NuCachedSource2.cpp revision a814c1fdc2acf0ed2ee3b175110f6039be7c4873 
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      mLastFetchTimeUs(-1) {
183    mLooper->setName("NuCachedSource2");
184    mLooper->registerHandler(mReflector);
185    mLooper->start();
186
187    Mutex::Autolock autoLock(mLock);
188    (new AMessage(kWhatFetchMore, mReflector->id()))->post();
189}
190
191NuCachedSource2::~NuCachedSource2() {
192    mLooper->stop();
193    mLooper->unregisterHandler(mReflector->id());
194
195    delete mCache;
196    mCache = NULL;
197}
198
199status_t NuCachedSource2::initCheck() const {
200    return mSource->initCheck();
201}
202
203status_t NuCachedSource2::getSize(off_t *size) {
204    return mSource->getSize(size);
205}
206
207uint32_t NuCachedSource2::flags() {
208    return mSource->flags();
209}
210
211void NuCachedSource2::onMessageReceived(const sp<AMessage> &msg) {
212    switch (msg->what()) {
213        case kWhatFetchMore:
214        {
215            onFetch();
216            break;
217        }
218
219        case kWhatRead:
220        {
221            onRead(msg);
222            break;
223        }
224
225        default:
226            TRESPASS();
227    }
228}
229
230void NuCachedSource2::fetchInternal() {
231    LOG(VERBOSE) << "fetchInternal";
232
233    CHECK_EQ(mFinalStatus, (status_t)OK);
234
235    PageCache::Page *page = mCache->acquirePage();
236
237    ssize_t n = mSource->readAt(
238            mCacheOffset + mCache->totalSize(), page->mData, kPageSize);
239
240    Mutex::Autolock autoLock(mLock);
241
242    if (n < 0) {
243        LOG(ERROR) << "source returned error " << n;
244        mFinalStatus = n;
245        mCache->releasePage(page);
246    } else if (n == 0) {
247        LOG(INFO) << "ERROR_END_OF_STREAM";
248        mFinalStatus = ERROR_END_OF_STREAM;
249        mCache->releasePage(page);
250    } else {
251        page->mSize = n;
252        mCache->appendPage(page);
253    }
254}
255
256void NuCachedSource2::onFetch() {
257    LOG(VERBOSE) << "onFetch";
258
259    if (mFinalStatus != OK) {
260        LOG(VERBOSE) << "EOS reached, done prefetching for now";
261        mFetching = false;
262    }
263
264    bool keepAlive =
265        !mFetching
266            && mFinalStatus == OK
267            && ALooper::GetNowUs() >= mLastFetchTimeUs + kKeepAliveIntervalUs;
268
269    if (mFetching || keepAlive) {
270        if (keepAlive) {
271            LOG(INFO) << "Keep alive";
272        }
273
274        fetchInternal();
275
276        mLastFetchTimeUs = ALooper::GetNowUs();
277
278        if (mFetching && mCache->totalSize() >= kHighWaterThreshold) {
279            LOG(INFO) << "Cache full, done prefetching for now";
280            mFetching = false;
281        }
282    } else {
283        Mutex::Autolock autoLock(mLock);
284        restartPrefetcherIfNecessary_l();
285    }
286
287    (new AMessage(kWhatFetchMore, mReflector->id()))->post(
288            mFetching ? 0 : 100000ll);
289}
290
291void NuCachedSource2::onRead(const sp<AMessage> &msg) {
292    LOG(VERBOSE) << "onRead";
293
294    int64_t offset;
295    CHECK(msg->findInt64("offset", &offset));
296
297    void *data;
298    CHECK(msg->findPointer("data", &data));
299
300    size_t size;
301    CHECK(msg->findSize("size", &size));
302
303    ssize_t result = readInternal(offset, data, size);
304
305    if (result == -EAGAIN) {
306        msg->post(50000);
307        return;
308    }
309
310    Mutex::Autolock autoLock(mLock);
311
312    CHECK(mAsyncResult == NULL);
313
314    mAsyncResult = new AMessage;
315    mAsyncResult->setInt32("result", result);
316
317    mCondition.signal();
318}
319
320void NuCachedSource2::restartPrefetcherIfNecessary_l() {
321    static const size_t kGrayArea = 256 * 1024;
322
323    if (mFetching || mFinalStatus != OK) {
324        return;
325    }
326
327    if (mCacheOffset + mCache->totalSize() - mLastAccessPos
328            >= kLowWaterThreshold) {
329        return;
330    }
331
332    size_t maxBytes = mLastAccessPos - mCacheOffset;
333    if (maxBytes < kGrayArea) {
334        return;
335    }
336
337    maxBytes -= kGrayArea;
338
339    size_t actualBytes = mCache->releaseFromStart(maxBytes);
340    mCacheOffset += actualBytes;
341
342    LOG(INFO) << "restarting prefetcher, totalSize = " << mCache->totalSize();
343    mFetching = true;
344}
345
346ssize_t NuCachedSource2::readAt(off_t offset, void *data, size_t size) {
347    Mutex::Autolock autoSerializer(mSerializer);
348
349    LOG(VERBOSE) << "readAt offset " << offset << " size " << size;
350
351    Mutex::Autolock autoLock(mLock);
352
353    // If the request can be completely satisfied from the cache, do so.
354
355    if (offset >= mCacheOffset
356            && offset + size <= mCacheOffset + mCache->totalSize()) {
357        size_t delta = offset - mCacheOffset;
358        mCache->copy(delta, data, size);
359
360        mLastAccessPos = offset + size;
361
362        return size;
363    }
364
365    sp<AMessage> msg = new AMessage(kWhatRead, mReflector->id());
366    msg->setInt64("offset", offset);
367    msg->setPointer("data", data);
368    msg->setSize("size", size);
369
370    CHECK(mAsyncResult == NULL);
371    msg->post();
372
373    while (mAsyncResult == NULL) {
374        mCondition.wait(mLock);
375    }
376
377    int32_t result;
378    CHECK(mAsyncResult->findInt32("result", &result));
379
380    mAsyncResult.clear();
381
382    if (result > 0) {
383        mLastAccessPos = offset + result;
384    }
385
386    return (ssize_t)result;
387}
388
389size_t NuCachedSource2::cachedSize() {
390    Mutex::Autolock autoLock(mLock);
391    return mCacheOffset + mCache->totalSize();
392}
393
394size_t NuCachedSource2::approxDataRemaining(bool *eos) {
395    Mutex::Autolock autoLock(mLock);
396    return approxDataRemaining_l(eos);
397}
398
399size_t NuCachedSource2::approxDataRemaining_l(bool *eos) {
400    *eos = (mFinalStatus != OK);
401    off_t lastBytePosCached = mCacheOffset + mCache->totalSize();
402    if (mLastAccessPos < lastBytePosCached) {
403        return lastBytePosCached - mLastAccessPos;
404    }
405    return 0;
406}
407
408ssize_t NuCachedSource2::readInternal(off_t offset, void *data, size_t size) {
409    LOG(VERBOSE) << "readInternal offset " << offset << " size " << size;
410
411    Mutex::Autolock autoLock(mLock);
412
413    if (offset < mCacheOffset
414            || offset >= (off_t)(mCacheOffset + mCache->totalSize())) {
415        static const off_t kPadding = 32768;
416
417        // In the presence of multiple decoded streams, once of them will
418        // trigger this seek request, the other one will request data "nearby"
419        // soon, adjust the seek position so that that subsequent request
420        // does not trigger another seek.
421        off_t seekOffset = (offset > kPadding) ? offset - kPadding : 0;
422
423        seekInternal_l(seekOffset);
424    }
425
426    size_t delta = offset - mCacheOffset;
427
428    if (mFinalStatus != OK) {
429        if (delta >= mCache->totalSize()) {
430            return mFinalStatus;
431        }
432
433        size_t avail = mCache->totalSize() - delta;
434        mCache->copy(delta, data, avail);
435
436        return avail;
437    }
438
439    if (offset + size <= mCacheOffset + mCache->totalSize()) {
440        mCache->copy(delta, data, size);
441
442        return size;
443    }
444
445    LOG(VERBOSE) << "deferring read";
446
447    return -EAGAIN;
448}
449
450status_t NuCachedSource2::seekInternal_l(off_t offset) {
451    mLastAccessPos = offset;
452
453    if (offset >= mCacheOffset
454            && offset <= (off_t)(mCacheOffset + mCache->totalSize())) {
455        return OK;
456    }
457
458    LOG(INFO) << "new range: offset= " << offset;
459
460    mCacheOffset = offset;
461
462    size_t totalSize = mCache->totalSize();
463    CHECK_EQ(mCache->releaseFromStart(totalSize), totalSize);
464
465    mFinalStatus = OK;
466    mFetching = true;
467
468    return OK;
469}
470
471}  // namespace android
472
473