Mail::SpamAssassin::AsyncLoop(3pm)
NAME
Mail::SpamAssassin::AsyncLoop - scanner asynchronous event loop
DESCRIPTION
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.
METHODS
- $obj = $async->start_lookup($obj)
- Register the start of a long-running asynchronous lookup operation. $obj is a hash reference containing the following items:
- key (required)
A key string, unique to this lookup. This is what is reported in debug messages, used as the key for "get_lookup()", etc.
- id (required)
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". - type (required)
A string, typically one word, used to describe the type of
lookup in log messages, such as "DNSBL", "MX", "TXT". - poll_callback (optional)
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. - completed_callback (optional)
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. - zone (optional)
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. - timeout_initial (optional)
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. - timeout_min (optional)
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.
- $obj = $async->get_lookup($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()".
- @objs = $async->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()".
- $async->log_lookups_timing()
- Log sorted timing for all completed lookups.
- $alldone = $async->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.
- $async->abort_remaining_lookups()
- Abort any remaining lookups.
- $async->set_response_packet($id, $pkt, $key, $timestamp)
- 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.
- $async->report_id_complete($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.
- $time = $async->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.