EventThread.cpp revision 921e6ac4b7610a178285898d191eb0e3afe906c0 
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    : mHw(const_cast<DisplayHardware&>(flinger->getDefaultDisplayHardware())), // XXX: eventthread will need rework
40      mLastVSyncTimestamp(0),
41      mVSyncTimestamp(0),
42      mUseSoftwareVSync(false),
43      mDeliveredEvents(0),
44      mDebugVsyncEnabled(false) {
45}
46
47void EventThread::onFirstRef() {
48    mHw.setVSyncHandler(this);
49    run("EventThread", PRIORITY_URGENT_DISPLAY + PRIORITY_MORE_FAVORABLE);
50}
51
52sp<EventThread::Connection> EventThread::createEventConnection() const {
53    return new Connection(const_cast<EventThread*>(this));
54}
55
56status_t EventThread::registerDisplayEventConnection(
57        const sp<EventThread::Connection>& connection) {
58    Mutex::Autolock _l(mLock);
59    mDisplayEventConnections.add(connection);
60    mCondition.broadcast();
61    return NO_ERROR;
62}
63
64status_t EventThread::unregisterDisplayEventConnection(
65        const wp<EventThread::Connection>& connection) {
66    Mutex::Autolock _l(mLock);
67    mDisplayEventConnections.remove(connection);
68    mCondition.broadcast();
69    return NO_ERROR;
70}
71
72void EventThread::removeDisplayEventConnection(
73        const wp<EventThread::Connection>& connection) {
74    Mutex::Autolock _l(mLock);
75    mDisplayEventConnections.remove(connection);
76}
77
78void EventThread::setVsyncRate(uint32_t count,
79        const sp<EventThread::Connection>& connection) {
80    if (int32_t(count) >= 0) { // server must protect against bad params
81        Mutex::Autolock _l(mLock);
82        const int32_t new_count = (count == 0) ? -1 : count;
83        if (connection->count != new_count) {
84            connection->count = new_count;
85            mCondition.broadcast();
86        }
87    }
88}
89
90void EventThread::requestNextVsync(
91        const sp<EventThread::Connection>& connection) {
92    Mutex::Autolock _l(mLock);
93    if (connection->count < 0) {
94        connection->count = 0;
95        mCondition.broadcast();
96    }
97}
98
99void EventThread::onScreenReleased() {
100    Mutex::Autolock _l(mLock);
101    if (!mUseSoftwareVSync) {
102        // disable reliance on h/w vsync
103        mUseSoftwareVSync = true;
104        mCondition.broadcast();
105    }
106}
107
108void EventThread::onScreenAcquired() {
109    Mutex::Autolock _l(mLock);
110    if (mUseSoftwareVSync) {
111        // resume use of h/w vsync
112        mUseSoftwareVSync = false;
113        mCondition.broadcast();
114    }
115}
116
117
118void EventThread::onVSyncReceived(int, nsecs_t timestamp) {
119    Mutex::Autolock _l(mLock);
120    mVSyncTimestamp = timestamp;
121    mCondition.broadcast();
122}
123
124bool EventThread::threadLoop() {
125
126    nsecs_t timestamp;
127    DisplayEventReceiver::Event vsync;
128    Vector< wp<EventThread::Connection> > displayEventConnections;
129
130    do {
131        Mutex::Autolock _l(mLock);
132        do {
133            // latch VSYNC event if any
134            timestamp = mVSyncTimestamp;
135            mVSyncTimestamp = 0;
136
137            // check if we should be waiting for VSYNC events
138            bool waitForNextVsync = false;
139            size_t count = mDisplayEventConnections.size();
140            for (size_t i=0 ; i<count ; i++) {
141                sp<Connection> connection =
142                        mDisplayEventConnections.itemAt(i).promote();
143                if (connection!=0 && connection->count >= 0) {
144                    // at least one continuous mode or active one-shot event
145                    waitForNextVsync = true;
146                    break;
147                }
148            }
149
150            if (timestamp) {
151                if (!waitForNextVsync) {
152                    // we received a VSYNC but we have no clients
153                    // don't report it, and disable VSYNC events
154                    disableVSyncLocked();
155                } else {
156                    // report VSYNC event
157                    break;
158                }
159            } else {
160                // never disable VSYNC events immediately, instead
161                // we'll wait to receive the event and we'll
162                // reevaluate whether we need to dispatch it and/or
163                // disable VSYNC events then.
164                if (waitForNextVsync) {
165                    // enable
166                    enableVSyncLocked();
167                }
168            }
169
170            // wait for something to happen
171            if (mUseSoftwareVSync && waitForNextVsync) {
172                // h/w vsync cannot be used (screen is off), so we use
173                // a  timeout instead. it doesn't matter how imprecise this
174                // is, we just need to make sure to serve the clients
175                if (mCondition.waitRelative(mLock, ms2ns(16)) == TIMED_OUT) {
176                    mVSyncTimestamp = systemTime(SYSTEM_TIME_MONOTONIC);
177                }
178            } else {
179                mCondition.wait(mLock);
180            }
181        } while(true);
182
183        // process vsync event
184        mDeliveredEvents++;
185        mLastVSyncTimestamp = timestamp;
186
187        // now see if we still need to report this VSYNC event
188        const size_t count = mDisplayEventConnections.size();
189        for (size_t i=0 ; i<count ; i++) {
190            bool reportVsync = false;
191            sp<Connection> connection =
192                    mDisplayEventConnections.itemAt(i).promote();
193            if (connection == 0)
194                continue;
195
196            const int32_t count = connection->count;
197            if (count >= 1) {
198                if (count==1 || (mDeliveredEvents % count) == 0) {
199                    // continuous event, and time to report it
200                    reportVsync = true;
201                }
202            } else if (count >= -1) {
203                if (count == 0) {
204                    // fired this time around
205                    reportVsync = true;
206                }
207                connection->count--;
208            }
209            if (reportVsync) {
210                displayEventConnections.add(connection);
211            }
212        }
213    } while (!displayEventConnections.size());
214
215    // dispatch vsync events to listeners...
216    vsync.header.type = DisplayEventReceiver::DISPLAY_EVENT_VSYNC;
217    vsync.header.timestamp = timestamp;
218    vsync.vsync.count = mDeliveredEvents;
219
220    const size_t count = displayEventConnections.size();
221    for (size_t i=0 ; i<count ; i++) {
222        sp<Connection> conn(displayEventConnections[i].promote());
223        // make sure the connection didn't die
224        if (conn != NULL) {
225            status_t err = conn->postEvent(vsync);
226            if (err == -EAGAIN || err == -EWOULDBLOCK) {
227                // The destination doesn't accept events anymore, it's probably
228                // full. For now, we just drop the events on the floor.
229                // Note that some events cannot be dropped and would have to be
230                // re-sent later. Right-now we don't have the ability to do
231                // this, but it doesn't matter for VSYNC.
232            } else if (err < 0) {
233                // handle any other error on the pipe as fatal. the only
234                // reasonable thing to do is to clean-up this connection.
235                // The most common error we'll get here is -EPIPE.
236                removeDisplayEventConnection(displayEventConnections[i]);
237            }
238        } else {
239            // somehow the connection is dead, but we still have it in our list
240            // just clean the list.
241            removeDisplayEventConnection(displayEventConnections[i]);
242        }
243    }
244
245    // clear all our references without holding mLock
246    displayEventConnections.clear();
247
248    return true;
249}
250
251void EventThread::enableVSyncLocked() {
252    if (!mUseSoftwareVSync) {
253        // never enable h/w VSYNC when screen is off
254        mHw.eventControl(DisplayHardware::EVENT_VSYNC, true);
255    }
256    mDebugVsyncEnabled = true;
257}
258
259void EventThread::disableVSyncLocked() {
260    mHw.eventControl(DisplayHardware::EVENT_VSYNC, 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