SERVER-16677 added platform-dependent class to management creation/locking of mongod.lock in data directory.

1 files changed, 95 insertions, 0 deletions

diff --git a/src/mongo/db/storage/storage_engine_lock_file.h b/src/mongo/db/storage/storage_engine_lock_file.h
new file mode 100644
index 00000000000..b28ccc29823
--- /dev/null
+++ b/src/mongo/db/storage/storage_engine_lock_file.h
@@ -0,0 +1,95 @@
+/**
+ *    Copyright (C) 2014 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#pragma once
+
+#include <boost/scoped_ptr.hpp>
+#include <string>
+
+#include "mongo/base/disallow_copying.h"
+#include "mongo/base/status.h"
+
+namespace mongo {
+
+    class StorageEngineLockFile {
+        MONGO_DISALLOW_COPYING(StorageEngineLockFile);
+    public:
+
+        /**
+         * Checks existing lock file, if present, to see if it contains data from a previous
+         * unclean shutdown. A clean shutdown should have produced a zero length lock file.
+         * Uses open() to read existing lock file or create new file.
+         * Uses boost::filesystem to check lock file so may throw boost::exception.
+         */
+        StorageEngineLockFile(const std::string& dbpath);
+
+        virtual ~StorageEngineLockFile();
+
+        /**
+         * Returns the path to the lock file.
+         */
+        std::string getFilespec() const;
+
+        /**
+         * Returns true if lock file was not zeroed out due to previous unclean shutdown.
+         * This state is evaluated at object initialization to allow storage engine
+         * to make decisions on recovery based on this information after open() has been called.
+         */
+        bool createdByUncleanShutdown() const;
+
+        /**
+         * Opens and locks 'mongod.lock' in 'dbpath' directory.
+         */
+        Status open();
+
+        /**
+         * Closes lock file handles.
+         */
+        void close();
+
+        /**
+         * Writes current process ID to file.
+         * Fails if lock file has not been opened.
+         */
+        Status writePid();
+
+        /**
+         * Truncates file contents and releases file locks.
+         */
+        void clearPidAndUnlock();
+
+    private:
+        std::string _dbpath;
+        std::string _filespec;
+        bool _uncleanShutdown;
+
+        class LockFileHandle;
+        boost::scoped_ptr<LockFileHandle> _lockFileHandle;
+    };
+
+}  // namespace mongo