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1 // Copyright (c) 2011 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 #ifndef NET_HTTP_PARTIAL_DATA_H_ | |
6 #define NET_HTTP_PARTIAL_DATA_H_ | |
7 | |
8 #include "base/basictypes.h" | |
9 #include "net/base/completion_callback.h" | |
10 #include "net/http/http_byte_range.h" | |
11 #include "net/http/http_request_headers.h" | |
12 | |
13 namespace disk_cache { | |
14 class Entry; | |
15 } | |
16 | |
17 namespace net { | |
18 | |
19 class HttpResponseHeaders; | |
20 class IOBuffer; | |
21 | |
22 // This class provides support for dealing with range requests and the | |
23 // subsequent partial-content responses. We use sparse cache entries to store | |
24 // these requests. This class is tightly integrated with HttpCache::Transaction | |
25 // and it is intended to allow a cleaner implementation of that class. | |
26 // | |
27 // In order to fulfill range requests, we may have to perform a sequence of | |
28 // reads from the cache, interleaved with reads from the network / writes to the | |
29 // cache. This class basically keeps track of the data required to perform each | |
30 // of those individual network / cache requests. | |
31 class PartialData { | |
32 public: | |
33 PartialData(); | |
34 ~PartialData(); | |
35 | |
36 // Performs initialization of the object by examining the request |headers| | |
37 // and verifying that we can process the requested range. Returns true if | |
38 // we can process the requested range, and false otherwise. | |
39 bool Init(const HttpRequestHeaders& headers); | |
40 | |
41 // Sets the headers that we should use to make byte range requests. This is a | |
42 // subset of the request extra headers, with byte-range related headers | |
43 // removed. | |
44 void SetHeaders(const HttpRequestHeaders& headers); | |
45 | |
46 // Restores the byte-range headers, by appending the byte range to the headers | |
47 // provided to SetHeaders(). | |
48 void RestoreHeaders(HttpRequestHeaders* headers) const; | |
49 | |
50 // Starts the checks to perform a cache validation. Returns 0 when there is no | |
51 // need to perform more operations because we reached the end of the request | |
52 // (so 0 bytes should be actually returned to the user), a positive number to | |
53 // indicate that PrepareCacheValidation should be called, or an appropriate | |
54 // error code. If this method returns ERR_IO_PENDING, the |callback| will be | |
55 // notified when the result is ready. | |
56 int ShouldValidateCache(disk_cache::Entry* entry, | |
57 const CompletionCallback& callback); | |
58 | |
59 // Builds the required |headers| to perform the proper cache validation for | |
60 // the next range to be fetched. | |
61 void PrepareCacheValidation(disk_cache::Entry* entry, | |
62 HttpRequestHeaders* headers); | |
63 | |
64 // Returns true if the current range is stored in the cache. | |
65 bool IsCurrentRangeCached() const; | |
66 | |
67 // Returns true if the current range is the last one needed to fulfill the | |
68 // user's request. | |
69 bool IsLastRange() const; | |
70 | |
71 // Extracts info from headers already stored in the cache. Returns false if | |
72 // there is any problem with the headers. |truncated| should be true if we | |
73 // have an incomplete 200 entry. | |
74 bool UpdateFromStoredHeaders(const HttpResponseHeaders* headers, | |
75 disk_cache::Entry* entry, bool truncated); | |
76 | |
77 // Sets the byte current range to start again at zero (for a truncated entry). | |
78 void SetRangeToStartDownload(); | |
79 | |
80 // Returns true if the requested range is valid given the stored data. | |
81 bool IsRequestedRangeOK(); | |
82 | |
83 // Returns true if the response headers match what we expect, false otherwise. | |
84 bool ResponseHeadersOK(const HttpResponseHeaders* headers); | |
85 | |
86 // Fixes the response headers to include the right content length and range. | |
87 // |success| is the result of the whole request so if it's false, we'll change | |
88 // the result code to be 416. | |
89 void FixResponseHeaders(HttpResponseHeaders* headers, bool success); | |
90 | |
91 // Fixes the content length that we want to store in the cache. | |
92 void FixContentLength(HttpResponseHeaders* headers); | |
93 | |
94 // Reads up to |data_len| bytes from the cache and stores them in the provided | |
95 // buffer (|data|). Basically, this is just a wrapper around the API of the | |
96 // cache that provides the right arguments for the current range. When the IO | |
97 // operation completes, OnCacheReadCompleted() must be called with the result | |
98 // of the operation. | |
99 int CacheRead(disk_cache::Entry* entry, IOBuffer* data, int data_len, | |
100 const net::CompletionCallback& callback); | |
101 | |
102 // Writes |data_len| bytes to cache. This is basically a wrapper around the | |
103 // API of the cache that provides the right arguments for the current range. | |
104 int CacheWrite(disk_cache::Entry* entry, IOBuffer* data, int data_len, | |
105 const net::CompletionCallback& callback); | |
106 | |
107 // This method should be called when CacheRead() finishes the read, to update | |
108 // the internal state about the current range. | |
109 void OnCacheReadCompleted(int result); | |
110 | |
111 // This method should be called after receiving data from the network, to | |
112 // update the internal state about the current range. | |
113 void OnNetworkReadCompleted(int result); | |
114 | |
115 bool initial_validation() const { return initial_validation_; } | |
116 | |
117 private: | |
118 class Core; | |
119 // Returns the length to use when scanning the cache. | |
120 int GetNextRangeLen(); | |
121 | |
122 // Completion routine for our callback. | |
123 void GetAvailableRangeCompleted(int result, int64 start); | |
124 | |
125 int64 current_range_start_; | |
126 int64 current_range_end_; | |
127 int64 cached_start_; | |
128 int64 resource_size_; | |
129 int cached_min_len_; | |
130 HttpByteRange byte_range_; // The range requested by the user. | |
131 // The clean set of extra headers (no ranges). | |
132 HttpRequestHeaders extra_headers_; | |
133 bool range_present_; // True if next range entry is already stored. | |
134 bool final_range_; | |
135 bool sparse_entry_; | |
136 bool truncated_; // We have an incomplete 200 stored. | |
137 bool initial_validation_; // Only used for truncated entries. | |
138 Core* core_; | |
139 CompletionCallback callback_; | |
140 | |
141 DISALLOW_COPY_AND_ASSIGN(PartialData); | |
142 }; | |
143 | |
144 } // namespace net | |
145 | |
146 #endif // NET_HTTP_PARTIAL_DATA_H_ | |
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