resolver_cancel_gate.h

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/*
 * Copyright (C) Max Dymond, <cmeister2@gmail.com>, et al.
 *
 * SPDX-License-Identifier: curl
 */

 
#ifndef PROTO_FUZZER_RESOLVER_CANCEL_GATE_H_
#define PROTO_FUZZER_RESOLVER_CANCEL_GATE_H_
 
#include <chrono>
#include <condition_variable>
#include <mutex>
 
namespace proto_fuzzer {
 
namespace resolver_cancel_detail {

struct GateState {
  std::mutex mutex;
  std::condition_variable released;
  bool armed = false;
  bool first_lookup_waiting = false;
};

inline GateState& State() {
  static GateState state;
  return state;
}
 
}  // namespace resolver_cancel_detail

class ScopedResolverCancelGate {
 public:
  ScopedResolverCancelGate() {
    auto& state = resolver_cancel_detail::State();
    std::lock_guard<std::mutex> lock(state.mutex);
    state.first_lookup_waiting = false;
    state.armed = true;
  }
 
  ~ScopedResolverCancelGate() {
    auto& state = resolver_cancel_detail::State();
    {
      std::lock_guard<std::mutex> lock(state.mutex);
      state.armed = false;
    }
    state.released.notify_all();
  }
 
  ScopedResolverCancelGate(const ScopedResolverCancelGate&) = delete;
  ScopedResolverCancelGate& operator=(const ScopedResolverCancelGate&) = delete;
};

inline bool WaitForResolverCancelLookup(std::chrono::milliseconds timeout) {
  auto& state = resolver_cancel_detail::State();
  std::unique_lock<std::mutex> lock(state.mutex);
  return state.released.wait_for(lock, timeout, [&state] { return state.first_lookup_waiting; });
}

inline void WaitAtResolverCancelGate() {
  auto& state = resolver_cancel_detail::State();
  std::unique_lock<std::mutex> lock(state.mutex);
  if (!state.armed || state.first_lookup_waiting) {
    return;
  }
  state.first_lookup_waiting = true;
  state.released.notify_all();
  state.released.wait(lock, [&state] { return !state.armed; });
}
 
}  // namespace proto_fuzzer
 
#endif  // PROTO_FUZZER_RESOLVER_CANCEL_GATE_H_