peek referee extension

Author: kelvich

contrib/referee/Makefile

@@ -0,0 +1,14 @@
+EXTENSION = referee
+DATA = referee--1.0.sql
+REGRESS = referee
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = contrib/referee
+top_builddir = ../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif

contrib/referee/expected/referee.out

@@ -0,0 +1,89 @@
+CREATE EXTENSION referee;
+SELECT * FROM referee.decision;
+ key | node_id 
+-----+---------
+(0 rows)
+
+SELECT referee.get_winner(1);
+ get_winner 
+------------
+          1
+(1 row)
+
+SELECT referee.get_winner(2);
+ get_winner 
+------------
+          1
+(1 row)
+
+SELECT referee.get_winner(4);
+ get_winner 
+------------
+          1
+(1 row)
+
+SELECT referee.get_winner(1);
+ get_winner 
+------------
+          1
+(1 row)
+
+SELECT * FROM referee.decision;
+  key   | node_id 
+--------+---------
+ winner |       1
+(1 row)
+
+SELECT referee.clean();
+ clean 
+-------
+ t
+(1 row)
+
+SELECT referee.get_winner(4);
+ get_winner 
+------------
+          4
+(1 row)
+
+SELECT referee.get_winner(2);
+ get_winner 
+------------
+          4
+(1 row)
+
+SELECT referee.get_winner(1);
+ get_winner 
+------------
+          4
+(1 row)
+
+SELECT referee.get_winner(4);
+ get_winner 
+------------
+          4
+(1 row)
+
+SELECT * FROM referee.decision;
+  key   | node_id 
+--------+---------
+ winner |       4
+(1 row)
+
+SELECT referee.clean();
+ clean 
+-------
+ t
+(1 row)
+
+SELECT referee.clean();
+ clean 
+-------
+ t
+(1 row)
+
+SELECT * FROM referee.decision;
+ key | node_id 
+-----+---------
+(0 rows)
+

contrib/referee/referee--1.0.sql

@@ -0,0 +1,28 @@
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION referee" to load this file. \quit
+
+CREATE TABLE IF NOT EXISTS referee.decision(key text primary key not null, node_id int);
+
+CREATE OR REPLACE FUNCTION referee.get_winner(applicant_id int) RETURNS int AS
+$$
+DECLARE
+    winner_id int;
+BEGIN
+    insert into referee.decision values ('winner', applicant_id);
+    select node_id into winner_id from referee.decision where key = 'winner';
+    return winner_id;
+EXCEPTION WHEN others THEN
+    select node_id into winner_id from referee.decision where key = 'winner';
+    return winner_id;
+END
+$$
+LANGUAGE plpgsql;
+
+CREATE OR REPLACE FUNCTION referee.clean() RETURNS bool AS
+$$
+BEGIN
+    delete from referee.decision where key = 'winner';
+    return 'true';
+END
+$$
+LANGUAGE plpgsql;

contrib/referee/referee.control

@@ -0,0 +1,5 @@
+comment = 'Multimaster referee'
+default_version = '1.0'
+module_pathname = '$libdir/referee'
+schema = referee
+relocatable = false

contrib/referee/sql/referee.sql

@@ -0,0 +1,20 @@
+CREATE EXTENSION referee;
+
+SELECT * FROM referee.decision;
+
+SELECT referee.get_winner(1);
+SELECT referee.get_winner(2);
+SELECT referee.get_winner(4);
+SELECT referee.get_winner(1);
+SELECT * FROM referee.decision;
+
+SELECT referee.clean();
+SELECT referee.get_winner(4);
+SELECT referee.get_winner(2);
+SELECT referee.get_winner(1);
+SELECT referee.get_winner(4);
+SELECT * FROM referee.decision;
+
+SELECT referee.clean();
+SELECT referee.clean();
+SELECT * FROM referee.decision;