lockfree_event.cc | Explore in Territory

// Copyright 2022 The gRPC 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.
#include <grpc/support/port_platform.h>

#include "src/core/lib/event_engine/posix_engine/lockfree_event.h"

#include <atomic>
#include <cstdint>

#include "absl/status/status.h"

#include <grpc/support/atm.h>
#include <grpc/support/log.h>

#include "src/core/lib/event_engine/posix_engine/event_poller.h"
#include "src/core/lib/event_engine/posix_engine/posix_engine_closure.h"
#include "src/core/lib/gprpp/crash.h"
#include "src/core/lib/gprpp/status_helper.h"

//  'state' holds the to call when the fd is readable or writable respectively.
//    It can contain one of the following values:
//      kClosureReady     : The fd has an I/O event of interest but there is no
//                          closure yet to execute

//      kClosureNotReady : The fd has no I/O event of interest

//      closure ptr       : The closure to be executed when the fd has an I/O
//                          event of interest

//      shutdown_error | kShutdownBit :
//                         'shutdown_error' field ORed with kShutdownBit.
//                          This indicates that the fd is shutdown. Since all
//                          memory allocations are word-aligned, the lower two
//                          bits of the shutdown_error pointer are always 0. So
//                          it is safe to OR these with kShutdownBit

//    Valid state transitions:

//    <closure ptr> <-----3------ kClosureNotReady -----1------->  kClosureReady
//        |  |                         ^   |    ^                         |  |
//        |  |                         |   |    |                         |  |
//        |  +--------------4----------+   6    +---------2---------------+  |
//        |                                |                                 |
//        |                                v                                 |
//        +-----5------->  [shutdown_error | kShutdownBit] <-------7---------+

//     For 1, 4 : See SetReady() function
//     For 2, 3 : See NotifyOn() function
//     For 5,6,7: See SetShutdown() function

namespace grpc_event_engine {
namespace experimental {

void LockfreeEvent::InitEvent() { … }

void LockfreeEvent::DestroyEvent() { … }

void LockfreeEvent::NotifyOn(PosixEngineClosure* closure) { … }

bool LockfreeEvent::SetShutdown(absl::Status shutdown_error) { … }

void LockfreeEvent::SetReady() { … }

}  // namespace experimental
}  // namespace grpc_event_engine
chromium/third_party/grpc/src/src/core/lib/event_engine/posix_engine/lockfree_event.cc
