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+// Copyright (C) 2012 Internet Systems Consortium, Inc. ("ISC")
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+//
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+// Permission to use, copy, modify, and/or distribute this software for any
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+// purpose with or without fee is hereby granted, provided that the above
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+// copyright notice and this permission notice appear in all copies.
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+//
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+// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
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+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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+// AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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+// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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+// PERFORMANCE OF THIS SOFTWARE.
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+
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+#ifndef __INTERPROCESS_SYNC_NULL_H__
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+#define __INTERPROCESS_SYNC_NULL_H__
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+
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+#include "util/interprocess_sync.h"
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+
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+namespace isc {
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+namespace util {
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+
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+/// \brief Null Interprocess Sync Class
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+///
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+/// This class specifies a concrete implementation for a null (no effect)
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+/// interprocess synchronization mechanism. Please see the
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+/// InterprocessSync class documentation for usage.
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+class InterprocessSyncNull : public InterprocessSync {
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+public:
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+ /// \brief Constructor
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+ ///
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+ /// Creates a null interprocess synchronization object
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+ ///
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+ /// \param name Name of the synchronization task. This has to be
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+ /// identical among the various processes that need to be
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+ /// synchronized for the same task.
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+ InterprocessSyncNull(const std::string& task_name) :
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+ InterprocessSync(task_name)
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+ {}
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+
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+ /// \brief Destructor
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+ virtual ~InterprocessSyncNull();
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+
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+protected:
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+ /// \brief Acquire the lock (never blocks)
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+ ///
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+ /// \return Always returns true
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+ bool lock();
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+
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+ /// \brief Try to acquire a lock (doesn't block)
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+ ///
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+ /// \return Always returns true
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+ bool tryLock();
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+
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+ /// \brief Release the lock
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+ ///
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+ /// \return Always returns true
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+ bool unlock();
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+};
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+
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+} // namespace util
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+} // namespace isc
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+
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+#endif // __INTERPROCESS_SYNC_NULL_H__
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