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/connect.c

@@ -0,0 +1,171 @@
+// Copyright 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 "examples.h"
+
+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));
+
+    // 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.
+    count++;
+
+    natsMsg_Destroy(msg);
+}
+
+static void
+connectedCB(natsConnection *nc, void *closure)
+{
+    char url[256];
+
+    natsConnection_GetConnectedUrl(nc, url, sizeof(url));
+    printf("Connected to %s\n", url);
+}
+
+static void
+closedCB(natsConnection *nc, void *closure)
+{
+    bool        *closed = (bool*)closure;
+    const char  *err    = NULL;
+
+    natsConnection_GetLastError(nc, &err);
+    printf("Connect failed: %s\n", err);
+    *closed = true;
+}
+
+int main(int argc, char **argv)
+{
+    natsConnection      *conn  = NULL;
+    natsOptions         *opts  = NULL;
+    natsSubscription    *sub   = NULL;
+    bool                closed = false;
+    natsStatus          s;
+
+    opts = parseArgs(argc, argv, "");
+
+    // Set a max (re)connect attempts of 50 with a delay of 100 msec.
+    // Total time will then be around 5 seconds.
+
+    s = natsOptions_SetMaxReconnect(opts, 50);
+    if (s == NATS_OK)
+        s = natsOptions_SetReconnectWait(opts, 100);
+
+    // Instruct the library to block the connect call for that
+    // long until it can get a connection or fails.
+    if (s == NATS_OK)
+        s = natsOptions_SetRetryOnFailedConnect(opts, true, NULL, NULL);
+
+    if (s != NATS_OK)
+    {
+        printf("Error: %u - %s\n", s, natsStatus_GetText(s));
+        nats_PrintLastErrorStack(stderr);
+        exit(1);
+    }
+
+    printf("Ensure no server is running, attempt to connect...\n");
+
+    // If the server is not running, this will block for about 5 seconds.
+    start = nats_Now();
+    s = natsConnection_Connect(&conn, opts);
+    elapsed = nats_Now() - start;
+
+    printf("natsConnection_Connect call took %" PRId64 " ms and returned: %s\n", elapsed, natsStatus_GetText(s));
+
+    // Close/destroy the connection in case you had a server running...
+    natsConnection_Destroy(conn);
+    conn = NULL;
+
+    // Now reduce the count, set a connected callback to allow
+    // connect to be done asynchronously and a closed callback
+    // to show that if connect fails, the callback is invoked.
+    s = natsOptions_SetMaxReconnect(opts, 10);
+    if (s == NATS_OK)
+        s = natsOptions_SetRetryOnFailedConnect(opts, true, connectedCB, NULL);
+    if (s == NATS_OK)
+        s = natsOptions_SetClosedCB(opts, closedCB, (void*)&closed);
+
+    if (s != NATS_OK)
+    {
+        printf("Error: %u - %s\n", s, natsStatus_GetText(s));
+        nats_PrintLastErrorStack(stderr);
+        exit(1);
+    }
+
+    printf("\n\n");
+    printf("Ensure no server is running, attempt to connect with async connect...\n");
+
+    // Start the connect. If no server is running, it should return
+    // NATS_NOT_YET_CONNECTED.
+    s = natsConnection_Connect(&conn, opts);
+    printf("natsConnection_Connect call returned: %s\n", natsStatus_GetText(s));
+
+    // Wait for the closed callback to be invoked
+    while (!closed)
+        nats_Sleep(100);
+
+    // Destroy the connection object
+    natsConnection_Destroy(conn);
+    conn = NULL;
+
+
+    // Now change the options to increase the attempts again.
+    s = natsOptions_SetMaxReconnect(opts, 10);
+    if (s == NATS_OK)
+        s = natsOptions_SetReconnectWait(opts, 1000);
+    // Remove the closed CB for this test
+    if (s == NATS_OK)
+        s = natsOptions_SetClosedCB(opts, NULL, NULL);
+
+    if (s != NATS_OK)
+    {
+        printf("Error: %u - %s\n", s, natsStatus_GetText(s));
+        nats_PrintLastErrorStack(stderr);
+        exit(1);
+    }
+
+    printf("\n\n");
+    printf("Ensure no server is running, attempt to connect with async connect...\n");
+
+    s = natsConnection_Connect(&conn, opts);
+    printf("Connect returned: %s\n", natsStatus_GetText(s));
+
+    // Create a subscription and send a message...
+    s = natsConnection_Subscribe(&sub, conn, subj, onMsg, NULL);
+    if (s == NATS_OK)
+        s = natsConnection_Publish(conn, "foo", (const void*)"hello", 5);
+
+    printf("\nStart a server now...\n\n");
+
+    // Wait for the connect to succeed and message to be received.
+    while ((s == NATS_OK) && (count != 1))
+        nats_Sleep(100);
+
+    printf("Received %d message\n", (int) count);
+
+    // Destroy all our objects to avoid report of memory leak
+    natsSubscription_Destroy(sub);
+    natsConnection_Destroy(conn);
+    natsOptions_Destroy(opts);
+
+    // To silence reports of memory still in used with valgrind
+    nats_Close();
+
+    return 0;
+}