/*
* GetOrEstablishConnection returns a PGconn which can be used to execute
* queries on a remote PostgreSQL server. If no suitable connection to the
* specified node on the specified port yet exists, the function establishes
* a new connection and adds it to the connection cache before returning it.
*
* Returned connections are guaranteed to be in the CONNECTION_OK state. If the
* requested connection cannot be established, or if it was previously created
* but is now in an unrecoverable bad state, this function returns NULL.
*
* This function throws an error if a hostname over 255 characters is provided.
*/
PGconn *
GetOrEstablishConnection(char *nodeName, int32 nodePort)
{
PGconn *connection = NULL;
NodeConnectionKey nodeConnectionKey;
NodeConnectionEntry *nodeConnectionEntry = NULL;
bool entryFound = false;
bool needNewConnection = true;
char *userName = CurrentUserName();
/* check input */
if (strnlen(nodeName, MAX_NODE_LENGTH + 1) > MAX_NODE_LENGTH)
{
ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("hostname exceeds the maximum length of %d",
MAX_NODE_LENGTH)));
}
/* if first call, initialize the connection hash */
if (NodeConnectionHash == NULL)
{
NodeConnectionHash = CreateNodeConnectionHash();
}
memset(&nodeConnectionKey, 0, sizeof(nodeConnectionKey));
strncpy(nodeConnectionKey.nodeName, nodeName, MAX_NODE_LENGTH);
nodeConnectionKey.nodePort = nodePort;
strncpy(nodeConnectionKey.nodeUser, userName, NAMEDATALEN);
nodeConnectionEntry = hash_search(NodeConnectionHash, &nodeConnectionKey,
HASH_FIND, &entryFound);
if (entryFound)
{
connection = nodeConnectionEntry->connection;
if (PQstatus(connection) == CONNECTION_OK)
{
needNewConnection = false;
}
else
{
PurgeConnection(connection);
}
}
if (needNewConnection)
{
connection = ConnectToNode(nodeName, nodePort, nodeConnectionKey.nodeUser);
if (connection != NULL)
{
nodeConnectionEntry = hash_search(NodeConnectionHash, &nodeConnectionKey,
HASH_ENTER, &entryFound);
nodeConnectionEntry->connection = connection;
}
}
return connection;
}
/*
* GetConnection returns a PGconn which can be used to execute queries on a
* remote PostgreSQL server. If no suitable connection to the specified node on
* the specified port yet exists, the function establishes a new connection and
* returns that.
*
* Returned connections are guaranteed to be in the CONNECTION_OK state. If the
* requested connection cannot be established, or if it was previously created
* but is now in an unrecoverable bad state, this function returns NULL.
*
* This function throws an error if a hostname over 255 characters is provided.
*/
PGconn *
GetConnection(char *nodeName, int32 nodePort)
{
PGconn *connection = NULL;
NodeConnectionKey nodeConnectionKey;
NodeConnectionEntry *nodeConnectionEntry = NULL;
bool entryFound = false;
bool needNewConnection = true;
/* check input */
if (strnlen(nodeName, MAX_NODE_LENGTH + 1) > MAX_NODE_LENGTH)
{
ereport(ERROR, (errmsg("hostnames may not exceed 255 characters")));
}
/* if first call, initialize the connection hash */
if (NodeConnectionHash == NULL)
{
NodeConnectionHash = CreateNodeConnectionHash();
}
memset(&nodeConnectionKey, 0, sizeof(nodeConnectionKey));
strncpy(nodeConnectionKey.nodeName, nodeName, MAX_NODE_LENGTH);
nodeConnectionKey.nodePort = nodePort;
nodeConnectionEntry = hash_search(NodeConnectionHash, &nodeConnectionKey,
HASH_FIND, &entryFound);
if (entryFound)
{
connection = nodeConnectionEntry->connection;
if (PQstatus(connection) == CONNECTION_OK)
{
needNewConnection = false;
}
else
{
PurgeConnection(connection);
}
}
if (needNewConnection)
{
StringInfo nodePortString = makeStringInfo();
appendStringInfo(nodePortString, "%d", nodePort);
connection = ConnectToNode(nodeName, nodePortString->data);
if (connection != NULL)
{
nodeConnectionEntry = hash_search(NodeConnectionHash, &nodeConnectionKey,
HASH_ENTER, &entryFound);
nodeConnectionEntry->connection = connection;
}
}
return connection;
}
void Conexiune(Thread* thread){
GetText t;
GetFile f = SetSendPackage(thread);
int server = ConnectToNode(nodlist.addr[thread->id]);
if (server){
do{
send(server, &f, sizeof(f), 0);
recv(server, &t, sizeof(GetText),0);
Scriere(t,f);
f.from = nodlist.length*100 + f.from;
}while(t.length > 0);
}
close(server);
}
/*
* get_and_purge_connection first gets a connection using the provided hostname
* and port before immediately passing that connection to PurgeConnection. This
* is to test PurgeConnection behvaior when circumventing the cache.
*/
Datum
connect_and_purge_connection(PG_FUNCTION_ARGS)
{
char *nodeName = PG_GETARG_CSTRING(0);
int32 nodePort = PG_GETARG_INT32(1);
char *nodeUser = CurrentUserName();
PGconn *connection = ConnectToNode(nodeName, nodePort, nodeUser);
if (connection == NULL)
{
PG_RETURN_BOOL(false);
}
PurgeConnection(connection);
PG_RETURN_BOOL(true);
}
