Adding a function to wait for publisher confirms (#841)

* Adding a function to wait for publisher confirms
- Also added an example program to demo it

examples/CMakeLists.txt

@@ -27,6 +27,9 @@ target_link_libraries(amqp_listen PRIVATE examples-common rabbitmq::rabbitmq)
 add_executable(amqp_producer amqp_producer.c)
 target_link_libraries(amqp_producer PRIVATE examples-common rabbitmq::rabbitmq)
 
+add_executable(amqp_confirm_select amqp_confirm_select.c)
+target_link_libraries(amqp_confirm_select PRIVATE examples-common rabbitmq::rabbitmq)
+
 add_executable(amqp_connect_timeout amqp_connect_timeout.c)
 target_link_libraries(amqp_connect_timeout PRIVATE examples-common rabbitmq::rabbitmq)
 

examples/amqp_confirm_select.c

@@ -0,0 +1,189 @@
+// Copyright 2007 - 2021, Alan Antonuk and the rabbitmq-c contributors.
+// SPDX-License-Identifier: mit
+
+#include <inttypes.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <rabbitmq-c/amqp.h>
+#include <rabbitmq-c/tcp_socket.h>
+
+#include "utils.h"
+
+#if ((defined(_WIN32)) || (defined(__MINGW32__)) || (defined(__MINGW64__)))
+#ifndef WINVER
+#define WINVER 0x0502
+#endif
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif
+#include <winsock2.h>
+#else
+#include <sys/time.h>
+#endif
+
+#define SUMMARY_EVERY_US 5000
+
+static void send_batch(amqp_connection_state_t conn, char const *queue_name,
+                       int rate_limit, int message_count) {
+  uint64_t start_time = now_microseconds();
+  int i;
+  int sent = 0;
+  int previous_sent = 0;
+  uint64_t previous_report_time = start_time;
+  uint64_t next_summary_time = start_time + SUMMARY_EVERY_US;
+
+  char message[256];
+  amqp_bytes_t message_bytes;
+
+  for (i = 0; i < (int)sizeof(message); i++) {
+    message[i] = i & 0xff;
+  }
+
+  message_bytes.len = sizeof(message);
+  message_bytes.bytes = message;
+
+  for (i = 0; i < message_count; i++) {
+    uint64_t now = now_microseconds();
+
+    die_on_error(amqp_basic_publish(conn, 1, amqp_cstring_bytes("amq.direct"),
+                                    amqp_cstring_bytes(queue_name), 0, 0, NULL,
+                                    message_bytes),
+                 "Publishing");
+    sent++;
+    if (now > next_summary_time) {
+      int countOverInterval = sent - previous_sent;
+      double intervalRate =
+          countOverInterval / ((now - previous_report_time) / 1000000.0);
+      printf("%d ms: Sent %d - %d since last report (%d Hz)\n",
+             (int)(now - start_time) / 1000, sent, countOverInterval,
+             (int)intervalRate);
+
+      previous_sent = sent;
+      previous_report_time = now;
+      next_summary_time += SUMMARY_EVERY_US;
+    }
+
+    while (((i * 1000000.0) / (now - start_time)) > rate_limit) {
+      microsleep(2000);
+      now = now_microseconds();
+    }
+  }
+
+  {
+    uint64_t stop_time = now_microseconds();
+    int total_delta = (int)(stop_time - start_time);
+
+    printf("PRODUCER - Message count: %d\n", message_count);
+    printf("Total time, milliseconds: %d\n", total_delta / 1000);
+    printf("Overall messages-per-second: %g\n",
+           (message_count / (total_delta / 1000000.0)));
+  }
+}
+
+#define CONSUME_TIMEOUT_USEC 100
+#define WAITING_TIMEOUT_USEC (30 * 1000)
+void wait_for_acks(amqp_connection_state_t conn) {
+  uint64_t start_time = now_microseconds();
+  struct timeval timeout = {0, CONSUME_TIMEOUT_USEC};
+  uint64_t now = 0;
+  amqp_publisher_confirm_t result = {};
+
+  for (;;) {
+    amqp_rpc_reply_t ret;
+
+    now = now_microseconds();
+
+    if (now > start_time + WAITING_TIMEOUT_USEC) {
+      return;
+    }
+
+    amqp_maybe_release_buffers(conn);
+    ret = amqp_publisher_confirm_wait(conn, &timeout, &result);
+
+    if (AMQP_RESPONSE_LIBRARY_EXCEPTION == ret.reply_type) {
+      if (AMQP_STATUS_UNEXPECTED_STATE == ret.library_error) {
+        fprintf(stderr, "An unexpected method was received\n");
+        return;
+      } else if (AMQP_STATUS_TIMEOUT == ret.library_error) {
+        // Timeout means you're done; no publisher confirms were waiting!
+        return;
+      } else {
+        die_on_amqp_error(ret, "Waiting for publisher confirmation");
+      }
+    }
+
+    switch (result.method) {
+      case AMQP_BASIC_ACK_METHOD:
+        fprintf(stderr, "Got an ACK!\n");
+        fprintf(stderr, "Here's the ACK:\n");
+        fprintf(stderr, "\tdelivery_tag: «%" PRIu64 "»\n",
+                result.payload.ack.delivery_tag);
+        fprintf(stderr, "\tmultiple: «%d»\n", result.payload.ack.multiple);
+        break;
+      case AMQP_BASIC_NACK_METHOD:
+        fprintf(stderr, "NACK\n");
+        break;
+      case AMQP_BASIC_REJECT_METHOD:
+        fprintf(stderr, "REJECT\n");
+        break;
+      default:
+        fprintf(stderr, "Unexpected method «%s» is.\n",
+                amqp_method_name(result.method));
+    };
+  }
+}
+
+int main(int argc, char const *const *argv) {
+  char const *hostname;
+  int port, status;
+  int rate_limit;
+  int message_count;
+  amqp_socket_t *socket = NULL;
+  amqp_connection_state_t conn;
+
+  if (argc < 5) {
+    fprintf(stderr,
+            "Usage: amqp_producer host port rate_limit message_count\n");
+    return 1;
+  }
+
+  hostname = argv[1];
+  port = atoi(argv[2]);
+  rate_limit = atoi(argv[3]);
+  message_count = atoi(argv[4]);
+
+  conn = amqp_new_connection();
+
+  socket = amqp_tcp_socket_new(conn);
+  if (!socket) {
+    die("creating TCP socket");
+  }
+
+  status = amqp_socket_open(socket, hostname, port);
+  if (status) {
+    die("opening TCP socket");
+  }
+
+  die_on_amqp_error(amqp_login(conn, "/", 0, 131072, 0, AMQP_SASL_METHOD_PLAIN,
+                               "guest", "guest"),
+                    "Logging in");
+  amqp_channel_open(conn, 1);
+  die_on_amqp_error(amqp_get_rpc_reply(conn), "Opening channel");
+
+  // Enable confirm_select
+  amqp_confirm_select(conn, 1);
+  die_on_amqp_error(amqp_get_rpc_reply(conn), "Enable confirm-select");
+
+  send_batch(conn, "test queue", rate_limit, message_count);
+
+  wait_for_acks(conn);
+  die_on_amqp_error(amqp_channel_close(conn, 1, AMQP_REPLY_SUCCESS),
+                    "Closing channel");
+  die_on_amqp_error(amqp_connection_close(conn, AMQP_REPLY_SUCCESS),
+                    "Closing connection");
+  die_on_error(amqp_destroy_connection(conn), "Ending connection");
+  return 0;
+}

include/rabbitmq-c/amqp.h

@@ -2433,6 +2433,54 @@ AMQP_EXPORT
 int AMQP_CALL amqp_set_rpc_timeout(amqp_connection_state_t state,
                                    const struct timeval *timeout);
 
+/**
+ * Possible payload permutations for publisher confirms.
+ **/
+typedef union amqp_publisher_confirm_payload_t_ {
+  amqp_basic_ack_t ack; /* basic.ack */
+  amqp_basic_nack_t nack; /* basic.nack */
+  amqp_basic_reject_t reject; /* basic.reject */
+} amqp_publisher_confirm_payload_t;
+
+/**
+ * Return information from publisher confirm wait
+ **/
+typedef struct amqp_publisher_confirm_t_ {
+  amqp_publisher_confirm_payload_t payload; /* The response payload; check the `method` value to see which value you should use in the union */
+  amqp_channel_t channel; /* The channel where the confirmation was received */
+  amqp_method_number_t method; /* The method which was received */
+} amqp_publisher_confirm_t;
+
+/**
+ * amqp_publisher_confirm_wait
+ *
+ * Wait for a publisher confirm when one or more channel is in select mode.
+ * If the response has a `reply_type` of `AMQP_RESPONSE_LIBRARY_EXCEPTION` _and_
+ * the `library_error` is `AMQP_STATUS_UNEXPECTED_STATE`, then the frame
+ * received was not an ack.
+ *
+ * In the event that there are no publisher confirms received during the
+ * allotted time, `reply_type` will be `AMQP_RESPONSE_LIBRARY_EXCEPTION`
+ * and the `library_error` will be `AMQP_STATUS_TIMEOUT`.
+ *
+ * When a publisher confirm is received, `reply_type` will equal
+ * `AMQP_RESPONSE_NORMAL`, and the `result` out parameter will
+ * contain all of the information you need:
+ * 
+ * - The `channel` will identify which channel the publisher confirm was received on
+ * - The `method` will tell you whether this is an `ack`, `nack`, or `reject`
+ * - The `payload` is a union, and based on the `method` it will use one of `amqp_basic_ack_t`, `amqp_basic_nack_t`, or `amqp_basic_reject_t`
+ *
+ * \param [in] state connection state
+ * \param [in] timeout when waiting for the frame. Passing NULL will result in
+ * blocking behavior
+ * \param [out] The result of the publisher confirm wait.
+ */
+AMQP_EXPORT
+amqp_rpc_reply_t AMQP_CALL amqp_publisher_confirm_wait(
+    amqp_connection_state_t state, const struct timeval *timeout,
+    amqp_publisher_confirm_t *result);
+
 AMQP_END_DECLS
 
 #endif /* RABBITMQ_C_RABBITMQ_C_H */

librabbitmq/amqp_api.c

@@ -364,3 +364,58 @@ int amqp_set_rpc_timeout(amqp_connection_state_t state,
   }
   return AMQP_STATUS_OK;
 }
+
+amqp_rpc_reply_t amqp_publisher_confirm_wait(amqp_connection_state_t state,
+                                             const struct timeval *timeout,
+                                             amqp_publisher_confirm_t *result) {
+  int res;
+  amqp_frame_t frame;
+  amqp_rpc_reply_t ret;
+
+  memset(&ret, 0x0, sizeof(ret));
+  memset(result, 0x0, sizeof(amqp_publisher_confirm_t));
+
+  res = amqp_simple_wait_frame_noblock(state, &frame, timeout);
+
+  if (AMQP_STATUS_OK != res) {
+    ret.reply_type = AMQP_RESPONSE_LIBRARY_EXCEPTION;
+    ret.library_error = res;
+    return ret;
+  } else if (AMQP_FRAME_METHOD != frame.frame_type ||
+             (AMQP_BASIC_ACK_METHOD != frame.payload.method.id &&
+              AMQP_BASIC_NACK_METHOD != frame.payload.method.id &&
+              AMQP_BASIC_REJECT_METHOD != frame.payload.method.id)) {
+    amqp_put_back_frame(state, &frame);
+    ret.reply_type = AMQP_RESPONSE_LIBRARY_EXCEPTION;
+    ret.library_error = AMQP_STATUS_UNEXPECTED_STATE;
+    return ret;
+  }
+
+  switch (frame.payload.method.id) {
+    case AMQP_BASIC_ACK_METHOD:
+      memcpy(&(result->payload.ack), frame.payload.method.decoded,
+             sizeof(amqp_basic_ack_t));
+      break;
+
+    case AMQP_BASIC_NACK_METHOD:
+      memcpy(&(result->payload.nack), frame.payload.method.decoded,
+             sizeof(amqp_basic_nack_t));
+      break;
+
+    case AMQP_BASIC_REJECT_METHOD:
+      memcpy(&(result->payload.reject), frame.payload.method.decoded,
+             sizeof(amqp_basic_reject_t));
+      break;
+
+    default:
+      amqp_put_back_frame(state, &frame);
+      ret.reply_type = AMQP_RESPONSE_LIBRARY_EXCEPTION;
+      ret.library_error = AMQP_STATUS_UNSUPPORTED;
+      return ret;
+  }
+  result->method = frame.payload.method.id;
+  result->channel = frame.channel;
+  ret.reply_type = AMQP_RESPONSE_NORMAL;
+
+  return ret;
+}