2 * Copyright 2015 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 <boost/context/all.hpp>
22 #include <boost/version.hpp>
23 #include <folly/AtomicIntrusiveLinkedList.h>
24 #include <folly/CPortability.h>
25 #include <folly/IntrusiveList.h>
26 #include <folly/experimental/fibers/BoostContextCompatibility.h>
27 #include <folly/io/async/Request.h>
28 #include <folly/Portability.h>
30 namespace folly { namespace fibers {
37 * @brief Fiber object used by FiberManager to execute tasks.
39 * Each Fiber object can be executing at most one task at a time. In active
40 * phase it is running the task function and keeps its context.
41 * Fiber is also used to pass data to blocked task and thus unblock it.
42 * Each Fiber may be associated with a single FiberManager.
47 * Sets data for the blocked task
49 * @param data this data will be returned by await() when task is resumed.
51 void setData(intptr_t data);
53 Fiber(const Fiber&) = delete;
54 Fiber& operator=(const Fiber&) = delete;
59 * Retrieve this fiber's base stack and stack size.
61 * @return This fiber's stack pointer and stack size.
63 std::pair<void*, size_t> getStack() const {
65 std::min<void*>(fcontext_.stackLimit(), fcontext_.stackBase());
66 const size_t size = std::abs<intptr_t>(
67 reinterpret_cast<intptr_t>(fcontext_.stackBase()) -
68 reinterpret_cast<intptr_t>(fcontext_.stackLimit()));
69 return { stack, size };
74 INVALID, /**< Does't have task function */
75 NOT_STARTED, /**< Has task function, not started */
76 READY_TO_RUN, /**< Was started, blocked, then unblocked */
77 RUNNING, /**< Is running right now */
78 AWAITING, /**< Is currently blocked */
79 AWAITING_IMMEDIATE, /**< Was preempted to run an immediate function,
80 and will be resumed right away */
81 YIELDED, /**< The fiber yielded execution voluntarily */
84 State state_{INVALID}; /**< current Fiber state */
87 friend class FiberManager;
89 explicit Fiber(FiberManager& fiberManager);
91 void init(bool recordStackUsed);
94 void setFunction(F&& func);
96 template <typename F, typename G>
97 void setFunctionFinally(F&& func, G&& finally);
99 static void fiberFuncHelper(intptr_t fiber);
103 * Switch out of fiber context into the main context,
104 * performing necessary housekeeping for the new state.
106 * @param state New state, must not be RUNNING.
108 * @return The value passed back from the main context.
110 intptr_t preempt(State state);
113 * Examines how much of the stack we used at this moment and
114 * registers with the FiberManager (for monitoring).
116 void recordStackPosition();
118 FiberManager& fiberManager_; /**< Associated FiberManager */
119 FContext fcontext_; /**< current task execution context */
120 intptr_t data_; /**< Used to keep some data with the Fiber */
121 std::shared_ptr<RequestContext> rcontext_; /**< current RequestContext */
122 std::function<void()> func_; /**< task function */
123 bool recordStackUsed_{false};
124 bool stackFilledWithMagic_{false};
127 * Points to next fiber in remote ready list
129 folly::AtomicIntrusiveLinkedListHook<Fiber> nextRemoteReady_;
131 static constexpr size_t kUserBufferSize = 256;
132 std::aligned_storage<kUserBufferSize>::type userBuffer_;
134 void* getUserBuffer();
136 std::function<void()> resultFunc_;
137 std::function<void()> finallyFunc_;
142 LocalData(const LocalData& other);
143 LocalData& operator=(const LocalData& other);
145 template <typename T>
148 assert(*dataType_ == typeid(T));
149 return *reinterpret_cast<T*>(data_);
157 template <typename T>
158 FOLLY_NOINLINE T& getSlow();
160 static void* allocateHeapBuffer(size_t size);
161 static void freeHeapBuffer(void* buffer);
163 template <typename T>
164 static void dataCopyConstructor(void*, const void*);
165 template <typename T>
166 static void dataBufferDestructor(void*);
167 template <typename T>
168 static void dataHeapDestructor(void*);
170 static constexpr size_t kBufferSize = 128;
171 std::aligned_storage<kBufferSize>::type buffer_;
174 const std::type_info* dataType_;
175 void (*dataDestructor_)(void*);
176 void (*dataCopyConstructor_)(void*, const void*);
177 void* data_{nullptr};
180 LocalData localData_;
182 folly::IntrusiveListHook listHook_; /**< list hook for different FiberManager
189 #include <folly/experimental/fibers/Fiber-inl.h>