util_tdb: move timeout chainlock variants from source3/lib/util/util_tdb.c

We're about to use them for dbwrap.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

3 files changed, 98 insertions, 1 deletions

diff --git a/lib/util/util_tdb.c b/lib/util/util_tdb.c
index 41c9b50251..c005c82791 100644
--- a/lib/util/util_tdb.c
+++ b/lib/util/util_tdb.c
@@ -21,6 +21,7 @@
 */
 
 #include "includes.h"
+#include "system/filesys.h"
 #include "../lib/tdb/include/tdb.h"
 #include "../lib/util/util_tdb.h"
 
@@ -301,6 +302,84 @@ int32_t tdb_change_int32_atomic(struct tdb_context *tdb, const char *keystr, int
 	return ret;
 }
 
+static sig_atomic_t gotalarm;
+
+/***************************************************************
+ Signal function to tell us we timed out.
+****************************************************************/
+
+static void gotalarm_sig(int signum)
+{
+	gotalarm = 1;
+}
+
+/****************************************************************************
+ Lock a chain with timeout (in seconds).
+****************************************************************************/
+
+static int tdb_chainlock_with_timeout_internal( TDB_CONTEXT *tdb, TDB_DATA key, unsigned int timeout, int rw_type)
+{
+	/* Allow tdb_chainlock to be interrupted by an alarm. */
+	int ret;
+	gotalarm = 0;
+
+	if (timeout) {
+		CatchSignal(SIGALRM, gotalarm_sig);
+		tdb_setalarm_sigptr(tdb, &gotalarm);
+		alarm(timeout);
+	}
+
+	if (rw_type == F_RDLCK)
+		ret = tdb_chainlock_read(tdb, key);
+	else
+		ret = tdb_chainlock(tdb, key);
+
+	if (timeout) {
+		alarm(0);
+		tdb_setalarm_sigptr(tdb, NULL);
+		CatchSignal(SIGALRM, SIG_IGN);
+		if (gotalarm && (ret != 0)) {
+			DEBUG(0,("tdb_chainlock_with_timeout_internal: alarm (%u) timed out for key %s in tdb %s\n",
+				timeout, key.dptr, tdb_name(tdb)));
+			/* TODO: If we time out waiting for a lock, it might
+			 * be nice to use F_GETLK to get the pid of the
+			 * process currently holding the lock and print that
+			 * as part of the debugging message. -- mbp */
+			return -1;
+		}
+	}
+
+	return ret == 0 ? 0 : -1;
+}
+
+/****************************************************************************
+ Write lock a chain. Return non-zero if timeout or lock failed.
+****************************************************************************/
+
+int tdb_chainlock_with_timeout( TDB_CONTEXT *tdb, TDB_DATA key, unsigned int timeout)
+{
+	return tdb_chainlock_with_timeout_internal(tdb, key, timeout, F_WRLCK);
+}
+
+int tdb_lock_bystring_with_timeout(TDB_CONTEXT *tdb, const char *keyval,
+				   int timeout)
+{
+	TDB_DATA key = string_term_tdb_data(keyval);
+
+	return tdb_chainlock_with_timeout(tdb, key, timeout);
+}
+
+/****************************************************************************
+ Read lock a chain by string. Return non-zero if timeout or lock failed.
+****************************************************************************/
+
+int tdb_read_lock_bystring_with_timeout(TDB_CONTEXT *tdb, const char *keyval, unsigned int timeout)
+{
+	TDB_DATA key = string_term_tdb_data(keyval);
+
+	return tdb_chainlock_with_timeout_internal(tdb, key, timeout, F_RDLCK);
+}
+
 /****************************************************************************
  Atomic unsigned integer change. Returns old value. To create, set initial value in *oldval. 
 ****************************************************************************/
diff --git a/lib/util/util_tdb.h b/lib/util/util_tdb.h
index 0b6f3f18a4..d8a2333035 100644
--- a/lib/util/util_tdb.h
+++ b/lib/util/util_tdb.h
@@ -52,6 +52,24 @@ int tdb_read_lock_bystring(struct tdb_context *tdb, const char *keyval);
 void tdb_read_unlock_bystring(struct tdb_context *tdb, const char *keyval);
 
 /****************************************************************************
+ Lock a chain, with timeout.
+****************************************************************************/
+int tdb_chainlock_with_timeout( struct tdb_context *tdb, TDB_DATA key,
+				unsigned int timeout);
+
+/****************************************************************************
+ Lock a chain by string, with timeout Return non-zero if lock failed.
+****************************************************************************/
+int tdb_lock_bystring_with_timeout(struct tdb_context *tdb, const char *keyval,
+				   int timeout);
+
+/****************************************************************************
+ Readlock a chain by string, with timeout Return non-zero if lock failed.
+****************************************************************************/
+int tdb_read_lock_bystring_with_timeout(TDB_CONTEXT *tdb, const char *keyval,
+					unsigned int timeout);
+
+/****************************************************************************
  Fetch a int32_t value by a arbitrary blob key, return -1 if not found.
  Output is int32_t in native byte order.
 ****************************************************************************/
diff --git a/lib/util/wscript_build b/lib/util/wscript_build
index a955ab6a48..82943a08f2 100755
--- a/lib/util/wscript_build
+++ b/lib/util/wscript_build
@@ -41,7 +41,7 @@ bld.SAMBA_SUBSYSTEM('UNIX_PRIVS',
 bld.SAMBA_LIBRARY('util_tdb',
 	source='util_tdb.c',
 	local_include=False,
-	public_deps='tdb talloc',
+	public_deps='tdb talloc samba-util',
 	private_library=True
 	)