1 /* 2 * 3 * Copyright 2017 gRPC authors. 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 */ 18 19 #ifndef GRPC_CORE_LIB_GPRPP_FORK_H 20 #define GRPC_CORE_LIB_GPRPP_FORK_H 21 22 #include <grpc/support/port_platform.h> 23 24 #include "src/core/lib/gprpp/atomic.h" 25 26 /* 27 * NOTE: FORKING IS NOT GENERALLY SUPPORTED, THIS IS ONLY INTENDED TO WORK 28 * AROUND VERY SPECIFIC USE CASES. 29 */ 30 31 namespace grpc_core { 32 33 namespace internal { 34 class ExecCtxState; 35 class ThreadState; 36 } // namespace internal 37 38 class Fork { 39 public: 40 typedef void (*child_postfork_func)(void); 41 42 static void GlobalInit(); 43 static void GlobalShutdown(); 44 45 // Returns true if fork suppport is enabled, false otherwise 46 static bool Enabled(); 47 48 // Increment the count of active ExecCtxs. 49 // Will block until a pending fork is complete if one is in progress. IncExecCtxCount()50 static void IncExecCtxCount() { 51 if (GPR_UNLIKELY(support_enabled_.Load(MemoryOrder::RELAXED))) { 52 DoIncExecCtxCount(); 53 } 54 } 55 56 // Decrement the count of active ExecCtxs DecExecCtxCount()57 static void DecExecCtxCount() { 58 if (GPR_UNLIKELY(support_enabled_.Load(MemoryOrder::RELAXED))) { 59 DoDecExecCtxCount(); 60 } 61 } 62 63 // Provide a function that will be invoked in the child's postfork handler to 64 // reset the polling engine's internal state. 65 static void SetResetChildPollingEngineFunc( 66 child_postfork_func reset_child_polling_engine); 67 static child_postfork_func GetResetChildPollingEngineFunc(); 68 69 // Check if there is a single active ExecCtx 70 // (the one used to invoke this function). If there are more, 71 // return false. Otherwise, return true and block creation of 72 // more ExecCtx s until AlloWExecCtx() is called 73 // 74 static bool BlockExecCtx(); 75 static void AllowExecCtx(); 76 77 // Increment the count of active threads. 78 static void IncThreadCount(); 79 80 // Decrement the count of active threads. 81 static void DecThreadCount(); 82 83 // Await all core threads to be joined. 84 static void AwaitThreads(); 85 86 // Test only: overrides environment variables/compile flags 87 // Must be called before grpc_init() 88 static void Enable(bool enable); 89 90 private: 91 static void DoIncExecCtxCount(); 92 static void DoDecExecCtxCount(); 93 94 static internal::ExecCtxState* exec_ctx_state_; 95 static internal::ThreadState* thread_state_; 96 static grpc_core::Atomic<bool> support_enabled_; 97 static bool override_enabled_; 98 static child_postfork_func reset_child_polling_engine_; 99 }; 100 101 } // namespace grpc_core 102 103 #endif /* GRPC_CORE_LIB_GPRPP_FORK_H */ 104