Added UpdatesOnly to kwWatchOptions (#818)

* Added UpdatesOnly to kwWatchOptions * PR feedback: the freed pointer
nats-io · Nov 13, 2024 · adb9074 · adb9074
1 parent 54d247a
commit adb9074
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Showing 3 changed files with 23 additions and 2 deletions.
diff --git a/src/kv.c b/src/kv.c
@@ -1135,6 +1135,8 @@ kvStore_WatchMulti(kvWatcher **new_watcher, kvStore *kv, const char **keys, int
         {
             if (opts->MetaOnly)
                 so.Config.HeadersOnly = true;
+            if (opts->UpdatesOnly)
+                so.Config.DeliverPolicy = js_DeliverNew;
             if (opts->IgnoreDeletes)
                 w->ignoreDel = true;
         }
@@ -1148,10 +1150,17 @@ kvStore_WatchMulti(kvWatcher **new_watcher, kvStore *kv, const char **keys, int
             natsSubscription *sub = w->sub;
 
             natsSub_Lock(sub);
-            if ((sub->jsi != NULL) && (sub->jsi->pending == 0))
+            if ((opts == NULL) || !opts->UpdatesOnly)
+            {
+                if ((sub->jsi != NULL) && (sub->jsi->pending == 0))
+                {
+                    w->initDone = true;
+                    w->retMarker = true;
+                }
+            }
+            else
             {
                 w->initDone = true;
-                w->retMarker = true;
             }
             natsSub_Unlock(sub);
         }

diff --git a/src/nats.h b/src/nats.h
@@ -1426,6 +1426,7 @@ typedef struct kvWatchOptions
         bool            IncludeHistory;
         bool            MetaOnly;
         int64_t         Timeout;        ///< How long to wait (in milliseconds) for some operations to complete.
+        bool            UpdatesOnly;    ///< Only receive updates, no initial snapshot.
 
 } kvWatchOptions;
 

diff --git a/test/test.c b/test/test.c
@@ -32121,6 +32121,17 @@ void test_KeyValueWatch(void)
     natsThread_Join(t);
     natsThread_Destroy(t);
     kvWatcher_Destroy(w);
+    w = NULL;
+
+    // Now try with UpdatesOnly and make sure we don't get the initial values.
+    test("Create watcher with UpdatesOnly: ");
+    kvWatchOptions o = {.UpdatesOnly = true};
+    s = kvStore_Watch(&w, kv, "t.*", &o);
+    testCond(s == NATS_OK);
+
+    IFOK(s, kvStore_PutString(NULL, kv, "t.age", "57"));
+    testCond(_expectUpdate(w, "t.age", "57", 11));
+    kvWatcher_Destroy(w);
     kvStore_Destroy(kv);
 
     JS_TEARDOWN;