mirror of https://github.com/citusdata/citus.git
137 lines
4.0 KiB
C
137 lines
4.0 KiB
C
/*-------------------------------------------------------------------------
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*
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* connection_management.h
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* Central management of connections and their life-cycle
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*
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* Copyright (c) 2016, Citus Data, Inc.
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef CONNECTION_MANAGMENT_H
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#define CONNECTION_MANAGMENT_H
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#include "distributed/transaction_management.h"
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#include "distributed/remote_transaction.h"
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#include "lib/ilist.h"
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#include "utils/hsearch.h"
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#include "utils/timestamp.h"
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/* maximum (textual) lengths of hostname and port */
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#define MAX_NODE_LENGTH 255 /* includes 0 byte */
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/* forward declare, to avoid forcing large headers on everyone */
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struct pg_conn; /* target of the PGconn typedef */
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struct MemoryContextData;
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/*
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* Flags determining connection establishment behaviour.
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*/
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enum MultiConnectionMode
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{
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/* force establishment of a new connection */
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FORCE_NEW_CONNECTION = 1 << 0,
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/* mark returned connection as having session lifespan */
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SESSION_LIFESPAN = 1 << 1
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};
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/* declaring this directly above makes uncrustify go crazy */
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typedef enum MultiConnectionMode MultiConnectionMode;
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typedef struct MultiConnection
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{
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/* connection details, useful for error messages and such. */
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char hostname[MAX_NODE_LENGTH];
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int32 port;
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char user[NAMEDATALEN];
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char database[NAMEDATALEN];
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/* underlying libpq connection */
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struct pg_conn *pgConn;
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/* is the connection intended to be kept after transaction end */
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bool sessionLifespan;
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/* is the connection currently in use, and shouldn't be used by anything else */
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bool claimedExclusively;
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/* time connection establishment was started, for timeout */
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TimestampTz connectionStart;
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/* membership in list of list of connections in ConnectionHashEntry */
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dlist_node connectionNode;
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/* information about the associated remote transaction */
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RemoteTransaction remoteTransaction;
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/* membership in list of in-progress transactions */
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dlist_node transactionNode;
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} MultiConnection;
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/*
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* Central connection management hash, mapping (host, port, user, database) to
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* a list of connections.
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*
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* This hash is used to keep track of which connections are open to which
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* node. Besides allowing connection reuse, that information is e.g. used to
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* handle closing connections after the end of a transaction.
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*/
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/* hash key */
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typedef struct ConnectionHashKey
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{
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char hostname[MAX_NODE_LENGTH];
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int32 port;
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char user[NAMEDATALEN];
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char database[NAMEDATALEN];
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} ConnectionHashKey;
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/* hash entry */
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typedef struct ConnectionHashEntry
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{
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ConnectionHashKey key;
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dlist_head *connections;
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} ConnectionHashEntry;
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/* maximum duration to wait for connection */
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extern int NodeConnectionTimeout;
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/* the hash table */
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extern HTAB *ConnectionHash;
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/* context for all connection and transaction related memory */
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extern struct MemoryContextData *ConnectionContext;
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extern void AfterXactConnectionHandling(bool isCommit);
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extern void InitializeConnectionManagement(void);
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/* Low-level connection establishment APIs */
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extern MultiConnection * GetNodeConnection(uint32 flags, const char *hostname,
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int32 port);
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extern MultiConnection * StartNodeConnection(uint32 flags, const char *hostname,
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int32 port);
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extern MultiConnection * GetNodeUserDatabaseConnection(uint32 flags, const char *hostname,
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int32 port, const char *user, const
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char *database);
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extern MultiConnection * StartNodeUserDatabaseConnection(uint32 flags,
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const char *hostname,
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int32 port,
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const char *user,
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const char *database);
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extern MultiConnection * GetConnectionFromPGconn(struct pg_conn *pqConn);
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extern void CloseConnection(MultiConnection *connection);
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extern void CloseConnectionByPGconn(struct pg_conn *pqConn);
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/* dealing with a connection */
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extern void FinishConnectionEstablishment(MultiConnection *connection);
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extern void ClaimConnectionExclusively(MultiConnection *connection);
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extern void UnclaimConnection(MultiConnection *connection);
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#endif /* CONNECTION_MANAGMENT_H */
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