1 // Copyright 2013 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 // Chromium settings and storage represent user-selected preferences and
6 // information and MUST not be extracted, overwritten or modified except
7 // through Chromium defined APIs.
8 
9 #ifndef COMPONENTS_WEBDATA_COMMON_WEB_DATABASE_SERVICE_H_
10 #define COMPONENTS_WEBDATA_COMMON_WEB_DATABASE_SERVICE_H_
11 
12 #include <memory>
13 
14 #include "base/callback_forward.h"
15 #include "base/compiler_specific.h"
16 #include "base/files/file_path.h"
17 #include "base/macros.h"
18 #include "base/memory/ref_counted.h"
19 #include "base/memory/ref_counted_delete_on_sequence.h"
20 #include "base/memory/weak_ptr.h"
21 #include "base/observer_list.h"
22 #include "base/single_thread_task_runner.h"
23 #include "components/webdata/common/web_data_service_base.h"
24 #include "components/webdata/common/web_database.h"
25 #include "components/webdata/common/webdata_export.h"
26 
27 class WebDatabaseBackend;
28 
29 namespace base {
30 class Location;
31 }
32 
33 class WDTypedResult;
34 class WebDataServiceConsumer;
35 
36 
37 ////////////////////////////////////////////////////////////////////////////////
38 //
39 // WebDatabaseService defines the interface to a generic data repository
40 // responsible for controlling access to the web database (metadata associated
41 // with web pages).
42 //
43 ////////////////////////////////////////////////////////////////////////////////
44 
45 class WEBDATA_EXPORT WebDatabaseService
46     : public base::RefCountedDeleteOnSequence<WebDatabaseService> {
47  public:
48   using ReadTask =
49       base::OnceCallback<std::unique_ptr<WDTypedResult>(WebDatabase*)>;
50   using WriteTask = base::OnceCallback<WebDatabase::State(WebDatabase*)>;
51 
52   // Types for managing DB loading callbacks.
53   using DBLoadErrorCallback =
54       base::OnceCallback<void(sql::InitStatus, const std::string&)>;
55 
56   // WebDatabaseService lives on the UI sequence and posts tasks to the DB
57   // sequence.  |path| points to the WebDatabase file.
58   WebDatabaseService(
59       const base::FilePath& path,
60       scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner,
61       scoped_refptr<base::SingleThreadTaskRunner> db_task_runner);
62 
63   // Adds |table| as a WebDatabaseTable that will participate in
64   // managing the database, transferring ownership. All calls to this
65   // method must be made before |LoadDatabase| is called.
66   virtual void AddTable(std::unique_ptr<WebDatabaseTable> table);
67 
68   // Initializes the web database service.
69   virtual void LoadDatabase();
70 
71   // Unloads the database and shuts down the service.
72   virtual void ShutdownDatabase();
73 
74   // Gets a pointer to the WebDatabase (owned by WebDatabaseService).
75   // TODO(caitkp): remove this method once SyncServices no longer depend on it.
76   virtual WebDatabase* GetDatabaseOnDB() const;
77 
78   // Returns a pointer to the WebDatabaseBackend.
79   scoped_refptr<WebDatabaseBackend> GetBackend() const;
80 
81   // Schedule an update/write task on the DB sequence.
82   virtual void ScheduleDBTask(const base::Location& from_here, WriteTask task);
83 
84   // Schedule a read task on the DB sequence.
85   virtual WebDataServiceBase::Handle ScheduleDBTaskWithResult(
86       const base::Location& from_here,
87       ReadTask task,
88       WebDataServiceConsumer* consumer);
89 
90   // Cancel an existing request for a task on the DB sequence.
91   // TODO(caitkp): Think about moving the definition of the Handle type to
92   // somewhere else.
93   virtual void CancelRequest(WebDataServiceBase::Handle h);
94 
95   // Register a callback to be notified that the database has failed to load.
96   // Multiple callbacks may be registered, and each will be called at most once
97   // (following a database load failure), then cleared.
98   // Note: if the database load is already complete, then the callback will NOT
99   // be stored or called.
100   void RegisterDBErrorCallback(DBLoadErrorCallback callback);
101 
102  private:
103   class BackendDelegate;
104   friend class BackendDelegate;
105   friend class base::RefCountedDeleteOnSequence<WebDatabaseService>;
106   friend class base::DeleteHelper<WebDatabaseService>;
107 
108   using ErrorCallbacks = std::vector<DBLoadErrorCallback>;
109 
110   virtual ~WebDatabaseService();
111 
112   void OnDatabaseLoadDone(sql::InitStatus status,
113                           const std::string& diagnostics);
114 
115   base::FilePath path_;
116 
117   // The primary owner is |WebDatabaseService| but is refcounted because
118   // PostTask on DB sequence may outlive us.
119   scoped_refptr<WebDatabaseBackend> web_db_backend_;
120 
121   // Callbacks to be called if the DB has failed to load.
122   ErrorCallbacks error_callbacks_;
123 
124   scoped_refptr<base::SingleThreadTaskRunner> db_task_runner_;
125 
126   // All vended weak pointers are invalidated in ShutdownDatabase().
127   base::WeakPtrFactory<WebDatabaseService> weak_ptr_factory_{this};
128 
129   DISALLOW_COPY_AND_ASSIGN(WebDatabaseService);
130 };
131 
132 #endif  // COMPONENTS_WEBDATA_COMMON_WEB_DATABASE_SERVICE_H_
133