1 /* 2 * Copyright (C) 2012 The Android Open Source Project 3 * 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 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 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. 15 */ 16 17 #ifndef ANDROID_FENCE_H 18 #define ANDROID_FENCE_H 19 20 #include <stdint.h> 21 22 #include <utils/Flattenable.h> 23 #include <utils/RefBase.h> 24 #include <utils/Timers.h> 25 26 namespace android { 27 28 class String8; 29 30 // =========================================================================== 31 // Fence 32 // =========================================================================== 33 34 class Fence 35 : public LightRefBase<Fence>, public Flattenable<Fence> 36 { 37 public: 38 static const sp<Fence> NO_FENCE; 39 static constexpr nsecs_t SIGNAL_TIME_PENDING = INT64_MAX; 40 static constexpr nsecs_t SIGNAL_TIME_INVALID = -1; 41 static inline bool isValidTimestamp(nsecs_t time) { 42 return time >= 0 && time < INT64_MAX; 43 } 44 45 // TIMEOUT_NEVER may be passed to the wait method to indicate that it 46 // should wait indefinitely for the fence to signal. 47 enum { TIMEOUT_NEVER = -1 }; 48 49 // Construct a new Fence object with an invalid file descriptor. This 50 // should be done when the Fence object will be set up by unflattening 51 // serialized data. 52 Fence(); 53 54 // Construct a new Fence object to manage a given fence file descriptor. 55 // When the new Fence object is destructed the file descriptor will be 56 // closed. 57 explicit Fence(int fenceFd); 58 59 // Not copyable or movable. 60 Fence(const Fence& rhs) = delete; 61 Fence& operator=(const Fence& rhs) = delete; 62 Fence(Fence&& rhs) = delete; 63 Fence& operator=(Fence&& rhs) = delete; 64 65 // Check whether the Fence has an open fence file descriptor. Most Fence 66 // methods treat an invalid file descriptor just like a valid fence that 67 // is already signalled, so using this is usually not necessary. 68 bool isValid() const { return mFenceFd != -1; } 69 70 // wait waits for up to timeout milliseconds for the fence to signal. If 71 // the fence signals then NO_ERROR is returned. If the timeout expires 72 // before the fence signals then -ETIME is returned. A timeout of 73 // TIMEOUT_NEVER may be used to indicate that the call should wait 74 // indefinitely for the fence to signal. 75 status_t wait(int timeout); 76 77 // waitForever is a convenience function for waiting forever for a fence to 78 // signal (just like wait(TIMEOUT_NEVER)), but issuing an error to the 79 // system log and fence state to the kernel log if the wait lasts longer 80 // than a warning timeout. 81 // The logname argument should be a string identifying 82 // the caller and will be included in the log message. 83 status_t waitForever(const char* logname); 84 85 // merge combines two Fence objects, creating a new Fence object that 86 // becomes signaled when both f1 and f2 are signaled (even if f1 or f2 is 87 // destroyed before it becomes signaled). The name argument specifies the 88 // human-readable name to associated with the new Fence object. 89 static sp<Fence> merge(const char* name, const sp<Fence>& f1, 90 const sp<Fence>& f2); 91 92 static sp<Fence> merge(const String8& name, const sp<Fence>& f1, 93 const sp<Fence>& f2); 94 95 // Return a duplicate of the fence file descriptor. The caller is 96 // responsible for closing the returned file descriptor. On error, -1 will 97 // be returned and errno will indicate the problem. 98 int dup() const; 99 100 // getSignalTime returns the system monotonic clock time at which the 101 // fence transitioned to the signaled state. If the fence is not signaled 102 // then SIGNAL_TIME_PENDING is returned. If the fence is invalid or if an 103 // error occurs then SIGNAL_TIME_INVALID is returned. 104 nsecs_t getSignalTime() const; 105 106 enum class Status { 107 Invalid, // Fence is invalid 108 Unsignaled, // Fence is valid but has not yet signaled 109 Signaled, // Fence is valid and has signaled 110 }; 111 112 // getStatus() returns whether the fence has signaled yet. Prefer this to 113 // getSignalTime() or wait() if all you care about is whether the fence has 114 // signaled. 115 inline Status getStatus() { 116 // The sync_wait call underlying wait() has been measured to be 117 // significantly faster than the sync_fence_info call underlying 118 // getSignalTime(), which might otherwise appear to be the more obvious 119 // way to check whether a fence has signaled. 120 switch (wait(0)) { 121 case NO_ERROR: 122 return Status::Signaled; 123 case -ETIME: 124 return Status::Unsignaled; 125 default: 126 return Status::Invalid; 127 } 128 } 129 130 // Flattenable interface 131 size_t getFlattenedSize() const; 132 size_t getFdCount() const; 133 status_t flatten(void*& buffer, size_t& size, int*& fds, size_t& count) const; 134 status_t unflatten(void const*& buffer, size_t& size, int const*& fds, size_t& count); 135 136 private: 137 // Only allow instantiation using ref counting. 138 friend class LightRefBase<Fence>; 139 ~Fence(); 140 141 int mFenceFd; 142 }; 143 144 }; // namespace android 145 146 #endif // ANDROID_FENCE_H 147
