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