Changeset 895 for trunk/server/lib/tdb/common/open.c

Timestamp:

Mar 18, 2016, 7:53:30 PM (9 years ago)

Author:

Silvan Scherrer

Message:

tdb: Use DosSetFileLocks directly for db locks.

This is to overcome some fcntl() API incompleteness in kLIBC
(like inability to upgrade locks or join adjacent lock regions
into one). It made the torture test run a bit better but there
are still two major problems both coming from DosSetFileLocks
impl (which fcntl() is currently based upon too): a) inability to
detect deadlocks and b) missing atomic unlock/lock support if
unlock/lock regions don't match.

With the current implementation, tdborture works fine for 1 or 2
worker processes but hangs when there are 3 or more. [Before that,
it would only work with 1 process and would likely to corrupt
the database and terminate if there were 2 or more processes].

Author: Dmitriy Kuminov (@dmik).

File:

• trunk/server/lib/tdb/common/open.c (modified) (6 diffs)

trunk/server/lib/tdb/common/open.c

@@ -162 +162 @@
         return check_header_hash(tdb, false, m1, m2);
 }
+
+#ifdef __OS2__
+static int os2_create_lockfile(struct tdb_context *tdb, const char *name, const char *origin)
+{
+        /* name could be null, so handle it */
+        if (name == NULL)
+                return 0;
+
+        char lock_name[_MAX_PATH + 5];
+        snprintf(lock_name, sizeof(lock_name), "%s.lock", name);
+        tdb->lock_fd = open(lock_name, tdb->open_flags | O_CREAT | O_TRUNC, 0777);
+        if (tdb->lock_fd == -1) {
+                TDB_LOG((tdb, TDB_DEBUG_ERROR, "os2_create_lockfile: cannot create lock file %s, errno=%d\n",
+                         lock_name, errno));
+                return -1;
+        }
+
+        return 0;
+}
+#endif
 
 _PUBLIC_ struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
@@ -304 +324 @@
 
 #ifdef __OS2__
-        if (os2_crtActiveLock(tdb, name, "tdb_open_ex") != 0)
+        if (os2_create_lockfile(tdb, name, "tdb_open_ex") != 0)
                 goto fail;
 #endif
@@ -476 +496 @@
 
 #ifdef __OS2__
-        close(tdb->hActiveLock);
-        tdb->hActiveLock = -1;
+        close(tdb->lock_fd);
+        tdb->lock_fd = -1;
 #endif
         if (!tdb)
@@ -548 +568 @@
 
 #ifdef __OS2__
-        close(tdb->hActiveLock);
-        tdb->hActiveLock = -1;
+        close(tdb->lock_fd);
+        tdb->lock_fd = -1;
 #endif
 
@@ -620 +640 @@
 
 #ifdef __OS2__
-        close(tdb->hActiveLock);
-        tdb->hActiveLock = -1;
-
-        if (os2_crtActiveLock(tdb, tdb->name, "tdb_reopen") != 0)
+        close(tdb->lock_fd);
+        tdb->lock_fd = -1;
+
+        if (os2_create_lockfile(tdb, tdb->name, "tdb_reopen") != 0)
                 goto fail;
 #endif
@@ -679 +699 @@
         return 0;
 }
-#ifdef __OS2__
-int os2_crtActiveLock(struct tdb_context *tdb, const char *name, const char *origin)
-{
-        // name could be null, so handle it
-        if (name == NULL)
-                return 0;
-
-        struct stat st;
-        bool emptytdb = false;
-        char activeLockName[_MAX_PATH];
-        char *emptyString = "used for active lock\n\0";
-        sprintf(activeLockName, "%s_AL", name);
-
-        if ((stat(activeLockName, &st) == -1) || (st.st_size < strlen(emptyString)))
-                emptytdb = true;
-
-        tdb->hActiveLock = open(activeLockName, tdb->open_flags | O_CREAT, 0777);
-        if (tdb->hActiveLock == -1) {
-                TDB_LOG((tdb, TDB_DEBUG_ERROR, "os2_crtActiveLock: cannot create activeLock %s called from %s %s\n",
-                        activeLockName, origin, strerror(errno)));
-                errno = EINVAL;
-                return -1;
-        }
-
-        // we try to truncate the db when called from tdb_open_ex
-        // but if it's not working it's ok as well
-        if (emptytdb)
-                tdb_write_all(tdb->hActiveLock, emptyString, strlen(emptyString));
-
-        return 0;
-} 
-#endif