git subrepo clone (merge) --branch=v3.6.1 https://github.com/nats-io/nats.c.git deps/nats.c

subrepo:
  subdir:   "deps/nats.c"
  merged:   "66cec7f"
upstream:
  origin:   "https://github.com/nats-io/nats.c.git"
  branch:   "v3.6.1"
  commit:   "66cec7f"
git-subrepo:
  version:  "0.4.6"
  commit:   "b8b46501e"

deps/nats.c/examples/libevent-sub.c

@@ -0,0 +1,115 @@
+// Copyright 2016-2018 The NATS Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "adapters/libevent.h"
+#include "examples.h"
+
+static const char *usage = ""\
+"-gd            use global message delivery thread pool\n" \
+"-count         number of expected messages\n";
+
+static void
+onMsg(natsConnection *nc, natsSubscription *sub, natsMsg *msg, void *closure)
+{
+    if (print)
+        printf("Received msg: %s - %.*s\n",
+               natsMsg_GetSubject(msg),
+               natsMsg_GetDataLength(msg),
+               natsMsg_GetData(msg));
+
+    natsMsg_Destroy(msg);
+
+    if (start == 0)
+        start = nats_Now();
+
+    // We should be using a mutex to protect those variables since
+    // they are used from the subscription's delivery and the main
+    // threads. For demo purposes, this is fine.
+    if (++count == total)
+    {
+        elapsed = nats_Now() - start;
+
+        natsConnection_Close(nc);
+    }
+}
+
+int main(int argc, char **argv)
+{
+    natsConnection      *conn  = NULL;
+    natsOptions         *opts  = NULL;
+    natsSubscription    *sub   = NULL;
+    natsStatus          s      = NATS_OK;
+    struct event_base   *evLoop= NULL;
+
+    nats_Open(-1);
+
+    opts = parseArgs(argc, argv, usage);
+
+    printf("Listening on '%s'.\n", subj);
+
+    // One time initialization of things that we need.
+    natsLibevent_Init();
+
+    // Create a loop.
+    evLoop = event_base_new();
+    if (evLoop == NULL)
+        s = NATS_ERR;
+
+    // Indicate which loop and callbacks to use once connected.
+    if (s == NATS_OK)
+        s = natsOptions_SetEventLoop(opts, (void*) evLoop,
+                                     natsLibevent_Attach,
+                                     natsLibevent_Read,
+                                     natsLibevent_Write,
+                                     natsLibevent_Detach);
+
+    if (s == NATS_OK)
+        s = natsConnection_Connect(&conn, opts);
+
+    if (s == NATS_OK)
+        s = natsConnection_Subscribe(&sub, conn, subj, onMsg, NULL);
+
+    // For maximum performance, set no limit on the number of pending messages.
+    if (s == NATS_OK)
+        s = natsSubscription_SetPendingLimits(sub, -1, -1);
+
+    // Run the event loop.
+    // This call will return when the connection is closed (either after
+    // receiving all messages, or disconnected and unable to reconnect).
+    if (s == NATS_OK)
+        event_base_dispatch(evLoop);
+
+    if (s == NATS_OK)
+    {
+        printPerf("Received");
+    }
+    else
+    {
+        printf("Error: %d - %s\n", s, natsStatus_GetText(s));
+        nats_PrintLastErrorStack(stderr);
+    }
+
+    // Destroy all our objects to avoid report of memory leak
+    natsSubscription_Destroy(sub);
+    natsConnection_Destroy(conn);
+    natsOptions_Destroy(opts);
+
+    if (evLoop != NULL)
+        event_base_free(evLoop);
+
+    // To silence reports of memory still in used with valgrind
+    nats_Close();
+    libevent_global_shutdown();
+
+    return 0;
+}