- use flock to lock data dir rather than a lock file.

 - removed troublesome global constructor in Mutex initialization.


git-svn-id: https://svn.apache.org/repos/asf/incubator/qpid/trunk/qpid@671604 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 16 insertions, 26 deletions

diff --git a/cpp/src/qpid/DataDir.cpp b/cpp/src/qpid/DataDir.cpp
index e9c6aaad53..879f4de202 100644
--- a/cpp/src/qpid/DataDir.cpp
+++ b/cpp/src/qpid/DataDir.cpp
@@ -23,6 +23,7 @@
 #include "qpid/log/Statement.h"
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/file.h>
 #include <fcntl.h>
 #include <cerrno>
 
@@ -30,7 +31,8 @@ namespace qpid {
 
 DataDir::DataDir (std::string path) :
     enabled (!path.empty ()),
-    dirPath (path)
+    dirPath (path),
+    dirFd(-1)
 {
     if (!enabled)
     {
@@ -40,7 +42,6 @@ DataDir::DataDir (std::string path) :
 
     const  char *cpath = dirPath.c_str ();
     struct stat  s;
-
     if (::stat(cpath, &s)) {
         if (errno == ENOENT) {
             if (::mkdir(cpath, 0755))
@@ -49,34 +50,23 @@ DataDir::DataDir (std::string path) :
         else
             throw Exception ("Data directory not found: " + path);
     }
-
-    std::string lockFile (path);
-    lockFile = lockFile + "/lock";
-    int fd = ::open (lockFile.c_str (), O_CREAT | O_EXCL,
-                     S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
-    if (fd == -1)
-    {
-        if (errno == EEXIST)
-            throw Exception ("Data directory is locked by another process: " + path);
-        if (errno == EACCES)
-            throw Exception ("Insufficient privileges for data directory: " + path);
-        throw Exception(
-            QPID_MSG("Error locking " << lockFile << ": " << strError(errno)));
+    int dirFd = ::open(path.c_str(), 0);
+    if (dirFd == -1)
+        throw Exception(QPID_MSG("Can't open data directory: " << dirPath << ": " << strError(errno)));
+    int result = ::flock(dirFd, LOCK_EX | LOCK_NB);
+    if (result != 0) {
+        if (errno == EWOULDBLOCK)
+            throw Exception(QPID_MSG("Data directory locked by another process: " << path));
+        throw  Exception(QPID_MSG("Cannot lock data directory: " << strError(errno)));
     }
-
     QPID_LOG (info, "Locked data directory: " << dirPath);
 }
 
-DataDir::~DataDir ()
-{
-    if (dirPath.empty ())
-        return;
-
-    std::string lockFile (dirPath);
-    lockFile = lockFile + "/lock";
-
-    ::unlink (lockFile.c_str ());
-    QPID_LOG (info, "Unlocked data directory: " << dirPath);
+DataDir::~DataDir () {
+    if (dirFd != -1) {
+        ::close(dirFd);         // Closing the fd unlocks the directory.
+        QPID_LOG (info, "Unlocked data directory: " << dirPath);
+    }
 }
 
 } // namespace qpid