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Side by Side Diff: net/disk_cache/blockfile/sparse_control_v3.h

Issue 992733002: Remove //net (except for Android test stuff) and sdch (Closed) Base URL: git@github.com:domokit/mojo.git@master
Patch Set: Created 5 years, 9 months ago
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1 // Copyright (c) 2012 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_DISK_CACHE_BLOCKFILE_SPARSE_CONTROL_V3_H_
6 #define NET_DISK_CACHE_BLOCKFILE_SPARSE_CONTROL_V3_H_
7
8 #include <string>
9 #include <vector>
10
11 #include "base/basictypes.h"
12 #include "base/compiler_specific.h"
13 #include "net/base/completion_callback.h"
14 #include "net/disk_cache/blockfile/bitmap.h"
15 #include "net/disk_cache/disk_format.h"
16
17 namespace net {
18 class IOBuffer;
19 class DrainableIOBuffer;
20 }
21
22 namespace disk_cache {
23
24 class Entry;
25 class EntryImpl;
26
27 // This class provides support for the sparse capabilities of the disk cache.
28 // Basically, sparse IO is directed from EntryImpl to this class, and we split
29 // the operation into multiple small pieces, sending each one to the
30 // appropriate entry. An instance of this class is asociated with each entry
31 // used directly for sparse operations (the entry passed in to the constructor).
32 class SparseControl {
33 public:
34 typedef net::CompletionCallback CompletionCallback;
35
36 // The operation to perform.
37 enum SparseOperation {
38 kNoOperation,
39 kReadOperation,
40 kWriteOperation,
41 kGetRangeOperation
42 };
43
44 explicit SparseControl(EntryImpl* entry);
45 ~SparseControl();
46
47 // Performs a quick test to see if the entry is sparse or not, without
48 // generating disk IO (so the answer provided is only a best effort).
49 bool CouldBeSparse() const;
50
51 // Performs an actual sparse read or write operation for this entry. |op| is
52 // the operation to perform, |offset| is the desired sparse offset, |buf| and
53 // |buf_len| specify the actual data to use and |callback| is the callback
54 // to use for asynchronous operations. See the description of the Read /
55 // WriteSparseData for details about the arguments. The return value is the
56 // number of bytes read or written, or a net error code.
57 int StartIO(SparseOperation op, int64 offset, net::IOBuffer* buf,
58 int buf_len, const CompletionCallback& callback);
59
60 // Implements Entry::GetAvailableRange().
61 int GetAvailableRange(int64 offset, int len, int64* start);
62
63 // Cancels the current sparse operation (if any).
64 void CancelIO();
65
66 // Returns OK if the entry can be used for new IO or ERR_IO_PENDING if we are
67 // busy. If the entry is busy, we'll invoke the callback when we are ready
68 // again. See disk_cache::Entry::ReadyToUse() for more info.
69 int ReadyToUse(const CompletionCallback& completion_callback);
70
71 // Deletes the children entries of |entry|.
72 static void DeleteChildren(EntryImpl* entry);
73
74 private:
75 // Initializes the object for the current entry. If this entry already stores
76 // sparse data, or can be used to do it, it updates the relevant information
77 // on disk and returns net::OK. Otherwise it returns a net error code.
78 int Init();
79
80 // Creates a new sparse entry or opens an aready created entry from disk.
81 // These methods just read / write the required info from disk for the current
82 // entry, and verify that everything is correct. The return value is a net
83 // error code.
84 int CreateSparseEntry();
85 int OpenSparseEntry(int data_len);
86
87 // Opens and closes a child entry. A child entry is a regular EntryImpl object
88 // with a key derived from the key of the resource to store and the range
89 // stored by that child.
90 bool OpenChild();
91 void CloseChild();
92
93 // Continues the current operation (open) without a current child.
94 bool ContinueWithoutChild(const std::string& key);
95
96 // Writes to disk the tracking information for this entry.
97 void WriteSparseData();
98
99 // Performs a single operation with the current child. Returns true when we
100 // should move on to the next child and false when we should interrupt our
101 // work.
102 bool DoChildIO();
103
104 // Performs the required work after a single IO operations finishes.
105 void DoChildIOCompleted(int result);
106
107 std::string GenerateChildKey();
108
109 // Deletes the current child and continues the current operation (open).
110 bool KillChildAndContinue(const std::string& key, bool fatal);
111
112 // Returns true if the required child is tracked by the parent entry, i.e. it
113 // was already created.
114 bool ChildPresent();
115
116 // Sets the bit for the current child to the provided |value|. In other words,
117 // starts or stops tracking this child.
118 void SetChildBit(bool value);
119
120 // Verify that the range to be accessed for the current child is appropriate.
121 // Returns false if an error is detected or there is no need to perform the
122 // current IO operation (for instance if the required range is not stored by
123 // the child).
124 bool VerifyRange();
125
126 // Updates the contents bitmap for the current range, based on the result of
127 // the current operation.
128 void UpdateRange(int result);
129
130 // Returns the number of bytes stored at |block_index|, if its allocation-bit
131 // is off (because it is not completely filled).
132 int PartialBlockLength(int block_index) const;
133
134 // Initializes the sparse info for the current child.
135 void InitChildData();
136
137 // Performs the required work for GetAvailableRange for one child.
138 int DoGetAvailableRange();
139
140 // Reports to the user that we are done.
141 void DoUserCallback();
142 void DoAbortCallbacks();
143
144 // Invoked by the callback of asynchronous operations.
145 void OnChildIOCompleted(int result);
146
147 EntryImpl* entry_; // The sparse entry.
148 EntryImpl* child_; // The current child entry.
149 SparseOperation operation_;
150 bool pending_; // True if any child IO operation returned pending.
151 bool finished_;
152 bool init_;
153 bool range_found_; // True if GetAvailableRange found something.
154 bool abort_; // True if we should abort the current operation ASAP.
155
156 SparseHeader sparse_header_; // Data about the children of entry_.
157 Bitmap children_map_; // The actual bitmap of children.
158 SparseData child_data_; // Parent and allocation map of child_.
159 Bitmap child_map_; // The allocation map as a bitmap.
160
161 CompletionCallback user_callback_;
162 std::vector<CompletionCallback> abort_callbacks_;
163 int64 offset_; // Current sparse offset.
164 scoped_refptr<net::DrainableIOBuffer> user_buf_;
165 int buf_len_; // Bytes to read or write.
166 int child_offset_; // Offset to use for the current child.
167 int child_len_; // Bytes to read or write for this child.
168 int result_;
169
170 DISALLOW_COPY_AND_ASSIGN(SparseControl);
171 };
172
173 } // namespace disk_cache
174
175 #endif // NET_DISK_CACHE_BLOCKFILE_SPARSE_CONTROL_V3_H_
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