EventThread.cpp revision 616c0cdf2c9e9a86e54f727640a6673bd99fda8e 
1/*
2 * Copyright (C) 2011 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#include <stdint.h>
18#include <sys/types.h>
19
20#include <gui/IDisplayEventConnection.h>
21#include <gui/DisplayEventReceiver.h>
22
23#include <utils/Errors.h>
24
25#include "DisplayHardware/DisplayHardware.h"
26#include "DisplayEventConnection.h"
27#include "EventThread.h"
28#include "SurfaceFlinger.h"
29
30// ---------------------------------------------------------------------------
31
32namespace android {
33
34// ---------------------------------------------------------------------------
35
36EventThread::EventThread(const sp<SurfaceFlinger>& flinger)
37    : mFlinger(flinger),
38      mHw(flinger->graphicPlane(0).displayHardware()),
39      mDeliveredEvents(0)
40{
41}
42
43void EventThread::onFirstRef() {
44    run("EventThread", PRIORITY_URGENT_DISPLAY + PRIORITY_MORE_FAVORABLE);
45}
46
47status_t EventThread::registerDisplayEventConnection(
48        const sp<DisplayEventConnection>& connection) {
49    Mutex::Autolock _l(mLock);
50    ConnectionInfo info;
51    mDisplayEventConnections.add(connection, info);
52    mCondition.signal();
53    return NO_ERROR;
54}
55
56status_t EventThread::unregisterDisplayEventConnection(
57        const wp<DisplayEventConnection>& connection) {
58    Mutex::Autolock _l(mLock);
59    mDisplayEventConnections.removeItem(connection);
60    mCondition.signal();
61    return NO_ERROR;
62}
63
64void EventThread::removeDisplayEventConnection(
65        const wp<DisplayEventConnection>& connection) {
66    Mutex::Autolock _l(mLock);
67    mDisplayEventConnections.removeItem(connection);
68}
69
70EventThread::ConnectionInfo* EventThread::getConnectionInfoLocked(
71        const wp<DisplayEventConnection>& connection) {
72    ssize_t index = mDisplayEventConnections.indexOfKey(connection);
73    if (index < 0) return NULL;
74    return &mDisplayEventConnections.editValueAt(index);
75}
76
77void EventThread::setVsyncRate(uint32_t count,
78        const wp<DisplayEventConnection>& connection) {
79    if (int32_t(count) >= 0) { // server must protect against bad params
80        Mutex::Autolock _l(mLock);
81        ConnectionInfo* info = getConnectionInfoLocked(connection);
82        if (info) {
83            info->count = (count == 0) ? -1 : count;
84            mCondition.signal();
85        }
86    }
87}
88
89void EventThread::requestNextVsync(
90        const wp<DisplayEventConnection>& connection) {
91    Mutex::Autolock _l(mLock);
92    ConnectionInfo* info = getConnectionInfoLocked(connection);
93    if (info) {
94        if (info->count < 0) {
95            info->count = 0;
96        }
97        mCondition.signal();
98    }
99}
100
101bool EventThread::threadLoop() {
102
103    nsecs_t timestamp;
104    DisplayEventReceiver::Event vsync;
105    Vector< wp<DisplayEventConnection> > displayEventConnections;
106
107    { // scope for the lock
108        Mutex::Autolock _l(mLock);
109        do {
110            // see if we need to wait for the VSYNC at all
111            do {
112                bool waitForNextVsync = false;
113                size_t count = mDisplayEventConnections.size();
114                for (size_t i=0 ; i<count ; i++) {
115                    const ConnectionInfo& info(
116                            mDisplayEventConnections.valueAt(i));
117                    if (info.count >= 0) {
118                        // at least one continuous mode or active one-shot event
119                        waitForNextVsync = true;
120                        break;
121                    }
122                }
123
124                if (waitForNextVsync)
125                    break;
126
127                mCondition.wait(mLock);
128            } while(true);
129
130            // at least one listener requested VSYNC
131            mLock.unlock();
132            timestamp = mHw.waitForVSync();
133            mLock.lock();
134            mDeliveredEvents++;
135
136            // now see if we still need to report this VSYNC event
137            bool reportVsync = false;
138            size_t count = mDisplayEventConnections.size();
139            for (size_t i=0 ; i<count ; i++) {
140                const ConnectionInfo& info(
141                        mDisplayEventConnections.valueAt(i));
142                if (info.count >= 1) {
143                    if (info.count==1 || (mDeliveredEvents % info.count) == 0) {
144                        // continuous event, and time to report it
145                        reportVsync = true;
146                    }
147                } else if (info.count >= -1) {
148                    ConnectionInfo& info(
149                            mDisplayEventConnections.editValueAt(i));
150                    if (info.count == 0) {
151                        // fired this time around
152                        reportVsync = true;
153                    }
154                    info.count--;
155                }
156                if (reportVsync) {
157                    displayEventConnections.add(mDisplayEventConnections.keyAt(i));
158                }
159            }
160
161            if (reportVsync) {
162                break;
163            }
164        } while (true);
165
166        // dispatch vsync events to listeners...
167        vsync.header.type = DisplayEventReceiver::DISPLAY_EVENT_VSYNC;
168        vsync.header.timestamp = timestamp;
169        vsync.vsync.count = mDeliveredEvents;
170    }
171
172    const size_t count = displayEventConnections.size();
173    for (size_t i=0 ; i<count ; i++) {
174        sp<DisplayEventConnection> conn(displayEventConnections[i].promote());
175        // make sure the connection didn't die
176        if (conn != NULL) {
177            status_t err = conn->postEvent(vsync);
178            if (err == -EAGAIN || err == -EWOULDBLOCK) {
179                // The destination doesn't accept events anymore, it's probably
180                // full. For now, we just drop the events on the floor.
181                // Note that some events cannot be dropped and would have to be
182                // re-sent later. Right-now we don't have the ability to do
183                // this, but it doesn't matter for VSYNC.
184            } else if (err < 0) {
185                // handle any other error on the pipe as fatal. the only
186                // reasonable thing to do is to clean-up this connection.
187                // The most common error we'll get here is -EPIPE.
188                removeDisplayEventConnection(displayEventConnections[i]);
189            }
190        } else {
191            // somehow the connection is dead, but we still have it in our list
192            // just clean the list.
193            removeDisplayEventConnection(displayEventConnections[i]);
194        }
195    }
196
197    // clear all our references without holding mLock
198    displayEventConnections.clear();
199
200    return true;
201}
202
203status_t EventThread::readyToRun() {
204    ALOGI("EventThread ready to run.");
205    return NO_ERROR;
206}
207
208void EventThread::dump(String8& result, char* buffer, size_t SIZE) const {
209    Mutex::Autolock _l(mLock);
210    result.append("VSYNC state:\n");
211    snprintf(buffer, SIZE, "  numListeners=%u, events-delivered: %u\n",
212            mDisplayEventConnections.size(), mDeliveredEvents);
213    result.append(buffer);
214}
215
216// ---------------------------------------------------------------------------
217
218}; // namespace android
219