1 files changed, 57 insertions, 0 deletions
diff --git a/searchcore/src/apps/vespa-feed-bm/pending_tracker.h b/searchcore/src/apps/vespa-feed-bm/pending_tracker.h
new file mode 100644
index 00000000000..3698832068f
--- /dev/null
+++ b/searchcore/src/apps/vespa-feed-bm/pending_tracker.h
@@ -0,0 +1,57 @@
+// Copyright Verizon Media. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#pragma once
+
+#include <mutex>
+#include <condition_variable>
+
+namespace feedbm {
+
+/*
+ * Class to track number of pending operations, used as backpressure during
+ * benchmark feeding.
+ */
+class PendingTracker {
+    uint32_t                _pending;
+    uint32_t                _limit;
+    std::mutex              _mutex;
+    std::condition_variable _cond;
+
+public:
+    PendingTracker(uint32_t limit)
+        : _pending(0u),
+          _limit(limit),
+          _mutex(),
+          _cond()
+    {
+    }
+
+    ~PendingTracker()
+    {
+        drain();
+    }
+
+    void release() {
+        std::unique_lock<std::mutex> guard(_mutex);
+        --_pending;
+        if (_pending < _limit) {
+            _cond.notify_all();
+        }
+    }
+    void retain() {
+        std::unique_lock<std::mutex> guard(_mutex);
+        while (_pending >= _limit) {
+            _cond.wait(guard);
+        }
+        ++_pending;
+    }
+
+    void drain() {
+        std::unique_lock<std::mutex> guard(_mutex);
+        while (_pending > 0) {
+            _cond.wait(guard);
+        }
+    }
+};
+
+}