144 lines
4.1 KiB
SQL
144 lines
4.1 KiB
SQL
--
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-- A stored procedure to reallocate a user's previous address, otherwise
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-- provide a free address.
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--
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-- Using this SP reduces the usual set dialogue of queries to a single
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-- query:
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--
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-- START TRANSACTION; SELECT FOR UPDATE; UPDATE; COMMIT; -> CALL sp()
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--
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-- The stored procedure is executed on an database instance within a single
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-- round trip which often leads to reduced deadlocking and significant
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-- performance improvements especially on multi-master clusters, perhaps even
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-- by an order of magnitude or more.
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--
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-- To use this stored procedure the corresponding queries.conf statements must
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-- be configured as follows:
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--
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-- allocate_begin = ""
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-- allocate_find = "\
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-- CALL fr_dhcp_allocate_previous_or_new_framedipaddress( \
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-- '%{control:${pool_name}}', \
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-- '%{DHCP-Gateway-IP-Address}', \
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-- '${pool_key}', \
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-- ${lease_duration}, \
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-- '%{%{${req_attribute_name}}:-0.0.0.0}' \
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-- )"
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-- allocate_update = ""
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-- allocate_commit = ""
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--
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DELIMITER $$
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DROP PROCEDURE IF EXISTS fr_dhcp_allocate_previous_or_new_framedipaddress;
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CREATE PROCEDURE fr_dhcp_allocate_previous_or_new_framedipaddress (
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IN v_pool_name VARCHAR(30),
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IN v_gateway VARCHAR(15),
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IN v_pool_key VARCHAR(30),
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IN v_lease_duration INT,
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IN v_requested_address VARCHAR(15)
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)
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SQL SECURITY INVOKER
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proc:BEGIN
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DECLARE r_address VARCHAR(15);
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DECLARE EXIT HANDLER FOR SQLEXCEPTION
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BEGIN
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ROLLBACK;
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RESIGNAL;
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END;
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SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
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START TRANSACTION;
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-- Reissue an existing IP address lease when re-authenticating a session
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--
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SELECT framedipaddress INTO r_address
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FROM dhcpippool
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WHERE pool_name = v_pool_name
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AND expiry_time > NOW()
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AND pool_key = v_pool_key
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AND `status` IN ('dynamic', 'static')
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LIMIT 1
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FOR UPDATE;
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-- FOR UPDATE SKIP LOCKED; -- Better performance, but limited support
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-- NOTE: You should enable SKIP LOCKED here (as well as any other
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-- instances) if your database server supports it. If it is not
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-- supported and you are not running a multi-master cluster (e.g.
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-- Galera or MaxScale) then you should instead consider using the
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-- SP in procedure-no-skip-locked.sql which will be faster and
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-- less likely to result in thread starvation under highly
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-- concurrent load.
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-- Reissue an user's previous IP address, provided that the lease is
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-- available (i.e. enable sticky IPs)
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--
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-- When using this SELECT you should delete the one above. You must also
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-- set allocate_clear = "" in queries.conf to persist the associations
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-- for expired leases.
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--
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-- SELECT framedipaddress INTO r_address
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-- FROM dhcpippool
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-- WHERE pool_name = v_pool_name
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-- AND pool_key = v_pool_key
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-- AND `status` IN ('dynamic', 'static')
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-- LIMIT 1
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-- FOR UPDATE;
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-- -- FOR UPDATE SKIP LOCKED; -- Better performance, but limited support
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-- Issue the requested IP address if it is available
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--
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IF r_address IS NULL AND v_requested_address <> '0.0.0.0' THEN
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SELECT framedipaddress INTO r_address
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FROM dhcpippool
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WHERE pool_name = v_pool_name
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AND framedipaddress = v_requested_address
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AND `status` = 'dynamic'
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AND ( pool_key = v_pool_key OR expiry_time < NOW() )
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FOR UPDATE;
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-- FOR UPDATE SKIP LOCKED; -- Better performance, but limited support
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END IF;
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-- If we didn't reallocate a previous address then pick the least
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-- recently used address from the pool which maximises the likelihood
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-- of re-assigning the other addresses to their recent user
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--
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IF r_address IS NULL THEN
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SELECT framedipaddress INTO r_address
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FROM dhcpippool
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WHERE pool_name = v_pool_name
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AND expiry_time < NOW()
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AND `status` = 'dynamic'
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ORDER BY
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expiry_time
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LIMIT 1
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FOR UPDATE;
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-- FOR UPDATE SKIP LOCKED; -- Better performance, but limited support
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END IF;
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-- Return nothing if we failed to allocated an address
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--
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IF r_address IS NULL THEN
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COMMIT;
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LEAVE proc;
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END IF;
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-- Update the pool having allocated an IP address
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--
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UPDATE dhcpippool
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SET
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gateway = v_gateway,
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pool_key = v_pool_key,
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expiry_time = NOW() + INTERVAL v_lease_duration SECOND
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WHERE framedipaddress = r_address;
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COMMIT;
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-- Return the address that we allocated
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SELECT r_address;
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END$$
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DELIMITER ;
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