getdns_cancel_callback(3)

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2getdns_cancel_callback(3)           getdns           getdns_cancel_callback(3)
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NAME

7       getdns_cancel_callback -- cancel an outstanding asyn getdns request
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LIBRARY

11       DNS Resolver library (libgetdns, -lgetdns)
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SYNOPSIS

15       #include <getdns.h>
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17       getdns_return_t
18       getdns_cancel_callback (getdns_context_t context,
19          getdns_transaction_t *transaction_id)
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DESCRIPTION

23       To  cancel  an  outstanding  callback, use getdns_cancel_callback. This
24       causes  the  API  to  call  the  callback  with  a   callback_type   of
25       GETDNS_CALLBACK_CANCEL  if the callback for this transaction_id has not
26       already been called. The callback code for cancellation should clean up
27       any  memory  related  to the identified call, such as to deallocate the
28       memory for the userarg.  getdns_cancel_callback()  may  return  immedi‐
29       ately, even before the callback finishes its work and returns.
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32       context see getdns_context (3)
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35       transaction_id  populated  by the API and used to identify the callback
36          (for example to getdns_cancel_callback), can be NULL, set  to  0  if
37          the function fails
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RETURN VALUES

43       Upon  successful  completion  the functions return GETDNS_RETURN_GOOD ,
44       otherwise the following error values are returned:
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47       GETDNS_RETURN_INVALID_PARAMETER if context == NULL
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49       GETDNS_RETURN_UNKNOWN_TRANSACTION if the transaction_id that is unknown
50       or belongs to a callback that has already been called
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EXAMPLES

54       TBD
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FILES

58       /etc/hosts
59       /etc/resolv.conf
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