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| 1 Overview of chrome://sync-internals | |
| 2 ----------------------------------- | |
| 3 | |
| 4 This note explains how chrome://sync-internals (also known as | |
| 5 about:sync) interacts with the sync service/backend. | |
| 6 | |
| 7 Basically, chrome://sync-internals sends messages to the sync backend | |
| 8 and the sync backend sends the reply asynchronously. The sync backend | |
| 9 also asynchronously raises events which chrome://sync-internals listen | |
| 10 to. | |
| 11 | |
| 12 A message and its reply has a name and a list of arguments, which is | |
| 13 basically a wrapper around an immutable ListValue. | |
| 14 | |
| 15 An event has a name and a details object, which is represented by a | |
| 16 JsEventDetails (js_event_details.h) object, which is basically a | |
| 17 wrapper around an immutable DictionaryValue. | |
| 18 | |
| 19 Message/event flow | |
| 20 ------------------ | |
| 21 | |
| 22 chrome://sync-internals is represented by SyncInternalsUI | |
| 23 (chrome/browser/ui/webui/sync_internals_ui.h). SyncInternalsUI | |
| 24 interacts with the sync service via a JsController (js_controller.h) | |
| 25 object, which has a ProcessJsMessage() method that just delegates to | |
| 26 an underlying JsBackend instance (js_backend.h). The SyncInternalsUI | |
| 27 object also registers itself (as a JsEventHandler | |
| 28 [js_event_handler.h]) to the JsController object, and any events | |
| 29 raised by the JsBackend are propagated to the JsController and then to | |
| 30 the registered JsEventHandlers. | |
| 31 | |
| 32 The ProcessJsMessage() takes a WeakHandle (weak_handle.h) to a | |
| 33 JsReplyHandler (js_reply_handler.h), which the backend uses to send | |
| 34 replies safely across threads. SyncInternalsUI implements | |
| 35 JsReplyHandler, so it simply passes itself as the reply handler when | |
| 36 it calls ProcessJsMessage() on the JsController. | |
| 37 | |
| 38 The following objects live on the UI thread: | |
| 39 | |
| 40 - SyncInternalsUI (implements JsEventHandler, JsReplyHandler) | |
| 41 - SyncJsController (implements JsController, JsEventHandler) | |
| 42 | |
| 43 The following objects live on the sync thread: | |
| 44 | |
| 45 - SyncManager::SyncInternal (implements JsBackend) | |
| 46 | |
| 47 Of course, none of these objects need to know where the other objects | |
| 48 live, since they interact via WeakHandles. | |
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Chromium Code Reviews
Issue 9699057:
[Sync] Move 'sync' target to sync/ (Closed)
Base URL: svn://svn.chromium.org/chrome/trunk/src