EventThread.cpp revision 0f2f5ff75b7b48ceb64270655ee6b62d09bf4d00 
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/String8.h>
28#include <utils/Trace.h>
29
30#include "EventThread.h"
31#include "SurfaceFlinger.h"
32
33// ---------------------------------------------------------------------------
34namespace android {
35// ---------------------------------------------------------------------------
36
37EventThread::EventThread(const sp<SurfaceFlinger>& flinger)
38    : mFlinger(flinger),
39      mLastVSyncTimestamp(0),
40      mVSyncTimestamp(0),
41      mUseSoftwareVSync(false),
42      mDeliveredEvents(0),
43      mDebugVsyncEnabled(false) {
44}
45
46void EventThread::onFirstRef() {
47    run("EventThread", PRIORITY_URGENT_DISPLAY + PRIORITY_MORE_FAVORABLE);
48}
49
50sp<EventThread::Connection> EventThread::createEventConnection() const {
51    return new Connection(const_cast<EventThread*>(this));
52}
53
54status_t EventThread::registerDisplayEventConnection(
55        const sp<EventThread::Connection>& connection) {
56    Mutex::Autolock _l(mLock);
57    mDisplayEventConnections.add(connection);
58    mCondition.broadcast();
59    return NO_ERROR;
60}
61
62status_t EventThread::unregisterDisplayEventConnection(
63        const wp<EventThread::Connection>& connection) {
64    Mutex::Autolock _l(mLock);
65    mDisplayEventConnections.remove(connection);
66    mCondition.broadcast();
67    return NO_ERROR;
68}
69
70void EventThread::removeDisplayEventConnection(
71        const wp<EventThread::Connection>& connection) {
72    Mutex::Autolock _l(mLock);
73    mDisplayEventConnections.remove(connection);
74}
75
76void EventThread::setVsyncRate(uint32_t count,
77        const sp<EventThread::Connection>& connection) {
78    if (int32_t(count) >= 0) { // server must protect against bad params
79        Mutex::Autolock _l(mLock);
80        const int32_t new_count = (count == 0) ? -1 : count;
81        if (connection->count != new_count) {
82            connection->count = new_count;
83            mCondition.broadcast();
84        }
85    }
86}
87
88void EventThread::requestNextVsync(
89        const sp<EventThread::Connection>& connection) {
90    Mutex::Autolock _l(mLock);
91    if (connection->count < 0) {
92        connection->count = 0;
93        mCondition.broadcast();
94    }
95}
96
97void EventThread::onScreenReleased() {
98    Mutex::Autolock _l(mLock);
99    if (!mUseSoftwareVSync) {
100        // disable reliance on h/w vsync
101        mUseSoftwareVSync = true;
102        mCondition.broadcast();
103    }
104}
105
106void EventThread::onScreenAcquired() {
107    Mutex::Autolock _l(mLock);
108    if (mUseSoftwareVSync) {
109        // resume use of h/w vsync
110        mUseSoftwareVSync = false;
111        mCondition.broadcast();
112    }
113}
114
115
116void EventThread::onVSyncReceived(int, nsecs_t timestamp) {
117    Mutex::Autolock _l(mLock);
118    mVSyncTimestamp = timestamp;
119    mCondition.broadcast();
120}
121
122bool EventThread::threadLoop() {
123
124    nsecs_t timestamp;
125    DisplayEventReceiver::Event vsync;
126    Vector< wp<EventThread::Connection> > displayEventConnections;
127
128    do {
129        Mutex::Autolock _l(mLock);
130        do {
131            // latch VSYNC event if any
132            timestamp = mVSyncTimestamp;
133            mVSyncTimestamp = 0;
134
135            // check if we should be waiting for VSYNC events
136            bool waitForNextVsync = false;
137            size_t count = mDisplayEventConnections.size();
138            for (size_t i=0 ; i<count ; i++) {
139                sp<Connection> connection =
140                        mDisplayEventConnections.itemAt(i).promote();
141                if (connection!=0 && connection->count >= 0) {
142                    // at least one continuous mode or active one-shot event
143                    waitForNextVsync = true;
144                    break;
145                }
146            }
147
148            if (timestamp) {
149                if (!waitForNextVsync) {
150                    // we received a VSYNC but we have no clients
151                    // don't report it, and disable VSYNC events
152                    disableVSyncLocked();
153                } else {
154                    // report VSYNC event
155                    break;
156                }
157            } else {
158                // never disable VSYNC events immediately, instead
159                // we'll wait to receive the event and we'll
160                // reevaluate whether we need to dispatch it and/or
161                // disable VSYNC events then.
162                if (waitForNextVsync) {
163                    // enable
164                    enableVSyncLocked();
165                }
166            }
167
168            // wait for something to happen
169            if (mUseSoftwareVSync && waitForNextVsync) {
170                // h/w vsync cannot be used (screen is off), so we use
171                // a  timeout instead. it doesn't matter how imprecise this
172                // is, we just need to make sure to serve the clients
173                if (mCondition.waitRelative(mLock, ms2ns(16)) == TIMED_OUT) {
174                    mVSyncTimestamp = systemTime(SYSTEM_TIME_MONOTONIC);
175                }
176            } else {
177                mCondition.wait(mLock);
178            }
179        } while(true);
180
181        // process vsync event
182        mDeliveredEvents++;
183        mLastVSyncTimestamp = timestamp;
184
185        // now see if we still need to report this VSYNC event
186        const size_t count = mDisplayEventConnections.size();
187        for (size_t i=0 ; i<count ; i++) {
188            bool reportVsync = false;
189            sp<Connection> connection =
190                    mDisplayEventConnections.itemAt(i).promote();
191            if (connection == 0)
192                continue;
193
194            const int32_t count = connection->count;
195            if (count >= 1) {
196                if (count==1 || (mDeliveredEvents % count) == 0) {
197                    // continuous event, and time to report it
198                    reportVsync = true;
199                }
200            } else if (count >= -1) {
201                if (count == 0) {
202                    // fired this time around
203                    reportVsync = true;
204                }
205                connection->count--;
206            }
207            if (reportVsync) {
208                displayEventConnections.add(connection);
209            }
210        }
211    } while (!displayEventConnections.size());
212
213    // dispatch vsync events to listeners...
214    vsync.header.type = DisplayEventReceiver::DISPLAY_EVENT_VSYNC;
215    vsync.header.timestamp = timestamp;
216    vsync.vsync.count = mDeliveredEvents;
217
218    const size_t count = displayEventConnections.size();
219    for (size_t i=0 ; i<count ; i++) {
220        sp<Connection> conn(displayEventConnections[i].promote());
221        // make sure the connection didn't die
222        if (conn != NULL) {
223            status_t err = conn->postEvent(vsync);
224            if (err == -EAGAIN || err == -EWOULDBLOCK) {
225                // The destination doesn't accept events anymore, it's probably
226                // full. For now, we just drop the events on the floor.
227                // Note that some events cannot be dropped and would have to be
228                // re-sent later. Right-now we don't have the ability to do
229                // this, but it doesn't matter for VSYNC.
230            } else if (err < 0) {
231                // handle any other error on the pipe as fatal. the only
232                // reasonable thing to do is to clean-up this connection.
233                // The most common error we'll get here is -EPIPE.
234                removeDisplayEventConnection(displayEventConnections[i]);
235            }
236        } else {
237            // somehow the connection is dead, but we still have it in our list
238            // just clean the list.
239            removeDisplayEventConnection(displayEventConnections[i]);
240        }
241    }
242
243    // clear all our references without holding mLock
244    displayEventConnections.clear();
245
246    return true;
247}
248
249void EventThread::enableVSyncLocked() {
250    if (!mUseSoftwareVSync) {
251        // never enable h/w VSYNC when screen is off
252        mFlinger->eventControl(SurfaceFlinger::EVENT_VSYNC, true);
253        mPowerHAL.vsyncHint(true);
254    }
255    mDebugVsyncEnabled = true;
256}
257
258void EventThread::disableVSyncLocked() {
259    mFlinger->eventControl(SurfaceFlinger::EVENT_VSYNC, false);
260    mPowerHAL.vsyncHint(false);
261    mDebugVsyncEnabled = false;
262}
263
264status_t EventThread::readyToRun() {
265    ALOGI("EventThread ready to run.");
266    return NO_ERROR;
267}
268
269void EventThread::dump(String8& result, char* buffer, size_t SIZE) const {
270    Mutex::Autolock _l(mLock);
271    result.appendFormat("VSYNC state: %s\n",
272            mDebugVsyncEnabled?"enabled":"disabled");
273    result.appendFormat("  soft-vsync: %s\n",
274            mUseSoftwareVSync?"enabled":"disabled");
275    result.appendFormat("  numListeners=%u,\n  events-delivered: %u\n",
276            mDisplayEventConnections.size(), mDeliveredEvents);
277    for (size_t i=0 ; i<mDisplayEventConnections.size() ; i++) {
278        sp<Connection> connection =
279                mDisplayEventConnections.itemAt(i).promote();
280        result.appendFormat("    %p: count=%d\n",
281                connection.get(), connection!=NULL ? connection->count : 0);
282    }
283}
284
285// ---------------------------------------------------------------------------
286
287EventThread::Connection::Connection(
288        const sp<EventThread>& eventThread)
289    : count(-1), mEventThread(eventThread), mChannel(new BitTube())
290{
291}
292
293EventThread::Connection::~Connection() {
294    mEventThread->unregisterDisplayEventConnection(this);
295}
296
297void EventThread::Connection::onFirstRef() {
298    // NOTE: mEventThread doesn't hold a strong reference on us
299    mEventThread->registerDisplayEventConnection(this);
300}
301
302sp<BitTube> EventThread::Connection::getDataChannel() const {
303    return mChannel;
304}
305
306void EventThread::Connection::setVsyncRate(uint32_t count) {
307    mEventThread->setVsyncRate(count, this);
308}
309
310void EventThread::Connection::requestNextVsync() {
311    mEventThread->requestNextVsync(this);
312}
313
314status_t EventThread::Connection::postEvent(
315        const DisplayEventReceiver::Event& event) {
316    ssize_t size = DisplayEventReceiver::sendEvents(mChannel, &event, 1);
317    return size < 0 ? status_t(size) : status_t(NO_ERROR);
318}
319
320// ---------------------------------------------------------------------------
321
322}; // namespace android
323