97 lines
4.3 KiB
Ruby
97 lines
4.3 KiB
Ruby
# frozen_string_literal: true
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class SpeedUpMaxConcurrentDeleteTrigger < ActiveRecord::Migration[4.2]
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tag :predeploy
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def up
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if connection.adapter_name == "PostgreSQL"
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search_path = Shard.current.name
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# tl;dr sacrifice some responsiveness to max_concurrent changes for faster performance
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# don't get the count every single time - it's usually safe to just set the next one in line
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# since the max_concurrent doesn't change all that often for a strand
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execute(<<~SQL) # rubocop:disable Rails/SquishedSQLHeredocs
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CREATE OR REPLACE FUNCTION #{connection.quote_table_name("delayed_jobs_after_delete_row_tr_fn")} () RETURNS trigger AS $$
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DECLARE
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running_count integer;
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should_lock boolean;
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should_be_precise boolean;
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BEGIN
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IF OLD.strand IS NOT NULL THEN
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should_lock := true;
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should_be_precise := OLD.id % (OLD.max_concurrent * 4) = 0;
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IF NOT should_be_precise AND OLD.max_concurrent > 16 THEN
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running_count := (SELECT COUNT(*) FROM (
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SELECT 1 as one FROM delayed_jobs WHERE strand = OLD.strand AND next_in_strand = 't' LIMIT OLD.max_concurrent
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) subquery_for_count);
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should_lock := running_count < OLD.max_concurrent;
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END IF;
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IF should_lock THEN
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PERFORM pg_advisory_xact_lock(half_md5_as_bigint(OLD.strand));
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END IF;
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IF should_be_precise THEN
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running_count := (SELECT COUNT(*) FROM (
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SELECT 1 as one FROM delayed_jobs WHERE strand = OLD.strand AND next_in_strand = 't' LIMIT OLD.max_concurrent
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) subquery_for_count);
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IF running_count < OLD.max_concurrent THEN
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UPDATE delayed_jobs SET next_in_strand = 't' WHERE id IN (
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SELECT id FROM delayed_jobs j2 WHERE next_in_strand = 'f' AND
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j2.strand = OLD.strand ORDER BY j2.id ASC LIMIT (OLD.max_concurrent - running_count) FOR UPDATE
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);
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END IF;
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ELSE
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-- n-strands don't require precise ordering; we can make this query more performant
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IF OLD.max_concurrent > 1 THEN
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UPDATE delayed_jobs SET next_in_strand = 't' WHERE id =
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(SELECT id FROM delayed_jobs j2 WHERE next_in_strand = 'f' AND
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j2.strand = OLD.strand ORDER BY j2.id ASC LIMIT 1 FOR UPDATE SKIP LOCKED);
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ELSE
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UPDATE delayed_jobs SET next_in_strand = 't' WHERE id =
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(SELECT id FROM delayed_jobs j2 WHERE next_in_strand = 'f' AND
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j2.strand = OLD.strand ORDER BY j2.id ASC LIMIT 1 FOR UPDATE);
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END IF;
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END IF;
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END IF;
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RETURN OLD;
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END;
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$$ LANGUAGE plpgsql SET search_path TO #{search_path};
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SQL
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end
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end
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def down
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if connection.adapter_name == "PostgreSQL"
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search_path = Shard.current.name
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execute(<<~SQL) # rubocop:disable Rails/SquishedSQLHeredocs
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CREATE OR REPLACE FUNCTION #{connection.quote_table_name("delayed_jobs_after_delete_row_tr_fn")} () RETURNS trigger AS $$
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DECLARE
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running_count integer;
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BEGIN
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IF OLD.strand IS NOT NULL THEN
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PERFORM pg_advisory_xact_lock(half_md5_as_bigint(OLD.strand));
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IF OLD.id % 20 = 0 THEN
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running_count := (SELECT COUNT(*) FROM (
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SELECT 1 as one FROM delayed_jobs WHERE strand = OLD.strand AND next_in_strand = 't' LIMIT OLD.max_concurrent
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) subquery_for_count);
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IF running_count < OLD.max_concurrent THEN
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UPDATE delayed_jobs SET next_in_strand = 't' WHERE id IN (
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SELECT id FROM delayed_jobs j2 WHERE next_in_strand = 'f' AND
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j2.strand = OLD.strand ORDER BY j2.id ASC LIMIT (OLD.max_concurrent - running_count) FOR UPDATE
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);
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END IF;
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ELSE
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UPDATE delayed_jobs SET next_in_strand = 't' WHERE id =
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(SELECT id FROM delayed_jobs j2 WHERE next_in_strand = 'f' AND
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j2.strand = OLD.strand ORDER BY j2.id ASC LIMIT 1 FOR UPDATE);
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END IF;
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END IF;
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RETURN OLD;
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END;
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$$ LANGUAGE plpgsql SET search_path TO #{search_path};
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SQL
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end
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end
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end
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