interprocess_sync.h

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// Copyright (C) 2012-2015 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef INTERPROCESS_SYNC_H
#define INTERPROCESS_SYNC_H

#include <string>

namespace isc {
namespace log {
namespace interprocess {

class InterprocessSyncLocker; // forward declaration

class InterprocessSync {
  // InterprocessSyncLocker is the only code outside this class that
  // should be allowed to call the lock(), tryLock() and unlock()
  // methods.
  friend class InterprocessSyncLocker;

public:
    InterprocessSync(const std::string& task_name) :
        task_name_(task_name), is_locked_(false)
    {}

    virtual ~InterprocessSync() {}

protected:
    virtual bool lock() = 0;

    virtual bool tryLock() = 0;

    virtual bool unlock() = 0;

    const std::string task_name_; 
    bool is_locked_;              
};

class InterprocessSyncLocker {
public:
    InterprocessSyncLocker(InterprocessSync& sync) :
        sync_(sync)
    {}

    ~InterprocessSyncLocker() {
        if (isLocked())
            unlock();
    }

    bool lock() {
        return (sync_.lock());
    }

    bool tryLock() {
        return (sync_.tryLock());
    }

    bool isLocked() const {
        return (sync_.is_locked_);
    }

    bool unlock() {
        return (sync_.unlock());
    }

protected:
    InterprocessSync& sync_; 
};

} // namespace interprocess
} // namespace log
} // namespace isc

#endif // INTERPROCESS_SYNC_H