Tcl

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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Tcl


load ./chilkat.dll

set success 0

set socket [new_CkSocket]

#  Connect to the server using TLS.
set bTls 1
set maxWaitMs 5000
set success [CkSocket_Connect $socket "example.com" 5000 $bTls $maxWaitMs]
if {$success == 0} then {
    puts [CkSocket_lastErrorText $socket]
    delete_CkSocket $socket
    exit
}

#  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.
set bAvailable [CkSocket_PollDataAvailable $socket]
if {$bAvailable != 1} then {
    puts "No data is immediately available."
} else {
    puts "Data is available to read."
}


delete_CkSocket $socket