Fence.h revision ea74d3b78d607cde17790a7bb83e6f68ffd34cfd 
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
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(unsigned 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 String8& name, const sp<Fence>& f1,
83            const sp<Fence>& f2);
84
85    // Return a duplicate of the fence file descriptor. The caller is
86    // responsible for closing the returned file descriptor. On error, -1 will
87    // be returned and errno will indicate the problem.
88    int dup() const;
89
90    // getSignalTime returns the system monotonic clock time at which the
91    // fence transitioned to the signaled state.  If the fence is not signaled
92    // then INT64_MAX is returned.  If the fence is invalid or if an error
93    // occurs then -1 is returned.
94    nsecs_t getSignalTime() const;
95
96    // Flattenable interface
97    size_t getFlattenedSize() const;
98    size_t getFdCount() const;
99    status_t flatten(void* buffer, size_t size,
100            int fds[], size_t count) const;
101    status_t unflatten(void const* buffer, size_t size,
102            int fds[], size_t count);
103
104private:
105    // Only allow instantiation using ref counting.
106    friend class LightRefBase<Fence>;
107    virtual ~Fence();
108
109    // Disallow copying
110    Fence(const Fence& rhs);
111    Fence& operator = (const Fence& rhs);
112    const Fence& operator = (const Fence& rhs) const;
113
114    int mFenceFd;
115};
116
117}; // namespace android
118
119#endif // ANDROID_FENCE_H
120