);
#endif
    }
 
    DLLLOCAL int unlock() {
#ifndef NDEBUG
        if (wr_tid != -1) {
            wr_tid = -1;
        }
#endif
        return pthread_rwlock_unlock(&m);
    }
 
    DLLLOCAL int rdlock() {
        return pthread_rwlock_rdlock(&m);
    }
 
    DLLLOCAL int tryrdlock() {
        return pthread_rwlock_tryrdlock(&m);
    }
 
protected:
    pthread_rwlock_t m;
#ifndef NDEBUG
    int wr_tid = -1;
#endif
 
    QoreRWLock& operator=(const QoreRWLock&) = delete;
};
 
 
class QoreAutoRWReadLocker {
private:
    DLLLOCAL QoreAutoRWReadLocker(const QoreAutoRWReadLocker&);
 
    DLLLOCAL QoreAutoRWReadLocker& operator=(const QoreAutoRWReadLocker&);
 
    DLLLOCAL void *operator new(size_t);
 
protected:
    QoreRWLock *l;
 
public:
    DLLLOCAL QoreAutoRWReadLocker(QoreRWLock &n_l) : l(&n_l) {
        l->rdlock();
    }
 
    DLLLOCAL QoreAutoRWReadLocker(QoreRWLock *n_l) : l(n_l) {
        if (l)
            l->rdlock();
    }
 
    DLLLOCAL ~QoreAutoRWReadLocker() {
        if (l)
            l->unlock();
    }
};
 
 
class QoreAutoRWWriteLocker {
private:
    DLLLOCAL QoreAutoRWWriteLocker(const QoreAutoRWWriteLocker&);
 
    DLLLOCAL QoreAutoRWWriteLocker& operator=(const QoreAutoRWWriteLocker&);
 
    DLLLOCAL void *operator new(size_t);
 
protected:
    QoreRWLock *l;
 
public:
    DLLLOCAL QoreAutoRWWriteLocker(QoreRWLock &n_l) : l(&n_l) {
        l->wrlock();
    }
 
    DLLLOCAL QoreAutoRWWriteLocker(QoreRWLock *n_l) : l(n_l) {
        if (l)
            l->wrlock();
    }
 
    DLLLOCAL ~QoreAutoRWWriteLocker() {
        if (l)
            l->unlock();
    }
};
 
 
class QoreSafeRWReadLocker {
public:
    DLLLOCAL QoreSafeRWReadLocker() : l(nullptr), locked(false) {
    }
 
    DLLLOCAL QoreSafeRWReadLocker(QoreRWLock& n_l) : l(&n_l) {
        l->rdlock();
        locked = true;
    }
 
    DLLLOCAL QoreSafeRWReadLocker(QoreRWLock* n_l) : l(n_l) {
        l->rdlock();
        locked = true;
    }
 
    DLLLOCAL ~QoreSafeRWReadLocker() {
        if (locked) {
            l->unlock();
        }
    }
 
    DLLLOCAL void lock() {
        assert(!locked);
        assert(l);
        l->rdlock();
        locked = true;
    }
 
    DLLLOCAL void unlock() {
        assert(locked);
        assert(l);
        locked = false;
        l->unlock();
    }
 
    DLLLOCAL void stay_locked() {
        assert(locked);
        assert(l);
        locked = false;
    }
 
    DLLLOCAL void handoffTo(QoreRWLock& n) {
        if (l) {
            unlock();
        }
        l = &n;
        lock();
    }
 
protected:
    QoreRWLock* l;
 
    bool locked;
 
private:
    DLLLOCAL QoreSafeRWReadLocker(const QoreSafeRWReadLocker&) = delete;
 
    DLLLOCAL QoreSafeRWReadLocker& operator=(const QoreSafeRWReadLocker&) = delete;
 
    DLLLOCAL void* operator new(size_t) = delete;
};
 
 
class QoreSafeRWWriteLocker {
private:
    DLLLOCAL QoreSafeRWWriteLocker(const QoreSafeRWWriteLocker&);
 
    DLLLOCAL QoreSafeRWWriteLocker& operator=(const QoreSafeRWWriteLocker&);
 
    DLLLOCAL void *operator new(size_t);
 
protected:
    QoreRWLock *l;
 
    bool locked;
 
public:
    DLLLOCAL QoreSafeRWWriteLocker(QoreRWLock &n_l) : l(&n_l) {
        l->wrlock();
        locked = true;
    }
 
    DLLLOCAL QoreSafeRWWriteLocker(QoreRWLock *n_l) : l(n_l) {
        l->wrlock();
        locked = true;
    }
 
    DLLLOCAL ~QoreSafeRWWriteLocker() {
        if (locked)
            l->unlock();
    }
 
    DLLLOCAL void lock() {
        assert(!locked);
        l->wrlock();
        locked = true;
    }
 
    DLLLOCAL void unlock() {
        assert(locked);
        locked = false;
        l->unlock();
    }
 
    DLLLOCAL void stay_locked() {
        assert(locked);
        locked = false;
    }
};
 
class QoreOptionalRWWriteLocker {
protected:
    QoreRWLock* l;
 
public:
    DLLLOCAL QoreOptionalRWWriteLocker(QoreRWLock* n_l) : l(n_l->trywrlock() ? 0 : n_l) {
    }
 
    DLLLOCAL QoreOptionalRWWriteLocker(QoreRWLock& n_l) : l(n_l.trywrlock() ? 0 : &n_l) {
    }
 
    DLLLOCAL ~QoreOptionalRWWriteLocker() {
        if (l)
            l->unlock();
    }
 
    DLLLOCAL operator bool() const {
        return (bool)l;
    }
};
 
class QoreOptionalRWReadLocker {
protected:
    QoreRWLock* l;
 
public:
    DLLLOCAL QoreOptionalRWReadLocker(QoreRWLock* n_l) : l(n_l->tryrdlock() ? 0 : n_l) {
    }
 
    DLLLOCAL QoreOptionalRWReadLocker(QoreRWLock& n_l) : l(n_l.tryrdlock() ? 0 : &n_l) {
    }
 
    DLLLOCAL ~QoreOptionalRWReadLocker() {
        if (l)
            l->unlock();
    }
 
    DLLLOCAL operator bool() const {
        return (bool)l;
    }
};
 
class qore_var_rwlock_priv;
 
class QoreVarRWLock {
    friend class qore_var_rwlock_priv;
public:
    DLLLOCAL QoreVarRWLock();
 
    DLLLOCAL ~QoreVarRWLock();
 
    DLLLOCAL void wrlock();
 
    DLLLOCAL int trywrlock();
 
    DLLLOCAL void unlock();
 
    DLLLOCAL void rdlock();
 
    DLLLOCAL int tryrdlock();
 
protected:
    qore_var_rwlock_priv* priv;
 
    DLLLOCAL QoreVarRWLock(qore_var_rwlock_priv* p);
 
private:
    QoreVarRWLock(const QoreVarRWLock&) = delete;
    QoreVarRWLock& operator=(const QoreVarRWLock&) = delete;
};
 
#endif