Abstract native file-locking and directory detection/creation to portable classes LockFile and FileSysDir; resolves QPID-1148

git-svn-id: https://svn.apache.org/repos/asf/incubator/qpid/trunk/qpid@702513 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 54 insertions, 1 deletions

diff --git a/cpp/src/qpid/sys/LockFile.h b/cpp/src/qpid/sys/LockFile.h
index f06cd6a47d..2ff8c2f6d4 100644
--- a/cpp/src/qpid/sys/LockFile.h
+++ b/cpp/src/qpid/sys/LockFile.h
@@ -19,7 +19,60 @@
  *
  */
 
-#include "posix/LockFile.h"
+#include <boost/noncopyable.hpp>
+#include <boost/shared_ptr.hpp>
+#include <string>
+
+#include "IntegerTypes.h"
+
+namespace qpid {
+namespace sys {
+
+class LockFilePrivate;    
+
+/**
+ * @class LockFile
+ *
+ * LockFile represents a locked file suitable for a coarse-grain system
+ * lock. For example, the broker uses this to ensure that only one broker
+ * runs. A common usage idiom is to store the current "owner" process ID
+ * in the lock file - if the lock file exists, but the stored process ID
+ * doesn't, the old owner has probably died without cleaning up the lock
+ * file.
+ */
+class LockFile : private boost::noncopyable
+{
+    boost::shared_ptr<LockFilePrivate> impl;
+
+    std::string path;
+    bool created;
+
+public:
+    LockFile(const std::string& path_, bool create);
+    ~LockFile();
+
+    /**
+     * Read the process ID from the lock file. This method assumes that
+     * if there is a process ID in the file, it was written there by
+     * writePid(); thus, it's at the start of the file.
+     *
+     * Throws an exception if there is an error reading the file.
+     *
+     * @returns The stored process ID. No validity check is done on it.
+     */
+    pid_t readPid(void) const;
+
+    /**
+     * Write the current process's ID to the lock file. It's written at
+     * the start of the file and will overwrite any other content that
+     * may be in the file.
+     *
+     * Throws an exception if the write fails.
+     */
+    void writePid(void);
+};
+ 
+}}   /* namespace qpid::sys */
 
 #endif /*!_sys_LockFile_h*/