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1 // Copyright 2013 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #include "content/renderer/media/buffered_resource_loader.h" | |
6 | |
7 #include "base/bits.h" | |
8 #include "base/callback_helpers.h" | |
9 #include "base/metrics/histogram.h" | |
10 #include "base/strings/string_number_conversions.h" | |
11 #include "base/strings/string_util.h" | |
12 #include "content/public/common/url_constants.h" | |
13 #include "content/renderer/media/cache_util.h" | |
14 #include "media/base/media_log.h" | |
15 #include "net/http/http_byte_range.h" | |
16 #include "net/http/http_request_headers.h" | |
17 #include "third_party/WebKit/public/platform/WebString.h" | |
18 #include "third_party/WebKit/public/platform/WebURLError.h" | |
19 #include "third_party/WebKit/public/platform/WebURLResponse.h" | |
20 #include "third_party/WebKit/public/web/WebKit.h" | |
21 #include "third_party/WebKit/public/web/WebURLLoaderOptions.h" | |
22 | |
23 using blink::WebFrame; | |
24 using blink::WebString; | |
25 using blink::WebURLError; | |
26 using blink::WebURLLoader; | |
27 using blink::WebURLLoaderOptions; | |
28 using blink::WebURLRequest; | |
29 using blink::WebURLResponse; | |
30 | |
31 namespace content { | |
32 | |
33 static const int kHttpOK = 200; | |
34 static const int kHttpPartialContent = 206; | |
35 | |
36 // Define the number of bytes in a megabyte. | |
37 static const int kMegabyte = 1024 * 1024; | |
38 | |
39 // Minimum capacity of the buffer in forward or backward direction. | |
40 // | |
41 // 2MB is an arbitrary limit; it just seems to be "good enough" in practice. | |
42 static const int kMinBufferCapacity = 2 * kMegabyte; | |
43 | |
44 // Maximum capacity of the buffer in forward or backward direction. This is | |
45 // effectively the largest single read the code path can handle. | |
46 // 20MB is an arbitrary limit; it just seems to be "good enough" in practice. | |
47 static const int kMaxBufferCapacity = 20 * kMegabyte; | |
48 | |
49 // Maximum number of bytes outside the buffer we will wait for in order to | |
50 // fulfill a read. If a read starts more than 2MB away from the data we | |
51 // currently have in the buffer, we will not wait for buffer to reach the read's | |
52 // location and will instead reset the request. | |
53 static const int kForwardWaitThreshold = 2 * kMegabyte; | |
54 | |
55 // Computes the suggested backward and forward capacity for the buffer | |
56 // if one wants to play at |playback_rate| * the natural playback speed. | |
57 // Use a value of 0 for |bitrate| if it is unknown. | |
58 static void ComputeTargetBufferWindow(float playback_rate, int bitrate, | |
59 int* out_backward_capacity, | |
60 int* out_forward_capacity) { | |
61 static const int kDefaultBitrate = 200 * 1024 * 8; // 200 Kbps. | |
62 static const int kMaxBitrate = 20 * kMegabyte * 8; // 20 Mbps. | |
63 static const float kMaxPlaybackRate = 25.0; | |
64 static const int kTargetSecondsBufferedAhead = 10; | |
65 static const int kTargetSecondsBufferedBehind = 2; | |
66 | |
67 // Use a default bit rate if unknown and clamp to prevent overflow. | |
68 if (bitrate <= 0) | |
69 bitrate = kDefaultBitrate; | |
70 bitrate = std::min(bitrate, kMaxBitrate); | |
71 | |
72 // Only scale the buffer window for playback rates greater than 1.0 in | |
73 // magnitude and clamp to prevent overflow. | |
74 bool backward_playback = false; | |
75 if (playback_rate < 0.0f) { | |
76 backward_playback = true; | |
77 playback_rate *= -1.0f; | |
78 } | |
79 | |
80 playback_rate = std::max(playback_rate, 1.0f); | |
81 playback_rate = std::min(playback_rate, kMaxPlaybackRate); | |
82 | |
83 int bytes_per_second = (bitrate / 8.0) * playback_rate; | |
84 | |
85 // Clamp between kMinBufferCapacity and kMaxBufferCapacity. | |
86 *out_forward_capacity = std::max( | |
87 kTargetSecondsBufferedAhead * bytes_per_second, kMinBufferCapacity); | |
88 *out_backward_capacity = std::max( | |
89 kTargetSecondsBufferedBehind * bytes_per_second, kMinBufferCapacity); | |
90 | |
91 *out_forward_capacity = std::min(*out_forward_capacity, kMaxBufferCapacity); | |
92 *out_backward_capacity = std::min(*out_backward_capacity, kMaxBufferCapacity); | |
93 | |
94 if (backward_playback) | |
95 std::swap(*out_forward_capacity, *out_backward_capacity); | |
96 } | |
97 | |
98 BufferedResourceLoader::BufferedResourceLoader( | |
99 const GURL& url, | |
100 CORSMode cors_mode, | |
101 int64 first_byte_position, | |
102 int64 last_byte_position, | |
103 DeferStrategy strategy, | |
104 int bitrate, | |
105 float playback_rate, | |
106 media::MediaLog* media_log) | |
107 : buffer_(kMinBufferCapacity, kMinBufferCapacity), | |
108 loader_failed_(false), | |
109 defer_strategy_(strategy), | |
110 might_be_reused_from_cache_in_future_(true), | |
111 range_supported_(false), | |
112 saved_forward_capacity_(0), | |
113 url_(url), | |
114 cors_mode_(cors_mode), | |
115 first_byte_position_(first_byte_position), | |
116 last_byte_position_(last_byte_position), | |
117 single_origin_(true), | |
118 offset_(0), | |
119 content_length_(kPositionNotSpecified), | |
120 instance_size_(kPositionNotSpecified), | |
121 read_position_(0), | |
122 read_size_(0), | |
123 read_buffer_(NULL), | |
124 first_offset_(0), | |
125 last_offset_(0), | |
126 bitrate_(bitrate), | |
127 playback_rate_(playback_rate), | |
128 media_log_(media_log) { | |
129 | |
130 // Set the initial capacity of |buffer_| based on |bitrate_| and | |
131 // |playback_rate_|. | |
132 UpdateBufferWindow(); | |
133 } | |
134 | |
135 BufferedResourceLoader::~BufferedResourceLoader() {} | |
136 | |
137 void BufferedResourceLoader::Start( | |
138 const StartCB& start_cb, | |
139 const LoadingStateChangedCB& loading_cb, | |
140 const ProgressCB& progress_cb, | |
141 WebFrame* frame) { | |
142 // Make sure we have not started. | |
143 DCHECK(start_cb_.is_null()); | |
144 DCHECK(loading_cb_.is_null()); | |
145 DCHECK(progress_cb_.is_null()); | |
146 DCHECK(!start_cb.is_null()); | |
147 DCHECK(!loading_cb.is_null()); | |
148 DCHECK(!progress_cb.is_null()); | |
149 CHECK(frame); | |
150 | |
151 start_cb_ = start_cb; | |
152 loading_cb_ = loading_cb; | |
153 progress_cb_ = progress_cb; | |
154 | |
155 if (first_byte_position_ != kPositionNotSpecified) { | |
156 // TODO(hclam): server may not support range request so |offset_| may not | |
157 // equal to |first_byte_position_|. | |
158 offset_ = first_byte_position_; | |
159 } | |
160 | |
161 // Prepare the request. | |
162 WebURLRequest request(url_); | |
163 // TODO(mkwst): Split this into video/audio. | |
164 request.setRequestContext(WebURLRequest::RequestContextVideo); | |
165 | |
166 if (IsRangeRequest()) { | |
167 request.setHTTPHeaderField( | |
168 WebString::fromUTF8(net::HttpRequestHeaders::kRange), | |
169 WebString::fromUTF8(net::HttpByteRange::Bounded( | |
170 first_byte_position_, last_byte_position_).GetHeaderValue())); | |
171 } | |
172 | |
173 frame->setReferrerForRequest(request, blink::WebURL()); | |
174 | |
175 // Disable compression, compression for audio/video doesn't make sense... | |
176 request.setHTTPHeaderField( | |
177 WebString::fromUTF8(net::HttpRequestHeaders::kAcceptEncoding), | |
178 WebString::fromUTF8("identity;q=1, *;q=0")); | |
179 | |
180 // Check for our test WebURLLoader. | |
181 scoped_ptr<WebURLLoader> loader; | |
182 if (test_loader_) { | |
183 loader = test_loader_.Pass(); | |
184 } else { | |
185 WebURLLoaderOptions options; | |
186 if (cors_mode_ == kUnspecified) { | |
187 options.allowCredentials = true; | |
188 options.crossOriginRequestPolicy = | |
189 WebURLLoaderOptions::CrossOriginRequestPolicyAllow; | |
190 } else { | |
191 options.exposeAllResponseHeaders = true; | |
192 // The author header set is empty, no preflight should go ahead. | |
193 options.preflightPolicy = WebURLLoaderOptions::PreventPreflight; | |
194 options.crossOriginRequestPolicy = | |
195 WebURLLoaderOptions::CrossOriginRequestPolicyUseAccessControl; | |
196 if (cors_mode_ == kUseCredentials) | |
197 options.allowCredentials = true; | |
198 } | |
199 loader.reset(frame->createAssociatedURLLoader(options)); | |
200 } | |
201 | |
202 // Start the resource loading. | |
203 loader->loadAsynchronously(request, this); | |
204 active_loader_.reset(new ActiveLoader(loader.Pass())); | |
205 loading_cb_.Run(kLoading); | |
206 } | |
207 | |
208 void BufferedResourceLoader::Stop() { | |
209 // Reset callbacks. | |
210 start_cb_.Reset(); | |
211 loading_cb_.Reset(); | |
212 progress_cb_.Reset(); | |
213 read_cb_.Reset(); | |
214 | |
215 // Cancel and reset any active loaders. | |
216 active_loader_.reset(); | |
217 } | |
218 | |
219 void BufferedResourceLoader::Read( | |
220 int64 position, | |
221 int read_size, | |
222 uint8* buffer, | |
223 const ReadCB& read_cb) { | |
224 DCHECK(start_cb_.is_null()); | |
225 DCHECK(read_cb_.is_null()); | |
226 DCHECK(!read_cb.is_null()); | |
227 DCHECK(buffer); | |
228 DCHECK_GT(read_size, 0); | |
229 | |
230 // Save the parameter of reading. | |
231 read_cb_ = read_cb; | |
232 read_position_ = position; | |
233 read_size_ = read_size; | |
234 read_buffer_ = buffer; | |
235 | |
236 // Reads should immediately fail if the loader also failed. | |
237 if (loader_failed_) { | |
238 DoneRead(kFailed, 0); | |
239 return; | |
240 } | |
241 | |
242 // If we're attempting to read past the end of the file, return a zero | |
243 // indicating EOF. | |
244 // | |
245 // This can happen with callees that read in fixed-sized amounts for parsing | |
246 // or at the end of chunked 200 responses when we discover the actual length | |
247 // of the file. | |
248 if (instance_size_ != kPositionNotSpecified && | |
249 instance_size_ <= read_position_) { | |
250 DVLOG(1) << "Appear to have seeked beyond EOS; returning 0."; | |
251 DoneRead(kOk, 0); | |
252 return; | |
253 } | |
254 | |
255 // Make sure |offset_| and |read_position_| does not differ by a large | |
256 // amount. | |
257 if (read_position_ > offset_ + kint32max || | |
258 read_position_ < offset_ + kint32min) { | |
259 DoneRead(kCacheMiss, 0); | |
260 return; | |
261 } | |
262 | |
263 // Make sure |read_size_| is not too large for the buffer to ever be able to | |
264 // fulfill the read request. | |
265 if (read_size_ > kMaxBufferCapacity) { | |
266 DoneRead(kFailed, 0); | |
267 return; | |
268 } | |
269 | |
270 // Prepare the parameters. | |
271 first_offset_ = read_position_ - offset_; | |
272 last_offset_ = first_offset_ + read_size_; | |
273 | |
274 // If we can serve the request now, do the actual read. | |
275 if (CanFulfillRead()) { | |
276 ReadInternal(); | |
277 UpdateDeferBehavior(); | |
278 return; | |
279 } | |
280 | |
281 // If we expect the read request to be fulfilled later, expand capacity as | |
282 // necessary and disable deferring. | |
283 if (WillFulfillRead()) { | |
284 // Advance offset as much as possible to create additional capacity. | |
285 int advance = std::min(first_offset_, buffer_.forward_bytes()); | |
286 bool ret = buffer_.Seek(advance); | |
287 DCHECK(ret); | |
288 | |
289 offset_ += advance; | |
290 first_offset_ -= advance; | |
291 last_offset_ -= advance; | |
292 | |
293 // Expand capacity to accomodate a read that extends past the normal | |
294 // capacity. | |
295 // | |
296 // This can happen when reading in a large seek index or when the | |
297 // first byte of a read request falls within kForwardWaitThreshold. | |
298 if (last_offset_ > buffer_.forward_capacity()) { | |
299 saved_forward_capacity_ = buffer_.forward_capacity(); | |
300 buffer_.set_forward_capacity(last_offset_); | |
301 } | |
302 | |
303 // Make sure we stop deferring now that there's additional capacity. | |
304 DCHECK(!ShouldDefer()) | |
305 << "Capacity was not adjusted properly to prevent deferring."; | |
306 UpdateDeferBehavior(); | |
307 | |
308 return; | |
309 } | |
310 | |
311 // Make a callback to report failure. | |
312 DoneRead(kCacheMiss, 0); | |
313 } | |
314 | |
315 int64 BufferedResourceLoader::content_length() { | |
316 return content_length_; | |
317 } | |
318 | |
319 int64 BufferedResourceLoader::instance_size() { | |
320 return instance_size_; | |
321 } | |
322 | |
323 bool BufferedResourceLoader::range_supported() { | |
324 return range_supported_; | |
325 } | |
326 | |
327 ///////////////////////////////////////////////////////////////////////////// | |
328 // blink::WebURLLoaderClient implementation. | |
329 void BufferedResourceLoader::willSendRequest( | |
330 WebURLLoader* loader, | |
331 WebURLRequest& newRequest, | |
332 const WebURLResponse& redirectResponse) { | |
333 | |
334 // The load may have been stopped and |start_cb| is destroyed. | |
335 // In this case we shouldn't do anything. | |
336 if (start_cb_.is_null()) { | |
337 // Set the url in the request to an invalid value (empty url). | |
338 newRequest.setURL(blink::WebURL()); | |
339 return; | |
340 } | |
341 | |
342 // Only allow |single_origin_| if we haven't seen a different origin yet. | |
343 if (single_origin_) | |
344 single_origin_ = url_.GetOrigin() == GURL(newRequest.url()).GetOrigin(); | |
345 | |
346 url_ = newRequest.url(); | |
347 } | |
348 | |
349 void BufferedResourceLoader::didSendData( | |
350 WebURLLoader* loader, | |
351 unsigned long long bytes_sent, | |
352 unsigned long long total_bytes_to_be_sent) { | |
353 NOTIMPLEMENTED(); | |
354 } | |
355 | |
356 void BufferedResourceLoader::didReceiveResponse( | |
357 WebURLLoader* loader, | |
358 const WebURLResponse& response) { | |
359 DVLOG(1) << "didReceiveResponse: HTTP/" | |
360 << (response.httpVersion() == WebURLResponse::HTTP_0_9 ? "0.9" : | |
361 response.httpVersion() == WebURLResponse::HTTP_1_0 ? "1.0" : | |
362 response.httpVersion() == WebURLResponse::HTTP_1_1 ? "1.1" : | |
363 "Unknown") | |
364 << " " << response.httpStatusCode(); | |
365 DCHECK(active_loader_.get()); | |
366 | |
367 // The loader may have been stopped and |start_cb| is destroyed. | |
368 // In this case we shouldn't do anything. | |
369 if (start_cb_.is_null()) | |
370 return; | |
371 | |
372 uint32 reasons = GetReasonsForUncacheability(response); | |
373 might_be_reused_from_cache_in_future_ = reasons == 0; | |
374 UMA_HISTOGRAM_BOOLEAN("Media.CacheUseful", reasons == 0); | |
375 int shift = 0; | |
376 int max_enum = base::bits::Log2Ceiling(kMaxReason); | |
377 while (reasons) { | |
378 DCHECK_LT(shift, max_enum); // Sanity check. | |
379 if (reasons & 0x1) | |
380 UMA_HISTOGRAM_ENUMERATION("Media.UncacheableReason", shift, max_enum); | |
381 reasons >>= 1; | |
382 ++shift; | |
383 } | |
384 | |
385 // Expected content length can be |kPositionNotSpecified|, in that case | |
386 // |content_length_| is not specified and this is a streaming response. | |
387 content_length_ = response.expectedContentLength(); | |
388 | |
389 // We make a strong assumption that when we reach here we have either | |
390 // received a response from HTTP/HTTPS protocol or the request was | |
391 // successful (in particular range request). So we only verify the partial | |
392 // response for HTTP and HTTPS protocol. | |
393 if (url_.SchemeIsHTTPOrHTTPS()) { | |
394 bool partial_response = (response.httpStatusCode() == kHttpPartialContent); | |
395 bool ok_response = (response.httpStatusCode() == kHttpOK); | |
396 | |
397 if (IsRangeRequest()) { | |
398 // Check to see whether the server supports byte ranges. | |
399 std::string accept_ranges = | |
400 response.httpHeaderField("Accept-Ranges").utf8(); | |
401 range_supported_ = (accept_ranges.find("bytes") != std::string::npos); | |
402 | |
403 // If we have verified the partial response and it is correct, we will | |
404 // return kOk. It's also possible for a server to support range requests | |
405 // without advertising "Accept-Ranges: bytes". | |
406 if (partial_response && VerifyPartialResponse(response)) { | |
407 range_supported_ = true; | |
408 } else if (ok_response && first_byte_position_ == 0 && | |
409 last_byte_position_ == kPositionNotSpecified) { | |
410 // We accept a 200 response for a Range:0- request, trusting the | |
411 // Accept-Ranges header, because Apache thinks that's a reasonable thing | |
412 // to return. | |
413 instance_size_ = content_length_; | |
414 } else { | |
415 DoneStart(kFailed); | |
416 return; | |
417 } | |
418 } else { | |
419 instance_size_ = content_length_; | |
420 if (response.httpStatusCode() != kHttpOK) { | |
421 // We didn't request a range but server didn't reply with "200 OK". | |
422 DoneStart(kFailed); | |
423 return; | |
424 } | |
425 } | |
426 | |
427 } else { | |
428 CHECK_EQ(instance_size_, kPositionNotSpecified); | |
429 if (content_length_ != kPositionNotSpecified) { | |
430 if (first_byte_position_ == kPositionNotSpecified) | |
431 instance_size_ = content_length_; | |
432 else if (last_byte_position_ == kPositionNotSpecified) | |
433 instance_size_ = content_length_ + first_byte_position_; | |
434 } | |
435 } | |
436 | |
437 // Calls with a successful response. | |
438 DoneStart(kOk); | |
439 } | |
440 | |
441 void BufferedResourceLoader::didReceiveData( | |
442 WebURLLoader* loader, | |
443 const char* data, | |
444 int data_length, | |
445 int encoded_data_length) { | |
446 DVLOG(1) << "didReceiveData: " << data_length << " bytes"; | |
447 DCHECK(active_loader_.get()); | |
448 DCHECK_GT(data_length, 0); | |
449 | |
450 buffer_.Append(reinterpret_cast<const uint8*>(data), data_length); | |
451 | |
452 // If there is an active read request, try to fulfill the request. | |
453 if (HasPendingRead() && CanFulfillRead()) | |
454 ReadInternal(); | |
455 | |
456 // At last see if the buffer is full and we need to defer the downloading. | |
457 UpdateDeferBehavior(); | |
458 | |
459 // Consume excess bytes from our in-memory buffer if necessary. | |
460 if (buffer_.forward_bytes() > buffer_.forward_capacity()) { | |
461 int excess = buffer_.forward_bytes() - buffer_.forward_capacity(); | |
462 bool success = buffer_.Seek(excess); | |
463 DCHECK(success); | |
464 offset_ += first_offset_ + excess; | |
465 } | |
466 | |
467 // Notify latest progress and buffered offset. | |
468 progress_cb_.Run(offset_ + buffer_.forward_bytes() - 1); | |
469 Log(); | |
470 } | |
471 | |
472 void BufferedResourceLoader::didDownloadData( | |
473 blink::WebURLLoader* loader, | |
474 int dataLength, | |
475 int encoded_data_length) { | |
476 NOTIMPLEMENTED(); | |
477 } | |
478 | |
479 void BufferedResourceLoader::didReceiveCachedMetadata( | |
480 WebURLLoader* loader, | |
481 const char* data, | |
482 int data_length) { | |
483 NOTIMPLEMENTED(); | |
484 } | |
485 | |
486 void BufferedResourceLoader::didFinishLoading( | |
487 WebURLLoader* loader, | |
488 double finishTime, | |
489 int64_t total_encoded_data_length) { | |
490 DVLOG(1) << "didFinishLoading"; | |
491 DCHECK(active_loader_.get()); | |
492 | |
493 // We're done with the loader. | |
494 active_loader_.reset(); | |
495 loading_cb_.Run(kLoadingFinished); | |
496 | |
497 // If we didn't know the |instance_size_| we do now. | |
498 if (instance_size_ == kPositionNotSpecified) { | |
499 instance_size_ = offset_ + buffer_.forward_bytes(); | |
500 } | |
501 | |
502 // If there is a start callback, run it. | |
503 if (!start_cb_.is_null()) { | |
504 DCHECK(read_cb_.is_null()) | |
505 << "Shouldn't have a read callback during start"; | |
506 DoneStart(kOk); | |
507 return; | |
508 } | |
509 | |
510 // Don't leave read callbacks hanging around. | |
511 if (HasPendingRead()) { | |
512 // Try to fulfill with what is in the buffer. | |
513 if (CanFulfillRead()) | |
514 ReadInternal(); | |
515 else | |
516 DoneRead(kCacheMiss, 0); | |
517 } | |
518 } | |
519 | |
520 void BufferedResourceLoader::didFail( | |
521 WebURLLoader* loader, | |
522 const WebURLError& error) { | |
523 DVLOG(1) << "didFail: reason=" << error.reason | |
524 << ", isCancellation=" << error.isCancellation | |
525 << ", domain=" << error.domain.utf8().data() | |
526 << ", localizedDescription=" | |
527 << error.localizedDescription.utf8().data(); | |
528 DCHECK(active_loader_.get()); | |
529 | |
530 // We don't need to continue loading after failure. | |
531 // | |
532 // Keep it alive until we exit this method so that |error| remains valid. | |
533 scoped_ptr<ActiveLoader> active_loader = active_loader_.Pass(); | |
534 loader_failed_ = true; | |
535 loading_cb_.Run(kLoadingFailed); | |
536 | |
537 // Don't leave start callbacks hanging around. | |
538 if (!start_cb_.is_null()) { | |
539 DCHECK(read_cb_.is_null()) | |
540 << "Shouldn't have a read callback during start"; | |
541 DoneStart(kFailed); | |
542 return; | |
543 } | |
544 | |
545 // Don't leave read callbacks hanging around. | |
546 if (HasPendingRead()) { | |
547 DoneRead(kFailed, 0); | |
548 } | |
549 } | |
550 | |
551 bool BufferedResourceLoader::HasSingleOrigin() const { | |
552 DCHECK(start_cb_.is_null()) | |
553 << "Start() must complete before calling HasSingleOrigin()"; | |
554 return single_origin_; | |
555 } | |
556 | |
557 bool BufferedResourceLoader::DidPassCORSAccessCheck() const { | |
558 DCHECK(start_cb_.is_null()) | |
559 << "Start() must complete before calling DidPassCORSAccessCheck()"; | |
560 return !loader_failed_ && cors_mode_ != kUnspecified; | |
561 } | |
562 | |
563 void BufferedResourceLoader::UpdateDeferStrategy(DeferStrategy strategy) { | |
564 if (!might_be_reused_from_cache_in_future_ && strategy == kNeverDefer) | |
565 strategy = kCapacityDefer; | |
566 defer_strategy_ = strategy; | |
567 UpdateDeferBehavior(); | |
568 } | |
569 | |
570 void BufferedResourceLoader::SetPlaybackRate(float playback_rate) { | |
571 playback_rate_ = playback_rate; | |
572 | |
573 // This is a pause so don't bother updating the buffer window as we'll likely | |
574 // get unpaused in the future. | |
575 if (playback_rate_ == 0.0) | |
576 return; | |
577 | |
578 UpdateBufferWindow(); | |
579 } | |
580 | |
581 void BufferedResourceLoader::SetBitrate(int bitrate) { | |
582 DCHECK(bitrate >= 0); | |
583 bitrate_ = bitrate; | |
584 UpdateBufferWindow(); | |
585 } | |
586 | |
587 ///////////////////////////////////////////////////////////////////////////// | |
588 // Helper methods. | |
589 | |
590 void BufferedResourceLoader::UpdateBufferWindow() { | |
591 int backward_capacity; | |
592 int forward_capacity; | |
593 ComputeTargetBufferWindow( | |
594 playback_rate_, bitrate_, &backward_capacity, &forward_capacity); | |
595 | |
596 // This does not evict data from the buffer if the new capacities are less | |
597 // than the current capacities; the new limits will be enforced after the | |
598 // existing excess buffered data is consumed. | |
599 buffer_.set_backward_capacity(backward_capacity); | |
600 buffer_.set_forward_capacity(forward_capacity); | |
601 } | |
602 | |
603 void BufferedResourceLoader::UpdateDeferBehavior() { | |
604 if (!active_loader_) | |
605 return; | |
606 | |
607 SetDeferred(ShouldDefer()); | |
608 } | |
609 | |
610 void BufferedResourceLoader::SetDeferred(bool deferred) { | |
611 if (active_loader_->deferred() == deferred) | |
612 return; | |
613 | |
614 active_loader_->SetDeferred(deferred); | |
615 loading_cb_.Run(deferred ? kLoadingDeferred : kLoading); | |
616 } | |
617 | |
618 bool BufferedResourceLoader::ShouldDefer() const { | |
619 switch(defer_strategy_) { | |
620 case kNeverDefer: | |
621 return false; | |
622 | |
623 case kReadThenDefer: | |
624 DCHECK(read_cb_.is_null() || last_offset_ > buffer_.forward_bytes()) | |
625 << "We shouldn't stop deferring if we can fulfill the read"; | |
626 return read_cb_.is_null(); | |
627 | |
628 case kCapacityDefer: | |
629 return buffer_.forward_bytes() >= buffer_.forward_capacity(); | |
630 } | |
631 NOTREACHED(); | |
632 return false; | |
633 } | |
634 | |
635 bool BufferedResourceLoader::CanFulfillRead() const { | |
636 // If we are reading too far in the backward direction. | |
637 if (first_offset_ < 0 && (first_offset_ + buffer_.backward_bytes()) < 0) | |
638 return false; | |
639 | |
640 // If the start offset is too far ahead. | |
641 if (first_offset_ >= buffer_.forward_bytes()) | |
642 return false; | |
643 | |
644 // At the point, we verified that first byte requested is within the buffer. | |
645 // If the request has completed, then just returns with what we have now. | |
646 if (!active_loader_) | |
647 return true; | |
648 | |
649 // If the resource request is still active, make sure the whole requested | |
650 // range is covered. | |
651 if (last_offset_ > buffer_.forward_bytes()) | |
652 return false; | |
653 | |
654 return true; | |
655 } | |
656 | |
657 bool BufferedResourceLoader::WillFulfillRead() const { | |
658 // Trying to read too far behind. | |
659 if (first_offset_ < 0 && (first_offset_ + buffer_.backward_bytes()) < 0) | |
660 return false; | |
661 | |
662 // Trying to read too far ahead. | |
663 if ((first_offset_ - buffer_.forward_bytes()) >= kForwardWaitThreshold) | |
664 return false; | |
665 | |
666 // The resource request has completed, there's no way we can fulfill the | |
667 // read request. | |
668 if (!active_loader_) | |
669 return false; | |
670 | |
671 return true; | |
672 } | |
673 | |
674 void BufferedResourceLoader::ReadInternal() { | |
675 // Seek to the first byte requested. | |
676 bool ret = buffer_.Seek(first_offset_); | |
677 DCHECK(ret); | |
678 | |
679 // Then do the read. | |
680 int read = buffer_.Read(read_buffer_, read_size_); | |
681 offset_ += first_offset_ + read; | |
682 | |
683 // And report with what we have read. | |
684 DoneRead(kOk, read); | |
685 } | |
686 | |
687 int64 BufferedResourceLoader::first_byte_position() const { | |
688 return first_byte_position_; | |
689 } | |
690 | |
691 // static | |
692 bool BufferedResourceLoader::ParseContentRange( | |
693 const std::string& content_range_str, int64* first_byte_position, | |
694 int64* last_byte_position, int64* instance_size) { | |
695 const std::string kUpThroughBytesUnit = "bytes "; | |
696 if (content_range_str.find(kUpThroughBytesUnit) != 0) | |
697 return false; | |
698 std::string range_spec = | |
699 content_range_str.substr(kUpThroughBytesUnit.length()); | |
700 size_t dash_offset = range_spec.find("-"); | |
701 size_t slash_offset = range_spec.find("/"); | |
702 | |
703 if (dash_offset == std::string::npos || slash_offset == std::string::npos || | |
704 slash_offset < dash_offset || slash_offset + 1 == range_spec.length()) { | |
705 return false; | |
706 } | |
707 if (!base::StringToInt64(range_spec.substr(0, dash_offset), | |
708 first_byte_position) || | |
709 !base::StringToInt64(range_spec.substr(dash_offset + 1, | |
710 slash_offset - dash_offset - 1), | |
711 last_byte_position)) { | |
712 return false; | |
713 } | |
714 if (slash_offset == range_spec.length() - 2 && | |
715 range_spec[slash_offset + 1] == '*') { | |
716 *instance_size = kPositionNotSpecified; | |
717 } else { | |
718 if (!base::StringToInt64(range_spec.substr(slash_offset + 1), | |
719 instance_size)) { | |
720 return false; | |
721 } | |
722 } | |
723 if (*last_byte_position < *first_byte_position || | |
724 (*instance_size != kPositionNotSpecified && | |
725 *last_byte_position >= *instance_size)) { | |
726 return false; | |
727 } | |
728 | |
729 return true; | |
730 } | |
731 | |
732 bool BufferedResourceLoader::VerifyPartialResponse( | |
733 const WebURLResponse& response) { | |
734 int64 first_byte_position, last_byte_position, instance_size; | |
735 if (!ParseContentRange(response.httpHeaderField("Content-Range").utf8(), | |
736 &first_byte_position, &last_byte_position, | |
737 &instance_size)) { | |
738 return false; | |
739 } | |
740 | |
741 if (instance_size != kPositionNotSpecified) { | |
742 instance_size_ = instance_size; | |
743 } | |
744 | |
745 if (first_byte_position_ != kPositionNotSpecified && | |
746 first_byte_position_ != first_byte_position) { | |
747 return false; | |
748 } | |
749 | |
750 // TODO(hclam): I should also check |last_byte_position|, but since | |
751 // we will never make such a request that it is ok to leave it unimplemented. | |
752 return true; | |
753 } | |
754 | |
755 void BufferedResourceLoader::DoneRead(Status status, int bytes_read) { | |
756 if (saved_forward_capacity_) { | |
757 buffer_.set_forward_capacity(saved_forward_capacity_); | |
758 saved_forward_capacity_ = 0; | |
759 } | |
760 read_position_ = 0; | |
761 read_size_ = 0; | |
762 read_buffer_ = NULL; | |
763 first_offset_ = 0; | |
764 last_offset_ = 0; | |
765 Log(); | |
766 | |
767 base::ResetAndReturn(&read_cb_).Run(status, bytes_read); | |
768 } | |
769 | |
770 | |
771 void BufferedResourceLoader::DoneStart(Status status) { | |
772 base::ResetAndReturn(&start_cb_).Run(status); | |
773 } | |
774 | |
775 bool BufferedResourceLoader::IsRangeRequest() const { | |
776 return first_byte_position_ != kPositionNotSpecified; | |
777 } | |
778 | |
779 void BufferedResourceLoader::Log() { | |
780 media_log_->AddEvent( | |
781 media_log_->CreateBufferedExtentsChangedEvent( | |
782 offset_ - buffer_.backward_bytes(), | |
783 offset_, | |
784 offset_ + buffer_.forward_bytes())); | |
785 } | |
786 | |
787 } // namespace content | |
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