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fix #3354

src/utils/tokens_bucket.hpp

@@ -0,0 +1,58 @@
+/**
+ * Implementation of the token bucket algorithm.
+ *
+ * It uses a repetitive TimedEvent, started at construction, to fill the
+ * bucket.
+ *
+ * Every n seconds, it executes the given callback. If the callback
+ * returns true, we add a token (if the limit is not yet reached).
+ *
+ */
+
+#pragma once
+
+#include <utils/timed_events.hpp>
+#include <logger/logger.hpp>
+
+class TokensBucket
+{
+public:
+  TokensBucket(std::size_t max_size, std::chrono::milliseconds fill_duration, std::function<bool()> callback, std::string name):
+      limit(max_size),
+      tokens(limit),
+      fill_duration(fill_duration),
+      callback(std::move(callback))
+  {
+    log_debug("creating TokensBucket with max size: ", max_size);
+    TimedEvent event(std::move(fill_duration), [this]() { this->add_token(); }, std::move(name));
+    TimedEventsManager::instance().add_event(std::move(event));
+  }
+
+  bool use_token()
+  {
+    if (this->tokens > 0)
+      {
+        this->tokens--;
+        return true;
+      }
+    else
+      return false;
+  }
+
+  void set_limit(std::size_t limit)
+  {
+    this->limit = limit;
+  }
+
+private:
+  std::size_t limit;
+  std::size_t tokens;
+  std::chrono::milliseconds fill_duration;
+  std::function<bool()> callback;
+
+  void add_token()
+  {
+    if (this->callback() && this->tokens != limit)
+      this->tokens++;
+  }
+};