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/*-------------------------------------------------------------------------
*
* walreceiver.h
* Exports from replication/walreceiverfuncs.c.
*
* Portions Copyright (c) 2010-2023, PostgreSQL Global Development Group
*
* src/include/replication/walreceiver.h
*
*-------------------------------------------------------------------------
*/
#ifndef _WALRECEIVER_H
#define _WALRECEIVER_H
#include <netdb.h>
#include <sys/socket.h>
#include "access/xlog.h"
#include "access/xlogdefs.h"
#include "pgtime.h"
#include "port/atomics.h"
#include "replication/logicalproto.h"
#include "replication/walsender.h"
#include "storage/condition_variable.h"
#include "storage/latch.h"
#include "storage/spin.h"
#include "utils/tuplestore.h"
/* user-settable parameters */
extern PGDLLIMPORT int wal_receiver_status_interval;
extern PGDLLIMPORT int wal_receiver_timeout;
extern PGDLLIMPORT bool hot_standby_feedback;
/*
* MAXCONNINFO: maximum size of a connection string.
*
* XXX: Should this move to pg_config_manual.h?
*/
#define MAXCONNINFO 1024
/* Can we allow the standby to accept replication connection from another standby? */
#define AllowCascadeReplication() (EnableHotStandby && max_wal_senders > 0)
/*
* Values for WalRcv->walRcvState.
*/
typedef enum
{
WALRCV_STOPPED, /* stopped and mustn't start up again */
WALRCV_STARTING, /* launched, but the process hasn't
* initialized yet */
WALRCV_STREAMING, /* walreceiver is streaming */
WALRCV_WAITING, /* stopped streaming, waiting for orders */
WALRCV_RESTARTING, /* asked to restart streaming */
WALRCV_STOPPING /* requested to stop, but still running */
} WalRcvState;
/* Shared memory area for management of walreceiver process */
typedef struct
{
/*
* PID of currently active walreceiver process, its current state and
* start time (actually, the time at which it was requested to be
* started).
*/
pid_t pid;
WalRcvState walRcvState;
ConditionVariable walRcvStoppedCV;
pg_time_t startTime;
/*
* receiveStart and receiveStartTLI indicate the first byte position and
* timeline that will be received. When startup process starts the
* walreceiver, it sets these to the point where it wants the streaming to
* begin.
*/
XLogRecPtr receiveStart;
TimeLineID receiveStartTLI;
/*
* flushedUpto-1 is the last byte position that has already been received,
* and receivedTLI is the timeline it came from. At the first startup of
* walreceiver, these are set to receiveStart and receiveStartTLI. After
* that, walreceiver updates these whenever it flushes the received WAL to
* disk.
*/
XLogRecPtr flushedUpto;
TimeLineID receivedTLI;
/*
* latestChunkStart is the starting byte position of the current "batch"
* of received WAL. It's actually the same as the previous value of
* flushedUpto before the last flush to disk. Startup process can use
* this to detect whether it's keeping up or not.
*/
XLogRecPtr latestChunkStart;
/*
* Time of send and receive of any message received.
*/
TimestampTz lastMsgSendTime;
TimestampTz lastMsgReceiptTime;
/*
* Latest reported end of WAL on the sender
*/
XLogRecPtr latestWalEnd;
TimestampTz latestWalEndTime;
/*
* connection string; initially set to connect to the primary, and later
* clobbered to hide security-sensitive fields.
*/
char conninfo[MAXCONNINFO];
/*
* Host name (this can be a host name, an IP address, or a directory path)
* and port number of the active replication connection.
*/
char sender_host[NI_MAXHOST];
int sender_port;
/*
* replication slot name; is also used for walreceiver to connect with the
* primary
*/
char slotname[NAMEDATALEN];
/*
* If it's a temporary replication slot, it needs to be recreated when
* connecting.
*/
bool is_temp_slot;
/* set true once conninfo is ready to display (obfuscated pwds etc) */
bool ready_to_display;
/*
* Latch used by startup process to wake up walreceiver after telling it
* where to start streaming (after setting receiveStart and
* receiveStartTLI), and also to tell it to send apply feedback to the
* primary whenever specially marked commit records are applied. This is
* normally mapped to procLatch when walreceiver is running.
*/
Latch *latch;
slock_t mutex; /* locks shared variables shown above */
/*
* Like flushedUpto, but advanced after writing and before flushing,
* without the need to acquire the spin lock. Data can be read by another
* process up to this point, but shouldn't be used for data integrity
* purposes.
*/
pg_atomic_uint64 writtenUpto;
/*
* force walreceiver reply? This doesn't need to be locked; memory
* barriers for ordering are sufficient. But we do need atomic fetch and
* store semantics, so use sig_atomic_t.
*/
sig_atomic_t force_reply; /* used as a bool */
} WalRcvData;
extern PGDLLIMPORT WalRcvData *WalRcv;
typedef struct
{
bool logical; /* True if this is logical replication stream,
* false if physical stream. */
char *slotname; /* Name of the replication slot or NULL. */
XLogRecPtr startpoint; /* LSN of starting point. */
union
{
struct
{
TimeLineID startpointTLI; /* Starting timeline */
} physical;
struct
{
uint32 proto_version; /* Logical protocol version */
List *publication_names; /* String list of publications */
bool binary; /* Ask publisher to use binary */
char *streaming_str; /* Streaming of large transactions */
bool twophase; /* Streaming of two-phase transactions at
* prepare time */
char *origin; /* Only publish data originating from the
* specified origin */
} logical;
} proto;
} WalRcvStreamOptions;
struct WalReceiverConn;
typedef struct WalReceiverConn WalReceiverConn;
/*
* Status of walreceiver query execution.
*
* We only define statuses that are currently used.
*/
typedef enum
{
WALRCV_ERROR, /* There was error when executing the query. */
WALRCV_OK_COMMAND, /* Query executed utility or replication
* command. */
WALRCV_OK_TUPLES, /* Query returned tuples. */
WALRCV_OK_COPY_IN, /* Query started COPY FROM. */
WALRCV_OK_COPY_OUT, /* Query started COPY TO. */
WALRCV_OK_COPY_BOTH /* Query started COPY BOTH replication
* protocol. */
} WalRcvExecStatus;
/*
* Return value for walrcv_exec, returns the status of the execution and
* tuples if any.
*/
typedef struct WalRcvExecResult
{
WalRcvExecStatus status;
int sqlstate;
char *err;
Tuplestorestate *tuplestore;
TupleDesc tupledesc;
} WalRcvExecResult;
/* WAL receiver - libpqwalreceiver hooks */
/*
* walrcv_connect_fn
*
* Establish connection to a cluster. 'logical' is true if the
* connection is logical, and false if the connection is physical.
* 'appname' is a name associated to the connection, to use for example
* with fallback_application_name or application_name. Returns the
* details about the connection established, as defined by
* WalReceiverConn for each WAL receiver module. On error, NULL is
* returned with 'err' including the error generated.
*/
typedef WalReceiverConn *(*walrcv_connect_fn) (const char *conninfo,
bool logical,
bool must_use_password,
const char *appname,
char **err);
/*
* walrcv_check_conninfo_fn
*
* Parse and validate the connection string given as of 'conninfo'.
*/
typedef void (*walrcv_check_conninfo_fn) (const char *conninfo,
bool must_use_password);
/*
* walrcv_get_conninfo_fn
*
* Returns a user-displayable conninfo string. Note that any
* security-sensitive fields should be obfuscated.
*/
typedef char *(*walrcv_get_conninfo_fn) (WalReceiverConn *conn);
/*
* walrcv_get_senderinfo_fn
*
* Provide information of the WAL sender this WAL receiver is connected
* to, as of 'sender_host' for the host of the sender and 'sender_port'
* for its port.
*/
typedef void (*walrcv_get_senderinfo_fn) (WalReceiverConn *conn,
char **sender_host,
int *sender_port);
/*
* walrcv_identify_system_fn
*
* Run IDENTIFY_SYSTEM on the cluster connected to and validate the
* identity of the cluster. Returns the system ID of the cluster
* connected to. 'primary_tli' is the timeline ID of the sender.
*/
typedef char *(*walrcv_identify_system_fn) (WalReceiverConn *conn,
TimeLineID *primary_tli);
/*
* walrcv_server_version_fn
*
* Returns the version number of the cluster connected to.
*/
typedef int (*walrcv_server_version_fn) (WalReceiverConn *conn);
/*
* walrcv_readtimelinehistoryfile_fn
*
* Fetch from cluster the timeline history file for timeline 'tli'.
* Returns the name of the timeline history file as of 'filename', its
* contents as of 'content' and its 'size'.
*/
typedef void (*walrcv_readtimelinehistoryfile_fn) (WalReceiverConn *conn,
TimeLineID tli,
char **filename,
char **content,
int *size);
/*
* walrcv_startstreaming_fn
*
* Start streaming WAL data from given streaming options. Returns true
* if the connection has switched successfully to copy-both mode and false
* if the server received the command and executed it successfully, but
* didn't switch to copy-mode.
*/
typedef bool (*walrcv_startstreaming_fn) (WalReceiverConn *conn,
const WalRcvStreamOptions *options);
/*
* walrcv_endstreaming_fn
*
* Stop streaming of WAL data. Returns the next timeline ID of the cluster
* connected to in 'next_tli', or 0 if there was no report.
*/
typedef void (*walrcv_endstreaming_fn) (WalReceiverConn *conn,
TimeLineID *next_tli);
/*
* walrcv_receive_fn
*
* Receive a message available from the WAL stream. 'buffer' is a pointer
* to a buffer holding the message received. Returns the length of the data,
* 0 if no data is available yet ('wait_fd' is a socket descriptor which can
* be waited on before a retry), and -1 if the cluster ended the COPY.
*/
typedef int (*walrcv_receive_fn) (WalReceiverConn *conn,
char **buffer,
pgsocket *wait_fd);
/*
* walrcv_send_fn
*
* Send a message of size 'nbytes' to the WAL stream with 'buffer' as
* contents.
*/
typedef void (*walrcv_send_fn) (WalReceiverConn *conn,
const char *buffer,
int nbytes);
/*
* walrcv_create_slot_fn
*
* Create a new replication slot named 'slotname'. 'temporary' defines
* if the slot is temporary. 'snapshot_action' defines the behavior wanted
* for an exported snapshot (see replication protocol for more details).
* 'lsn' includes the LSN position at which the created slot became
* consistent. Returns the name of the exported snapshot for a logical
* slot, or NULL for a physical slot.
*/
typedef char *(*walrcv_create_slot_fn) (WalReceiverConn *conn,
const char *slotname,
bool temporary,
bool two_phase,
CRSSnapshotAction snapshot_action,
XLogRecPtr *lsn);
/*
* walrcv_get_backend_pid_fn
*
* Returns the PID of the remote backend process.
*/
typedef pid_t (*walrcv_get_backend_pid_fn) (WalReceiverConn *conn);
/*
* walrcv_exec_fn
*
* Send generic queries (and commands) to the remote cluster. 'nRetTypes'
* is the expected number of returned attributes, and 'retTypes' an array
* including their type OIDs. Returns the status of the execution and
* tuples if any.
*/
typedef WalRcvExecResult *(*walrcv_exec_fn) (WalReceiverConn *conn,
const char *query,
const int nRetTypes,
const Oid *retTypes);
/*
* walrcv_disconnect_fn
*
* Disconnect with the cluster.
*/
typedef void (*walrcv_disconnect_fn) (WalReceiverConn *conn);
typedef struct WalReceiverFunctionsType
{
walrcv_connect_fn walrcv_connect;
walrcv_check_conninfo_fn walrcv_check_conninfo;
walrcv_get_conninfo_fn walrcv_get_conninfo;
walrcv_get_senderinfo_fn walrcv_get_senderinfo;
walrcv_identify_system_fn walrcv_identify_system;
walrcv_server_version_fn walrcv_server_version;
walrcv_readtimelinehistoryfile_fn walrcv_readtimelinehistoryfile;
walrcv_startstreaming_fn walrcv_startstreaming;
walrcv_endstreaming_fn walrcv_endstreaming;
walrcv_receive_fn walrcv_receive;
walrcv_send_fn walrcv_send;
walrcv_create_slot_fn walrcv_create_slot;
walrcv_get_backend_pid_fn walrcv_get_backend_pid;
walrcv_exec_fn walrcv_exec;
walrcv_disconnect_fn walrcv_disconnect;
} WalReceiverFunctionsType;
extern PGDLLIMPORT WalReceiverFunctionsType *WalReceiverFunctions;
#define walrcv_connect(conninfo, logical, must_use_password, appname, err) \
WalReceiverFunctions->walrcv_connect(conninfo, logical, must_use_password, appname, err)
#define walrcv_check_conninfo(conninfo, must_use_password) \
WalReceiverFunctions->walrcv_check_conninfo(conninfo, must_use_password)
#define walrcv_get_conninfo(conn) \
WalReceiverFunctions->walrcv_get_conninfo(conn)
#define walrcv_get_senderinfo(conn, sender_host, sender_port) \
WalReceiverFunctions->walrcv_get_senderinfo(conn, sender_host, sender_port)
#define walrcv_identify_system(conn, primary_tli) \
WalReceiverFunctions->walrcv_identify_system(conn, primary_tli)
#define walrcv_server_version(conn) \
WalReceiverFunctions->walrcv_server_version(conn)
#define walrcv_readtimelinehistoryfile(conn, tli, filename, content, size) \
WalReceiverFunctions->walrcv_readtimelinehistoryfile(conn, tli, filename, content, size)
#define walrcv_startstreaming(conn, options) \
WalReceiverFunctions->walrcv_startstreaming(conn, options)
#define walrcv_endstreaming(conn, next_tli) \
WalReceiverFunctions->walrcv_endstreaming(conn, next_tli)
#define walrcv_receive(conn, buffer, wait_fd) \
WalReceiverFunctions->walrcv_receive(conn, buffer, wait_fd)
#define walrcv_send(conn, buffer, nbytes) \
WalReceiverFunctions->walrcv_send(conn, buffer, nbytes)
#define walrcv_create_slot(conn, slotname, temporary, two_phase, snapshot_action, lsn) \
WalReceiverFunctions->walrcv_create_slot(conn, slotname, temporary, two_phase, snapshot_action, lsn)
#define walrcv_get_backend_pid(conn) \
WalReceiverFunctions->walrcv_get_backend_pid(conn)
#define walrcv_exec(conn, exec, nRetTypes, retTypes) \
WalReceiverFunctions->walrcv_exec(conn, exec, nRetTypes, retTypes)
#define walrcv_disconnect(conn) \
WalReceiverFunctions->walrcv_disconnect(conn)
static inline void
walrcv_clear_result(WalRcvExecResult *walres)
{
if (!walres)
return;
if (walres->err)
pfree(walres->err);
if (walres->tuplestore)
tuplestore_end(walres->tuplestore);
if (walres->tupledesc)
FreeTupleDesc(walres->tupledesc);
pfree(walres);
}
/* prototypes for functions in walreceiver.c */
extern void WalReceiverMain(void) pg_attribute_noreturn();
extern void ProcessWalRcvInterrupts(void);
extern void WalRcvForceReply(void);
/* prototypes for functions in walreceiverfuncs.c */
extern Size WalRcvShmemSize(void);
extern void WalRcvShmemInit(void);
extern void ShutdownWalRcv(void);
extern bool WalRcvStreaming(void);
extern bool WalRcvRunning(void);
extern void RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr,
const char *conninfo, const char *slotname,
bool create_temp_slot);
extern XLogRecPtr GetWalRcvFlushRecPtr(XLogRecPtr *latestChunkStart, TimeLineID *receiveTLI);
extern XLogRecPtr GetWalRcvWriteRecPtr(void);
extern int GetReplicationApplyDelay(void);
extern int GetReplicationTransferLatency(void);
#endif /* _WALRECEIVER_H */