1 /*
2 * Copyright (C) 2009 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 "rsLocklessFifo.h"
18
19 using namespace android;
20
21
LocklessCommandFifo()22 LocklessCommandFifo::LocklessCommandFifo()
23 {
24 }
25
~LocklessCommandFifo()26 LocklessCommandFifo::~LocklessCommandFifo()
27 {
28 if (!mInShutdown) {
29 shutdown();
30 }
31 free(mBuffer);
32 }
33
shutdown()34 void LocklessCommandFifo::shutdown()
35 {
36 mInShutdown = true;
37 mSignalToWorker.set();
38 }
39
init(uint32_t sizeInBytes)40 bool LocklessCommandFifo::init(uint32_t sizeInBytes)
41 {
42 // Add room for a buffer reset command
43 mBuffer = static_cast<uint8_t *>(malloc(sizeInBytes + 4));
44 if (!mBuffer) {
45 LOGE("LocklessFifo allocation failure");
46 return false;
47 }
48
49 if (!mSignalToControl.init() || !mSignalToWorker.init()) {
50 LOGE("Signal setup failed");
51 free(mBuffer);
52 return false;
53 }
54
55 mInShutdown = false;
56 mSize = sizeInBytes;
57 mPut = mBuffer;
58 mGet = mBuffer;
59 mEnd = mBuffer + (sizeInBytes) - 1;
60 //dumpState("init");
61 return true;
62 }
63
getFreeSpace() const64 uint32_t LocklessCommandFifo::getFreeSpace() const
65 {
66 int32_t freeSpace = 0;
67 //dumpState("getFreeSpace");
68
69 if (mPut >= mGet) {
70 freeSpace = mEnd - mPut;
71 } else {
72 freeSpace = mGet - mPut;
73 }
74
75 if (freeSpace < 0) {
76 freeSpace = 0;
77 }
78 return freeSpace;
79 }
80
isEmpty() const81 bool LocklessCommandFifo::isEmpty() const
82 {
83 return mPut == mGet;
84 }
85
86
reserve(uint32_t sizeInBytes)87 void * LocklessCommandFifo::reserve(uint32_t sizeInBytes)
88 {
89 // Add space for command header and loop token;
90 sizeInBytes += 8;
91
92 //dumpState("reserve");
93 if (getFreeSpace() < sizeInBytes) {
94 makeSpace(sizeInBytes);
95 }
96
97 return mPut + 4;
98 }
99
commit(uint32_t command,uint32_t sizeInBytes)100 void LocklessCommandFifo::commit(uint32_t command, uint32_t sizeInBytes)
101 {
102 if (mInShutdown) {
103 return;
104 }
105 //dumpState("commit 1");
106 reinterpret_cast<uint16_t *>(mPut)[0] = command;
107 reinterpret_cast<uint16_t *>(mPut)[1] = sizeInBytes;
108 mPut += ((sizeInBytes + 3) & ~3) + 4;
109 //dumpState("commit 2");
110 mSignalToWorker.set();
111 }
112
commitSync(uint32_t command,uint32_t sizeInBytes)113 void LocklessCommandFifo::commitSync(uint32_t command, uint32_t sizeInBytes)
114 {
115 if (mInShutdown) {
116 return;
117 }
118 commit(command, sizeInBytes);
119 flush();
120 }
121
flush()122 void LocklessCommandFifo::flush()
123 {
124 //dumpState("flush 1");
125 while(mPut != mGet) {
126 mSignalToControl.wait();
127 }
128 //dumpState("flush 2");
129 }
130
get(uint32_t * command,uint32_t * bytesData)131 const void * LocklessCommandFifo::get(uint32_t *command, uint32_t *bytesData)
132 {
133 while(1) {
134 //dumpState("get");
135 while(isEmpty() && !mInShutdown) {
136 mSignalToControl.set();
137 mSignalToWorker.wait();
138 }
139
140 if (mInShutdown) {
141 *command = 0;
142 *bytesData = 0;
143 return 0;
144 }
145
146 *command = reinterpret_cast<const uint16_t *>(mGet)[0];
147 *bytesData = reinterpret_cast<const uint16_t *>(mGet)[1];
148 if (*command) {
149 // non-zero command is valid
150 return mGet+4;
151 }
152
153 // zero command means reset to beginning.
154 mGet = mBuffer;
155 }
156 }
157
next()158 void LocklessCommandFifo::next()
159 {
160 uint32_t bytes = reinterpret_cast<const uint16_t *>(mGet)[1];
161 mGet += ((bytes + 3) & ~3) + 4;
162 if (isEmpty()) {
163 mSignalToControl.set();
164 }
165 //dumpState("next");
166 }
167
makeSpace(uint32_t bytes)168 void LocklessCommandFifo::makeSpace(uint32_t bytes)
169 {
170 //dumpState("make space");
171 if ((mPut+bytes) > mEnd) {
172 // Need to loop regardless of where get is.
173 while((mGet > mPut) && (mBuffer+4 >= mGet)) {
174 usleep(100);
175 }
176
177 // Toss in a reset then the normal wait for space will do the rest.
178 reinterpret_cast<uint16_t *>(mPut)[0] = 0;
179 reinterpret_cast<uint16_t *>(mPut)[1] = 0;
180 mPut = mBuffer;
181 }
182
183 // it will fit here so we just need to wait for space.
184 while(getFreeSpace() < bytes) {
185 usleep(100);
186 }
187
188 }
189
dumpState(const char * s) const190 void LocklessCommandFifo::dumpState(const char *s) const
191 {
192 LOGV("%s put %p, get %p, buf %p, end %p", s, mPut, mGet, mBuffer, mEnd);
193 }
194
Signal()195 LocklessCommandFifo::Signal::Signal()
196 {
197 mSet = true;
198 }
199
~Signal()200 LocklessCommandFifo::Signal::~Signal()
201 {
202 pthread_mutex_destroy(&mMutex);
203 pthread_cond_destroy(&mCondition);
204 }
205
init()206 bool LocklessCommandFifo::Signal::init()
207 {
208 int status = pthread_mutex_init(&mMutex, NULL);
209 if (status) {
210 LOGE("LocklessFifo mutex init failure");
211 return false;
212 }
213
214 status = pthread_cond_init(&mCondition, NULL);
215 if (status) {
216 LOGE("LocklessFifo condition init failure");
217 pthread_mutex_destroy(&mMutex);
218 return false;
219 }
220
221 return true;
222 }
223
set()224 void LocklessCommandFifo::Signal::set()
225 {
226 int status;
227
228 status = pthread_mutex_lock(&mMutex);
229 if (status) {
230 LOGE("LocklessCommandFifo: error %i locking for set condition.", status);
231 return;
232 }
233
234 mSet = true;
235
236 status = pthread_cond_signal(&mCondition);
237 if (status) {
238 LOGE("LocklessCommandFifo: error %i on set condition.", status);
239 }
240
241 status = pthread_mutex_unlock(&mMutex);
242 if (status) {
243 LOGE("LocklessCommandFifo: error %i unlocking for set condition.", status);
244 }
245 }
246
wait()247 void LocklessCommandFifo::Signal::wait()
248 {
249 int status;
250
251 status = pthread_mutex_lock(&mMutex);
252 if (status) {
253 LOGE("LocklessCommandFifo: error %i locking for condition.", status);
254 return;
255 }
256
257 if (!mSet) {
258 status = pthread_cond_wait(&mCondition, &mMutex);
259 if (status) {
260 LOGE("LocklessCommandFifo: error %i waiting on condition.", status);
261 }
262 }
263 mSet = false;
264
265 status = pthread_mutex_unlock(&mMutex);
266 if (status) {
267 LOGE("LocklessCommandFifo: error %i unlocking for condition.", status);
268 }
269 }
270
271