1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
|
// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_SYNC_DRIVER_NON_BLOCKING_DATA_TYPE_CONTROLLER_H_
#define COMPONENTS_SYNC_DRIVER_NON_BLOCKING_DATA_TYPE_CONTROLLER_H_
#include "base/memory/scoped_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/sequenced_task_runner.h"
#include "sync/internal_api/public/base/model_type.h"
#include "sync/internal_api/public/sync_context_proxy.h"
namespace syncer {
class ModelTypeSyncProxy;
}
namespace sync_driver {
// Lives on the UI thread and manages the interactions between many sync
// components.
//
// There are three main parts to this controller:
// - The SyncContextProxy, represening the sync thread.
// - The ModelTypeSyncProxy, representing the model type thread.
// - The user-set state for this type (prefs), which lives on the UI thread.
//
// The ModelTypeSyncProxy can exist in three different states. Those
// states are:
// - Enabled: Changes are being synced.
// - Disconnected: Changes would be synced, but there is no connection between
// the sync thread and the model thread.
// - Disabled: Syncing is intentionally disabled. The type proxy may clear any
// of its local state associated with sync when this happens, since
// this is expected to last a while.
//
// This controller is responsible for transitioning the type proxy into and out
// of these states. It does this by posting tasks to the model type thread.
//
// The type proxy is enabled when the user has indicated a desire to sync this
// type, and the ModelTypeSyncProxy and SyncContextProxy are available.
//
// The type proxy is disconnected during initialization, or when either the
// NonBlockingDataTypeController or SyncContextProxy have not yet registered.
// It can also be disconnected later on if the sync backend becomes
// unavailable.
//
// The type proxy is disabled if the user has disabled sync for this type. The
// signal indicating this state will be sent to the type proxy when the pref is
// first changed, or when the type proxy first connects to the controller.
//
// This class is structured using some state machine patterns. It's a bit
// awkward at times, but this seems to be the clearest way to express the
// behaviors this class must implement.
class NonBlockingDataTypeController {
public:
NonBlockingDataTypeController(syncer::ModelType type, bool is_preferred);
~NonBlockingDataTypeController();
// Connects the ModelTypeSyncProxy to this controller.
//
// There is no "undo" for this operation. The NonBlockingDataTypeController
// will only ever deal with a single type proxy.
void InitializeType(
const scoped_refptr<base::SequencedTaskRunner>& task_runner,
const base::WeakPtr<syncer_v2::ModelTypeSyncProxyImpl>& type_sync_proxy);
// Initialize the connection to the SyncContextProxy.
//
// This process may be reversed with ClearSyncContextProxy().
void InitializeSyncContext(
scoped_ptr<syncer_v2::SyncContextProxy> sync_context_proxy);
// Disconnect from the current SyncContextProxy.
void ClearSyncContext();
// Sets the current preferred state.
//
// Represents a choice to sync or not sync this type. This is expected to
// last a long time, so local state may be deleted if this setting is toggled
// to false.
void SetIsPreferred(bool is_preferred);
private:
enum TypeState { ENABLED, DISABLED, DISCONNECTED };
// Figures out which signals need to be sent then send then sends them.
void UpdateState();
// Sends an enable signal to the ModelTypeSyncProxyImpl.
void SendEnableSignal();
// Sends a disable signal to the ModelTypeSyncProxyImpl.
void SendDisableSignal();
// Sends a disconnect signal to the ModelTypeSyncProxyImpl.
void SendDisconnectSignal();
// Returns true if this type should be synced.
bool IsPreferred() const;
// Returns true if this object has access to the ModelTypeSyncProxyImpl.
bool IsSyncProxyConnected() const;
// Returns true if this object has access to the SyncContextProxy.
bool IsSyncBackendConnected() const;
// Returns the state that the type sync proxy should be in.
TypeState GetDesiredState() const;
// The ModelType we're controlling. Kept mainly for debugging.
const syncer::ModelType type_;
// Returns the state that the type sync proxy is actually in, from this
// class' point of view.
//
// This state is inferred based on the most recently sent signals, and is
// intended to represent the state the sync proxy will be in by the time any
// tasks we post to it now will be run. Due to threading / queueing effects,
// this may or may not be the actual state at this point in time.
TypeState current_state_;
// Whether or not the user wants to sync this type.
bool is_preferred_;
// The ModelTypeSyncProxyImpl and its associated thread. May be NULL.
scoped_refptr<base::SequencedTaskRunner> task_runner_;
base::WeakPtr<syncer_v2::ModelTypeSyncProxyImpl> type_sync_proxy_;
// The SyncContextProxy that connects to the current sync backend. May be
// NULL.
scoped_ptr<syncer_v2::SyncContextProxy> sync_context_proxy_;
DISALLOW_COPY_AND_ASSIGN(NonBlockingDataTypeController);
};
} // namespace sync_driver
#endif // COMPONENTS_SYNC_DRIVER_NON_BLOCKING_DATA_TYPE_CONTROLLER_H_
|