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b64d92f1a5
Several upcoming performance/scalability improvements require atomic operations. This new API avoids the need to splatter compiler and architecture dependent code over all the locations employing atomic ops. For several of the potential usages it'd be problematic to maintain both, a atomics using implementation and one using spinlocks or similar. In all likelihood one of the implementations would not get tested regularly under concurrency. To avoid that scenario the new API provides a automatic fallback of atomic operations to spinlocks. All properties of atomic operations are maintained. This fallback - obviously - isn't as fast as just using atomic ops, but it's not bad either. For one of the future users the atomics ontop spinlocks implementation was actually slightly faster than the old purely spinlock using implementation. That's important because it reduces the fear of regressing older platforms when improving the scalability for new ones. The API, loosely modeled after the C11 atomics support, currently provides 'atomic flags' and 32 bit unsigned integers. If the platform efficiently supports atomic 64 bit unsigned integers those are also provided. To implement atomics support for a platform/architecture/compiler for a type of atomics 32bit compare and exchange needs to be implemented. If available and more efficient native support for flags, 32 bit atomic addition, and corresponding 64 bit operations may also be provided. Additional useful atomic operations are implemented generically ontop of these. The implementation for various versions of gcc, msvc and sun studio have been tested. Additional existing stub implementations for * Intel icc * HUPX acc * IBM xlc are included but have never been tested. These will likely require fixes based on buildfarm and user feedback. As atomic operations also require barriers for some operations the existing barrier support has been moved into the atomics code. Author: Andres Freund with contributions from Oskari Saarenmaa Reviewed-By: Amit Kapila, Robert Haas, Heikki Linnakangas and Álvaro Herrera Discussion: CA+TgmoYBW+ux5-8Ja=Mcyuy8=VXAnVRHp3Kess6Pn3DMXAPAEA@mail.gmail.com, 20131015123303.GH5300@awork2.anarazel.de, 20131028205522.GI20248@awork2.anarazel.de
72 lines
2.1 KiB
PL/PgSQL
72 lines
2.1 KiB
PL/PgSQL
--
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-- Test the LOCK statement
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--
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-- Setup
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CREATE SCHEMA lock_schema1;
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SET search_path = lock_schema1;
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CREATE TABLE lock_tbl1 (a BIGINT);
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CREATE VIEW lock_view1 AS SELECT 1;
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CREATE ROLE regress_rol_lock1;
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ALTER ROLE regress_rol_lock1 SET search_path = lock_schema1;
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GRANT USAGE ON SCHEMA lock_schema1 TO regress_rol_lock1;
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-- Try all valid lock options; also try omitting the optional TABLE keyword.
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BEGIN TRANSACTION;
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LOCK TABLE lock_tbl1 IN ACCESS SHARE MODE;
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LOCK lock_tbl1 IN ROW SHARE MODE;
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LOCK TABLE lock_tbl1 IN ROW EXCLUSIVE MODE;
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LOCK TABLE lock_tbl1 IN SHARE UPDATE EXCLUSIVE MODE;
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LOCK TABLE lock_tbl1 IN SHARE MODE;
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LOCK lock_tbl1 IN SHARE ROW EXCLUSIVE MODE;
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LOCK TABLE lock_tbl1 IN EXCLUSIVE MODE;
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LOCK TABLE lock_tbl1 IN ACCESS EXCLUSIVE MODE;
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ROLLBACK;
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-- Try using NOWAIT along with valid options.
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BEGIN TRANSACTION;
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LOCK TABLE lock_tbl1 IN ACCESS SHARE MODE NOWAIT;
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LOCK TABLE lock_tbl1 IN ROW SHARE MODE NOWAIT;
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LOCK TABLE lock_tbl1 IN ROW EXCLUSIVE MODE NOWAIT;
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LOCK TABLE lock_tbl1 IN SHARE UPDATE EXCLUSIVE MODE NOWAIT;
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LOCK TABLE lock_tbl1 IN SHARE MODE NOWAIT;
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LOCK TABLE lock_tbl1 IN SHARE ROW EXCLUSIVE MODE NOWAIT;
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LOCK TABLE lock_tbl1 IN EXCLUSIVE MODE NOWAIT;
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LOCK TABLE lock_tbl1 IN ACCESS EXCLUSIVE MODE NOWAIT;
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LOCK TABLE lock_view1 IN EXCLUSIVE MODE; -- Will fail; can't lock a non-table
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ROLLBACK;
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-- Verify that we can lock a table with inheritance children.
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CREATE TABLE lock_tbl2 (b BIGINT) INHERITS (lock_tbl1);
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CREATE TABLE lock_tbl3 () INHERITS (lock_tbl2);
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BEGIN TRANSACTION;
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LOCK TABLE lock_tbl1 * IN ACCESS EXCLUSIVE MODE;
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ROLLBACK;
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-- Verify that we can't lock a child table just because we have permission
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-- on the parent, but that we can lock the parent only.
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GRANT UPDATE ON TABLE lock_tbl1 TO regress_rol_lock1;
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SET ROLE regress_rol_lock1;
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BEGIN;
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LOCK TABLE lock_tbl1 * IN ACCESS EXCLUSIVE MODE;
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ROLLBACK;
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BEGIN;
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LOCK TABLE ONLY lock_tbl1;
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ROLLBACK;
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RESET ROLE;
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--
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-- Clean up
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--
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DROP VIEW lock_view1;
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DROP TABLE lock_tbl3;
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DROP TABLE lock_tbl2;
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DROP TABLE lock_tbl1;
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DROP SCHEMA lock_schema1 CASCADE;
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DROP ROLE regress_rol_lock1;
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-- atomic ops tests
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RESET search_path;
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SELECT test_atomic_ops();
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