1 files changed, 50 insertions, 4 deletions

diff --git a/lib/ThreadsafeQueue.h b/lib/ThreadsafeQueue.h
index 815dfe0..8b385d6 100644
--- a/lib/ThreadsafeQueue.h
+++ b/lib/ThreadsafeQueue.h
@@ -2,7 +2,7 @@
    Copyright (C) 2007, 2008, 2009, 2010, 2011 Her Majesty the Queen in
    Right of Canada (Communications Research Center Canada)
 
-   Copyright (C) 2018
+   Copyright (C) 2023
    Matthias P. Braendli, matthias.braendli@mpb.li
 
    An implementation for a threadsafe queue, depends on C++11
@@ -32,6 +32,7 @@
 #include <condition_variable>
 #include <queue>
 #include <utility>
+#include <cassert>
 
 /* This queue is meant to be used by two threads. One producer
  * that pushes elements into the queue, and one consumer that
@@ -69,7 +70,6 @@ public:
         }
         size_t queue_size = the_queue.size();
         lock.unlock();
-
         the_rx_notification.notify_one();
 
         return queue_size;
@@ -93,11 +93,57 @@ public:
         return queue_size;
     }
 
+    struct push_overflow_result { bool overflowed; size_t new_size; };
+
+    /* Push one element into the queue, and if queue is
+     * full remove one element from the other end.
+     *
+     * max_size == 0 is not allowed.
+     *
+     * returns the new queue size and a flag if overflow occurred.
+     */
+    push_overflow_result push_overflow(T const& val, size_t max_size)
+    {
+        assert(max_size > 0);
+        std::unique_lock<std::mutex> lock(the_mutex);
+
+        bool overflow = false;
+        while (the_queue.size() >= max_size) {
+            overflow = true;
+            the_queue.pop();
+        }
+        the_queue.push(val);
+        const size_t queue_size = the_queue.size();
+        lock.unlock();
+
+        the_rx_notification.notify_one();
+
+        return {overflow, queue_size};
+    }
+
+    push_overflow_result push_overflow(T&& val, size_t max_size)
+    {
+        assert(max_size > 0);
+        std::unique_lock<std::mutex> lock(the_mutex);
+
+        bool overflow = false;
+        while (the_queue.size() >= max_size) {
+            overflow = true;
+            the_queue.pop();
+        }
+        the_queue.emplace(std::move(val));
+        const size_t queue_size = the_queue.size();
+        lock.unlock();
+
+        the_rx_notification.notify_one();
+
+        return {overflow, queue_size};
+    }
+
+
     /* Push one element into the queue, but wait until the
      * queue size goes below the threshold.
      *
-     * Notify waiting thread.
-     *
      * returns the new queue size.
      */
     size_t push_wait_if_full(T const& val, size_t threshold)