Add an optional target queue to for database operations#801
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sharplet wants to merge 2 commits intostephencelis:masterfrom
Open
Add an optional target queue to for database operations#801sharplet wants to merge 2 commits intostephencelis:masterfrom
sharplet wants to merge 2 commits intostephencelis:masterfrom
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The optional target queue is useful for synchronising other work with respect to database operations. Provided the target queue is also a serial queue, work submitted to the private connection queue and work submitted directly to the target queue will still be executed in serial. The queue context is now set on the target queue if present. The connection queue inherits values set on the target queue, so the call to `DispatchQueue.getSpecific`, using `queueKey`, returns `queueContext` as expected. For this logic to still be thread-safe, the target queue must be a serial queue. `queueKey` is now an instance variable so that every connection gets a unique key, ensuring that connections can't write over one another's context variables. The `attributes:` parameter is also removed from the call to initialise the database queue, as `[]` (i.e., serial) is already the default.
jberkel
reviewed
Aug 21, 2021
| /// synchronized with respect to database operations. | ||
| /// | ||
| /// **Important:** The target queue **must not** be a concurrent queue, or access | ||
| /// to the returned connection is no longer guaranteed be thread-safe. |
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could this be asserted in code?
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That would be nice! Currently I'm not aware of public API to check whether a queue is serial or concurrent. 🤔
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Perhaps related to #937 |
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The optional target queue is useful for synchronising other work with respect to database operations. Provided the target queue is also a serial queue, work submitted to the private connection queue and work submitted directly to the target queue will still be executed in serial.
The queue context is now set on the target queue if present. The connection queue inherits values set on the target queue, so the call to
DispatchQueue.getSpecific, usingqueueKey, returnsqueueContextas expected. For this logic to still be thread-safe, the target queue must be a serial queue.queueKeyis now an instance variable so that every connection gets a unique key, ensuring that connections can't write over one another's context variables.The
attributes:parameter is also removed from the call to initialise the database queue, as[](i.e., serial) is already the default.