EventThread.cpp revision 1b03149f3533db04e72e088d3fdd09d0087ca594 
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.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(const_cast<DisplayHardware&>(flinger->getDefaultDisplayHardware())), // XXX: eventthread will need rework
42      mLastVSyncTimestamp(0),
43      mVSyncTimestamp(0),
44      mUseSoftwareVSync(false),
45      mDeliveredEvents(0),
46      mDebugVsyncEnabled(false)
47{
48}
49
50void EventThread::onFirstRef() {
51    mHw.setVSyncHandler(this);
52    run("EventThread", PRIORITY_URGENT_DISPLAY + PRIORITY_MORE_FAVORABLE);
53}
54
55sp<EventThread::Connection> EventThread::createEventConnection() const {
56    return new Connection(const_cast<EventThread*>(this));
57}
58
59status_t EventThread::registerDisplayEventConnection(
60        const sp<EventThread::Connection>& connection) {
61    Mutex::Autolock _l(mLock);
62    mDisplayEventConnections.add(connection);
63    mCondition.broadcast();
64    return NO_ERROR;
65}
66
67status_t EventThread::unregisterDisplayEventConnection(
68        const wp<EventThread::Connection>& connection) {
69    Mutex::Autolock _l(mLock);
70    mDisplayEventConnections.remove(connection);
71    mCondition.broadcast();
72    return NO_ERROR;
73}
74
75void EventThread::removeDisplayEventConnection(
76        const wp<EventThread::Connection>& connection) {
77    Mutex::Autolock _l(mLock);
78    mDisplayEventConnections.remove(connection);
79}
80
81void EventThread::setVsyncRate(uint32_t count,
82        const sp<EventThread::Connection>& connection) {
83    if (int32_t(count) >= 0) { // server must protect against bad params
84        Mutex::Autolock _l(mLock);
85        const int32_t new_count = (count == 0) ? -1 : count;
86        if (connection->count != new_count) {
87            connection->count = new_count;
88            mCondition.broadcast();
89        }
90    }
91}
92
93void EventThread::requestNextVsync(
94        const sp<EventThread::Connection>& connection) {
95    Mutex::Autolock _l(mLock);
96    if (connection->count < 0) {
97        connection->count = 0;
98        mCondition.broadcast();
99    }
100}
101
102void EventThread::onScreenReleased() {
103    Mutex::Autolock _l(mLock);
104    if (!mUseSoftwareVSync) {
105        // disable reliance on h/w vsync
106        mUseSoftwareVSync = true;
107        mCondition.broadcast();
108    }
109}
110
111void EventThread::onScreenAcquired() {
112    Mutex::Autolock _l(mLock);
113    if (mUseSoftwareVSync) {
114        // resume use of h/w vsync
115        mUseSoftwareVSync = false;
116        mCondition.broadcast();
117    }
118}
119
120
121void EventThread::onVSyncReceived(int, nsecs_t timestamp) {
122    Mutex::Autolock _l(mLock);
123    mVSyncTimestamp = timestamp;
124    mCondition.broadcast();
125}
126
127bool EventThread::threadLoop() {
128
129    nsecs_t timestamp;
130    DisplayEventReceiver::Event vsync;
131    Vector< wp<EventThread::Connection> > displayEventConnections;
132
133    do {
134        Mutex::Autolock _l(mLock);
135        do {
136            // latch VSYNC event if any
137            timestamp = mVSyncTimestamp;
138            mVSyncTimestamp = 0;
139
140            // check if we should be waiting for VSYNC events
141            bool waitForNextVsync = false;
142            size_t count = mDisplayEventConnections.size();
143            for (size_t i=0 ; i<count ; i++) {
144                sp<Connection> connection =
145                        mDisplayEventConnections.itemAt(i).promote();
146                if (connection!=0 && connection->count >= 0) {
147                    // at least one continuous mode or active one-shot event
148                    waitForNextVsync = true;
149                    break;
150                }
151            }
152
153            if (timestamp) {
154                if (!waitForNextVsync) {
155                    // we received a VSYNC but we have no clients
156                    // don't report it, and disable VSYNC events
157                    disableVSyncLocked();
158                } else {
159                    // report VSYNC event
160                    break;
161                }
162            } else {
163                // never disable VSYNC events immediately, instead
164                // we'll wait to receive the event and we'll
165                // reevaluate whether we need to dispatch it and/or
166                // disable VSYNC events then.
167                if (waitForNextVsync) {
168                    // enable
169                    enableVSyncLocked();
170                }
171            }
172
173            // wait for something to happen
174            if (mUseSoftwareVSync && waitForNextVsync) {
175                // h/w vsync cannot be used (screen is off), so we use
176                // a  timeout instead. it doesn't matter how imprecise this
177                // is, we just need to make sure to serve the clients
178                if (mCondition.waitRelative(mLock, ms2ns(16)) == TIMED_OUT) {
179                    mVSyncTimestamp = systemTime(SYSTEM_TIME_MONOTONIC);
180                }
181            } else {
182                mCondition.wait(mLock);
183            }
184        } while(true);
185
186        // process vsync event
187        mDeliveredEvents++;
188        mLastVSyncTimestamp = timestamp;
189
190        // now see if we still need to report this VSYNC event
191        const size_t count = mDisplayEventConnections.size();
192        for (size_t i=0 ; i<count ; i++) {
193            bool reportVsync = false;
194            sp<Connection> connection =
195                    mDisplayEventConnections.itemAt(i).promote();
196            if (connection == 0)
197                continue;
198
199            const int32_t count = connection->count;
200            if (count >= 1) {
201                if (count==1 || (mDeliveredEvents % count) == 0) {
202                    // continuous event, and time to report it
203                    reportVsync = true;
204                }
205            } else if (count >= -1) {
206                if (count == 0) {
207                    // fired this time around
208                    reportVsync = true;
209                }
210                connection->count--;
211            }
212            if (reportVsync) {
213                displayEventConnections.add(connection);
214            }
215        }
216    } while (!displayEventConnections.size());
217
218    // dispatch vsync events to listeners...
219    vsync.header.type = DisplayEventReceiver::DISPLAY_EVENT_VSYNC;
220    vsync.header.timestamp = timestamp;
221    vsync.vsync.count = mDeliveredEvents;
222
223    const size_t count = displayEventConnections.size();
224    for (size_t i=0 ; i<count ; i++) {
225        sp<Connection> conn(displayEventConnections[i].promote());
226        // make sure the connection didn't die
227        if (conn != NULL) {
228            status_t err = conn->postEvent(vsync);
229            if (err == -EAGAIN || err == -EWOULDBLOCK) {
230                // The destination doesn't accept events anymore, it's probably
231                // full. For now, we just drop the events on the floor.
232                // Note that some events cannot be dropped and would have to be
233                // re-sent later. Right-now we don't have the ability to do
234                // this, but it doesn't matter for VSYNC.
235            } else if (err < 0) {
236                // handle any other error on the pipe as fatal. the only
237                // reasonable thing to do is to clean-up this connection.
238                // The most common error we'll get here is -EPIPE.
239                removeDisplayEventConnection(displayEventConnections[i]);
240            }
241        } else {
242            // somehow the connection is dead, but we still have it in our list
243            // just clean the list.
244            removeDisplayEventConnection(displayEventConnections[i]);
245        }
246    }
247
248    // clear all our references without holding mLock
249    displayEventConnections.clear();
250
251    return true;
252}
253
254void EventThread::enableVSyncLocked() {
255    if (!mUseSoftwareVSync) {
256        // never enable h/w VSYNC when screen is off
257        mHw.eventControl(DisplayHardware::EVENT_VSYNC, true);
258    }
259    mDebugVsyncEnabled = true;
260}
261
262void EventThread::disableVSyncLocked() {
263    mHw.eventControl(DisplayHardware::EVENT_VSYNC, false);
264    mDebugVsyncEnabled = false;
265}
266
267status_t EventThread::readyToRun() {
268    ALOGI("EventThread ready to run.");
269    return NO_ERROR;
270}
271
272void EventThread::dump(String8& result, char* buffer, size_t SIZE) const {
273    Mutex::Autolock _l(mLock);
274    result.appendFormat("VSYNC state: %s\n",
275            mDebugVsyncEnabled?"enabled":"disabled");
276    result.appendFormat("  soft-vsync: %s\n",
277            mUseSoftwareVSync?"enabled":"disabled");
278    result.appendFormat("  numListeners=%u,\n  events-delivered: %u\n",
279            mDisplayEventConnections.size(), mDeliveredEvents);
280    for (size_t i=0 ; i<mDisplayEventConnections.size() ; i++) {
281        sp<Connection> connection =
282                mDisplayEventConnections.itemAt(i).promote();
283        result.appendFormat("    %p: count=%d\n",
284                connection.get(), connection!=NULL ? connection->count : 0);
285    }
286}
287
288// ---------------------------------------------------------------------------
289
290EventThread::Connection::Connection(
291        const sp<EventThread>& eventThread)
292    : count(-1), mEventThread(eventThread), mChannel(new BitTube())
293{
294}
295
296EventThread::Connection::~Connection() {
297    mEventThread->unregisterDisplayEventConnection(this);
298}
299
300void EventThread::Connection::onFirstRef() {
301    // NOTE: mEventThread doesn't hold a strong reference on us
302    mEventThread->registerDisplayEventConnection(this);
303}
304
305sp<BitTube> EventThread::Connection::getDataChannel() const {
306    return mChannel;
307}
308
309void EventThread::Connection::setVsyncRate(uint32_t count) {
310    mEventThread->setVsyncRate(count, this);
311}
312
313void EventThread::Connection::requestNextVsync() {
314    mEventThread->requestNextVsync(this);
315}
316
317status_t EventThread::Connection::postEvent(
318        const DisplayEventReceiver::Event& event) {
319    ssize_t size = DisplayEventReceiver::sendEvents(mChannel, &event, 1);
320    return size < 0 ? status_t(size) : status_t(NO_ERROR);
321}
322
323// ---------------------------------------------------------------------------
324
325}; // namespace android
326