How to pass a parameter to an async call in swift.
In a function when i try to pass a stack local auto variable to an async block, in some scenario I could see the passed parameter has changed in below code. The possible reason I could think of is that as soon as the function (handleNewFlow) is returned, the stack memory location (for supportedFlow) is freed to be taken by other functions:
// The TCP flows are actually run through the flow copying process
override func handleNewFlow(_ flow: NEAppProxyFlow) -> Bool {
// See the doc comment for `canHandleNewFlow(_:)` for an explanation of
// why the code below is structured this way.
let (supportedFlow, proxyServer, proxyPort, shouldBlock) = self.core.supportedFlowForFlow(flow, remote_endpoint: nil )
// os_log(.debug, log: self.log, "Provider did handle flow with server :: %{public}@ and port :: %{public}@", proxyServer!, proxyPort!)
if (supportedFlow != nil) {
self.queue.async {
if (shouldBlock == true) {
// TODO with proper handling of flow
os_log(.debug, log: self.log, "TransparentProxy Provider want to block this TCP flow, flow: 0x%zx", flow.osLogID)
let error = NSError(domain: "", code: 0, userInfo: [NSLocalizedDescriptionKey : "Connection Refused"])
flow.closeReadWithError(error)
flow.closeWriteWithError(error)
} else {
self.core.handleNewSupportedFlow(supportedFlow!, proxyServer!, proxyPort!)
}
}
os_log(.debug, log: self.log, "Provider did handle new flow, flow: 0x%zx", flow.osLogID)
return true
} else {
os_log(.debug, log: self.log, "Provider did not handle new flow, flow: 0x%zx", flow.osLogID)
return false
}
}
In above code I could see the value 'supportedFlow' is not correct always when 'self.core.handleNewSupportedFlow()' is called:
self.core.handleNewSupportedFlow(supportedFlow!, proxyServer!, proxyPort!)
Can someone help me in passing 'supportedFlow' as thread function parameter in async block?
