Event database access

Added tables that store event access interfaces and event states per
interface, as well as functions which allow events to be retrieved:
 * events.interfaces lists access interfaces,
 * events.unprocessed_events lists events which haven't been processed
for each type of interface, with a "pre-processed" flag
 * events.ep_read() is a set of function variants which will read events
 * events.ep_access() is a set of function variants which read events
then update their states.

legacyworlds-server-data/db-structure/parts/030-data/170-events.sql

@@ -402,6 +402,66 @@ ALTER TABLE events.field_values
 GRANT SELECT ON events.field_values TO :dbuser;
 
 
+/*
+ * Event viewing interfaces
+ * ------------------------
+ * 
+ * This table stores the list of interfaces which can be used to access the
+ * events. It allows the system to handle multiple types of event viewing or
+ * processing: for example the web interface and email notifications.
+ */
+CREATE TABLE events.interfaces(
+
+	/* A short string that identifies the interface */
+	evi_id		VARCHAR(8) NOT NULL PRIMARY KEY ,
+
+	/* A description of the interface */
+	evi_descr	TEXT NOT NULL
+
+);
+
+/* Directly insert interface types */
+INSERT INTO events.interfaces( evi_id , evi_descr ) VALUES
+	( 'game' , 'The game''s main interface' ) ,
+	( 'mail' , 'The e-mail notifications system' );
+
+
+/*
+ * Events to process
+ * -----------------
+ * 
+ * This table stores the list of events which need to be processed for each
+ * interface.
+ */
+CREATE TABLE events.unprocessed_events(
+	/* The event's identifier */
+	event_id			BIGINT NOT NULL ,
+
+	/* The interface's identifier */
+	evi_id				VARCHAR(8) NOT NULL ,
+
+	/* Whether the interface has pre-processed the event, but not displayed
+	 * or sent it yet. This is used with e.g. the email notification system,
+	 * which waits for more events once a first event is ready. When the
+	 * server restarts, the field is set back to FALSE.
+	 */
+	upe_preprocessed	BOOLEAN NOT NULL
+							DEFAULT FALSE ,
+	
+	/* Use both the event and interface as the primary key */
+	PRIMARY KEY( event_id , evi_id )
+);
+
+CREATE INDEX idx_unprocessed_interface
+	ON events.unprocessed_events( evi_id );
+
+ALTER TABLE events.unprocessed_events
+	ADD CONSTRAINT fk_unprocessed_event
+		FOREIGN KEY ( event_id ) REFERENCES events.events_v2 ( event_id )
+			ON DELETE CASCADE ,
+	ADD CONSTRAINT fk_unprocessed_interface
+		FOREIGN KEY ( evi_id ) REFERENCES events.interfaces ( evi_id );
+
 
 /*
  * OLD B6M1 CODE BELOW!