RenderTask.h revision 298a146754e35cbc650aa991ebff1a41eefdbe80 
1/*
2 * Copyright (C) 2013 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 RENDERTASK_H_
18#define RENDERTASK_H_
19
20#include <cutils/compiler.h>
21#include <utils/Timers.h>
22
23namespace android {
24class Mutex;
25class Condition;
26namespace uirenderer {
27namespace renderthread {
28
29#define METHOD_INVOKE_PAYLOAD_SIZE (8 * sizeof(void*))
30
31/*
32 * Notes about memory management
33 *
34 * RenderThread will only invoke RenderTask::run(). It is the responsibility
35 * of the RenderTask to know if it needs to suicide at the end of run() or
36 * if some other lifecycle is being used. As such, it is not valid to reference
37 * anything on RenderTask after the first call to run().
38 *
39 * For example SignalingRenderTask
40 * is expected to be stack allocated by the calling thread, so it does not
41 * suicide in run() but instead relies on the caller to destroy it.
42 *
43 * MethodInvokeRenderTask however is currently allocated with new, so it will
44 * suicide at the end of run(). TODO: Replace this with a small pool to avoid
45 * malloc/free churn of small objects?
46 */
47
48class ANDROID_API RenderTask {
49public:
50    ANDROID_API RenderTask() : mNext(nullptr), mRunAt(0) {}
51    ANDROID_API virtual ~RenderTask() {}
52
53    ANDROID_API virtual void run() = 0;
54
55    RenderTask* mNext;
56    nsecs_t mRunAt; // nano-seconds on the SYSTEM_TIME_MONOTONIC clock
57};
58
59class SignalingRenderTask : public RenderTask {
60public:
61    // Takes ownership of task, caller owns lock and signal
62    SignalingRenderTask(RenderTask* task, Mutex* lock, Condition* signal)
63            : mTask(task), mLock(lock), mSignal(signal), mHasRun(false) {}
64    virtual void run() override;
65    bool hasRun() const { return mHasRun; }
66
67private:
68    RenderTask* mTask;
69    Mutex* mLock;
70    Condition* mSignal;
71    bool mHasRun;
72};
73
74typedef void* (*RunnableMethod)(void* data);
75
76class MethodInvokeRenderTask : public RenderTask {
77public:
78    explicit MethodInvokeRenderTask(RunnableMethod method)
79        : mMethod(method), mReturnPtr(nullptr) {}
80
81    void* payload() { return mData; }
82    void setReturnPtr(void** retptr) { mReturnPtr = retptr; }
83
84    virtual void run() override {
85        void* retval = mMethod(mData);
86        if (mReturnPtr) {
87            *mReturnPtr = retval;
88        }
89        // Commit suicide
90        delete this;
91    }
92private:
93    RunnableMethod mMethod;
94    char mData[METHOD_INVOKE_PAYLOAD_SIZE];
95    void** mReturnPtr;
96};
97
98} /* namespace renderthread */
99} /* namespace uirenderer */
100} /* namespace android */
101#endif /* RENDERTASK_H_ */
102