Replace dispatch_semaphore use with os_unfair_lock.
#324
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
thomasvl
reviewed
Oct 5, 2022
| // the session has been created (or fails to be created) to avoid a hang. | ||
| session = _delegateDispatcher.session; | ||
| if (!session) { | ||
| session = creationBlock(_delegateDispatcher); |
There was a problem hiding this comment.
Try/catch on this to avoid going to a bad state?
There was a problem hiding this comment.
Or maybe just a try/finally? Or are you comfortable in it should never throw?
There was a problem hiding this comment.
Was thinking it should be fine, but for safety's sake yeah it should probably have try/finally to ensure the lock is released.
|
Do we also raise the min versions? |
I thought I saw one build error about availability, but now I don't see it. |
a162c0e to
8908422
Compare
thomasvl
previously approved these changes
Oct 7, 2022
Xcode 14 thread checker has flagged potential priority inversion issues relating to use of `dispatch_semaphore` when handling session creation and dispatcher resetting. This replaces uses of semaphores with `os_unfair_lock` which is available on iOS 10+ and all other platforms we're concerned with. To avoid the danger of leaking the lock, this also refactors session creation by having `GTMSessionFetcher` instances provide a session creation block to the service, which is only called if the service does not have an active `NSURLSession`.
Ensures that even if `creationBlock` throws, the lock is properly unlocked.
15ebc6d to
7bcef09
Compare
thomasvl
approved these changes
Oct 7, 2022
thomasvl
added a commit
to thomasvl/gtm-session-fetcher
that referenced
this pull request
Nov 8, 2022
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Xcode 14 thread checker has flagged potential priority inversion issues relating to use of
dispatch_semaphorewhen handling session creation and dispatcher resetting. This replaces uses of semaphores withos_unfair_lockwhich is available on iOS 10+ and all other platforms we're concerned with.To avoid the danger of leaking the lock, this also refactors session creation by having
GTMSessionFetcherinstances provide a session creation block to the service, which is only called if the service does not have an activeNSURLSession.