connection.h

/*-------------------------------------------------------------------------
 *
 * connection.h
 *
 * Declarations for public functions and types related to connection hash
 * functionality.
 *
 * Copyright (c) 2014, Citus Data, Inc.
 *
 *-------------------------------------------------------------------------
 */

#ifndef PG_SHARD_CONNECTION_H
#define PG_SHARD_CONNECTION_H

#include "c.h"
#include "libpq-fe.h"


/* maximum duration to wait for connection */
#define CLIENT_CONNECT_TIMEOUT_SECONDS "5"

/* maximum (textual) lengths of hostname */
#define MAX_NODE_LENGTH 255

/* times to attempt connection (or reconnection) */
#define MAX_CONNECT_ATTEMPTS 2

/* SQL statement for testing */
#define TEST_SQL "DO $$ BEGIN RAISE EXCEPTION 'Raised remotely!'; END $$"


/*
 * NodeConnectionKey acts as the key to index into the (process-local) hash
 * keeping track of open connections. Node name and port are sufficient.
 */
typedef struct NodeConnectionKey
{
	char nodeName[MAX_NODE_LENGTH + 1];	/* hostname of host to connect to */
	int32 nodePort;						/* port of host to connect to */
} NodeConnectionKey;


/* NodeConnectionEntry keeps track of connections themselves. */
typedef struct NodeConnectionEntry
{
	NodeConnectionKey cacheKey;	/* hash entry key */
	PGconn *connection;			/* connection to remote server, if any */
} NodeConnectionEntry;


/* function declarations for obtaining and using a connection */
extern PGconn * GetConnection(char *nodeName, int32 nodePort);
extern void PurgeConnection(PGconn *connection);
extern void ReportRemoteError(PGconn *connection, PGresult *result);


#endif /* PG_SHARD_CONNECTION_H */