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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 "webkit/renderer/media/buffered_resource_loader.h" | |
6 | |
7 #include "base/bits.h" | |
8 #include "base/callback_helpers.h" | |
9 #include "base/format_macros.h" | |
10 #include "base/metrics/histogram.h" | |
11 #include "base/strings/string_number_conversions.h" | |
12 #include "base/strings/string_util.h" | |
13 #include "base/strings/stringprintf.h" | |
14 #include "media/base/media_log.h" | |
15 #include "net/http/http_request_headers.h" | |
16 #include "third_party/WebKit/public/platform/WebString.h" | |
17 #include "third_party/WebKit/public/platform/WebURLError.h" | |
18 #include "third_party/WebKit/public/platform/WebURLResponse.h" | |
19 #include "third_party/WebKit/public/web/WebKit.h" | |
20 #include "third_party/WebKit/public/web/WebURLLoaderOptions.h" | |
21 #include "webkit/renderer/media/cache_util.h" | |
22 | |
23 using WebKit::WebFrame; | |
24 using WebKit::WebString; | |
25 using WebKit::WebURLError; | |
26 using WebKit::WebURLLoader; | |
27 using WebKit::WebURLLoaderOptions; | |
28 using WebKit::WebURLRequest; | |
29 using WebKit::WebURLResponse; | |
30 | |
31 namespace webkit_media { | |
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 request.setTargetType(WebURLRequest::TargetIsMedia); | |
164 | |
165 if (IsRangeRequest()) { | |
166 request.setHTTPHeaderField( | |
167 WebString::fromUTF8(net::HttpRequestHeaders::kRange), | |
168 WebString::fromUTF8(GenerateHeaders(first_byte_position_, | |
169 last_byte_position_))); | |
170 } | |
171 | |
172 frame->setReferrerForRequest(request, WebKit::WebURL()); | |
173 | |
174 // Disable compression, compression for audio/video doesn't make sense... | |
175 request.setHTTPHeaderField( | |
176 WebString::fromUTF8(net::HttpRequestHeaders::kAcceptEncoding), | |
177 WebString::fromUTF8("identity;q=1, *;q=0")); | |
178 | |
179 // Check for our test WebURLLoader. | |
180 scoped_ptr<WebURLLoader> loader; | |
181 if (test_loader_) { | |
182 loader = test_loader_.Pass(); | |
183 } else { | |
184 WebURLLoaderOptions options; | |
185 if (cors_mode_ == kUnspecified) { | |
186 options.allowCredentials = true; | |
187 options.crossOriginRequestPolicy = | |
188 WebURLLoaderOptions::CrossOriginRequestPolicyAllow; | |
189 } else { | |
190 options.exposeAllResponseHeaders = true; | |
191 options.crossOriginRequestPolicy = | |
192 WebURLLoaderOptions::CrossOriginRequestPolicyUseAccessControl; | |
193 if (cors_mode_ == kUseCredentials) | |
194 options.allowCredentials = true; | |
195 } | |
196 loader.reset(frame->createAssociatedURLLoader(options)); | |
197 } | |
198 | |
199 // Start the resource loading. | |
200 loader->loadAsynchronously(request, this); | |
201 active_loader_.reset(new ActiveLoader(loader.Pass())); | |
202 loading_cb_.Run(kLoading); | |
203 } | |
204 | |
205 void BufferedResourceLoader::Stop() { | |
206 // Reset callbacks. | |
207 start_cb_.Reset(); | |
208 loading_cb_.Reset(); | |
209 progress_cb_.Reset(); | |
210 read_cb_.Reset(); | |
211 | |
212 // Cancel and reset any active loaders. | |
213 active_loader_.reset(); | |
214 } | |
215 | |
216 void BufferedResourceLoader::Read( | |
217 int64 position, | |
218 int read_size, | |
219 uint8* buffer, | |
220 const ReadCB& read_cb) { | |
221 DCHECK(start_cb_.is_null()); | |
222 DCHECK(read_cb_.is_null()); | |
223 DCHECK(!read_cb.is_null()); | |
224 DCHECK(buffer); | |
225 DCHECK_GT(read_size, 0); | |
226 | |
227 // Save the parameter of reading. | |
228 read_cb_ = read_cb; | |
229 read_position_ = position; | |
230 read_size_ = read_size; | |
231 read_buffer_ = buffer; | |
232 | |
233 // Reads should immediately fail if the loader also failed. | |
234 if (loader_failed_) { | |
235 DoneRead(kFailed, 0); | |
236 return; | |
237 } | |
238 | |
239 // If we're attempting to read past the end of the file, return a zero | |
240 // indicating EOF. | |
241 // | |
242 // This can happen with callees that read in fixed-sized amounts for parsing | |
243 // or at the end of chunked 200 responses when we discover the actual length | |
244 // of the file. | |
245 if (instance_size_ != kPositionNotSpecified && | |
246 instance_size_ <= read_position_) { | |
247 DVLOG(1) << "Appear to have seeked beyond EOS; returning 0."; | |
248 DoneRead(kOk, 0); | |
249 return; | |
250 } | |
251 | |
252 // Make sure |offset_| and |read_position_| does not differ by a large | |
253 // amount. | |
254 if (read_position_ > offset_ + kint32max || | |
255 read_position_ < offset_ + kint32min) { | |
256 DoneRead(kCacheMiss, 0); | |
257 return; | |
258 } | |
259 | |
260 // Make sure |read_size_| is not too large for the buffer to ever be able to | |
261 // fulfill the read request. | |
262 if (read_size_ > kMaxBufferCapacity) { | |
263 DoneRead(kFailed, 0); | |
264 return; | |
265 } | |
266 | |
267 // Prepare the parameters. | |
268 first_offset_ = read_position_ - offset_; | |
269 last_offset_ = first_offset_ + read_size_; | |
270 | |
271 // If we can serve the request now, do the actual read. | |
272 if (CanFulfillRead()) { | |
273 ReadInternal(); | |
274 UpdateDeferBehavior(); | |
275 return; | |
276 } | |
277 | |
278 // If we expect the read request to be fulfilled later, expand capacity as | |
279 // necessary and disable deferring. | |
280 if (WillFulfillRead()) { | |
281 // Advance offset as much as possible to create additional capacity. | |
282 int advance = std::min(first_offset_, buffer_.forward_bytes()); | |
283 bool ret = buffer_.Seek(advance); | |
284 DCHECK(ret); | |
285 | |
286 offset_ += advance; | |
287 first_offset_ -= advance; | |
288 last_offset_ -= advance; | |
289 | |
290 // Expand capacity to accomodate a read that extends past the normal | |
291 // capacity. | |
292 // | |
293 // This can happen when reading in a large seek index or when the | |
294 // first byte of a read request falls within kForwardWaitThreshold. | |
295 if (last_offset_ > buffer_.forward_capacity()) { | |
296 saved_forward_capacity_ = buffer_.forward_capacity(); | |
297 buffer_.set_forward_capacity(last_offset_); | |
298 } | |
299 | |
300 // Make sure we stop deferring now that there's additional capacity. | |
301 DCHECK(!ShouldDefer()) | |
302 << "Capacity was not adjusted properly to prevent deferring."; | |
303 UpdateDeferBehavior(); | |
304 | |
305 return; | |
306 } | |
307 | |
308 // Make a callback to report failure. | |
309 DoneRead(kCacheMiss, 0); | |
310 } | |
311 | |
312 int64 BufferedResourceLoader::content_length() { | |
313 return content_length_; | |
314 } | |
315 | |
316 int64 BufferedResourceLoader::instance_size() { | |
317 return instance_size_; | |
318 } | |
319 | |
320 bool BufferedResourceLoader::range_supported() { | |
321 return range_supported_; | |
322 } | |
323 | |
324 ///////////////////////////////////////////////////////////////////////////// | |
325 // WebKit::WebURLLoaderClient implementation. | |
326 void BufferedResourceLoader::willSendRequest( | |
327 WebURLLoader* loader, | |
328 WebURLRequest& newRequest, | |
329 const WebURLResponse& redirectResponse) { | |
330 | |
331 // The load may have been stopped and |start_cb| is destroyed. | |
332 // In this case we shouldn't do anything. | |
333 if (start_cb_.is_null()) { | |
334 // Set the url in the request to an invalid value (empty url). | |
335 newRequest.setURL(WebKit::WebURL()); | |
336 return; | |
337 } | |
338 | |
339 // Only allow |single_origin_| if we haven't seen a different origin yet. | |
340 if (single_origin_) | |
341 single_origin_ = url_.GetOrigin() == GURL(newRequest.url()).GetOrigin(); | |
342 | |
343 url_ = newRequest.url(); | |
344 } | |
345 | |
346 void BufferedResourceLoader::didSendData( | |
347 WebURLLoader* loader, | |
348 unsigned long long bytes_sent, | |
349 unsigned long long total_bytes_to_be_sent) { | |
350 NOTIMPLEMENTED(); | |
351 } | |
352 | |
353 void BufferedResourceLoader::didReceiveResponse( | |
354 WebURLLoader* loader, | |
355 const WebURLResponse& response) { | |
356 DVLOG(1) << "didReceiveResponse: HTTP/" | |
357 << (response.httpVersion() == WebURLResponse::HTTP_0_9 ? "0.9" : | |
358 response.httpVersion() == WebURLResponse::HTTP_1_0 ? "1.0" : | |
359 response.httpVersion() == WebURLResponse::HTTP_1_1 ? "1.1" : | |
360 "Unknown") | |
361 << " " << response.httpStatusCode(); | |
362 DCHECK(active_loader_.get()); | |
363 | |
364 // The loader may have been stopped and |start_cb| is destroyed. | |
365 // In this case we shouldn't do anything. | |
366 if (start_cb_.is_null()) | |
367 return; | |
368 | |
369 uint32 reasons = GetReasonsForUncacheability(response); | |
370 might_be_reused_from_cache_in_future_ = reasons == 0; | |
371 UMA_HISTOGRAM_BOOLEAN("Media.CacheUseful", reasons == 0); | |
372 int shift = 0; | |
373 int max_enum = base::bits::Log2Ceiling(kMaxReason); | |
374 while (reasons) { | |
375 DCHECK_LT(shift, max_enum); // Sanity check. | |
376 if (reasons & 0x1) | |
377 UMA_HISTOGRAM_ENUMERATION("Media.UncacheableReason", shift, max_enum); | |
378 reasons >>= 1; | |
379 ++shift; | |
380 } | |
381 | |
382 // Expected content length can be |kPositionNotSpecified|, in that case | |
383 // |content_length_| is not specified and this is a streaming response. | |
384 content_length_ = response.expectedContentLength(); | |
385 | |
386 // We make a strong assumption that when we reach here we have either | |
387 // received a response from HTTP/HTTPS protocol or the request was | |
388 // successful (in particular range request). So we only verify the partial | |
389 // response for HTTP and HTTPS protocol. | |
390 if (url_.SchemeIs(kHttpScheme) || url_.SchemeIs(kHttpsScheme)) { | |
391 bool partial_response = (response.httpStatusCode() == kHttpPartialContent); | |
392 bool ok_response = (response.httpStatusCode() == kHttpOK); | |
393 | |
394 if (IsRangeRequest()) { | |
395 // Check to see whether the server supports byte ranges. | |
396 std::string accept_ranges = | |
397 response.httpHeaderField("Accept-Ranges").utf8(); | |
398 range_supported_ = (accept_ranges.find("bytes") != std::string::npos); | |
399 | |
400 // If we have verified the partial response and it is correct, we will | |
401 // return kOk. It's also possible for a server to support range requests | |
402 // without advertising "Accept-Ranges: bytes". | |
403 if (partial_response && VerifyPartialResponse(response)) { | |
404 range_supported_ = true; | |
405 } else if (ok_response && first_byte_position_ == 0 && | |
406 last_byte_position_ == kPositionNotSpecified) { | |
407 // We accept a 200 response for a Range:0- request, trusting the | |
408 // Accept-Ranges header, because Apache thinks that's a reasonable thing | |
409 // to return. | |
410 instance_size_ = content_length_; | |
411 } else { | |
412 DoneStart(kFailed); | |
413 return; | |
414 } | |
415 } else { | |
416 instance_size_ = content_length_; | |
417 if (response.httpStatusCode() != kHttpOK) { | |
418 // We didn't request a range but server didn't reply with "200 OK". | |
419 DoneStart(kFailed); | |
420 return; | |
421 } | |
422 } | |
423 | |
424 } else { | |
425 CHECK_EQ(instance_size_, kPositionNotSpecified); | |
426 if (content_length_ != kPositionNotSpecified) { | |
427 if (first_byte_position_ == kPositionNotSpecified) | |
428 instance_size_ = content_length_; | |
429 else if (last_byte_position_ == kPositionNotSpecified) | |
430 instance_size_ = content_length_ + first_byte_position_; | |
431 } | |
432 } | |
433 | |
434 // Calls with a successful response. | |
435 DoneStart(kOk); | |
436 } | |
437 | |
438 void BufferedResourceLoader::didReceiveData( | |
439 WebURLLoader* loader, | |
440 const char* data, | |
441 int data_length, | |
442 int encoded_data_length) { | |
443 DVLOG(1) << "didReceiveData: " << data_length << " bytes"; | |
444 DCHECK(active_loader_.get()); | |
445 DCHECK_GT(data_length, 0); | |
446 | |
447 buffer_.Append(reinterpret_cast<const uint8*>(data), data_length); | |
448 | |
449 // If there is an active read request, try to fulfill the request. | |
450 if (HasPendingRead() && CanFulfillRead()) | |
451 ReadInternal(); | |
452 | |
453 // At last see if the buffer is full and we need to defer the downloading. | |
454 UpdateDeferBehavior(); | |
455 | |
456 // Consume excess bytes from our in-memory buffer if necessary. | |
457 if (buffer_.forward_bytes() > buffer_.forward_capacity()) { | |
458 int excess = buffer_.forward_bytes() - buffer_.forward_capacity(); | |
459 bool success = buffer_.Seek(excess); | |
460 DCHECK(success); | |
461 offset_ += first_offset_ + excess; | |
462 } | |
463 | |
464 // Notify latest progress and buffered offset. | |
465 progress_cb_.Run(offset_ + buffer_.forward_bytes() - 1); | |
466 Log(); | |
467 } | |
468 | |
469 void BufferedResourceLoader::didDownloadData( | |
470 WebKit::WebURLLoader* loader, | |
471 int dataLength) { | |
472 NOTIMPLEMENTED(); | |
473 } | |
474 | |
475 void BufferedResourceLoader::didReceiveCachedMetadata( | |
476 WebURLLoader* loader, | |
477 const char* data, | |
478 int data_length) { | |
479 NOTIMPLEMENTED(); | |
480 } | |
481 | |
482 void BufferedResourceLoader::didFinishLoading( | |
483 WebURLLoader* loader, | |
484 double finishTime) { | |
485 DVLOG(1) << "didFinishLoading"; | |
486 DCHECK(active_loader_.get()); | |
487 | |
488 // We're done with the loader. | |
489 active_loader_.reset(); | |
490 loading_cb_.Run(kLoadingFinished); | |
491 | |
492 // If we didn't know the |instance_size_| we do now. | |
493 if (instance_size_ == kPositionNotSpecified) { | |
494 instance_size_ = offset_ + buffer_.forward_bytes(); | |
495 } | |
496 | |
497 // If there is a start callback, run it. | |
498 if (!start_cb_.is_null()) { | |
499 DCHECK(read_cb_.is_null()) | |
500 << "Shouldn't have a read callback during start"; | |
501 DoneStart(kOk); | |
502 return; | |
503 } | |
504 | |
505 // Don't leave read callbacks hanging around. | |
506 if (HasPendingRead()) { | |
507 // Try to fulfill with what is in the buffer. | |
508 if (CanFulfillRead()) | |
509 ReadInternal(); | |
510 else | |
511 DoneRead(kCacheMiss, 0); | |
512 } | |
513 } | |
514 | |
515 void BufferedResourceLoader::didFail( | |
516 WebURLLoader* loader, | |
517 const WebURLError& error) { | |
518 DVLOG(1) << "didFail: reason=" << error.reason | |
519 << ", isCancellation=" << error.isCancellation | |
520 << ", domain=" << error.domain.utf8().data() | |
521 << ", localizedDescription=" | |
522 << error.localizedDescription.utf8().data(); | |
523 DCHECK(active_loader_.get()); | |
524 | |
525 // We don't need to continue loading after failure. | |
526 // | |
527 // Keep it alive until we exit this method so that |error| remains valid. | |
528 scoped_ptr<ActiveLoader> active_loader = active_loader_.Pass(); | |
529 loader_failed_ = true; | |
530 loading_cb_.Run(kLoadingFailed); | |
531 | |
532 // Don't leave start callbacks hanging around. | |
533 if (!start_cb_.is_null()) { | |
534 DCHECK(read_cb_.is_null()) | |
535 << "Shouldn't have a read callback during start"; | |
536 DoneStart(kFailed); | |
537 return; | |
538 } | |
539 | |
540 // Don't leave read callbacks hanging around. | |
541 if (HasPendingRead()) { | |
542 DoneRead(kFailed, 0); | |
543 } | |
544 } | |
545 | |
546 bool BufferedResourceLoader::HasSingleOrigin() const { | |
547 DCHECK(start_cb_.is_null()) | |
548 << "Start() must complete before calling HasSingleOrigin()"; | |
549 return single_origin_; | |
550 } | |
551 | |
552 bool BufferedResourceLoader::DidPassCORSAccessCheck() const { | |
553 DCHECK(start_cb_.is_null()) | |
554 << "Start() must complete before calling DidPassCORSAccessCheck()"; | |
555 return !loader_failed_ && cors_mode_ != kUnspecified; | |
556 } | |
557 | |
558 void BufferedResourceLoader::UpdateDeferStrategy(DeferStrategy strategy) { | |
559 if (!might_be_reused_from_cache_in_future_ && strategy == kNeverDefer) | |
560 strategy = kCapacityDefer; | |
561 defer_strategy_ = strategy; | |
562 UpdateDeferBehavior(); | |
563 } | |
564 | |
565 void BufferedResourceLoader::SetPlaybackRate(float playback_rate) { | |
566 playback_rate_ = playback_rate; | |
567 | |
568 // This is a pause so don't bother updating the buffer window as we'll likely | |
569 // get unpaused in the future. | |
570 if (playback_rate_ == 0.0) | |
571 return; | |
572 | |
573 UpdateBufferWindow(); | |
574 } | |
575 | |
576 void BufferedResourceLoader::SetBitrate(int bitrate) { | |
577 DCHECK(bitrate >= 0); | |
578 bitrate_ = bitrate; | |
579 UpdateBufferWindow(); | |
580 } | |
581 | |
582 ///////////////////////////////////////////////////////////////////////////// | |
583 // Helper methods. | |
584 | |
585 void BufferedResourceLoader::UpdateBufferWindow() { | |
586 int backward_capacity; | |
587 int forward_capacity; | |
588 ComputeTargetBufferWindow( | |
589 playback_rate_, bitrate_, &backward_capacity, &forward_capacity); | |
590 | |
591 // This does not evict data from the buffer if the new capacities are less | |
592 // than the current capacities; the new limits will be enforced after the | |
593 // existing excess buffered data is consumed. | |
594 buffer_.set_backward_capacity(backward_capacity); | |
595 buffer_.set_forward_capacity(forward_capacity); | |
596 } | |
597 | |
598 void BufferedResourceLoader::UpdateDeferBehavior() { | |
599 if (!active_loader_) | |
600 return; | |
601 | |
602 SetDeferred(ShouldDefer()); | |
603 } | |
604 | |
605 void BufferedResourceLoader::SetDeferred(bool deferred) { | |
606 if (active_loader_->deferred() == deferred) | |
607 return; | |
608 | |
609 active_loader_->SetDeferred(deferred); | |
610 loading_cb_.Run(deferred ? kLoadingDeferred : kLoading); | |
611 } | |
612 | |
613 bool BufferedResourceLoader::ShouldDefer() const { | |
614 switch(defer_strategy_) { | |
615 case kNeverDefer: | |
616 return false; | |
617 | |
618 case kReadThenDefer: | |
619 DCHECK(read_cb_.is_null() || last_offset_ > buffer_.forward_bytes()) | |
620 << "We shouldn't stop deferring if we can fulfill the read"; | |
621 return read_cb_.is_null(); | |
622 | |
623 case kCapacityDefer: | |
624 return buffer_.forward_bytes() >= buffer_.forward_capacity(); | |
625 } | |
626 NOTREACHED(); | |
627 return false; | |
628 } | |
629 | |
630 bool BufferedResourceLoader::CanFulfillRead() const { | |
631 // If we are reading too far in the backward direction. | |
632 if (first_offset_ < 0 && (first_offset_ + buffer_.backward_bytes()) < 0) | |
633 return false; | |
634 | |
635 // If the start offset is too far ahead. | |
636 if (first_offset_ >= buffer_.forward_bytes()) | |
637 return false; | |
638 | |
639 // At the point, we verified that first byte requested is within the buffer. | |
640 // If the request has completed, then just returns with what we have now. | |
641 if (!active_loader_) | |
642 return true; | |
643 | |
644 // If the resource request is still active, make sure the whole requested | |
645 // range is covered. | |
646 if (last_offset_ > buffer_.forward_bytes()) | |
647 return false; | |
648 | |
649 return true; | |
650 } | |
651 | |
652 bool BufferedResourceLoader::WillFulfillRead() const { | |
653 // Trying to read too far behind. | |
654 if (first_offset_ < 0 && (first_offset_ + buffer_.backward_bytes()) < 0) | |
655 return false; | |
656 | |
657 // Trying to read too far ahead. | |
658 if ((first_offset_ - buffer_.forward_bytes()) >= kForwardWaitThreshold) | |
659 return false; | |
660 | |
661 // The resource request has completed, there's no way we can fulfill the | |
662 // read request. | |
663 if (!active_loader_) | |
664 return false; | |
665 | |
666 return true; | |
667 } | |
668 | |
669 void BufferedResourceLoader::ReadInternal() { | |
670 // Seek to the first byte requested. | |
671 bool ret = buffer_.Seek(first_offset_); | |
672 DCHECK(ret); | |
673 | |
674 // Then do the read. | |
675 int read = buffer_.Read(read_buffer_, read_size_); | |
676 offset_ += first_offset_ + read; | |
677 | |
678 // And report with what we have read. | |
679 DoneRead(kOk, read); | |
680 } | |
681 | |
682 int64 BufferedResourceLoader::first_byte_position() const { | |
683 return first_byte_position_; | |
684 } | |
685 | |
686 // static | |
687 bool BufferedResourceLoader::ParseContentRange( | |
688 const std::string& content_range_str, int64* first_byte_position, | |
689 int64* last_byte_position, int64* instance_size) { | |
690 const std::string kUpThroughBytesUnit = "bytes "; | |
691 if (content_range_str.find(kUpThroughBytesUnit) != 0) | |
692 return false; | |
693 std::string range_spec = | |
694 content_range_str.substr(kUpThroughBytesUnit.length()); | |
695 size_t dash_offset = range_spec.find("-"); | |
696 size_t slash_offset = range_spec.find("/"); | |
697 | |
698 if (dash_offset == std::string::npos || slash_offset == std::string::npos || | |
699 slash_offset < dash_offset || slash_offset + 1 == range_spec.length()) { | |
700 return false; | |
701 } | |
702 if (!base::StringToInt64(range_spec.substr(0, dash_offset), | |
703 first_byte_position) || | |
704 !base::StringToInt64(range_spec.substr(dash_offset + 1, | |
705 slash_offset - dash_offset - 1), | |
706 last_byte_position)) { | |
707 return false; | |
708 } | |
709 if (slash_offset == range_spec.length() - 2 && | |
710 range_spec[slash_offset + 1] == '*') { | |
711 *instance_size = kPositionNotSpecified; | |
712 } else { | |
713 if (!base::StringToInt64(range_spec.substr(slash_offset + 1), | |
714 instance_size)) { | |
715 return false; | |
716 } | |
717 } | |
718 if (*last_byte_position < *first_byte_position || | |
719 (*instance_size != kPositionNotSpecified && | |
720 *last_byte_position >= *instance_size)) { | |
721 return false; | |
722 } | |
723 | |
724 return true; | |
725 } | |
726 | |
727 bool BufferedResourceLoader::VerifyPartialResponse( | |
728 const WebURLResponse& response) { | |
729 int64 first_byte_position, last_byte_position, instance_size; | |
730 if (!ParseContentRange(response.httpHeaderField("Content-Range").utf8(), | |
731 &first_byte_position, &last_byte_position, | |
732 &instance_size)) { | |
733 return false; | |
734 } | |
735 | |
736 if (instance_size != kPositionNotSpecified) { | |
737 instance_size_ = instance_size; | |
738 } | |
739 | |
740 if (first_byte_position_ != kPositionNotSpecified && | |
741 first_byte_position_ != first_byte_position) { | |
742 return false; | |
743 } | |
744 | |
745 // TODO(hclam): I should also check |last_byte_position|, but since | |
746 // we will never make such a request that it is ok to leave it unimplemented. | |
747 return true; | |
748 } | |
749 | |
750 std::string BufferedResourceLoader::GenerateHeaders( | |
751 int64 first_byte_position, | |
752 int64 last_byte_position) { | |
753 // Construct the value for the range header. | |
754 std::string header; | |
755 if (first_byte_position > kPositionNotSpecified && | |
756 last_byte_position > kPositionNotSpecified) { | |
757 if (first_byte_position <= last_byte_position) { | |
758 header = base::StringPrintf("bytes=%" PRId64 "-%" PRId64, | |
759 first_byte_position, | |
760 last_byte_position); | |
761 } | |
762 } else if (first_byte_position > kPositionNotSpecified) { | |
763 header = base::StringPrintf("bytes=%" PRId64 "-", | |
764 first_byte_position); | |
765 } else if (last_byte_position > kPositionNotSpecified) { | |
766 NOTIMPLEMENTED() << "Suffix range not implemented"; | |
767 } | |
768 return header; | |
769 } | |
770 | |
771 void BufferedResourceLoader::DoneRead(Status status, int bytes_read) { | |
772 if (saved_forward_capacity_) { | |
773 buffer_.set_forward_capacity(saved_forward_capacity_); | |
774 saved_forward_capacity_ = 0; | |
775 } | |
776 read_position_ = 0; | |
777 read_size_ = 0; | |
778 read_buffer_ = NULL; | |
779 first_offset_ = 0; | |
780 last_offset_ = 0; | |
781 Log(); | |
782 | |
783 base::ResetAndReturn(&read_cb_).Run(status, bytes_read); | |
784 } | |
785 | |
786 | |
787 void BufferedResourceLoader::DoneStart(Status status) { | |
788 base::ResetAndReturn(&start_cb_).Run(status); | |
789 } | |
790 | |
791 bool BufferedResourceLoader::IsRangeRequest() const { | |
792 return first_byte_position_ != kPositionNotSpecified; | |
793 } | |
794 | |
795 void BufferedResourceLoader::Log() { | |
796 media_log_->AddEvent( | |
797 media_log_->CreateBufferedExtentsChangedEvent( | |
798 offset_ - buffer_.backward_bytes(), | |
799 offset_, | |
800 offset_ + buffer_.forward_bytes())); | |
801 } | |
802 | |
803 } // namespace webkit_media | |
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