mirror of
https://github.com/Diggsey/sqlxmq.git
synced 2024-10-31 21:58:58 +00:00
287 lines
8.5 KiB
MySQL
287 lines
8.5 KiB
MySQL
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-- The UDT for creating messages
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CREATE TYPE mq_new_t AS (
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-- Unique message ID
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id UUID,
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-- Delay before message is processed
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delay INTERVAL,
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-- Number of retries if initial processing fails
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retries INT,
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-- Initial backoff between retries
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retry_backoff INTERVAL,
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-- Name of channel
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channel_name TEXT,
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-- Arguments to channel
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channel_args TEXT,
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-- Interval for two-phase commit (or NULL to disable two-phase commit)
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commit_interval INTERVAL,
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-- Whether this message should be processed in order with respect to other
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-- ordered messages.
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ordered BOOLEAN,
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-- Name of message
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name TEXT,
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-- JSON payload
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payload_json TEXT,
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-- Binary payload
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payload_bytes BYTEA
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);
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-- Small, frequently updated table of messages
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CREATE TABLE mq_msgs (
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id UUID PRIMARY KEY,
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created_at TIMESTAMPTZ DEFAULT NOW(),
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attempt_at TIMESTAMPTZ DEFAULT NOW(),
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attempts INT NOT NULL DEFAULT 5,
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retry_backoff INTERVAL NOT NULL DEFAULT INTERVAL '1 second',
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channel_name TEXT NOT NULL,
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channel_args TEXT NOT NULL,
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commit_interval INTERVAL,
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after_message_id UUID DEFAULT uuid_nil() REFERENCES mq_msgs(id) ON DELETE SET DEFAULT
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);
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-- Insert dummy message so that the 'nil' UUID can be referenced
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INSERT INTO mq_msgs (id, channel_name, channel_args, after_message_id) VALUES (uuid_nil(), '', '', NULL);
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-- Internal helper function to check that a UUID is neither NULL nor NIL
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CREATE FUNCTION mq_uuid_exists(
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id UUID
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) RETURNS BOOLEAN AS $$
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SELECT id IS NOT NULL AND id != uuid_nil()
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$$ LANGUAGE SQL IMMUTABLE;
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-- Index for polling
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CREATE INDEX ON mq_msgs(channel_name, channel_args, attempt_at) WHERE id != uuid_nil() AND NOT mq_uuid_exists(after_message_id);
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-- Index for adding messages
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CREATE INDEX ON mq_msgs(channel_name, channel_args, created_at, id) WHERE id != uuid_nil() AND after_message_id IS NOT NULL;
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-- Index for ensuring strict message order
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CREATE UNIQUE INDEX ON mq_msgs(channel_name, channel_args, after_message_id);
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-- Large, less frequently updated table of message payloads
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CREATE TABLE mq_payloads(
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id UUID PRIMARY KEY,
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name TEXT NOT NULL,
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payload_json JSONB,
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payload_bytes BYTEA
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);
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-- Internal helper function to return the most recently added message in a queue.
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CREATE FUNCTION mq_latest_message(from_channel_name TEXT, from_channel_args TEXT)
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RETURNS UUID AS $$
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SELECT COALESCE(
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(
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SELECT id FROM mq_msgs
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WHERE channel_name = from_channel_name
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AND channel_args = from_channel_args
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AND after_message_id IS NOT NULL
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AND id != uuid_nil()
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ORDER BY created_at DESC, id DESC
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LIMIT 1
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),
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uuid_nil()
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)
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$$ LANGUAGE SQL STABLE;
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-- Internal helper function to randomly select a set of channels with "ready" messages.
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CREATE FUNCTION mq_active_channels(channel_names TEXT[], batch_size INT)
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RETURNS TABLE(name TEXT, args TEXT) AS $$
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SELECT channel_name, channel_args
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FROM mq_msgs
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WHERE id != uuid_nil()
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AND attempt_at <= NOW()
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AND (channel_names IS NULL OR channel_name = ANY(channel_names))
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AND NOT mq_uuid_exists(after_message_id)
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GROUP BY channel_name, channel_args
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ORDER BY RANDOM()
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LIMIT batch_size
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$$ LANGUAGE SQL STABLE;
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-- Main entry-point for task runner: pulls a batch of messages from the queue.
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CREATE FUNCTION mq_poll(channel_names TEXT[], batch_size INT DEFAULT 1)
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RETURNS TABLE(
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id UUID,
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is_committed BOOLEAN,
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name TEXT,
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payload_json TEXT,
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payload_bytes BYTEA,
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retry_backoff INTERVAL,
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wait_time INTERVAL
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) AS $$
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BEGIN
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RETURN QUERY UPDATE mq_msgs
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SET
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attempt_at = CASE WHEN mq_msgs.attempts = 1 THEN NULL ELSE NOW() + mq_msgs.retry_backoff END,
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attempts = mq_msgs.attempts - 1,
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retry_backoff = mq_msgs.retry_backoff * 2
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FROM (
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SELECT
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msgs.id
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FROM mq_active_channels(channel_names, batch_size) AS active_channels
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INNER JOIN LATERAL (
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SELECT * FROM mq_msgs
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WHERE mq_msgs.id != uuid_nil()
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AND mq_msgs.attempt_at <= NOW()
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AND mq_msgs.channel_name = active_channels.name
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AND mq_msgs.channel_args = active_channels.args
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AND NOT mq_uuid_exists(mq_msgs.after_message_id)
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ORDER BY mq_msgs.attempt_at ASC
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LIMIT batch_size
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) AS msgs ON TRUE
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LIMIT batch_size
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) AS messages_to_update
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LEFT JOIN mq_payloads ON mq_payloads.id = messages_to_update.id
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WHERE mq_msgs.id = messages_to_update.id
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RETURNING
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mq_msgs.id,
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mq_msgs.commit_interval IS NULL,
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mq_payloads.name,
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mq_payloads.payload_json::TEXT,
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mq_payloads.payload_bytes,
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mq_msgs.retry_backoff / 2,
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interval '0' AS wait_time;
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IF NOT FOUND THEN
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RETURN QUERY SELECT
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NULL::UUID,
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NULL::BOOLEAN,
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NULL::TEXT,
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NULL::TEXT,
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NULL::BYTEA,
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NULL::INTERVAL,
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MIN(mq_msgs.attempt_at) - NOW()
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FROM mq_msgs
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WHERE mq_msgs.id != uuid_nil()
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AND NOT mq_uuid_exists(mq_msgs.after_message_id)
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AND (channel_names IS NULL OR mq_msgs.channel_name = ANY(channel_names));
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END IF;
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END;
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$$ LANGUAGE plpgsql;
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-- Creates new messages
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CREATE FUNCTION mq_insert(new_messages mq_new_t[])
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RETURNS VOID AS $$
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BEGIN
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PERFORM pg_notify(CONCAT('mq_', channel_name), '')
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FROM unnest(new_messages) AS new_msgs
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GROUP BY channel_name;
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IF FOUND THEN
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PERFORM pg_notify('mq', '');
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END IF;
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INSERT INTO mq_payloads (
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id,
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name,
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payload_json,
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payload_bytes
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) SELECT
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id,
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name,
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payload_json::JSONB,
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payload_bytes
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FROM UNNEST(new_messages);
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INSERT INTO mq_msgs (
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id,
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attempt_at,
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attempts,
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retry_backoff,
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channel_name,
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channel_args,
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commit_interval,
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after_message_id
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)
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SELECT
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id,
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NOW() + delay + COALESCE(commit_interval, INTERVAL '0'),
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retries + 1,
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retry_backoff,
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channel_name,
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channel_args,
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commit_interval,
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CASE WHEN ordered
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THEN
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LAG(id, 1, mq_latest_message(channel_name, channel_args))
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OVER (PARTITION BY channel_name, channel_args, ordered ORDER BY id)
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ELSE
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NULL
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END
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FROM UNNEST(new_messages);
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END;
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$$ LANGUAGE plpgsql;
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-- Commits messages previously created with a non-NULL commit interval.
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CREATE FUNCTION mq_commit(msg_ids UUID[])
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RETURNS VOID AS $$
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BEGIN
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UPDATE mq_msgs
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SET
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attempt_at = attempt_at - commit_interval,
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commit_interval = NULL
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WHERE id = ANY(msg_ids)
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AND commit_interval IS NOT NULL;
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END;
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$$ LANGUAGE plpgsql;
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-- Deletes messages from the queue. This occurs when a message has been
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-- processed, or when it expires without being processed.
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CREATE FUNCTION mq_delete(msg_ids UUID[])
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RETURNS VOID AS $$
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BEGIN
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PERFORM pg_notify(CONCAT('mq_', channel_name), '')
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FROM mq_msgs
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WHERE id = ANY(msg_ids)
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AND after_message_id = uuid_nil()
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GROUP BY channel_name;
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IF FOUND THEN
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PERFORM pg_notify('mq', '');
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END IF;
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DELETE FROM mq_msgs WHERE id = ANY(msg_ids);
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DELETE FROM mq_payloads WHERE id = ANY(msg_ids);
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END;
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$$ LANGUAGE plpgsql;
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-- Can be called during the initial commit interval, or when processing
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-- a message. Indicates that the caller is still active and will prevent either
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-- the commit interval elapsing or the message being retried for the specified
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-- interval.
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CREATE FUNCTION mq_keep_alive(msg_ids UUID[], duration INTERVAL)
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RETURNS VOID AS $$
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UPDATE mq_msgs
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SET
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attempt_at = NOW() + duration,
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commit_interval = commit_interval + ((NOW() + duration) - attempt_at)
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WHERE id = ANY(msg_ids)
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AND attempt_at < NOW() + duration;
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$$ LANGUAGE SQL;
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-- Called during lengthy processing of a message to checkpoint the progress.
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-- As well as behaving like `mq_keep_alive`, the message payload can be
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-- updated.
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CREATE FUNCTION mq_checkpoint(
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msg_id UUID,
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duration INTERVAL,
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new_payload_json TEXT,
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new_payload_bytes BYTEA,
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extra_retries INT
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)
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RETURNS VOID AS $$
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UPDATE mq_msgs
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SET
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attempt_at = GREATEST(attempt_at, NOW() + duration),
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attempts = attempts + COALESCE(extra_retries, 0)
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WHERE id = msg_id;
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UPDATE mq_payloads
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SET
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payload_json = COALESCE(new_payload_json::JSONB, payload_json),
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payload_bytes = COALESCE(new_payload_bytes, payload_bytes)
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WHERE
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id = msg_id;
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$$ LANGUAGE SQL;
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