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¶
- $ent = $async->start_lookup($ent, $master_deadline)
- Register the start of a long-running asynchronous lookup
operation. $ent 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".
- 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.
Currently used to fetch by-zone timeouts.
- 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.
$ent is returned by this method, with its contents augmented by additional
information.
- $ent = $async->bgsend_and_start_lookup($domain, $type,
$class, $ent, $cb, %options)
- A common idiom: calls "bgsend", followed by a
call to "start_lookup", returning the argument $ent object as
modified by "start_lookup" and filled-in with a query ID.
- $ent = $async->get_lookup($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()".
- $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. Callbacks on completed queries will be called from
poll_responses().
If there are no lookups remaining, or if too much time 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.
$pkt may be undef, indicating that no response packet is available, but a
query has completed (e.g. was aborted or dismissed) and is no longer
"pending".
The DNS resolver's response packet $pkt will be made available to a callback
subroutine through its argument as well as in
"$ent-<gt"{response_packet}>.
- $async->report_id_complete($id,$key,$key,$timestamp)
- Legacy. Equivalent to
$self->set_response_packet($id,undef,$key,$timestamp), i.e. providing
undef as a response packet. 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.