promise_based_filter.h | Explore in Territory

// Copyright 2022 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.

#ifndef GRPC_SRC_CORE_LIB_CHANNEL_PROMISE_BASED_FILTER_H
#define GRPC_SRC_CORE_LIB_CHANNEL_PROMISE_BASED_FILTER_H

// Scaffolding to allow the per-call part of a filter to be authored in a
// promise-style. Most of this will be removed once the promises conversion is
// completed.

#include <grpc/support/port_platform.h>

#include <stdint.h>
#include <stdlib.h>

#include <atomic>
#include <initializer_list>
#include <memory>
#include <new>
#include <string>
#include <type_traits>
#include <utility>

#include "absl/container/inlined_vector.h"
#include "absl/functional/function_ref.h"
#include "absl/meta/type_traits.h"
#include "absl/status/status.h"
#include "absl/strings/string_view.h"
#include "absl/types/optional.h"

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

#include "src/core/lib/channel/call_finalization.h"
#include "src/core/lib/channel/channel_fwd.h"
#include "src/core/lib/channel/channel_stack.h"
#include "src/core/lib/channel/context.h"
#include "src/core/lib/event_engine/default_event_engine.h"  // IWYU pragma: keep
#include "src/core/lib/gprpp/debug_location.h"
#include "src/core/lib/gprpp/time.h"
#include "src/core/lib/iomgr/call_combiner.h"
#include "src/core/lib/iomgr/closure.h"
#include "src/core/lib/iomgr/error.h"
#include "src/core/lib/iomgr/exec_ctx.h"
#include "src/core/lib/iomgr/polling_entity.h"
#include "src/core/lib/promise/activity.h"
#include "src/core/lib/promise/arena_promise.h"
#include "src/core/lib/promise/context.h"
#include "src/core/lib/promise/pipe.h"
#include "src/core/lib/promise/poll.h"
#include "src/core/lib/resource_quota/arena.h"
#include "src/core/lib/slice/slice_buffer.h"
#include "src/core/lib/surface/call.h"
#include "src/core/lib/transport/error_utils.h"
#include "src/core/lib/transport/metadata_batch.h"
#include "src/core/lib/transport/transport.h"

namespace grpc_core {

class ChannelFilter { … };

// Designator for whether a filter is client side or server side.
// Please don't use this outside calls to MakePromiseBasedFilter - it's
// intended to be deleted once the promise conversion is complete.
enum class FilterEndpoint { … };

// Flags for MakePromiseBasedFilter.
static constexpr uint8_t kFilterExaminesServerInitialMetadata = …;
static constexpr uint8_t kFilterIsLast = …;
static constexpr uint8_t kFilterExaminesOutboundMessages = …;
static constexpr uint8_t kFilterExaminesInboundMessages = …;
static constexpr uint8_t kFilterExaminesCallContext = …;

namespace promise_filter_detail {

// Proxy channel filter for initialization failure, since we must leave a
// valid filter in place.
class InvalidChannelFilter : public ChannelFilter { … };

// Call data shared between all implementations of promise-based filters.
class BaseCallData : public Activity, private Wakeable { … };

class ClientCallData : public BaseCallData { … };

class ServerCallData : public BaseCallData { … };

// Specific call data per channel filter.
// Note that we further specialize for clients and servers since their
// implementations are very different.
template <FilterEndpoint endpoint>
class CallData;

// Client implementation of call data.
template <>
class CallData<FilterEndpoint::kClient> : public ClientCallData { … };

// Server implementation of call data.
template <>
class CallData<FilterEndpoint::kServer> : public ServerCallData { … };

struct BaseCallDataMethods { … };

template <typename CallData, uint8_t kFlags>
struct CallDataFilterWithFlagsMethods { … };

struct ChannelFilterMethods { … };

template <typename F, uint8_t kFlags>
struct ChannelFilterWithFlagsMethods { … };

}  // namespace promise_filter_detail

// F implements ChannelFilter and :
// class SomeChannelFilter : public ChannelFilter {
//  public:
//   static absl::StatusOr<SomeChannelFilter> Create(
//       ChannelArgs channel_args, ChannelFilter::Args filter_args);
// };
template <typename F, FilterEndpoint kEndpoint, uint8_t kFlags = 0>
absl::enable_if_t<std::is_base_of<ChannelFilter, F>::value, grpc_channel_filter>
MakePromiseBasedFilter(const char* name) { … }

}  // namespace grpc_core

#endif  // GRPC_SRC_CORE_LIB_CHANNEL_PROMISE_BASED_FILTER_H
chromium/third_party/grpc/src/src/core/lib/channel/promise_based_filter.h
