EventThread.cpp revision 8630320433bd15aca239522e54e711ef6372ab07 
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 "DisplayHardware.h"
31#include "EventThread.h"
32#include "SurfaceFlinger.h"
33
34// ---------------------------------------------------------------------------
35namespace android {
36// ---------------------------------------------------------------------------
37
38EventThread::EventThread(const sp<SurfaceFlinger>& flinger)
39    : mFlinger(flinger),
40      mLastVSyncTimestamp(0),
41      mVSyncTimestamp(0),
42      mUseSoftwareVSync(false),
43      mDeliveredEvents(0),
44      mDebugVsyncEnabled(false) {
45}
46
47void EventThread::onFirstRef() {
48    run("EventThread", PRIORITY_URGENT_DISPLAY + PRIORITY_MORE_FAVORABLE);
49}
50
51sp<EventThread::Connection> EventThread::createEventConnection() const {
52    return new Connection(const_cast<EventThread*>(this));
53}
54
55status_t EventThread::registerDisplayEventConnection(
56        const sp<EventThread::Connection>& connection) {
57    Mutex::Autolock _l(mLock);
58    mDisplayEventConnections.add(connection);
59    mCondition.broadcast();
60    return NO_ERROR;
61}
62
63status_t EventThread::unregisterDisplayEventConnection(
64        const wp<EventThread::Connection>& connection) {
65    Mutex::Autolock _l(mLock);
66    mDisplayEventConnections.remove(connection);
67    mCondition.broadcast();
68    return NO_ERROR;
69}
70
71void EventThread::removeDisplayEventConnection(
72        const wp<EventThread::Connection>& connection) {
73    Mutex::Autolock _l(mLock);
74    mDisplayEventConnections.remove(connection);
75}
76
77void EventThread::setVsyncRate(uint32_t count,
78        const sp<EventThread::Connection>& connection) {
79    if (int32_t(count) >= 0) { // server must protect against bad params
80        Mutex::Autolock _l(mLock);
81        const int32_t new_count = (count == 0) ? -1 : count;
82        if (connection->count != new_count) {
83            connection->count = new_count;
84            mCondition.broadcast();
85        }
86    }
87}
88
89void EventThread::requestNextVsync(
90        const sp<EventThread::Connection>& connection) {
91    Mutex::Autolock _l(mLock);
92    if (connection->count < 0) {
93        connection->count = 0;
94        mCondition.broadcast();
95    }
96}
97
98void EventThread::onScreenReleased() {
99    Mutex::Autolock _l(mLock);
100    if (!mUseSoftwareVSync) {
101        // disable reliance on h/w vsync
102        mUseSoftwareVSync = true;
103        mCondition.broadcast();
104    }
105}
106
107void EventThread::onScreenAcquired() {
108    Mutex::Autolock _l(mLock);
109    if (mUseSoftwareVSync) {
110        // resume use of h/w vsync
111        mUseSoftwareVSync = false;
112        mCondition.broadcast();
113    }
114}
115
116
117void EventThread::onVSyncReceived(int, nsecs_t timestamp) {
118    Mutex::Autolock _l(mLock);
119    mVSyncTimestamp = timestamp;
120    mCondition.broadcast();
121}
122
123bool EventThread::threadLoop() {
124
125    nsecs_t timestamp;
126    DisplayEventReceiver::Event vsync;
127    Vector< wp<EventThread::Connection> > displayEventConnections;
128
129    do {
130        Mutex::Autolock _l(mLock);
131        do {
132            // latch VSYNC event if any
133            timestamp = mVSyncTimestamp;
134            mVSyncTimestamp = 0;
135
136            // check if we should be waiting for VSYNC events
137            bool waitForNextVsync = false;
138            size_t count = mDisplayEventConnections.size();
139            for (size_t i=0 ; i<count ; i++) {
140                sp<Connection> connection =
141                        mDisplayEventConnections.itemAt(i).promote();
142                if (connection!=0 && connection->count >= 0) {
143                    // at least one continuous mode or active one-shot event
144                    waitForNextVsync = true;
145                    break;
146                }
147            }
148
149            if (timestamp) {
150                if (!waitForNextVsync) {
151                    // we received a VSYNC but we have no clients
152                    // don't report it, and disable VSYNC events
153                    disableVSyncLocked();
154                } else {
155                    // report VSYNC event
156                    break;
157                }
158            } else {
159                // never disable VSYNC events immediately, instead
160                // we'll wait to receive the event and we'll
161                // reevaluate whether we need to dispatch it and/or
162                // disable VSYNC events then.
163                if (waitForNextVsync) {
164                    // enable
165                    enableVSyncLocked();
166                }
167            }
168
169            // wait for something to happen
170            if (mUseSoftwareVSync && waitForNextVsync) {
171                // h/w vsync cannot be used (screen is off), so we use
172                // a  timeout instead. it doesn't matter how imprecise this
173                // is, we just need to make sure to serve the clients
174                if (mCondition.waitRelative(mLock, ms2ns(16)) == TIMED_OUT) {
175                    mVSyncTimestamp = systemTime(SYSTEM_TIME_MONOTONIC);
176                }
177            } else {
178                mCondition.wait(mLock);
179            }
180        } while(true);
181
182        // process vsync event
183        mDeliveredEvents++;
184        mLastVSyncTimestamp = timestamp;
185
186        // now see if we still need to report this VSYNC event
187        const size_t count = mDisplayEventConnections.size();
188        for (size_t i=0 ; i<count ; i++) {
189            bool reportVsync = false;
190            sp<Connection> connection =
191                    mDisplayEventConnections.itemAt(i).promote();
192            if (connection == 0)
193                continue;
194
195            const int32_t count = connection->count;
196            if (count >= 1) {
197                if (count==1 || (mDeliveredEvents % count) == 0) {
198                    // continuous event, and time to report it
199                    reportVsync = true;
200                }
201            } else if (count >= -1) {
202                if (count == 0) {
203                    // fired this time around
204                    reportVsync = true;
205                }
206                connection->count--;
207            }
208            if (reportVsync) {
209                displayEventConnections.add(connection);
210            }
211        }
212    } while (!displayEventConnections.size());
213
214    // dispatch vsync events to listeners...
215    vsync.header.type = DisplayEventReceiver::DISPLAY_EVENT_VSYNC;
216    vsync.header.timestamp = timestamp;
217    vsync.vsync.count = mDeliveredEvents;
218
219    const size_t count = displayEventConnections.size();
220    for (size_t i=0 ; i<count ; i++) {
221        sp<Connection> conn(displayEventConnections[i].promote());
222        // make sure the connection didn't die
223        if (conn != NULL) {
224            status_t err = conn->postEvent(vsync);
225            if (err == -EAGAIN || err == -EWOULDBLOCK) {
226                // The destination doesn't accept events anymore, it's probably
227                // full. For now, we just drop the events on the floor.
228                // Note that some events cannot be dropped and would have to be
229                // re-sent later. Right-now we don't have the ability to do
230                // this, but it doesn't matter for VSYNC.
231            } else if (err < 0) {
232                // handle any other error on the pipe as fatal. the only
233                // reasonable thing to do is to clean-up this connection.
234                // The most common error we'll get here is -EPIPE.
235                removeDisplayEventConnection(displayEventConnections[i]);
236            }
237        } else {
238            // somehow the connection is dead, but we still have it in our list
239            // just clean the list.
240            removeDisplayEventConnection(displayEventConnections[i]);
241        }
242    }
243
244    // clear all our references without holding mLock
245    displayEventConnections.clear();
246
247    return true;
248}
249
250void EventThread::enableVSyncLocked() {
251    if (!mUseSoftwareVSync) {
252        // never enable h/w VSYNC when screen is off
253        mFlinger->eventControl(SurfaceFlinger::EVENT_VSYNC, true);
254        mPowerHAL.vsyncHint(true);
255    }
256    mDebugVsyncEnabled = true;
257}
258
259void EventThread::disableVSyncLocked() {
260    mFlinger->eventControl(SurfaceFlinger::EVENT_VSYNC, false);
261    mPowerHAL.vsyncHint(false);
262    mDebugVsyncEnabled = false;
263}
264
265status_t EventThread::readyToRun() {
266    ALOGI("EventThread ready to run.");
267    return NO_ERROR;
268}
269
270void EventThread::dump(String8& result, char* buffer, size_t SIZE) const {
271    Mutex::Autolock _l(mLock);
272    result.appendFormat("VSYNC state: %s\n",
273            mDebugVsyncEnabled?"enabled":"disabled");
274    result.appendFormat("  soft-vsync: %s\n",
275            mUseSoftwareVSync?"enabled":"disabled");
276    result.appendFormat("  numListeners=%u,\n  events-delivered: %u\n",
277            mDisplayEventConnections.size(), mDeliveredEvents);
278    for (size_t i=0 ; i<mDisplayEventConnections.size() ; i++) {
279        sp<Connection> connection =
280                mDisplayEventConnections.itemAt(i).promote();
281        result.appendFormat("    %p: count=%d\n",
282                connection.get(), connection!=NULL ? connection->count : 0);
283    }
284}
285
286// ---------------------------------------------------------------------------
287
288EventThread::Connection::Connection(
289        const sp<EventThread>& eventThread)
290    : count(-1), mEventThread(eventThread), mChannel(new BitTube())
291{
292}
293
294EventThread::Connection::~Connection() {
295    mEventThread->unregisterDisplayEventConnection(this);
296}
297
298void EventThread::Connection::onFirstRef() {
299    // NOTE: mEventThread doesn't hold a strong reference on us
300    mEventThread->registerDisplayEventConnection(this);
301}
302
303sp<BitTube> EventThread::Connection::getDataChannel() const {
304    return mChannel;
305}
306
307void EventThread::Connection::setVsyncRate(uint32_t count) {
308    mEventThread->setVsyncRate(count, this);
309}
310
311void EventThread::Connection::requestNextVsync() {
312    mEventThread->requestNextVsync(this);
313}
314
315status_t EventThread::Connection::postEvent(
316        const DisplayEventReceiver::Event& event) {
317    ssize_t size = DisplayEventReceiver::sendEvents(mChannel, &event, 1);
318    return size < 0 ? status_t(size) : status_t(NO_ERROR);
319}
320
321// ---------------------------------------------------------------------------
322
323}; // namespace android
324