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tdutils/td/utils/FloodControlStrict.h

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+/*
+    This file is part of TON Blockchain Library.
+
+    TON Blockchain Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    TON Blockchain Library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with TON Blockchain Library.  If not, see <http://www.gnu.org/licenses/>.
+
+    Copyright 2017-2019 Telegram Systems LLP
+*/
+#pragma once
+
+#include "td/utils/common.h"
+
+#include <limits>
+
+namespace td {
+
+// More strict implementaions of flood control than FloodControlFast.
+// Should be just fine for small counters.
+class FloodControlStrict {
+ public:
+  int32 add_event(int32 now) {
+    events_.push_back(Event{now});
+    if (without_update_ > 0) {
+      without_update_--;
+    } else {
+      update(now);
+    }
+    return wakeup_at_;
+  }
+
+  // no more than count in each duration.
+  void add_limit(int32 duration, int32 count) {
+    limits_.push_back(Limit{duration, count, 0});
+  }
+
+  int32 get_wakeup_at() {
+    return wakeup_at_;
+  }
+
+  void clear_events() {
+    events_.clear();
+    for (auto &limit : limits_) {
+      limit.pos_ = 0;
+    }
+    without_update_ = 0;
+    wakeup_at_ = 0;
+  }
+
+  int32 update(int32 now) {
+    size_t min_pos = events_.size();
+
+    without_update_ = std::numeric_limits<size_t>::max();
+    for (auto &limit : limits_) {
+      if (limit.pos_ + limit.count_ < events_.size()) {
+        limit.pos_ = events_.size() - limit.count_;
+      }
+
+      // binary-search? :D
+      while (limit.pos_ < events_.size() && events_[limit.pos_].timestamp_ + limit.duration_ < now) {
+        limit.pos_++;
+      }
+
+      if (limit.count_ + limit.pos_ <= events_.size()) {
+        CHECK(limit.count_ + limit.pos_ == events_.size());
+        wakeup_at_ = max(wakeup_at_, events_[limit.pos_].timestamp_ + limit.duration_);
+        without_update_ = 0;
+      } else {
+        without_update_ = min(without_update_, limit.count_ + limit.pos_ - events_.size());
+      }
+
+      min_pos = min(min_pos, limit.pos_);
+    }
+
+    if (min_pos * 2 > events_.size()) {
+      for (auto &limit : limits_) {
+        limit.pos_ -= min_pos;
+      }
+      events_.erase(events_.begin(), events_.begin() + min_pos);
+    }
+    return wakeup_at_;
+  }
+
+ private:
+  int32 wakeup_at_ = 0;
+  struct Event {
+    int32 timestamp_;
+  };
+  struct Limit {
+    int32 duration_;
+    int32 count_;
+    size_t pos_;
+  };
+  size_t without_update_ = 0;
+  std::vector<Event> events_;
+  std::vector<Limit> limits_;
+};
+
+}  // namespace td