remove the global rrl_cb_called from the libctdb example

and psss it through the callback via private_data.

add a comment that the callback may sometimes have already been invoked
when the ctdb_readrecordlock_async() call returns
and that the application can use *private_data IF the application
needs to know if the callback has already triggered or not.

diff --git a/libctdb/tst.c b/libctdb/tst.c
index 090b26da3a71a43f13c59428fe0dd4ff4a1db086..f1a8e3d41b47afd1ba53fef8987e0df66cd1b822 100644 (file)
--- a/libctdb/tst.c
+++ b/libctdb/tst.c
@@ -81,15 +81,15 @@ static void rm_cb(struct ctdb_connection *ctdb,
  *
  * Pure read, or pure write are just special cases of this cycle.
  */
-static bool rrl_cb_called;
-
 static void rrl_cb(struct ctdb_db *ctdb_db,
                   struct ctdb_lock *lock, TDB_DATA outdata, void *private)
 {
        TDB_DATA data;
        char tmp[256];
+       bool *rrl_cb_called = private;
+
+       *rrl_cb_called = true;
 
-       rrl_cb_called = true;
        if (!lock) {
                printf("rrl_cb returned error\n");
                return;
@@ -134,6 +134,8 @@ int main(int argc, char *argv[])
        uint32_t recmaster;
        int ret;
        TDB_DATA msg;
+       bool rrl_cb_called = false;
+
 
        ctdb_connection = ctdb_connect("/tmp/ctdb.socket");
        if (!ctdb_connection)
@@ -194,8 +196,17 @@ int main(int argc, char *argv[])
                exit(10);
        }
 
+       /* In the non-contended case the callback might be invoked
+        * immediately, before ctdb_readrecordlock_async() returns.
+        * In the contended case the callback will be invoked later.
+        *
+        * Normally an application would not care whether the callback
+        * has already been invoked here or not, but if the application
+        * needs to know, it can use the *private_data pointer
+        * to pass data through to the callback and back.
+        */
        if (!ctdb_readrecordlock_async(ctdb_db_context, key,
-                                      rrl_cb, ctdb_db_context)) {
+                                      rrl_cb, &rrl_cb_called)) {
                printf("Failed to send READRECORDLOCK\n");
                exit(10);
        }