Adding upstream version 2.4.1.upstream/2.4.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 85 insertions, 0 deletions

diff --git a/src/lib/log/interprocess/interprocess_sync_file.h b/src/lib/log/interprocess/interprocess_sync_file.h
new file mode 100644
index 0000000..9613e7f
--- /dev/null
+++ b/src/lib/log/interprocess/interprocess_sync_file.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_FILE_H
+#define INTERPROCESS_SYNC_FILE_H
+
+#include <log/interprocess/interprocess_sync.h>
+#include <exceptions/exceptions.h>
+
+namespace isc {
+namespace log {
+namespace interprocess {
+
+/// \brief InterprocessSyncFileError
+///
+/// Exception that is thrown if it's not possible to open the
+/// lock file.
+class InterprocessSyncFileError : public Exception {
+public:
+    InterprocessSyncFileError(const char* file, size_t line,
+                              const char* what) :
+        isc::Exception(file, line, what) {}
+};
+
+/// \brief File-based Interprocess Sync Class
+///
+/// This class specifies a concrete implementation for a file-based
+/// interprocess synchronization mechanism. Please see the
+/// InterprocessSync class documentation for usage.
+///
+/// An InterprocessSyncFileError exception may be thrown if there is an
+/// issue opening the lock file.
+///
+/// Lock files are created typically in the local state directory
+/// (var). They are typically named like "<task_name>_lockfile".
+/// This implementation opens lock files lazily (only when
+/// necessary). It also leaves the lock files lying around as multiple
+/// processes may have locks on them.
+class InterprocessSyncFile : public InterprocessSync {
+public:
+    /// \brief Constructor
+    ///
+    /// Creates a file-based interprocess synchronization object
+    ///
+    /// \param task_name Name of the synchronization task. This has to be
+    /// identical among the various processes that need to be
+    /// synchronized for the same task.
+    InterprocessSyncFile(const std::string& task_name) :
+        InterprocessSync(task_name), fd_(-1)
+    {}
+
+    /// \brief Destructor
+    virtual ~InterprocessSyncFile();
+
+protected:
+    /// \brief Acquire the lock (blocks if something else has acquired a
+    /// lock on the same task name)
+    ///
+    /// \return Returns true if the lock was acquired, false otherwise.
+    bool lock();
+
+    /// \brief Try to acquire a lock (doesn't block)
+    ///
+    /// \return Returns true if the lock was acquired, false otherwise.
+    bool tryLock();
+
+    /// \brief Release the lock
+    ///
+    /// \return Returns true if the lock was released, false otherwise.
+    bool unlock();
+
+private:
+    bool do_lock(int cmd, short l_type);
+
+    int fd_; ///< The descriptor for the open file
+};
+
+} // namespace interprocess
+} // namespace log
+} // namespace isc
+
+#endif // INTERPROCESS_SYNC_FILE_H