NuCachedSource2.cpp revision d17875a226491e3de60fa32d764a4cc92de7f949 
1/*
2 * Copyright (C) 2010 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 LOG_TAG "NuCachedSource2"
18#include <utils/Log.h>
19
20#include "include/NuCachedSource2.h"
21
22#include <media/stagefright/foundation/ADebug.h>
23#include <media/stagefright/foundation/AMessage.h>
24#include <media/stagefright/MediaErrors.h>
25
26namespace android {
27
28struct PageCache {
29    PageCache(size_t pageSize);
30    ~PageCache();
31
32    struct Page {
33        void *mData;
34        size_t mSize;
35    };
36
37    Page *acquirePage();
38    void releasePage(Page *page);
39
40    void appendPage(Page *page);
41    size_t releaseFromStart(size_t maxBytes);
42
43    size_t totalSize() const {
44        return mTotalSize;
45    }
46
47    void copy(size_t from, void *data, size_t size);
48
49private:
50    size_t mPageSize;
51    size_t mTotalSize;
52
53    List<Page *> mActivePages;
54    List<Page *> mFreePages;
55
56    void freePages(List<Page *> *list);
57
58    DISALLOW_EVIL_CONSTRUCTORS(PageCache);
59};
60
61PageCache::PageCache(size_t pageSize)
62    : mPageSize(pageSize),
63      mTotalSize(0) {
64}
65
66PageCache::~PageCache() {
67    freePages(&mActivePages);
68    freePages(&mFreePages);
69}
70
71void PageCache::freePages(List<Page *> *list) {
72    List<Page *>::iterator it = list->begin();
73    while (it != list->end()) {
74        Page *page = *it;
75
76        free(page->mData);
77        delete page;
78        page = NULL;
79
80        ++it;
81    }
82}
83
84PageCache::Page *PageCache::acquirePage() {
85    if (!mFreePages.empty()) {
86        List<Page *>::iterator it = mFreePages.begin();
87        Page *page = *it;
88        mFreePages.erase(it);
89
90        return page;
91    }
92
93    Page *page = new Page;
94    page->mData = malloc(mPageSize);
95    page->mSize = 0;
96
97    return page;
98}
99
100void PageCache::releasePage(Page *page) {
101    page->mSize = 0;
102    mFreePages.push_back(page);
103}
104
105void PageCache::appendPage(Page *page) {
106    mTotalSize += page->mSize;
107    mActivePages.push_back(page);
108}
109
110size_t PageCache::releaseFromStart(size_t maxBytes) {
111    size_t bytesReleased = 0;
112
113    while (maxBytes > 0 && !mActivePages.empty()) {
114        List<Page *>::iterator it = mActivePages.begin();
115
116        Page *page = *it;
117
118        if (maxBytes < page->mSize) {
119            break;
120        }
121
122        mActivePages.erase(it);
123
124        maxBytes -= page->mSize;
125        bytesReleased += page->mSize;
126
127        releasePage(page);
128    }
129
130    mTotalSize -= bytesReleased;
131    return bytesReleased;
132}
133
134void PageCache::copy(size_t from, void *data, size_t size) {
135    LOG(VERBOSE) << "copy from " << from << " size " << size;
136
137    CHECK_LE(from + size, mTotalSize);
138
139    size_t offset = 0;
140    List<Page *>::iterator it = mActivePages.begin();
141    while (from >= offset + (*it)->mSize) {
142        offset += (*it)->mSize;
143        ++it;
144    }
145
146    size_t delta = from - offset;
147    size_t avail = (*it)->mSize - delta;
148
149    if (avail >= size) {
150        memcpy(data, (const uint8_t *)(*it)->mData + delta, size);
151        return;
152    }
153
154    memcpy(data, (const uint8_t *)(*it)->mData + delta, avail);
155    ++it;
156    data = (uint8_t *)data + avail;
157    size -= avail;
158
159    while (size > 0) {
160        size_t copy = (*it)->mSize;
161        if (copy > size) {
162            copy = size;
163        }
164        memcpy(data, (*it)->mData, copy);
165        data = (uint8_t *)data + copy;
166        size -= copy;
167        ++it;
168    }
169}
170
171////////////////////////////////////////////////////////////////////////////////
172
173NuCachedSource2::NuCachedSource2(const sp<DataSource> &source)
174    : mSource(source),
175      mReflector(new AHandlerReflector<NuCachedSource2>(this)),
176      mLooper(new ALooper),
177      mCache(new PageCache(kPageSize)),
178      mCacheOffset(0),
179      mFinalStatus(OK),
180      mLastAccessPos(0),
181      mFetching(true) {
182    mLooper->registerHandler(mReflector);
183    mLooper->start();
184
185    Mutex::Autolock autoLock(mLock);
186    (new AMessage(kWhatFetchMore, mReflector->id()))->post();
187}
188
189NuCachedSource2::~NuCachedSource2() {
190    mLooper->stop();
191    mLooper->unregisterHandler(mReflector->id());
192
193    delete mCache;
194    mCache = NULL;
195}
196
197status_t NuCachedSource2::initCheck() const {
198    return mSource->initCheck();
199}
200
201status_t NuCachedSource2::getSize(off_t *size) {
202    return mSource->getSize(size);
203}
204
205uint32_t NuCachedSource2::flags() {
206    return mSource->flags();
207}
208
209void NuCachedSource2::onMessageReceived(const sp<AMessage> &msg) {
210    switch (msg->what()) {
211        case kWhatFetchMore:
212        {
213            onFetch();
214            break;
215        }
216
217        case kWhatRead:
218        {
219            onRead(msg);
220            break;
221        }
222
223        default:
224            TRESPASS();
225    }
226}
227
228void NuCachedSource2::fetchInternal() {
229    LOG(VERBOSE) << "fetchInternal";
230
231    CHECK_EQ(mFinalStatus, (status_t)OK);
232
233    PageCache::Page *page = mCache->acquirePage();
234
235    ssize_t n = mSource->readAt(
236            mCacheOffset + mCache->totalSize(), page->mData, kPageSize);
237
238    Mutex::Autolock autoLock(mLock);
239
240    if (n < 0) {
241        LOG(ERROR) << "source returned error " << n;
242        mFinalStatus = n;
243        mCache->releasePage(page);
244    } else if (n == 0) {
245        LOG(INFO) << "ERROR_END_OF_STREAM";
246        mFinalStatus = ERROR_END_OF_STREAM;
247        mCache->releasePage(page);
248    } else {
249        page->mSize = n;
250        mCache->appendPage(page);
251    }
252}
253
254void NuCachedSource2::onFetch() {
255    LOG(VERBOSE) << "onFetch";
256
257    if (mFinalStatus != OK) {
258        LOG(VERBOSE) << "EOS reached, done prefetching for now";
259        mFetching = false;
260    }
261
262    if (mFetching) {
263        fetchInternal();
264
265        if (mCache->totalSize() >= kHighWaterThreshold) {
266            LOG(INFO) << "Cache full, done prefetching for now";
267            mFetching = false;
268        }
269    } else {
270        Mutex::Autolock autoLock(mLock);
271        restartPrefetcherIfNecessary_l();
272    }
273
274    (new AMessage(kWhatFetchMore, mReflector->id()))->post(
275            mFetching ? 0 : 100000ll);
276}
277
278void NuCachedSource2::onRead(const sp<AMessage> &msg) {
279    LOG(VERBOSE) << "onRead";
280
281    int64_t offset;
282    CHECK(msg->findInt64("offset", &offset));
283
284    void *data;
285    CHECK(msg->findPointer("data", &data));
286
287    size_t size;
288    CHECK(msg->findSize("size", &size));
289
290    ssize_t result = readInternal(offset, data, size);
291
292    if (result == -EAGAIN) {
293        msg->post(50000);
294        return;
295    }
296
297    Mutex::Autolock autoLock(mLock);
298
299    CHECK(mAsyncResult == NULL);
300
301    mAsyncResult = new AMessage;
302    mAsyncResult->setInt32("result", result);
303
304    mCondition.signal();
305}
306
307void NuCachedSource2::restartPrefetcherIfNecessary_l() {
308    static const size_t kGrayArea = 256 * 1024;
309
310    if (mFetching || mFinalStatus != OK) {
311        return;
312    }
313
314    if (mCacheOffset + mCache->totalSize() - mLastAccessPos
315            >= kLowWaterThreshold) {
316        return;
317    }
318
319    size_t maxBytes = mLastAccessPos - mCacheOffset;
320    if (maxBytes < kGrayArea) {
321        return;
322    }
323
324    maxBytes -= kGrayArea;
325
326    size_t actualBytes = mCache->releaseFromStart(maxBytes);
327    mCacheOffset += actualBytes;
328
329    LOG(INFO) << "restarting prefetcher, totalSize = " << mCache->totalSize();
330    mFetching = true;
331}
332
333ssize_t NuCachedSource2::readAt(off_t offset, void *data, size_t size) {
334    Mutex::Autolock autoSerializer(mSerializer);
335
336    LOG(VERBOSE) << "readAt offset " << offset << " size " << size;
337
338    Mutex::Autolock autoLock(mLock);
339
340    // If the request can be completely satisfied from the cache, do so.
341
342    if (offset >= mCacheOffset
343            && offset + size <= mCacheOffset + mCache->totalSize()) {
344        size_t delta = offset - mCacheOffset;
345        mCache->copy(delta, data, size);
346
347        mLastAccessPos = offset + size;
348
349        return size;
350    }
351
352    sp<AMessage> msg = new AMessage(kWhatRead, mReflector->id());
353    msg->setInt64("offset", offset);
354    msg->setPointer("data", data);
355    msg->setSize("size", size);
356
357    CHECK(mAsyncResult == NULL);
358    msg->post();
359
360    while (mAsyncResult == NULL) {
361        mCondition.wait(mLock);
362    }
363
364    int32_t result;
365    CHECK(mAsyncResult->findInt32("result", &result));
366
367    mAsyncResult.clear();
368
369    if (result > 0) {
370        mLastAccessPos = offset + result;
371    }
372
373    return (ssize_t)result;
374}
375
376size_t NuCachedSource2::cachedSize() {
377    Mutex::Autolock autoLock(mLock);
378    return mCacheOffset + mCache->totalSize();
379}
380
381size_t NuCachedSource2::approxDataRemaining(bool *eos) {
382    Mutex::Autolock autoLock(mLock);
383    return approxDataRemaining_l(eos);
384}
385
386size_t NuCachedSource2::approxDataRemaining_l(bool *eos) {
387    *eos = (mFinalStatus != OK);
388    off_t lastBytePosCached = mCacheOffset + mCache->totalSize();
389    if (mLastAccessPos < lastBytePosCached) {
390        return lastBytePosCached - mLastAccessPos;
391    }
392    return 0;
393}
394
395ssize_t NuCachedSource2::readInternal(off_t offset, void *data, size_t size) {
396    LOG(VERBOSE) << "readInternal offset " << offset << " size " << size;
397
398    Mutex::Autolock autoLock(mLock);
399
400    if (offset < mCacheOffset
401            || offset >= (off_t)(mCacheOffset + mCache->totalSize())) {
402        static const off_t kPadding = 32768;
403
404        // In the presence of multiple decoded streams, once of them will
405        // trigger this seek request, the other one will request data "nearby"
406        // soon, adjust the seek position so that that subsequent request
407        // does not trigger another seek.
408        off_t seekOffset = (offset > kPadding) ? offset - kPadding : 0;
409
410        seekInternal_l(seekOffset);
411    }
412
413    size_t delta = offset - mCacheOffset;
414
415    if (mFinalStatus != OK) {
416        if (delta >= mCache->totalSize()) {
417            return mFinalStatus;
418        }
419
420        size_t avail = mCache->totalSize() - delta;
421        mCache->copy(delta, data, avail);
422
423        return avail;
424    }
425
426    if (offset + size <= mCacheOffset + mCache->totalSize()) {
427        mCache->copy(delta, data, size);
428
429        return size;
430    }
431
432    LOG(VERBOSE) << "deferring read";
433
434    return -EAGAIN;
435}
436
437status_t NuCachedSource2::seekInternal_l(off_t offset) {
438    mLastAccessPos = offset;
439
440    if (offset >= mCacheOffset
441            && offset <= (off_t)(mCacheOffset + mCache->totalSize())) {
442        return OK;
443    }
444
445    LOG(INFO) << "new range: offset= " << offset;
446
447    mCacheOffset = offset;
448
449    size_t totalSize = mCache->totalSize();
450    CHECK_EQ(mCache->releaseFromStart(totalSize), totalSize);
451
452    mFinalStatus = OK;
453    mFetching = true;
454
455    return OK;
456}
457
458}  // namespace android
459
460