79 lines
2.1 KiB
Perl
79 lines
2.1 KiB
Perl
#!/usr/bin/perl
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#
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# DW::TaskQueue::Dedup
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#
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# Memcache-based deduplication for task queue jobs. Uses LJ::MemCache::add()
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# (atomic, fails if key exists) to prevent duplicate tasks from being enqueued.
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#
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# Authors:
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# Mark Smith <mark@dreamwidth.org>
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#
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# Copyright (c) 2019-2026 by Dreamwidth Studios, LLC.
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#
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# This program is free software; you may redistribute it and/or modify it under
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# the same terms as Perl itself. For a copy of the license, please reference
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# 'perldoc perlartistic' or 'perldoc perlgpl'.
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#
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package DW::TaskQueue::Dedup;
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use strict;
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use v5.10;
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use Log::Log4perl;
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my $log = Log::Log4perl->get_logger(__PACKAGE__);
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use LJ::MemCache;
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# claim_unique($class, $queue_name, $uniqkey, $ttl)
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#
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# Attempts to claim a unique slot for a task. Returns 1 if the claim was
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# successful (no duplicate exists), 0 if a duplicate is already pending.
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# Uses LJ::MemCache::add() which is atomic -- it only succeeds if the key
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# does not already exist.
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sub claim_unique {
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my ( $class, $queue_name, $uniqkey, $ttl ) = @_;
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return 0 unless defined $queue_name && defined $uniqkey;
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$ttl ||= 3600;
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my $key = "taskdedup:$queue_name:$uniqkey";
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my $rv = LJ::MemCache::add( $key, 1, $ttl );
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if ($rv) {
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$log->debug("Claimed unique slot: $key (ttl=$ttl)");
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}
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else {
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$log->debug("Duplicate task, skipping: $key");
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}
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return $rv ? 1 : 0;
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}
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# release_unique($class, $queue_name, $uniqkey)
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#
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# Releases a unique slot after task completion, allowing the same task
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# to be enqueued again.
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sub release_unique {
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my ( $class, $queue_name, $uniqkey ) = @_;
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return unless defined $queue_name && defined $uniqkey;
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my $key = "taskdedup:$queue_name:$uniqkey";
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LJ::MemCache::delete($key);
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$log->debug("Released unique slot: $key");
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}
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# is_pending($class, $queue_name, $uniqkey)
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#
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# Checks whether a task with the given unique key is currently pending.
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# Returns 1 if pending, 0 if not.
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sub is_pending {
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my ( $class, $queue_name, $uniqkey ) = @_;
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return 0 unless defined $queue_name && defined $uniqkey;
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my $key = "taskdedup:$queue_name:$uniqkey";
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return LJ::MemCache::get($key) ? 1 : 0;
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}
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1;
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