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Avoid double continuation resume in URLSession delegate in corner case #28

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Merged
simonjbeaumont merged 1 commit into from
Nov 23, 2023
Merged

Avoid double continuation resume in URLSession delegate in corner case #28

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8 changes: 6 additions & 2 deletions ...RLSession/URLSessionBidirectionalStreaming/BidirectionalStreamingURLSessionDelegate.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -164,7 +164,8 @@ final class BidirectionalStreamingURLSessionDelegate: NSObject, URLSessionTaskDe
{
callbackLock.withLock {
debug("Task delegate: didReceive response")
self.responseContinuation?.resume(returning: response)
responseContinuation?.resume(returning: response)
responseContinuation = nil
return .allow
}
}
Expand All @@ -173,7 +174,10 @@ final class BidirectionalStreamingURLSessionDelegate: NSObject, URLSessionTaskDe
callbackLock.withLock {
debug("Task delegate: didCompleteWithError (error: \(String(describing: error)))")
responseBodyStreamSource.finish(throwing: error)
if let error { responseContinuation?.resume(throwing: error) }
if let error {
responseContinuation?.resume(throwing: error)
responseContinuation = nil
}
}
}
}
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12 changes: 12 additions & 0 deletions ...onTests/URLSessionBidirectionalStreamingTests/URLSessionBidirectionalStreamingTests.swift
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Expand Up @@ -238,6 +238,15 @@ class URLSessionBidirectionalStreamingTests: XCTestCase {
}
}

func testStreamingDownload_1kChunk_100Chunks_100BDownloadWatermark() async throws {
try await testStreamingDownload(
responseChunk: (1...1024).map { _ in .random(in: (.min..<(.max))) }[...],
numResponseChunks: 100,
responseStreamWatermarks: (low: 100, high: 100),
verification: .none
)
}

func testStreamingDownload_1kChunk_10kChunks_100BDownloadWatermark() async throws {
try await testStreamingDownload(
responseChunk: (1...1024).map { _ in .random(in: (.min..<(.max))) }[...],
Expand Down Expand Up @@ -306,6 +315,8 @@ class URLSessionBidirectionalStreamingTests: XCTestCase {
case count
// Add some artificial delay to simulate business logic to show how the backpressure mechanism works (or not).
case delay(TimeAmount)
// Do no verification: useful for just pulling as fast as possible for testing for races.
case none
}

func testStreamingDownload(
Expand Down Expand Up @@ -389,6 +400,7 @@ class URLSessionBidirectionalStreamingTests: XCTestCase {
print("Client doing fake work for \(delay)s")
try await Task.sleep(nanoseconds: UInt64(delay.nanoseconds))
}
case .none: break
}

group.cancelAll()
Expand Down