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Side by Side Diff: sync/syncable/directory_backing_store.h

Issue 2130453004: [Sync] Move //sync to //components/sync. (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: Rebase. Created 4 years, 4 months ago
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1 // Copyright 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 SYNC_SYNCABLE_DIRECTORY_BACKING_STORE_H_
6 #define SYNC_SYNCABLE_DIRECTORY_BACKING_STORE_H_
7
8 #include <stdint.h>
9
10 #include <memory>
11 #include <string>
12
13 #include "base/gtest_prod_util.h"
14 #include "base/macros.h"
15 #include "base/threading/non_thread_safe.h"
16 #include "sql/connection.h"
17 #include "sql/statement.h"
18 #include "sync/base/sync_export.h"
19 #include "sync/internal_api/public/base/model_type.h"
20 #include "sync/syncable/dir_open_result.h"
21 #include "sync/syncable/directory.h"
22 #include "sync/syncable/metahandle_set.h"
23
24 namespace sync_pb {
25 class EntitySpecifics;
26 }
27
28 namespace syncer {
29 namespace syncable {
30
31 SYNC_EXPORT extern const int32_t kCurrentDBVersion;
32 SYNC_EXPORT extern const int32_t kCurrentPageSizeKB;
33
34 struct ColumnSpec;
35
36 // Interface that provides persistence for a syncable::Directory object. You can
37 // load all the persisted data to prime a syncable::Directory on startup by
38 // invoking Load. The only other thing you (or more correctly, a Directory) can
39 // do here is save any changes that have occurred since calling Load, which can
40 // be done periodically as often as desired.
41 //
42 // The DirectoryBackingStore will own an sqlite lock on its database for most of
43 // its lifetime. You must not have two DirectoryBackingStore objects accessing
44 // the database simultaneously. Because the lock exists at the database level,
45 // not even two separate browser instances would be able to acquire it
46 // simultaneously.
47 //
48 // This class is abstract so that we can extend it in interesting ways for use
49 // in tests. The concrete class used in non-test scenarios is
50 // OnDiskDirectoryBackingStore.
51 class SYNC_EXPORT DirectoryBackingStore : public base::NonThreadSafe {
52 public:
53 explicit DirectoryBackingStore(const std::string& dir_name);
54 virtual ~DirectoryBackingStore();
55
56 // Loads and drops all currently persisted meta entries into |handles_map|
57 // and loads appropriate persisted kernel info into |kernel_load_info|.
58 // The function determines which entries can be safely dropped and inserts
59 // their keys into |metahandles_to_purge|. It is up to the caller to
60 // perform the actual cleanup.
61 //
62 // This function will migrate to the latest database version.
63 //
64 // NOTE: On success (return value of OPENED), the buckets are populated with
65 // newly allocated items, meaning ownership is bestowed upon the caller.
66 virtual DirOpenResult Load(Directory::MetahandlesMap* handles_map,
67 JournalIndex* delete_journals,
68 MetahandleSet* metahandles_to_purge,
69 Directory::KernelLoadInfo* kernel_load_info) = 0;
70
71 // Updates the on-disk store with the input |snapshot| as a database
72 // transaction. Does NOT open any syncable transactions as this would cause
73 // opening transactions elsewhere to block on synchronous I/O.
74 // DO NOT CALL THIS FROM MORE THAN ONE THREAD EVER. Also, whichever thread
75 // calls SaveChanges *must* be the thread that owns/destroys |this|.
76 //
77 // Returns true if the changes were saved successfully. Returns false if an
78 // error (of any kind) occurred. See also |SetCatastrophicErrorHandler| for a
79 // systematic way of handling underlying DB errors.
80 virtual bool SaveChanges(const Directory::SaveChangesSnapshot& snapshot);
81
82 // Set the catastrophic error handler.
83 //
84 // When a catastrophic error is encountered while accessing the underlying DB,
85 // |catastrophic_error_handler| will be invoked (via PostTask) on the thread
86 // on which this DirectoryBackingStore object lives.
87 //
88 // For a definition of what's catastrophic, see sql::IsErrorCatastrophic.
89 //
90 // |catastrophic_error_handler| must be initialized (i.e. !is_null()).
91 //
92 // A single operation (like Load or SaveChanges) may result in the
93 // |catastrophic_error_handler| being invoked several times.
94 //
95 // There can be at most one handler. If this method is invoked when there is
96 // already a handler, the existing handler is overwritten with
97 // |catastrophic_error_handler|.
98 virtual void SetCatastrophicErrorHandler(
99 const base::Closure& catastrophic_error_handler);
100
101 // Returns true on success, false on error.
102 bool GetDatabasePageSize(int* page_size);
103
104 protected:
105 // For test classes.
106 DirectoryBackingStore(const std::string& dir_name,
107 sql::Connection* connection);
108
109 // An accessor for the underlying sql::Connection. Avoid using outside of
110 // tests.
111 sql::Connection* db();
112
113 // Return true if the DB is open.
114 bool IsOpen() const;
115
116 // Open the DB at |path|.
117 // Return true on success, false on failure.
118 bool Open(const base::FilePath& path);
119
120 // Open an in memory DB.
121 // Return true on success, false on failure.
122 bool OpenInMemory();
123
124 // Initialize database tables. Return true on success, false on error.
125 bool InitializeTables();
126
127 // Load helpers for entries and attributes. Return true on success, false on
128 // error.
129 bool LoadEntries(Directory::MetahandlesMap* handles_map,
130 MetahandleSet* metahandles_to_purge);
131 bool LoadDeleteJournals(JournalIndex* delete_journals);
132 bool LoadInfo(Directory::KernelLoadInfo* info);
133
134 enum EntryTable {
135 METAS_TABLE,
136 DELETE_JOURNAL_TABLE,
137 };
138 // Removes each entry whose metahandle is in |handles| from the table
139 // specified by |from| table. Does synchronous I/O. Returns false on error.
140 bool DeleteEntries(EntryTable from, const MetahandleSet& handles);
141
142 // Serialization helpers for ModelType. These convert between
143 // the ModelType enum and the values we persist in the database to identify
144 // a model. We persist a default instance of the specifics protobuf as the
145 // ID, rather than the enum value.
146 static ModelType ModelIdToModelTypeEnum(const void* data, int length);
147 static std::string ModelTypeEnumToModelId(ModelType model_type);
148
149 static std::string GenerateCacheGUID();
150
151 // Checks that the references between sync nodes is consistent.
152 static bool VerifyReferenceIntegrity(
153 const Directory::MetahandlesMap* handles_map);
154
155 // Migration utilities.
156 bool RefreshColumns();
157 bool SetVersion(int version);
158 int GetVersion();
159
160 // Individual version migrations.
161 bool MigrateVersion67To68();
162 bool MigrateVersion68To69();
163 bool MigrateVersion69To70();
164 bool MigrateVersion70To71();
165 bool MigrateVersion71To72();
166 bool MigrateVersion72To73();
167 bool MigrateVersion73To74();
168 bool MigrateVersion74To75();
169 bool MigrateVersion75To76();
170 bool MigrateVersion76To77();
171 bool MigrateVersion77To78();
172 bool MigrateVersion78To79();
173 bool MigrateVersion79To80();
174 bool MigrateVersion80To81();
175 bool MigrateVersion81To82();
176 bool MigrateVersion82To83();
177 bool MigrateVersion83To84();
178 bool MigrateVersion84To85();
179 bool MigrateVersion85To86();
180 bool MigrateVersion86To87();
181 bool MigrateVersion87To88();
182 bool MigrateVersion88To89();
183 bool MigrateVersion89To90();
184
185 // Accessor for needs_column_refresh_. Used in tests.
186 bool needs_column_refresh() const;
187
188 // Destroys the existing Connection and creates a new one.
189 void ResetAndCreateConnection();
190
191 private:
192 friend class DirectoryBackingStoreTest;
193 friend class TestDirectoryBackingStore;
194 FRIEND_TEST_ALL_PREFIXES(DirectoryBackingStoreTest,
195 IncreaseDatabasePageSizeFrom4KTo32K);
196 FRIEND_TEST_ALL_PREFIXES(DirectoryBackingStoreTest,
197 CatastrophicErrorHandler_KeptAcrossReset);
198 FRIEND_TEST_ALL_PREFIXES(DirectoryBackingStoreTest,
199 CatastrophicErrorHandler_InvocationDuringLoad);
200 FRIEND_TEST_ALL_PREFIXES(
201 DirectoryBackingStoreTest,
202 CatastrophicErrorHandler_InvocationDuringSaveChanges);
203 FRIEND_TEST_ALL_PREFIXES(MigrationTest, ToCurrentVersion);
204
205 // Drop all tables in preparation for reinitialization.
206 void DropAllTables();
207
208 bool SafeToPurgeOnLoading(const EntryKernel& entry) const;
209
210 // Drops a table if it exists, harmless if the table did not already exist.
211 bool SafeDropTable(const char* table_name);
212
213 bool CreateTables();
214
215 // Create 'share_info' or 'temp_share_info' depending on value of
216 // is_temporary. Returns true on success, false on error.
217 bool CreateShareInfoTable(bool is_temporary);
218 bool CreateShareInfoTableVersion71(bool is_temporary);
219
220 // Create 'metas' or 'temp_metas' depending on value of is_temporary. Also
221 // create a 'deleted_metas' table using same schema. Returns true on success,
222 // false on error.
223 bool CreateMetasTable(bool is_temporary);
224
225 // Returns true on success, false on error.
226 bool CreateModelsTable();
227 bool CreateV71ModelsTable();
228 bool CreateV75ModelsTable();
229 bool CreateV81ModelsTable();
230
231 // Returns true on success, false on error.
232 bool MigrateToSpecifics(const char* old_columns,
233 const char* specifics_column,
234 void(*handler_function) (
235 sql::Statement* old_value_query,
236 int old_value_column,
237 sync_pb::EntitySpecifics* mutable_new_value));
238
239 // Returns true on success, false on error.
240 bool Vacuum();
241
242 // Returns true on success, false on error.
243 bool UpdatePageSizeIfNecessary();
244
245 // Prepares |save_statement| for saving entries in |table|.
246 void PrepareSaveEntryStatement(EntryTable table,
247 sql::Statement* save_statement);
248
249 const std::string dir_name_;
250 const int database_page_size_;
251
252 std::unique_ptr<sql::Connection> db_;
253 sql::Statement save_meta_statement_;
254 sql::Statement save_delete_journal_statement_;
255
256 // Set to true if migration left some old columns around that need to be
257 // discarded.
258 bool needs_metas_column_refresh_;
259 bool needs_share_info_column_refresh_;
260
261 // We keep a copy of the Closure so we reinstall it when the underlying
262 // sql::Connection is destroyed/recreated.
263 base::Closure catastrophic_error_handler_;
264
265 DISALLOW_COPY_AND_ASSIGN(DirectoryBackingStore);
266 };
267
268 } // namespace syncable
269 } // namespace syncer
270
271 #endif // SYNC_SYNCABLE_DIRECTORY_BACKING_STORE_H_
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