| /* |
| * |
| * Copyright 2017 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_CORE_LIB_IOMGR_CALL_COMBINER_H |
| #define GRPC_CORE_LIB_IOMGR_CALL_COMBINER_H |
| |
| #include <stddef.h> |
| |
| #include <grpc/support/atm.h> |
| |
| #include "src/core/lib/iomgr/closure.h" |
| #include "src/core/lib/iomgr/exec_ctx.h" |
| #include "src/core/lib/support/mpscq.h" |
| |
| // A simple, lock-free mechanism for serializing activity related to a |
| // single call. This is similar to a combiner but is more lightweight. |
| // |
| // It requires the callback (or, in the common case where the callback |
| // actually kicks off a chain of callbacks, the last callback in that |
| // chain) to explicitly indicate (by calling GRPC_CALL_COMBINER_STOP()) |
| // when it is done with the action that was kicked off by the original |
| // callback. |
| |
| extern grpc_tracer_flag grpc_call_combiner_trace; |
| |
| typedef struct { |
| gpr_atm size; // size_t, num closures in queue or currently executing |
| gpr_mpscq queue; |
| // Either 0 (if not cancelled and no cancellation closure set), |
| // a grpc_closure* (if the lowest bit is 0), |
| // or a grpc_error* (if the lowest bit is 1). |
| gpr_atm cancel_state; |
| } grpc_call_combiner; |
| |
| // Assumes memory was initialized to zero. |
| void grpc_call_combiner_init(grpc_call_combiner* call_combiner); |
| |
| void grpc_call_combiner_destroy(grpc_call_combiner* call_combiner); |
| |
| #ifndef NDEBUG |
| #define GRPC_CALL_COMBINER_START(exec_ctx, call_combiner, closure, error, \ |
| reason) \ |
| grpc_call_combiner_start((exec_ctx), (call_combiner), (closure), (error), \ |
| __FILE__, __LINE__, (reason)) |
| #define GRPC_CALL_COMBINER_STOP(exec_ctx, call_combiner, reason) \ |
| grpc_call_combiner_stop((exec_ctx), (call_combiner), __FILE__, __LINE__, \ |
| (reason)) |
| /// Starts processing \a closure on \a call_combiner. |
| void grpc_call_combiner_start(grpc_exec_ctx* exec_ctx, |
| grpc_call_combiner* call_combiner, |
| grpc_closure* closure, grpc_error* error, |
| const char* file, int line, const char* reason); |
| /// Yields the call combiner to the next closure in the queue, if any. |
| void grpc_call_combiner_stop(grpc_exec_ctx* exec_ctx, |
| grpc_call_combiner* call_combiner, |
| const char* file, int line, const char* reason); |
| #else |
| #define GRPC_CALL_COMBINER_START(exec_ctx, call_combiner, closure, error, \ |
| reason) \ |
| grpc_call_combiner_start((exec_ctx), (call_combiner), (closure), (error), \ |
| (reason)) |
| #define GRPC_CALL_COMBINER_STOP(exec_ctx, call_combiner, reason) \ |
| grpc_call_combiner_stop((exec_ctx), (call_combiner), (reason)) |
| /// Starts processing \a closure on \a call_combiner. |
| void grpc_call_combiner_start(grpc_exec_ctx* exec_ctx, |
| grpc_call_combiner* call_combiner, |
| grpc_closure* closure, grpc_error* error, |
| const char* reason); |
| /// Yields the call combiner to the next closure in the queue, if any. |
| void grpc_call_combiner_stop(grpc_exec_ctx* exec_ctx, |
| grpc_call_combiner* call_combiner, |
| const char* reason); |
| #endif |
| |
| /// Registers \a closure to be invoked by \a call_combiner when |
| /// grpc_call_combiner_cancel() is called. |
| /// |
| /// Once a closure is registered, it will always be scheduled exactly |
| /// once; this allows the closure to hold references that will be freed |
| /// regardless of whether or not the call was cancelled. If a cancellation |
| /// does occur, the closure will be scheduled with the cancellation error; |
| /// otherwise, it will be scheduled with GRPC_ERROR_NONE. |
| /// |
| /// The closure will be scheduled in the following cases: |
| /// - If grpc_call_combiner_cancel() was called prior to registering the |
| /// closure, it will be scheduled immediately with the cancelation error. |
| /// - If grpc_call_combiner_cancel() is called after registering the |
| /// closure, the closure will be scheduled with the cancellation error. |
| /// - If grpc_call_combiner_set_notify_on_cancel() is called again to |
| /// register a new cancellation closure, the previous cancellation |
| /// closure will be scheduled with GRPC_ERROR_NONE. |
| /// |
| /// If \a closure is NULL, then no closure will be invoked on |
| /// cancellation; this effectively unregisters the previously set closure. |
| /// However, most filters will not need to explicitly unregister their |
| /// callbacks, as this is done automatically when the call is destroyed. |
| void grpc_call_combiner_set_notify_on_cancel(grpc_exec_ctx* exec_ctx, |
| grpc_call_combiner* call_combiner, |
| grpc_closure* closure); |
| |
| /// Indicates that the call has been cancelled. |
| void grpc_call_combiner_cancel(grpc_exec_ctx* exec_ctx, |
| grpc_call_combiner* call_combiner, |
| grpc_error* error); |
| |
| #endif /* GRPC_CORE_LIB_IOMGR_CALL_COMBINER_H */ |