EventThread.cpp revision d94d3b890ac3d5731bd0397874d32aa4bc74bd61 
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#define ATRACE_TAG ATRACE_TAG_GRAPHICS
18
19#include <stdint.h>
20#include <sys/types.h>
21
22#include <gui/BitTube.h>
23#include <gui/IDisplayEventConnection.h>
24#include <gui/DisplayEventReceiver.h>
25
26#include <utils/Errors.h>
27#include <utils/Trace.h>
28
29#include "DisplayHardware/DisplayHardware.h"
30#include "EventThread.h"
31#include "SurfaceFlinger.h"
32
33// ---------------------------------------------------------------------------
34
35namespace android {
36
37// ---------------------------------------------------------------------------
38
39EventThread::EventThread(const sp<SurfaceFlinger>& flinger)
40    : mFlinger(flinger),
41      mHw(flinger->graphicPlane(0).editDisplayHardware()),
42      mLastVSyncTimestamp(0),
43      mVSyncTimestamp(0),
44      mDeliveredEvents(0)
45{
46}
47
48void EventThread::onFirstRef() {
49    mHw.setVSyncHandler(this);
50    run("EventThread", PRIORITY_URGENT_DISPLAY + PRIORITY_MORE_FAVORABLE);
51}
52
53sp<EventThread::Connection> EventThread::createEventConnection() const {
54    return new Connection(const_cast<EventThread*>(this));
55}
56
57nsecs_t EventThread::getLastVSyncTimestamp() const {
58    Mutex::Autolock _l(mLock);
59    return mLastVSyncTimestamp;
60}
61
62nsecs_t EventThread::getVSyncPeriod() const {
63    return mHw.getRefreshPeriod();
64
65}
66
67status_t EventThread::registerDisplayEventConnection(
68        const sp<EventThread::Connection>& connection) {
69    Mutex::Autolock _l(mLock);
70    mDisplayEventConnections.add(connection);
71    mCondition.signal();
72    return NO_ERROR;
73}
74
75status_t EventThread::unregisterDisplayEventConnection(
76        const wp<EventThread::Connection>& connection) {
77    Mutex::Autolock _l(mLock);
78    mDisplayEventConnections.remove(connection);
79    mCondition.signal();
80    return NO_ERROR;
81}
82
83void EventThread::removeDisplayEventConnection(
84        const wp<EventThread::Connection>& connection) {
85    Mutex::Autolock _l(mLock);
86    mDisplayEventConnections.remove(connection);
87}
88
89void EventThread::setVsyncRate(uint32_t count,
90        const sp<EventThread::Connection>& connection) {
91    if (int32_t(count) >= 0) { // server must protect against bad params
92        Mutex::Autolock _l(mLock);
93        const int32_t new_count = (count == 0) ? -1 : count;
94        if (connection->count != new_count) {
95            connection->count = new_count;
96            mCondition.signal();
97        }
98    }
99}
100
101void EventThread::requestNextVsync(
102        const sp<EventThread::Connection>& connection) {
103    Mutex::Autolock _l(mLock);
104    if (connection->count < 0) {
105        connection->count = 0;
106        mCondition.signal();
107    }
108}
109
110void EventThread::onVSyncReceived(int, nsecs_t timestamp) {
111    Mutex::Autolock _l(mLock);
112    mVSyncTimestamp = timestamp;
113    mCondition.signal();
114}
115
116bool EventThread::threadLoop() {
117
118    nsecs_t timestamp;
119    DisplayEventReceiver::Event vsync;
120    Vector< wp<EventThread::Connection> > displayEventConnections;
121
122    do {
123
124        Mutex::Autolock _l(mLock);
125        do {
126            // latch VSYNC event if any
127            timestamp = mVSyncTimestamp;
128            mVSyncTimestamp = 0;
129
130            // check if we should be waiting for VSYNC events
131            bool waitForNextVsync = false;
132            size_t count = mDisplayEventConnections.size();
133            for (size_t i=0 ; i<count ; i++) {
134                sp<Connection> connection =
135                        mDisplayEventConnections.itemAt(i).promote();
136                if (connection!=0 && connection->count >= 0) {
137                    // at least one continuous mode or active one-shot event
138                    waitForNextVsync = true;
139                    break;
140                }
141            }
142
143            if (timestamp) {
144                if (!waitForNextVsync) {
145                    // we received a VSYNC but we have no clients
146                    // don't report it, and disable VSYNC events
147                    mHw.getHwComposer().eventControl(
148                            HWComposer::EVENT_VSYNC, false);
149                } else {
150                    // report VSYNC event
151                    break;
152                }
153            } else {
154                // never disable VSYNC events immediately, instead
155                // we'll wait to receive the event and we'll
156                // reevaluate whether we need to dispatch it and/or
157                // disable VSYNC events then.
158                if (waitForNextVsync) {
159                    // enable
160                    mHw.getHwComposer().eventControl(
161                            HWComposer::EVENT_VSYNC, true);
162                }
163            }
164
165            // wait for something to happen
166            mCondition.wait(mLock);
167        } while(true);
168
169        // process vsync event
170
171        ATRACE_INT("VSYNC", mDeliveredEvents&1);
172        mDeliveredEvents++;
173        mLastVSyncTimestamp = timestamp;
174
175        // now see if we still need to report this VSYNC event
176        const size_t count = mDisplayEventConnections.size();
177        for (size_t i=0 ; i<count ; i++) {
178            bool reportVsync = false;
179            sp<Connection> connection =
180                    mDisplayEventConnections.itemAt(i).promote();
181            if (connection == 0)
182                continue;
183
184            const int32_t count = connection->count;
185            if (count >= 1) {
186                if (count==1 || (mDeliveredEvents % count) == 0) {
187                    // continuous event, and time to report it
188                    reportVsync = true;
189                }
190            } else if (count >= -1) {
191                if (count == 0) {
192                    // fired this time around
193                    reportVsync = true;
194                }
195                connection->count--;
196            }
197            if (reportVsync) {
198                displayEventConnections.add(connection);
199            }
200        }
201    } while (!displayEventConnections.size());
202
203    // dispatch vsync events to listeners...
204    vsync.header.type = DisplayEventReceiver::DISPLAY_EVENT_VSYNC;
205    vsync.header.timestamp = timestamp;
206    vsync.vsync.count = mDeliveredEvents;
207
208    const size_t count = displayEventConnections.size();
209    for (size_t i=0 ; i<count ; i++) {
210        sp<Connection> conn(displayEventConnections[i].promote());
211        // make sure the connection didn't die
212        if (conn != NULL) {
213            status_t err = conn->postEvent(vsync);
214            if (err == -EAGAIN || err == -EWOULDBLOCK) {
215                // The destination doesn't accept events anymore, it's probably
216                // full. For now, we just drop the events on the floor.
217                // Note that some events cannot be dropped and would have to be
218                // re-sent later. Right-now we don't have the ability to do
219                // this, but it doesn't matter for VSYNC.
220            } else if (err < 0) {
221                // handle any other error on the pipe as fatal. the only
222                // reasonable thing to do is to clean-up this connection.
223                // The most common error we'll get here is -EPIPE.
224                removeDisplayEventConnection(displayEventConnections[i]);
225            }
226        } else {
227            // somehow the connection is dead, but we still have it in our list
228            // just clean the list.
229            removeDisplayEventConnection(displayEventConnections[i]);
230        }
231    }
232
233    // clear all our references without holding mLock
234    displayEventConnections.clear();
235
236    return true;
237}
238
239status_t EventThread::readyToRun() {
240    ALOGI("EventThread ready to run.");
241    return NO_ERROR;
242}
243
244void EventThread::dump(String8& result, char* buffer, size_t SIZE) const {
245    Mutex::Autolock _l(mLock);
246    result.append("VSYNC state:\n");
247    snprintf(buffer, SIZE, "  numListeners=%u, events-delivered: %u\n",
248            mDisplayEventConnections.size(), mDeliveredEvents);
249    result.append(buffer);
250}
251
252// ---------------------------------------------------------------------------
253
254EventThread::Connection::Connection(
255        const sp<EventThread>& eventThread)
256    : count(-1), mEventThread(eventThread), mChannel(new BitTube())
257{
258}
259
260EventThread::Connection::~Connection() {
261    mEventThread->unregisterDisplayEventConnection(this);
262}
263
264void EventThread::Connection::onFirstRef() {
265    // NOTE: mEventThread doesn't hold a strong reference on us
266    mEventThread->registerDisplayEventConnection(this);
267}
268
269sp<BitTube> EventThread::Connection::getDataChannel() const {
270    return mChannel;
271}
272
273void EventThread::Connection::setVsyncRate(uint32_t count) {
274    mEventThread->setVsyncRate(count, this);
275}
276
277void EventThread::Connection::requestNextVsync() {
278    mEventThread->requestNextVsync(this);
279}
280
281status_t EventThread::Connection::postEvent(
282        const DisplayEventReceiver::Event& event) {
283    ssize_t size = DisplayEventReceiver::sendEvents(mChannel, &event, 1);
284    return size < 0 ? status_t(size) : status_t(NO_ERROR);
285}
286
287// ---------------------------------------------------------------------------
288
289}; // namespace android
290