Fence.h revision 5736f7dc1535452799ef2ea2026b7d1465567a31
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#include <sys/types.h> 22 23#include <ui/ANativeObjectBase.h> 24#include <ui/PixelFormat.h> 25#include <ui/Rect.h> 26#include <utils/Flattenable.h> 27#include <utils/String8.h> 28#include <utils/Timers.h> 29 30struct ANativeWindowBuffer; 31 32namespace android { 33 34// =========================================================================== 35// Fence 36// =========================================================================== 37 38class Fence 39 : public LightRefBase<Fence>, public Flattenable<Fence> 40{ 41public: 42 static const sp<Fence> NO_FENCE; 43 44 // TIMEOUT_NEVER may be passed to the wait method to indicate that it 45 // should wait indefinitely for the fence to signal. 46 enum { TIMEOUT_NEVER = -1 }; 47 48 // Construct a new Fence object with an invalid file descriptor. This 49 // should be done when the Fence object will be set up by unflattening 50 // serialized data. 51 Fence(); 52 53 // Construct a new Fence object to manage a given fence file descriptor. 54 // When the new Fence object is destructed the file descriptor will be 55 // closed. 56 Fence(int fenceFd); 57 58 // Check whether the Fence has an open fence file descriptor. Most Fence 59 // methods treat an invalid file descriptor just like a valid fence that 60 // is already signalled, so using this is usually not necessary. 61 bool isValid() const { return mFenceFd != -1; } 62 63 // wait waits for up to timeout milliseconds for the fence to signal. If 64 // the fence signals then NO_ERROR is returned. If the timeout expires 65 // before the fence signals then -ETIME is returned. A timeout of 66 // TIMEOUT_NEVER may be used to indicate that the call should wait 67 // indefinitely for the fence to signal. 68 status_t wait(int timeout); 69 70 // waitForever is a convenience function for waiting forever for a fence to 71 // signal (just like wait(TIMEOUT_NEVER)), but issuing an error to the 72 // system log and fence state to the kernel log if the wait lasts longer 73 // than a warning timeout. 74 // The logname argument should be a string identifying 75 // the caller and will be included in the log message. 76 status_t waitForever(const char* logname); 77 78 // merge combines two Fence objects, creating a new Fence object that 79 // becomes signaled when both f1 and f2 are signaled (even if f1 or f2 is 80 // destroyed before it becomes signaled). The name argument specifies the 81 // human-readable name to associated with the new Fence object. 82 static sp<Fence> merge(const char* name, const sp<Fence>& f1, 83 const sp<Fence>& f2); 84 85 static sp<Fence> merge(const String8& name, const sp<Fence>& f1, 86 const sp<Fence>& f2); 87 88 // Return a duplicate of the fence file descriptor. The caller is 89 // responsible for closing the returned file descriptor. On error, -1 will 90 // be returned and errno will indicate the problem. 91 int dup() const; 92 93 // getSignalTime returns the system monotonic clock time at which the 94 // fence transitioned to the signaled state. If the fence is not signaled 95 // then INT64_MAX is returned. If the fence is invalid or if an error 96 // occurs then -1 is returned. 97 nsecs_t getSignalTime() const; 98 99 // hasSignaled returns whether the fence has signaled yet. Prefer this to 100 // getSignalTime() or wait() if all you care about is whether the fence has 101 // signaled. 102 inline bool hasSignaled() { 103 // The sync_wait call underlying wait() has been measured to be 104 // significantly faster than the sync_fence_info call underlying 105 // getSignalTime(), which might otherwise appear to be the more obvious 106 // way to check whether a fence has signaled. 107 return wait(0) == NO_ERROR; 108 } 109 110 // Flattenable interface 111 size_t getFlattenedSize() const; 112 size_t getFdCount() const; 113 status_t flatten(void*& buffer, size_t& size, int*& fds, size_t& count) const; 114 status_t unflatten(void const*& buffer, size_t& size, int const*& fds, size_t& count); 115 116private: 117 // Only allow instantiation using ref counting. 118 friend class LightRefBase<Fence>; 119 ~Fence(); 120 121 // Disallow copying 122 Fence(const Fence& rhs); 123 Fence& operator = (const Fence& rhs); 124 const Fence& operator = (const Fence& rhs) const; 125 126 int mFenceFd; 127}; 128 129}; // namespace android 130 131#endif // ANDROID_FENCE_H 132