Mail::SpamAssassin::AsyncLoop - scanner asynchronous event loop
An asynchronous event loop used for long-running operations, performed "in the background" during the Mail::SpamAssassin::check() scan operation, such as DNS blocklist lookups.
start_lookup($obj)Register the start of a long-running asynchronous lookup operation. $obj
is a hash reference containing the following items:
A key string, unique to this lookup. This is what is reported in
debug messages, used as the key for get_lookup(), etc.
An ID string, also unique to this lookup. Typically, this is the DNS packet ID
as returned by DnsResolver's bgsend method. Sadly, the Net::DNS
architecture forces us to keep a separate ID string for this task instead of
reusing key -- if you are not using DNS lookups through DnsResolver, it
should be OK to just reuse key.
A string, typically one word, used to describe the type of lookup in log
messages, such as DNSBL, MX, TXT.
A code reference, which will be called periodically during the
background-processing period. If you will be performing an async lookup on a
non-DNS-based service, you will need to implement this so that it checks for
new responses and calls set_response_packet() or report_id_complete() as
appropriate. DNS-based lookups can leave it undefined, since
DnsResolver::poll_responses() will be called automatically anyway.
The code reference will be called with one argument, the $ent object.
A code reference which will be called when an asynchronous task (e.g. a DNS lookup) is completed, either normally, or aborted, e.g. by a timeout.
When a task has been reported as completed via set_response_packet()
the response (as provided to set_response_packet()) is stored in
$ent->{response_packet} (possibly undef, its semantics is defined by the
caller). When completion is reported via report_id_complete() or a
task was aborted, the $ent->{response_packet} is guaranteed to be undef.
If it is necessary to distinguish between the last two cases, the
$ent->{status} may be examined for a string 'ABORTING' or 'FINISHED'.
The code reference will be called with one argument, the $ent object.
A zone specification (typically a DNS zone name - e.g. host, domain, or RBL) which may be used as a key to look up per-zone settings. No semantics on this parameter is imposed by this module. Currently used to fetch by-zone timeouts.
An initial value of elapsed time for which we are willing to wait for a response (time in seconds, floating point value is allowed). When elapsed time since a query started exceeds the timeout value and there are no other queries to wait for, the query is aborted. The actual timeout value ranges from timeout_initial and gradually approaches timeout_min (see next parameter) as the number of already completed queries approaches the number of all queries started.
If a caller does not explicitly provide this parameter or its value is undefined, a default initial timeout value is settable by a configuration variable rbl_timeout.
If a value of the timeout_initial parameter is below timeout_min, the initial timeout is set to timeout_min.
A lower bound (in seconds) to which the actual timeout approaches as the number of queries completed approaches the number of all queries started. Defaults to 0.2 * timeout_initial.
$obj is returned by this method.
get_lookup($key)Retrieve the pending-lookup object for the given key $key.
If the lookup is complete, this will return undef.
Note that a lookup is still considered "pending" until complete_lookups() is
called, even if it has been reported as complete via set_response_packet()
or report_id_complete().
get_pending_lookups()Retrieve the lookup objects for all pending lookups.
Note that a lookup is still considered "pending" until complete_lookups() is
called, even if it has been reported as complete via set_response_packet()
or report_id_complete().
log_lookups_timing()Log sorted timing for all completed lookups.
complete_lookups()Perform a poll of the pending lookups, to see if any are completed; if they are, their <completed_callback> is called with the entry object for that lookup.
If there are no lookups remaining, or if too long has elapsed since any results
were returned, 1 is returned, otherwise 0.
abort_remaining_lookups()Abort any remaining lookups.
Register a "response packet" for a given query. $id is the ID for the
query, and must match the id supplied in start_lookup(). $pkt is the
packet object for the response. A parameter $key identifies an entry in a
hash %{$self->{pending_lookups}} where the object which spawned this query can
be found, and through which futher information about the query is accessible.
If this was called, $pkt will be available in the completed_callback
function as $ent-<gt{response_packet}>.
One or the other of set_response_packet() or report_id_complete()
should be called, but not both.
report_id_complete($id,$key,$key,$timestamp)Register that a query has completed, and is no longer "pending". $id is the
ID for the query, and must match the id supplied in start_lookup().
One or the other of set_response_packet() or report_id_complete()
should be called, but not both.
last_poll_responses_time()Get the time of the last call to poll_responses() (which is called
from complete_lookups(). If poll_responses() was never called or
abort_remaining_lookups() has been called last_poll_responses_time()
will return undef.