Xbase++

Wait for a Socket to Become Writable

Demonstrates Socket.SelectForWriting, which waits for the socket, or sockets in a socket set, to become writable. It returns 1 if writable, 0 on timeout, or -1 on error.

Background. A timeoutMs of 0 performs a nonblocking poll. This is useful before attempting to send when the peer may be applying flow control.

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LOCAL nSuccess
LOCAL oSocket
LOCAL nBTls
LOCAL nMaxWaitMs
LOCAL nReady

nSuccess := 0

oSocket := CreateObject("Chilkat.Socket")

//  Connect to the server using TLS.
nBTls := 1
nMaxWaitMs := 5000
nSuccess := oSocket:Connect("example.com", 5000, nBTls, nMaxWaitMs)
IF (nSuccess == 0)
    ? oSocket:LastErrorText
    oSocket:destroy()
    RETURN
ENDIF

//  Wait up to 5 seconds for the socket (or sockets in a socket set) to become writable.  Returns 1 if
//  writable, 0 on timeout, or -1 on error.
nReady := oSocket:SelectForWriting(5000)
IF (nReady < 0)
    ? oSocket:LastErrorText
    oSocket:destroy()
    RETURN
ENDIF

IF (nReady != 1)
    ? "The socket did not become writable before the timeout."
    oSocket:destroy()
    RETURN
ENDIF

? "The socket is ready for writing."

oSocket:destroy()