EventThread.cpp revision 478ae5eb5a0047e1b2988c896cff6363b455ee50 
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#include <stdint.h>
18#include <sys/types.h>
19
20#include <gui/IDisplayEventConnection.h>
21#include <gui/DisplayEventReceiver.h>
22
23#include <utils/Errors.h>
24
25#include "DisplayHardware/DisplayHardware.h"
26#include "DisplayEventConnection.h"
27#include "EventThread.h"
28#include "SurfaceFlinger.h"
29
30// ---------------------------------------------------------------------------
31
32namespace android {
33
34// ---------------------------------------------------------------------------
35
36EventThread::EventThread(const sp<SurfaceFlinger>& flinger)
37    : mFlinger(flinger),
38      mHw(flinger->graphicPlane(0).displayHardware()),
39      mDeliveredEvents(0)
40{
41}
42
43void EventThread::onFirstRef() {
44    run("EventThread", PRIORITY_URGENT_DISPLAY + PRIORITY_MORE_FAVORABLE);
45}
46
47status_t EventThread::registerDisplayEventConnection(
48        const sp<DisplayEventConnection>& connection) {
49    Mutex::Autolock _l(mLock);
50    ConnectionInfo info;
51    mDisplayEventConnections.add(connection, info);
52    mCondition.signal();
53    return NO_ERROR;
54}
55
56status_t EventThread::unregisterDisplayEventConnection(
57        const wp<DisplayEventConnection>& connection) {
58    Mutex::Autolock _l(mLock);
59    mDisplayEventConnections.removeItem(connection);
60    mCondition.signal();
61    return NO_ERROR;
62}
63
64void EventThread::removeDisplayEventConnection(
65        const wp<DisplayEventConnection>& connection) {
66    Mutex::Autolock _l(mLock);
67    mDisplayEventConnections.removeItem(connection);
68}
69
70EventThread::ConnectionInfo* EventThread::getConnectionInfoLocked(
71        const wp<DisplayEventConnection>& connection) {
72    ssize_t index = mDisplayEventConnections.indexOfKey(connection);
73    if (index < 0) return NULL;
74    return &mDisplayEventConnections.editValueAt(index);
75}
76
77void EventThread::setVsyncRate(uint32_t count,
78        const wp<DisplayEventConnection>& connection) {
79    if (int32_t(count) >= 0) { // server must protect against bad params
80        Mutex::Autolock _l(mLock);
81        ConnectionInfo* info = getConnectionInfoLocked(connection);
82        if (info) {
83            info->count = (count == 0) ? -1 : count;
84            mCondition.signal();
85        }
86    }
87}
88
89void EventThread::requestNextVsync(
90        const wp<DisplayEventConnection>& connection) {
91    Mutex::Autolock _l(mLock);
92    ConnectionInfo* info = getConnectionInfoLocked(connection);
93    if (info) {
94        if (info->count < 0) {
95            info->count = 0;
96        }
97        mCondition.signal();
98    }
99}
100
101bool EventThread::threadLoop() {
102
103    nsecs_t timestamp;
104    DisplayEventReceiver::Event vsync;
105    KeyedVector< wp<DisplayEventConnection>, ConnectionInfo > displayEventConnections;
106
107    { // scope for the lock
108        Mutex::Autolock _l(mLock);
109        do {
110            // wait for listeners
111            do {
112                bool waitForNextVsync = false;
113                size_t count = mDisplayEventConnections.size();
114                for (size_t i=0 ; i<count ; i++) {
115                    const ConnectionInfo& info(
116                            mDisplayEventConnections.valueAt(i));
117                    if (info.count >= 1) {
118                        // continuous mode
119                        waitForNextVsync = true;
120                    } else {
121                        // one-shot event
122                        if (info.count >= -1) {
123                            ConnectionInfo& info(
124                                    mDisplayEventConnections.editValueAt(i));
125                            info.count--;
126                            if (info.count == -1) {
127                                // fired this time around
128                                waitForNextVsync = true;
129                            }
130                        }
131                    }
132                }
133
134                if (waitForNextVsync)
135                    break;
136
137                mCondition.wait(mLock);
138            } while(true);
139
140            // wait for vsync
141            mLock.unlock();
142            timestamp = mHw.waitForVSync();
143            mLock.lock();
144            mDeliveredEvents++;
145
146            // make sure we still have some listeners
147        } while (!mDisplayEventConnections.size());
148
149        // dispatch vsync events to listeners...
150        vsync.header.type = DisplayEventReceiver::DISPLAY_EVENT_VSYNC;
151        vsync.header.timestamp = timestamp;
152        vsync.vsync.count = mDeliveredEvents;
153
154        // make a copy of our connection list, so we can
155        // dispatch events without holding mLock
156        displayEventConnections = mDisplayEventConnections;
157    }
158
159    const size_t count = displayEventConnections.size();
160    for (size_t i=0 ; i<count ; i++) {
161        sp<DisplayEventConnection> conn(displayEventConnections.keyAt(i).promote());
162        // make sure the connection didn't die
163        if (conn != NULL) {
164
165            const ConnectionInfo& info(
166                    displayEventConnections.valueAt(i));
167
168            if ((info.count > 1) && (mDeliveredEvents % info.count)) {
169                // continuous event, but not time to send this event yet
170                continue;
171            } else if (info.count < -1) {
172                // disabled event
173                continue;
174            } else if (info.count == 0) {
175                // impossible by construction. but we prefer to be safe.
176                continue;
177            }
178
179            // here, either:
180            // count = -1 : one-shot scheduled this time around
181            // count =  1 : continuous not rate-limited
182            // count >  1 : continuous, rate-limited
183            // Note: count == 0 is not possible by construction
184
185            status_t err = conn->postEvent(vsync);
186            if (err == -EAGAIN || err == -EWOULDBLOCK) {
187                // The destination doesn't accept events anymore, it's probably
188                // full. For now, we just drop the events on the floor.
189                // Note that some events cannot be dropped and would have to be
190                // re-sent later. Right-now we don't have the ability to do
191                // this, but it doesn't matter for VSYNC.
192            } else if (err < 0) {
193                // handle any other error on the pipe as fatal. the only
194                // reasonable thing to do is to clean-up this connection.
195                // The most common error we'll get here is -EPIPE.
196                removeDisplayEventConnection(displayEventConnections.keyAt(i));
197            }
198        } else {
199            // somehow the connection is dead, but we still have it in our list
200            // just clean the list.
201            removeDisplayEventConnection(displayEventConnections.keyAt(i));
202        }
203    }
204
205    // clear all our references without holding mLock
206    displayEventConnections.clear();
207
208    return true;
209}
210
211status_t EventThread::readyToRun() {
212    LOGI("EventThread ready to run.");
213    return NO_ERROR;
214}
215
216void EventThread::dump(String8& result, char* buffer, size_t SIZE) const {
217    Mutex::Autolock _l(mLock);
218    result.append("VSYNC state:\n");
219    snprintf(buffer, SIZE, "  numListeners=%u, events-delivered: %u\n",
220            mDisplayEventConnections.size(), mDeliveredEvents);
221    result.append(buffer);
222}
223
224// ---------------------------------------------------------------------------
225
226}; // namespace android
227