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Thread safety for URLSession #1210

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Merged
merged 2 commits into from
Sep 14, 2017
Merged

Thread safety for URLSession #1210

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35a309e
Thread safety
johnno1962 Sep 8, 2017
dba0829
Use the workQueue.
johnno1962 Sep 11, 2017
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9 changes: 6 additions & 3 deletions Foundation/URLSession/URLSession.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -192,6 +192,7 @@ public let NSURLSessionTransferSizeUnknown: Int64 = -1
open class URLSession : NSObject {
fileprivate let _configuration: _Configuration
fileprivate let multiHandle: _MultiHandle
fileprivate let taskIdentifierLock = NSLock()
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my only question is what is the preferred way, NSLock or a dispatch queue? I think we should be consistent. @phausler / @parkera do we have a preferred option?

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I’ve switched to using the workQueue for consistency

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also: the sessionDescription and delegate properties are also mutable and accessible from the outside. I suppose the should be locked too.

fileprivate var nextTaskIdentifier = 1
internal let workQueue: DispatchQueue
/// This queue is used to make public attributes on `URLSessionTask` instances thread safe.
Expand Down Expand Up @@ -406,9 +407,11 @@ extension URLSession._Request {

fileprivate extension URLSession {
func createNextTaskIdentifier() -> Int {
let i = nextTaskIdentifier
nextTaskIdentifier += 1
return i
return taskIdentifierLock.synchronized {
let i = nextTaskIdentifier
nextTaskIdentifier += 1
return i
}
}
}

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