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.
21 #include <folly/AtomicIntrusiveLinkedList.h>
22 #include <folly/CPortability.h>
23 #include <folly/Function.h>
24 #include <folly/IntrusiveList.h>
25 #include <folly/Portability.h>
26 #include <folly/experimental/fibers/BoostContextCompatibility.h>
27 #include <folly/io/async/Request.h>
28 #include <boost/context/all.hpp>
29 #include <boost/version.hpp>
39 * @brief Fiber object used by FiberManager to execute tasks.
41 * Each Fiber object can be executing at most one task at a time. In active
42 * phase it is running the task function and keeps its context.
43 * Fiber is also used to pass data to blocked task and thus unblock it.
44 * Each Fiber may be associated with a single FiberManager.
49 * Sets data for the blocked task
51 * @param data this data will be returned by await() when task is resumed.
53 void setData(intptr_t data);
55 Fiber(const Fiber&) = delete;
56 Fiber& operator=(const Fiber&) = delete;
61 * Retrieve this fiber's base stack and stack size.
63 * @return This fiber's stack pointer and stack size.
65 std::pair<void*, size_t> getStack() const {
67 std::min<void*>(fcontext_.stackLimit(), fcontext_.stackBase());
68 const size_t size = std::abs<intptr_t>(
69 reinterpret_cast<intptr_t>(fcontext_.stackBase()) -
70 reinterpret_cast<intptr_t>(fcontext_.stackLimit()));
76 INVALID, /**< Does't have task function */
77 NOT_STARTED, /**< Has task function, not started */
78 READY_TO_RUN, /**< Was started, blocked, then unblocked */
79 RUNNING, /**< Is running right now */
80 AWAITING, /**< Is currently blocked */
81 AWAITING_IMMEDIATE, /**< Was preempted to run an immediate function,
82 and will be resumed right away */
83 YIELDED, /**< The fiber yielded execution voluntarily */
86 State state_{INVALID}; /**< current Fiber state */
89 friend class FiberManager;
91 explicit Fiber(FiberManager& fiberManager);
93 void init(bool recordStackUsed);
96 void setFunction(F&& func);
98 template <typename F, typename G>
99 void setFunctionFinally(F&& func, G&& finally);
101 static void fiberFuncHelper(intptr_t fiber);
105 * Switch out of fiber context into the main context,
106 * performing necessary housekeeping for the new state.
108 * @param state New state, must not be RUNNING.
110 * @return The value passed back from the main context.
112 intptr_t preempt(State state);
115 * Examines how much of the stack we used at this moment and
116 * registers with the FiberManager (for monitoring).
118 void recordStackPosition();
120 FiberManager& fiberManager_; /**< Associated FiberManager */
121 FContext fcontext_; /**< current task execution context */
122 intptr_t data_; /**< Used to keep some data with the Fiber */
123 std::shared_ptr<RequestContext> rcontext_; /**< current RequestContext */
124 folly::Function<void()> func_; /**< task function */
125 bool recordStackUsed_{false};
126 bool stackFilledWithMagic_{false};
129 * Points to next fiber in remote ready list
131 folly::AtomicIntrusiveLinkedListHook<Fiber> nextRemoteReady_;
133 static constexpr size_t kUserBufferSize = 256;
134 std::aligned_storage<kUserBufferSize>::type userBuffer_;
136 void* getUserBuffer();
138 folly::Function<void()> resultFunc_;
139 folly::Function<void()> finallyFunc_;
144 LocalData(const LocalData& other);
145 LocalData& operator=(const LocalData& other);
147 template <typename T>
150 assert(*dataType_ == typeid(T));
151 return *reinterpret_cast<T*>(data_);
159 template <typename T>
160 FOLLY_NOINLINE T& getSlow();
162 static void* allocateHeapBuffer(size_t size);
163 static void freeHeapBuffer(void* buffer);
165 template <typename T>
166 static void dataCopyConstructor(void*, const void*);
167 template <typename T>
168 static void dataBufferDestructor(void*);
169 template <typename T>
170 static void dataHeapDestructor(void*);
172 static constexpr size_t kBufferSize = 128;
173 std::aligned_storage<kBufferSize>::type buffer_;
176 const std::type_info* dataType_;
177 void (*dataDestructor_)(void*);
178 void (*dataCopyConstructor_)(void*, const void*);
179 void* data_{nullptr};
182 LocalData localData_;
184 folly::IntrusiveListHook listHook_; /**< list hook for different FiberManager
186 folly::IntrusiveListHook globalListHook_; /**< list hook for global list */
192 #include <folly/experimental/fibers/Fiber-inl.h>