Tie multibuffers to URLs

media/blink/url_index.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MEDIA_BLINK_URL_INDEX_H_
+#define MEDIA_BLINK_URL_INDEX_H_
+
+#include <map>
+#include <vector>
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "media/blink/lru.h"
+#include "media/blink/media_blink_export.h"
+#include "media/blink/multibuffer.h"
+#include "third_party/WebKit/public/web/WebFrame.h"
+#include "url/gurl.h"
+
+namespace media {
+
+const int64 kPositionNotSpecified = -1;
+
+class UrlData;
+
+// A multibuffer for loading media resources which knows
+// how to create MultiBufferDataProviders to load data
+// into the cache.
+class MEDIA_BLINK_EXPORT ResourceMultiBuffer
+    : NON_EXPORTED_BASE(public MultiBuffer) {
+ public:
+  ResourceMultiBuffer(UrlData* url_data_, int block_shift);
+  ~ResourceMultiBuffer() override;
+
+  // MultiBuffer implementation.
+  scoped_ptr<MultiBuffer::DataProvider> CreateWriter(
+      const BlockId& pos) override;
+  bool RangeSupported() const override;
+  void OnEmpty() override;
+
+ protected:
+  // Do not access from destructor, it is a pointer to the
+  // object that contains us.
+  UrlData* url_data_;
+};
+
+class UrlIndex;
+
+// All the data & metadata for a single resource.
+// Data is cached using a MultiBuffer instance.
+class MEDIA_BLINK_EXPORT UrlData : public base::RefCounted<UrlData> {
+ public:
+  // Keep in sync with WebMediaPlayer::CORSMode.
+  enum CORSMode { CORS_UNSPECIFIED, CORS_ANONYMOUS, CORS_USE_CREDENTIALS };
+  typedef std::pair<GURL, CORSMode> KeyType;
+
+  // Accessors
+  const GURL& url() const { return url_; }
+
+  // Cross-origin access mode
+  CORSMode cors_mode() const { return cors_mode_; }
+
+  // Are HTTP range requests supported?
+  bool range_supported() const { return range_supported_; }
+
+  // True if we found a reason why this URL won't be stored in the
+  // HTTP disk cache.
+  bool cacheable() const { return cacheable_; }
+
+  // Last used time.
+  base::Time last_used() const { return last_used_; }
+
+  // Last modified time.
+  base::Time last_modified() const { return last_modified_; }
+
+  // Expiration time.
+  base::Time valid_until() const { return valid_until_; }
+
+  // The key used by UrlIndex to find this UrlData.
+  KeyType key() const;
+
+  // Length of data associated with url or |kPositionNotSpecified|
+  int64 length() const { return length_; }
+
+  // Returns the number of blocks cached for this resource.
+  size_t CachedSize();
+
+  // Returns our url_index, or nullptr if it's been destroyed.
+  UrlIndex* url_index() const { return url_index_.get(); }
+
+  // Notifies the url index that this is currently used.
+  // The url <-> URLData mapping will be eventually be invalidated if
+  // this is not called regularly.
+  void Use();
+
+  // Setters.
+  void set_length(int64 length);
+  void set_cacheable(bool cacheable);
+  void set_valid_until(base::Time valid_until);
+  void set_range_supported();
+  void set_last_modified(base::Time last_modified);
+
+  // A redirect has occured (or we've found a better UrlData for the same
+  // resource).
+  void RedirectTo(const scoped_refptr<UrlData>& to);
+
+  // Fail, tell all clients that a failure has occured.
+  void Fail();
+
+  // Callback for receving notifications when a redirect occurs.
+  typedef base::Callback<void(const scoped_refptr<UrlData>&)> RedirectCB;
+
+  // Register a callback to be called when a redirect occurs.
+  // Callbacks are cleared when a redirect occurs, so clients must call
+  // OnRedirect again if they wish to continue receiving callbacks.
+  void OnRedirect(const RedirectCB& cb);
+
+  // Returns true it is valid to keep using this to access cached data.
+  // A single media player instance may choose to ignore this for resources
+  // that have already been opened.
+  bool Valid() const;
+
+  // Virtual so we can override it for testing.
+  virtual ResourceMultiBuffer* multibuffer();
+
+  // Accessor
+  blink::WebFrame* frame() const { return frame_; }
+
+ protected:
+  UrlData(const GURL& url,
+          CORSMode cors_mode,
+          const base::WeakPtr<UrlIndex>& url_index);
+  virtual ~UrlData();
+
+ private:
+  friend class ResourceMultiBuffer;
+  friend class UrlIndex;
+  friend class base::RefCounted<UrlData>;
+
+  void OnEmpty();
+  void MergeFrom(const scoped_refptr<UrlData>& other);
+
+  // Url we represent, note that there may be multiple UrlData for
+  // the same url.
+  const GURL url_;
+
+  // Cross-origin access mode.
+  const CORSMode cors_mode_;
+
+  base::WeakPtr<UrlIndex> url_index_;
+
+  // Length of resource this url points to. (in bytes)
+  int64 length_;
+
+  // Does the server support ranges?
+  bool range_supported_;
+
+  // Set to false if we have reason to beleive the chrome disk cache
+  // will not cache this url.
+  bool cacheable_;
+
+  // Last time some media time used this resource.
+  // Note that we use base::Time rather than base::TimeTicks because
+  // TimeTicks will stop advancing when a machine goes to sleep.
+  // base::Time can go backwards, jump hours at a time and be generally
+  // unpredictable, but it doesn't stop, which is preferable here.
+  // (False negatives are better than false positivies.)
+  base::Time last_used_;
+
+  // Expiration time according to http headers.
+  base::Time valid_until_;
+
+  // Last modification time according to http headers.
+  base::Time last_modified_;
+
+  ResourceMultiBuffer multibuffer_;
+  std::vector<RedirectCB> redirect_callbacks_;
+
+  blink::WebFrame* frame_;
+
+  base::ThreadChecker thread_checker_;
+  DISALLOW_COPY_AND_ASSIGN(UrlData);
+};
+
+// The UrlIndex lets you look up UrlData instances by url.
+class MEDIA_BLINK_EXPORT UrlIndex {
+ public:
+  explicit UrlIndex(blink::WebFrame*);
+  UrlIndex(blink::WebFrame*, int block_shift);
+  virtual ~UrlIndex();
+
+  // Look up an UrlData in the index and return it. If none is found,
+  // create a new one. Note that newly created UrlData entries are NOT
+  // added to the index, instead you must call TryInsert on them after
+  // initializing relevant parameters, like whether it support
+  // ranges and it's last modified time.
+  scoped_refptr<UrlData> GetByUrl(const GURL& gurl,
+                                  UrlData::CORSMode cors_mode);
+
+  // Add the given UrlData to the index if possible. If a better UrlData
+  // is already present in the index, return it instead. (If not, we just
+  // return the given UrlData.) Please make sure to initialize all the data
+  // that can be gathered from HTTP headers in |url_data| before calling this.
+  // In particular, the following fields are important:
+  //   o range_supported: Entries which do not support ranges cannot be
+  //     shared and are not added to the index.
+  //   o valid_until, last_used: Entries have to be valid to be inserted
+  //     into the index, this means that they have to have been recently
+  //     used or have an Expires: header that says when they stop being valid.
+  //   o last_modified: Expired cache entries can be re-used if last_modified
+  //     matches.
+  // TODO(hubbe): Add etag support.
+  scoped_refptr<UrlData> TryInsert(const scoped_refptr<UrlData>& url_data);
+
+  blink::WebFrame* frame() const { return frame_; }
+
+ private:
+  friend class UrlData;
+  friend class ResourceMultiBuffer;
+  void RemoveUrlDataIfEmpty(const scoped_refptr<UrlData>& url_data);
+
+  // Virtual so we can override it in tests.
+  virtual scoped_refptr<UrlData> NewUrlData(const GURL& url,
+                                            UrlData::CORSMode cors_mode);
+
+  std::map<UrlData::KeyType, scoped_refptr<UrlData>> by_url_;
+  blink::WebFrame* frame_;
+  scoped_refptr<MultiBuffer::GlobalLRU> lru_;
+  bool prune_cb_active_;
+
+  // log2 of block size in multibuffer cache. Defaults to kBlockSizeShift.
+  // Currently only changed for testing purposes.
+  const int block_shift_;
+
+ protected:
+  base::WeakPtrFactory<UrlIndex> weak_factory_;
+};
+
+}  // namespace media
+#endif  // MEDIA_BLINK_URL_INDEX_H_