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Side by Side Diff: net/disk_cache/memory/mem_entry_impl.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_MEMORY_MEM_ENTRY_IMPL_H_
6 #define NET_DISK_CACHE_MEMORY_MEM_ENTRY_IMPL_H_
7
8 #include "base/containers/hash_tables.h"
9 #include "base/gtest_prod_util.h"
10 #include "base/memory/scoped_ptr.h"
11 #include "net/base/net_log.h"
12 #include "net/disk_cache/disk_cache.h"
13
14 namespace disk_cache {
15
16 class MemBackendImpl;
17
18 // This class implements the Entry interface for the memory-only cache. An
19 // object of this class represents a single entry on the cache. We use two
20 // types of entries, parent and child to support sparse caching.
21 //
22 // A parent entry is non-sparse until a sparse method is invoked (i.e.
23 // ReadSparseData, WriteSparseData, GetAvailableRange) when sparse information
24 // is initialized. It then manages a list of child entries and delegates the
25 // sparse API calls to the child entries. It creates and deletes child entries
26 // and updates the list when needed.
27 //
28 // A child entry is used to carry partial cache content, non-sparse methods like
29 // ReadData and WriteData cannot be applied to them. The lifetime of a child
30 // entry is managed by the parent entry that created it except that the entry
31 // can be evicted independently. A child entry does not have a key and it is not
32 // registered in the backend's entry map. It is registered in the backend's
33 // ranking list to enable eviction of a partial content.
34 //
35 // A sparse entry has a fixed maximum size and can be partially filled. There
36 // can only be one continous filled region in a sparse entry, as illustrated by
37 // the following example:
38 // | xxx ooooo |
39 // x = unfilled region
40 // o = filled region
41 // It is guranteed that there is at most one unfilled region and one filled
42 // region, and the unfilled region (if there is one) is always before the filled
43 // region. The book keeping for filled region in a sparse entry is done by using
44 // the variable |child_first_pos_| (inclusive).
45
46 class MemEntryImpl : public Entry {
47 public:
48 enum EntryType {
49 kParentEntry,
50 kChildEntry,
51 };
52
53 explicit MemEntryImpl(MemBackendImpl* backend);
54
55 // Performs the initialization of a EntryImpl that will be added to the
56 // cache.
57 bool CreateEntry(const std::string& key, net::NetLog* net_log);
58
59 // Permanently destroys this entry.
60 void InternalDoom();
61
62 void Open();
63 bool InUse();
64
65 MemEntryImpl* next() const {
66 return next_;
67 }
68
69 MemEntryImpl* prev() const {
70 return prev_;
71 }
72
73 void set_next(MemEntryImpl* next) {
74 next_ = next;
75 }
76
77 void set_prev(MemEntryImpl* prev) {
78 prev_ = prev;
79 }
80
81 EntryType type() const {
82 return parent_ ? kChildEntry : kParentEntry;
83 }
84
85 const net::BoundNetLog& net_log() {
86 return net_log_;
87 }
88
89 // Entry interface.
90 void Doom() override;
91 void Close() override;
92 std::string GetKey() const override;
93 base::Time GetLastUsed() const override;
94 base::Time GetLastModified() const override;
95 int32 GetDataSize(int index) const override;
96 int ReadData(int index,
97 int offset,
98 IOBuffer* buf,
99 int buf_len,
100 const CompletionCallback& callback) override;
101 int WriteData(int index,
102 int offset,
103 IOBuffer* buf,
104 int buf_len,
105 const CompletionCallback& callback,
106 bool truncate) override;
107 int ReadSparseData(int64 offset,
108 IOBuffer* buf,
109 int buf_len,
110 const CompletionCallback& callback) override;
111 int WriteSparseData(int64 offset,
112 IOBuffer* buf,
113 int buf_len,
114 const CompletionCallback& callback) override;
115 int GetAvailableRange(int64 offset,
116 int len,
117 int64* start,
118 const CompletionCallback& callback) override;
119 bool CouldBeSparse() const override;
120 void CancelSparseIO() override {}
121 int ReadyForSparseIO(const CompletionCallback& callback) override;
122
123 private:
124 typedef base::hash_map<int, MemEntryImpl*> EntryMap;
125
126 enum {
127 NUM_STREAMS = 3
128 };
129
130 ~MemEntryImpl() override;
131
132 // Do all the work for corresponding public functions. Implemented as
133 // separate functions to make logging of results simpler.
134 int InternalReadData(int index, int offset, IOBuffer* buf, int buf_len);
135 int InternalWriteData(int index, int offset, IOBuffer* buf, int buf_len,
136 bool truncate);
137 int InternalReadSparseData(int64 offset, IOBuffer* buf, int buf_len);
138 int InternalWriteSparseData(int64 offset, IOBuffer* buf, int buf_len);
139
140 // Old Entry interface.
141 int GetAvailableRange(int64 offset, int len, int64* start);
142
143 // Grows and cleans up the data buffer.
144 void PrepareTarget(int index, int offset, int buf_len);
145
146 // Updates ranking information.
147 void UpdateRank(bool modified);
148
149 // Initializes the children map and sparse info. This method is only called
150 // on a parent entry.
151 bool InitSparseInfo();
152
153 // Performs the initialization of a MemEntryImpl as a child entry.
154 // |parent| is the pointer to the parent entry. |child_id| is the ID of
155 // the new child.
156 bool InitChildEntry(MemEntryImpl* parent, int child_id, net::NetLog* net_log);
157
158 // Returns an entry responsible for |offset|. The returned entry can be a
159 // child entry or this entry itself if |offset| points to the first range.
160 // If such entry does not exist and |create| is true, a new child entry is
161 // created.
162 MemEntryImpl* OpenChild(int64 offset, bool create);
163
164 // Finds the first child located within the range [|offset|, |offset + len|).
165 // Returns the number of bytes ahead of |offset| to reach the first available
166 // bytes in the entry. The first child found is output to |child|.
167 int FindNextChild(int64 offset, int len, MemEntryImpl** child);
168
169 // Removes child indexed by |child_id| from the children map.
170 void DetachChild(int child_id);
171
172 std::string key_;
173 std::vector<char> data_[NUM_STREAMS]; // User data.
174 int32 data_size_[NUM_STREAMS];
175 int ref_count_;
176
177 int child_id_; // The ID of a child entry.
178 int child_first_pos_; // The position of the first byte in a child
179 // entry.
180 MemEntryImpl* next_; // Pointers for the LRU list.
181 MemEntryImpl* prev_;
182 MemEntryImpl* parent_; // Pointer to the parent entry.
183 scoped_ptr<EntryMap> children_;
184
185 base::Time last_modified_; // LRU information.
186 base::Time last_used_;
187 MemBackendImpl* backend_; // Back pointer to the cache.
188 bool doomed_; // True if this entry was removed from the cache.
189
190 net::BoundNetLog net_log_;
191
192 DISALLOW_COPY_AND_ASSIGN(MemEntryImpl);
193 };
194
195 } // namespace disk_cache
196
197 #endif // NET_DISK_CACHE_MEMORY_MEM_ENTRY_IMPL_H_
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