Add support for cancelling async opens #6193
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Make Realm.asyncOpen() return an AsyncOpenTask which can be used to get download progress notifications or cancel the async open.
| Realm is downloaded from the server before the completion callback is invoked. | ||
| This task object can be used to observe the state of the download or to cancel | ||
| it. This should be used instead of trying to observe the download via the sync | ||
| session as the sync session itself is created asynchronously, and may not exist |
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Is this Cocoa specific? The sync session is created here: https://github.com/realm/realm-object-store/blob/master/src/impl/realm_coordinator.cpp#L311 Which is called synchronously as part of calling RealmCoordinator::get_synchronized_realm()
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The very first thing that Cocoa's asyncOpen does is dispatch to a background queue, and get_synchronized_realm() is called from there.
| invoked. This task object can be used to observe the state of the download | ||
| or to cancel it. This should be used instead of trying to observe the | ||
| download via the sync session as the sync session itself is created | ||
| asynchronously, and may not exist yet when Realm.asyncOpen() returns. |
| @@ -276,12 +289,15 @@ + (void)asyncOpenWithConfiguration:(RLMRealmConfiguration *)configuration | |||
| } | |||
| }; | |||
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| dispatch_async(queue, ^{ | |||
| RLMAsyncOpenTask *ret = [RLMAsyncOpenTask new]; | |||
| dispatch_async(s_async_open_queue, ^{ | |||
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Why move this to its own queue?
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The only change here is to let the tests override the queue used, so that they can make it use a serial queue rather than the default of a concurrent queue to ensure that things happen in the desired order.
If the question is just "why is there a background queue involved at all?" then it's because there is a bit of i/o and cpu done on the source thread even as part of get_synchronized_realm().
Make Realm.asyncOpen() return an AsyncOpenTask which can be used to get download progress notifications or cancel the async open.