Xbase++

Poll a Socket for Available Data

Demonstrates Socket.PollDataAvailable, which performs a nonblocking check for readable activity and returns whether data or another read-ready condition is present.

Background. This lets an application check for incoming data without blocking, for example in an event loop that services multiple tasks.

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Xbase++

LOCAL nSuccess
LOCAL oSocket
LOCAL nBTls
LOCAL nMaxWaitMs
LOCAL nBAvailable

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

//  Perform a nonblocking check for readable data.  Returns 1 when data or another read-ready
//  condition is present, and 0 when nothing is immediately available.
nBAvailable := oSocket:PollDataAvailable()
IF (nBAvailable != 1)
    ? "No data is immediately available."
ELSE
    ? "Data is available to read."
ENDIF

oSocket:destroy()