| /* |
| * |
| * 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 |
| * |
| * 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_EXEC_CTX_H |
| #define GRPC_CORE_LIB_IOMGR_EXEC_CTX_H |
| |
| #include <grpc/support/port_platform.h> |
| |
| #include <grpc/support/atm.h> |
| #include <grpc/support/cpu.h> |
| #include <grpc/support/log.h> |
| |
| #include "src/core/lib/gpr/tls.h" |
| #include "src/core/lib/gprpp/fork.h" |
| #include "src/core/lib/iomgr/closure.h" |
| |
| typedef int64_t grpc_millis; |
| |
| #define GRPC_MILLIS_INF_FUTURE INT64_MAX |
| #define GRPC_MILLIS_INF_PAST INT64_MIN |
| |
| /** A workqueue represents a list of work to be executed asynchronously. |
| Forward declared here to avoid a circular dependency with workqueue.h. */ |
| typedef struct grpc_workqueue grpc_workqueue; |
| typedef struct grpc_combiner grpc_combiner; |
| |
| /* This exec_ctx is ready to return: either pre-populated, or cached as soon as |
| the finish_check returns true */ |
| #define GRPC_EXEC_CTX_FLAG_IS_FINISHED 1 |
| /* The exec_ctx's thread is (potentially) owned by a call or channel: care |
| should be given to not delete said call/channel from this exec_ctx */ |
| #define GRPC_EXEC_CTX_FLAG_THREAD_RESOURCE_LOOP 2 |
| /* This exec ctx was initialized by an internal thread, and should not |
| be counted by fork handlers */ |
| #define GRPC_EXEC_CTX_FLAG_IS_INTERNAL_THREAD 4 |
| |
| extern grpc_closure_scheduler* grpc_schedule_on_exec_ctx; |
| |
| gpr_timespec grpc_millis_to_timespec(grpc_millis millis, gpr_clock_type clock); |
| grpc_millis grpc_timespec_to_millis_round_down(gpr_timespec timespec); |
| grpc_millis grpc_timespec_to_millis_round_up(gpr_timespec timespec); |
| |
| namespace grpc_core { |
| /** Execution context. |
| * A bag of data that collects information along a callstack. |
| * It is created on the stack at public API entry points, and stored internally |
| * as a thread-local variable. |
| * |
| * Generally, to create an exec_ctx instance, add the following line at the top |
| * of the public API entry point or at the start of a thread's work function : |
| * |
| * grpc_core::ExecCtx exec_ctx; |
| * |
| * Access the created ExecCtx instance using : |
| * grpc_core::ExecCtx::Get() |
| * |
| * Specific responsibilities (this may grow in the future): |
| * - track a list of work that needs to be delayed until the top of the |
| * call stack (this provides a convenient mechanism to run callbacks |
| * without worrying about locking issues) |
| * - provide a decision maker (via IsReadyToFinish) that provides a |
| * signal as to whether a borrowed thread should continue to do work or |
| * should actively try to finish up and get this thread back to its owner |
| * |
| * CONVENTIONS: |
| * - Instance of this must ALWAYS be constructed on the stack, never |
| * heap allocated. |
| * - Exactly one instance of ExecCtx must be created per thread. Instances must |
| * always be called exec_ctx. |
| * - Do not pass exec_ctx as a parameter to a function. Always access it using |
| * grpc_core::ExecCtx::Get(). |
| */ |
| class ExecCtx { |
| public: |
| /** Default Constructor */ |
| |
| ExecCtx() : flags_(GRPC_EXEC_CTX_FLAG_IS_FINISHED) { |
| grpc_core::Fork::IncExecCtxCount(); |
| Set(this); |
| } |
| |
| /** Parameterised Constructor */ |
| ExecCtx(uintptr_t fl) : flags_(fl) { |
| if (!(GRPC_EXEC_CTX_FLAG_IS_INTERNAL_THREAD & flags_)) { |
| grpc_core::Fork::IncExecCtxCount(); |
| } |
| Set(this); |
| } |
| |
| /** Destructor */ |
| virtual ~ExecCtx() { |
| flags_ |= GRPC_EXEC_CTX_FLAG_IS_FINISHED; |
| Flush(); |
| Set(last_exec_ctx_); |
| if (!(GRPC_EXEC_CTX_FLAG_IS_INTERNAL_THREAD & flags_)) { |
| grpc_core::Fork::DecExecCtxCount(); |
| } |
| } |
| |
| /** Disallow copy and assignment operators */ |
| ExecCtx(const ExecCtx&) = delete; |
| ExecCtx& operator=(const ExecCtx&) = delete; |
| |
| unsigned starting_cpu() const { return starting_cpu_; } |
| |
| struct CombinerData { |
| /* currently active combiner: updated only via combiner.c */ |
| grpc_combiner* active_combiner; |
| /* last active combiner in the active combiner list */ |
| grpc_combiner* last_combiner; |
| }; |
| |
| /** Only to be used by grpc-combiner code */ |
| CombinerData* combiner_data() { return &combiner_data_; } |
| |
| /** Return pointer to grpc_closure_list */ |
| grpc_closure_list* closure_list() { return &closure_list_; } |
| |
| /** Return flags */ |
| uintptr_t flags() { return flags_; } |
| |
| /** Checks if there is work to be done */ |
| bool HasWork() { |
| return combiner_data_.active_combiner != nullptr || |
| !grpc_closure_list_empty(closure_list_); |
| } |
| |
| /** Flush any work that has been enqueued onto this grpc_exec_ctx. |
| * Caller must guarantee that no interfering locks are held. |
| * Returns true if work was performed, false otherwise. |
| */ |
| bool Flush(); |
| |
| /** Returns true if we'd like to leave this execution context as soon as |
| * possible: useful for deciding whether to do something more or not |
| * depending on outside context. |
| */ |
| bool IsReadyToFinish() { |
| if ((flags_ & GRPC_EXEC_CTX_FLAG_IS_FINISHED) == 0) { |
| if (CheckReadyToFinish()) { |
| flags_ |= GRPC_EXEC_CTX_FLAG_IS_FINISHED; |
| return true; |
| } |
| return false; |
| } else { |
| return true; |
| } |
| } |
| |
| /** Returns the stored current time relative to start if valid, |
| * otherwise refreshes the stored time, sets it valid and returns the new |
| * value. |
| */ |
| grpc_millis Now(); |
| |
| /** Invalidates the stored time value. A new time value will be set on calling |
| * Now(). |
| */ |
| void InvalidateNow() { now_is_valid_ = false; } |
| |
| /** To be used only by shutdown code in iomgr */ |
| void SetNowIomgrShutdown() { |
| now_ = GRPC_MILLIS_INF_FUTURE; |
| now_is_valid_ = true; |
| } |
| |
| /** To be used only for testing. |
| * Sets the now value. |
| */ |
| void TestOnlySetNow(grpc_millis new_val) { |
| now_ = new_val; |
| now_is_valid_ = true; |
| } |
| |
| static void TestOnlyGlobalInit(gpr_timespec new_val); |
| |
| /** Global initialization for ExecCtx. Called by iomgr. */ |
| static void GlobalInit(void); |
| |
| /** Global shutdown for ExecCtx. Called by iomgr. */ |
| static void GlobalShutdown(void) { gpr_tls_destroy(&exec_ctx_); } |
| |
| /** Gets pointer to current exec_ctx. */ |
| static ExecCtx* Get() { |
| return reinterpret_cast<ExecCtx*>(gpr_tls_get(&exec_ctx_)); |
| } |
| |
| static void Set(ExecCtx* exec_ctx) { |
| gpr_tls_set(&exec_ctx_, reinterpret_cast<intptr_t>(exec_ctx)); |
| } |
| |
| protected: |
| /** Check if ready to finish. */ |
| virtual bool CheckReadyToFinish() { return false; } |
| |
| /** Disallow delete on ExecCtx. */ |
| static void operator delete(void* p) { abort(); } |
| |
| private: |
| /** Set exec_ctx_ to exec_ctx. */ |
| |
| grpc_closure_list closure_list_ = GRPC_CLOSURE_LIST_INIT; |
| CombinerData combiner_data_ = {nullptr, nullptr}; |
| uintptr_t flags_; |
| |
| unsigned starting_cpu_ = gpr_cpu_current_cpu(); |
| |
| bool now_is_valid_ = false; |
| grpc_millis now_ = 0; |
| |
| GPR_TLS_CLASS_DECL(exec_ctx_); |
| ExecCtx* last_exec_ctx_ = Get(); |
| }; |
| } // namespace grpc_core |
| |
| #endif /* GRPC_CORE_LIB_IOMGR_EXEC_CTX_H */ |