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* Copyright 2015 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <grpc/support/port_platform.h>
#include <stddef.h>
#include <stdint.h>
#include <atomic>
#include <map>
#include <string>
#include <utility>
#include "absl/base/thread_annotations.h"
#include "absl/status/statusor.h"
#include "absl/strings/string_view.h"
#include "absl/types/optional.h"
#include <grpc/event_engine/memory_allocator.h>
#include <grpc/impl/codegen/compression_types.h>
#include <grpc/impl/codegen/grpc_types.h>
#include <grpc/slice.h>
#include "src/core/lib/channel/channel_args.h"
#include "src/core/lib/channel/channel_fwd.h"
#include "src/core/lib/channel/channel_stack.h" // IWYU pragma: keep
#include "src/core/lib/channel/channel_stack_builder.h"
#include "src/core/lib/channel/channelz.h"
#include "src/core/lib/gprpp/cpp_impl_of.h"
#include "src/core/lib/gprpp/debug_location.h"
#include "src/core/lib/gprpp/ref_counted.h"
#include "src/core/lib/gprpp/ref_counted_ptr.h"
#include "src/core/lib/gprpp/sync.h"
#include "src/core/lib/gprpp/time.h"
#include "src/core/lib/iomgr/iomgr_fwd.h"
#include "src/core/lib/resource_quota/memory_quota.h"
#include "src/core/lib/slice/slice.h"
#include "src/core/lib/surface/channel_stack_type.h"
#include "src/core/lib/transport/transport_fwd.h"
/** The same as grpc_channel_destroy, but doesn't create an ExecCtx, and so
* is safe to use from within core. */
void grpc_channel_destroy_internal(grpc_channel* channel);
/** Create a call given a grpc_channel, in order to call \a method.
Progress is tied to activity on \a pollset_set. The returned call object is
meant to be used with \a grpc_call_start_batch_and_execute, which relies on
callbacks to signal completions. \a method and \a host need
only live through the invocation of this function. If \a parent_call is
non-NULL, it must be a server-side call. It will be used to propagate
properties from the server call to this new client call, depending on the
value of \a propagation_mask (see propagation_bits.h for possible values) */
grpc_call* grpc_channel_create_pollset_set_call(
grpc_channel* channel, grpc_call* parent_call, uint32_t propagation_mask,
grpc_pollset_set* pollset_set, const grpc_slice& method,
const grpc_slice* host, grpc_core::Timestamp deadline, void* reserved);
/** Get a (borrowed) pointer to this channels underlying channel stack */
grpc_channel_stack* grpc_channel_get_channel_stack(grpc_channel* channel);
grpc_core::channelz::ChannelNode* grpc_channel_get_channelz_node(
grpc_channel* channel);
size_t grpc_channel_get_call_size_estimate(grpc_channel* channel);
void grpc_channel_update_call_size_estimate(grpc_channel* channel, size_t size);
namespace grpc_core {
struct RegisteredCall {
Slice path;
absl::optional<Slice> authority;
explicit RegisteredCall(const char* method_arg, const char* host_arg);
RegisteredCall(const RegisteredCall& other);
RegisteredCall& operator=(const RegisteredCall&) = delete;
struct CallRegistrationTable {
Mutex mu;
// The map key should be owned strings rather than unowned char*'s to
// guarantee that it outlives calls on the core channel (which may outlast the
// C++ or other wrapped language Channel that registered these calls).
std::map<std::pair<std::string, std::string>, RegisteredCall> map
int method_registration_attempts ABSL_GUARDED_BY(mu) = 0;
class Channel : public RefCounted<Channel>,
public CppImplOf<Channel, grpc_channel> {
static absl::StatusOr<RefCountedPtr<Channel>> Create(
const char* target, ChannelArgs args,
grpc_channel_stack_type channel_stack_type,
grpc_transport* optional_transport);
static absl::StatusOr<RefCountedPtr<Channel>> CreateWithBuilder(
ChannelStackBuilder* builder);
grpc_channel_stack* channel_stack() const { return channel_stack_.get(); }
grpc_compression_options compression_options() const {
return compression_options_;
channelz::ChannelNode* channelz_node() const { return channelz_node_.get(); }
size_t CallSizeEstimate() {
// We round up our current estimate to the NEXT value of kRoundUpSize.
// This ensures:
// 1. a consistent size allocation when our estimate is drifting slowly
// (which is common) - which tends to help most allocators reuse memory
// 2. a small amount of allowed growth over the estimate without hitting
// the arena size doubling case, reducing overall memory usage
static constexpr size_t kRoundUpSize = 256;
return (call_size_estimate_.load(std::memory_order_relaxed) +
2 * kRoundUpSize) &
~(kRoundUpSize - 1);
void UpdateCallSizeEstimate(size_t size);
absl::string_view target() const { return target_; }
MemoryAllocator* allocator() { return &allocator_; }
bool is_client() const { return is_client_; }
RegisteredCall* RegisterCall(const char* method, const char* host);
int TestOnlyRegisteredCalls() {
MutexLock lock(&;
int TestOnlyRegistrationAttempts() {
MutexLock lock(&;
return registration_table_.method_registration_attempts;
Channel(bool is_client, std::string target, ChannelArgs channel_args,
grpc_compression_options compression_options,
RefCountedPtr<grpc_channel_stack> channel_stack);
const bool is_client_;
const grpc_compression_options compression_options_;
std::atomic<size_t> call_size_estimate_;
CallRegistrationTable registration_table_;
RefCountedPtr<channelz::ChannelNode> channelz_node_;
MemoryAllocator allocator_;
std::string target_;
const RefCountedPtr<grpc_channel_stack> channel_stack_;
} // namespace grpc_core
inline grpc_compression_options grpc_channel_compression_options(
const grpc_channel* channel) {
return grpc_core::Channel::FromC(channel)->compression_options();
inline grpc_channel_stack* grpc_channel_get_channel_stack(
grpc_channel* channel) {
return grpc_core::Channel::FromC(channel)->channel_stack();
inline grpc_core::channelz::ChannelNode* grpc_channel_get_channelz_node(
grpc_channel* channel) {
return grpc_core::Channel::FromC(channel)->channelz_node();
inline void grpc_channel_internal_ref(grpc_channel* channel,
const char* reason) {
grpc_core::Channel::FromC(channel)->Ref(DEBUG_LOCATION, reason).release();
inline void grpc_channel_internal_unref(grpc_channel* channel,
const char* reason) {
grpc_core::Channel::FromC(channel)->Unref(DEBUG_LOCATION, reason);
// Return the channel's compression options.
grpc_compression_options grpc_channel_compression_options(
const grpc_channel* channel);
// Ping the channels peer (load balanced channels will select one sub-channel to
// ping); if the channel is not connected, posts a failed.
void grpc_channel_ping(grpc_channel* channel, grpc_completion_queue* cq,
void* tag, void* reserved);