Added timeout to flush and wait_for_acks

Author: accelerated

include/cppkafka/utils/buffered_producer.h

@@ -190,11 +190,27 @@ class CPPKAFKA_API BufferedProducer {
      *         with respect to other threads.
      */
     void flush();
+    
+    /**
+     * \brief Flushes the buffered messages and waits up to 'timeout'
+     *
+     * \param timeout The maximum time to wait until all acks are received
+     *
+     * \return True if the operation completes and all acks have been received.
+     */
+    bool flush(std::chrono::milliseconds timeout);
 
     /**
      * Waits for produced message's acknowledgements from the brokers
      */
     void wait_for_acks();
+    
+    /**
+     * Waits for produced message's acknowledgements from the brokers up to 'timeout'.
+     *
+     * \return True if the operation completes and all acks have been received.
+     */
+    bool wait_for_acks(std::chrono::milliseconds timeout);
 
     /**
      * Clears any buffered messages
@@ -515,6 +531,12 @@ void BufferedProducer<BufferType>::flush() {
     wait_for_acks();
 }
 
+template <typename BufferType>
+bool BufferedProducer<BufferType>::flush(std::chrono::milliseconds timeout) {
+    async_flush();
+    return wait_for_acks(timeout);
+}
+
 template <typename BufferType>
 void BufferedProducer<BufferType>::wait_for_acks() {
     while (pending_acks_ > 0) {
@@ -533,6 +555,31 @@ void BufferedProducer<BufferType>::wait_for_acks() {
     }
 }
 
+template <typename BufferType>
+bool BufferedProducer<BufferType>::wait_for_acks(std::chrono::milliseconds timeout) {
+    auto remaining = timeout;
+    auto start_time = std::chrono::high_resolution_clock::now();
+    while ((pending_acks_ > 0) && (remaining.count() > 0)) {
+        try {
+            producer_.flush(remaining);
+        }
+        catch (const HandleException& ex) {
+            // If we just hit the timeout, keep going, otherwise re-throw
+            if (ex.get_error() == RD_KAFKA_RESP_ERR__TIMED_OUT) {
+                // There is no time remaining
+                return (pending_acks_ == 0);
+            }
+            else {
+                throw;
+            }
+        }
+        // calculate remaining time
+        remaining = timeout - std::chrono::duration_cast<std::chrono::milliseconds>
+            (std::chrono::high_resolution_clock::now() - start_time);
+    }
+    return (pending_acks_ == 0);
+}
+
 template <typename BufferType>
 void BufferedProducer<BufferType>::clear() {
     std::lock_guard<std::mutex> lock(mutex_);