2 * Copyright 2016 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
22 #include <folly/AtomicIntrusiveLinkedList.h>
23 #include <folly/CPortability.h>
24 #include <folly/Function.h>
25 #include <folly/IntrusiveList.h>
26 #include <folly/Portability.h>
27 #include <folly/fibers/BoostContextCompatibility.h>
28 #include <folly/io/async/Request.h>
38 * @brief Fiber object used by FiberManager to execute tasks.
40 * Each Fiber object can be executing at most one task at a time. In active
41 * phase it is running the task function and keeps its context.
42 * Fiber is also used to pass data to blocked task and thus unblock it.
43 * Each Fiber may be associated with a single FiberManager.
48 * Sets data for the blocked task
50 * @param data this data will be returned by await() when task is resumed.
52 void setData(intptr_t data);
54 Fiber(const Fiber&) = delete;
55 Fiber& operator=(const Fiber&) = delete;
60 * Retrieve this fiber's base stack and stack size.
62 * @return This fiber's stack pointer and stack size.
64 std::pair<void*, size_t> getStack() const {
66 std::min<void*>(fcontext_.stackLimit(), fcontext_.stackBase());
67 const size_t size = std::abs(
68 reinterpret_cast<intptr_t>(fcontext_.stackBase()) -
69 reinterpret_cast<intptr_t>(fcontext_.stackLimit()));
75 INVALID, /**< Does't have task function */
76 NOT_STARTED, /**< Has task function, not started */
77 READY_TO_RUN, /**< Was started, blocked, then unblocked */
78 RUNNING, /**< Is running right now */
79 AWAITING, /**< Is currently blocked */
80 AWAITING_IMMEDIATE, /**< Was preempted to run an immediate function,
81 and will be resumed right away */
82 YIELDED, /**< The fiber yielded execution voluntarily */
85 State state_{INVALID}; /**< current Fiber state */
88 friend class FiberManager;
90 explicit Fiber(FiberManager& fiberManager);
92 void init(bool recordStackUsed);
95 void setFunction(F&& func);
97 template <typename F, typename G>
98 void setFunctionFinally(F&& func, G&& finally);
100 static void fiberFuncHelper(intptr_t fiber);
104 * Switch out of fiber context into the main context,
105 * performing necessary housekeeping for the new state.
107 * @param state New state, must not be RUNNING.
109 * @return The value passed back from the main context.
111 intptr_t preempt(State state);
114 * Examines how much of the stack we used at this moment and
115 * registers with the FiberManager (for monitoring).
117 void recordStackPosition();
119 FiberManager& fiberManager_; /**< Associated FiberManager */
120 FContext fcontext_; /**< current task execution context */
121 intptr_t data_; /**< Used to keep some data with the Fiber */
122 std::shared_ptr<RequestContext> rcontext_; /**< current RequestContext */
123 folly::Function<void()> func_; /**< task function */
124 bool recordStackUsed_{false};
125 bool stackFilledWithMagic_{false};
128 * Points to next fiber in remote ready list
130 folly::AtomicIntrusiveLinkedListHook<Fiber> nextRemoteReady_;
132 static constexpr size_t kUserBufferSize = 256;
133 std::aligned_storage<kUserBufferSize>::type userBuffer_;
135 void* getUserBuffer();
137 folly::Function<void()> resultFunc_;
138 folly::Function<void()> finallyFunc_;
143 LocalData(const LocalData& other);
144 LocalData& operator=(const LocalData& other);
146 template <typename T>
149 assert(*dataType_ == typeid(T));
150 return *reinterpret_cast<T*>(data_);
158 template <typename T>
159 FOLLY_NOINLINE T& getSlow();
161 static void* allocateHeapBuffer(size_t size);
162 static void freeHeapBuffer(void* buffer);
164 template <typename T>
165 static void dataCopyConstructor(void*, const void*);
166 template <typename T>
167 static void dataBufferDestructor(void*);
168 template <typename T>
169 static void dataHeapDestructor(void*);
171 static constexpr size_t kBufferSize = 128;
172 std::aligned_storage<kBufferSize>::type buffer_;
175 const std::type_info* dataType_;
176 void (*dataDestructor_)(void*);
177 void (*dataCopyConstructor_)(void*, const void*);
178 void* data_{nullptr};
181 LocalData localData_;
183 folly::IntrusiveListHook listHook_; /**< list hook for different FiberManager
185 folly::IntrusiveListHook globalListHook_; /**< list hook for global list */
186 std::thread::id threadId_{};
191 #include <folly/fibers/Fiber-inl.h>