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      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 
     30 struct ANativeWindowBuffer;
     31 
     32 namespace android {
     33 
     34 // ===========================================================================
     35 // Fence
     36 // ===========================================================================
     37 
     38 class Fence
     39     : public LightRefBase<Fence>, public Flattenable<Fence>
     40 {
     41 public:
     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 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, int*& fds, size_t& count) const;
    100     status_t unflatten(void const*& buffer, size_t& size, int const*& fds, size_t& count);
    101 
    102 private:
    103     // Only allow instantiation using ref counting.
    104     friend class LightRefBase<Fence>;
    105     ~Fence();
    106 
    107     // Disallow copying
    108     Fence(const Fence& rhs);
    109     Fence& operator = (const Fence& rhs);
    110     const Fence& operator = (const Fence& rhs) const;
    111 
    112     int mFenceFd;
    113 };
    114 
    115 }; // namespace android
    116 
    117 #endif // ANDROID_FENCE_H
    118