inline_pump.h

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/*
 * Copyright 2026 The A11 Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
#ifndef A11_CONCURRENCY_INLINE_PUMP_H_
#define A11_CONCURRENCY_INLINE_PUMP_H_
 
#include <cstddef>
#include <exception>
#include <string_view>
#include <utility>
 
#include <absl/log/log.h>
#include <absl/strings/str_cat.h>
 
#include "a11/exception_guard.h"
#include "thread/boost_primitives.h"
 
namespace a11 {
 
struct InlinePumpState {
  size_t depth = 0;
  bool again = false;
};
 
template <typename Once>
void DriveInline(thread::Mutex* absl_nonnull mu,
                 InlinePumpState* absl_nonnull state, std::string_view name,
                 Once&& once, size_t max_depth = 4) {
  {
    thread::MutexLock lock(mu);
    if (state->depth >= max_depth) {
      state->again = true;
      return;
    }
    ++state->depth;
  }
  while (true) {
    // Every pump body is A11's own -- the store writers and the session pump --
    // so inside A11 this is a plain call.
    const absl::Status raised =
        exception_guard::Attempt([&] { once(); }, absl::StrCat(name, " pump"));
    if (!raised.ok()) {
      LOG(ERROR) << raised.message();
    }
    thread::MutexLock lock(mu);
    if (!state->again) {
      --state->depth;
      return;
    }
    state->again = false;
  }
}
 
inline bool PumpIsDriving(const InlinePumpState& state) {
  return state.depth > 0;
}
 
}  // namespace a11
 
#endif  // A11_CONCURRENCY_INLINE_PUMP_H_