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dbutils.c
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dbutils.c
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/*
* dbutils.c - Database connection/management functions
*
* Copyright (c) 2ndQuadrant, 2010-2017
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <unistd.h>
#include <time.h>
#include <sys/time.h>
#include "repmgr.h"
#include "config.h"
#include "strutil.h"
#include "log.h"
#include "catalog/pg_control.h"
char repmgr_schema[MAXLEN] = "";
char repmgr_schema_quoted[MAXLEN] = "";
static int _get_node_record(PGconn *conn, char *cluster, char *sqlquery, t_node_info *node_info);
static bool _set_config(PGconn *conn, const char *config_param, const char *sqlquery);
/*
* _establish_db_connection()
*
* Connect to a database using a conninfo string.
*
* NOTE: *do not* use this for replication connections; use establish_db_connection_by_params() instead.
*/
PGconn *
_establish_db_connection(const char *conninfo, const bool exit_on_error, const bool log_notice, const bool verbose_only)
{
/* Make a connection to the database */
PGconn *conn = NULL;
char connection_string[MAXLEN];
strcpy(connection_string, conninfo);
strcat(connection_string, " fallback_application_name='repmgr'");
log_debug(_("connecting to: '%s'\n"), connection_string);
conn = PQconnectdb(connection_string);
/* Check to see that the backend connection was successfully made */
if ((PQstatus(conn) != CONNECTION_OK))
{
bool emit_log = true;
if (verbose_only == true && verbose_logging == false)
emit_log = false;
if (emit_log)
{
if (log_notice)
{
log_notice(_("connection to database failed: %s\n"),
PQerrorMessage(conn));
}
else
{
log_err(_("connection to database failed: %s\n"),
PQerrorMessage(conn));
}
}
if (exit_on_error)
{
PQfinish(conn);
exit(ERR_DB_CON);
}
}
/*
* set "synchronous_commit" to "local" in case synchronous replication is in use
*/
else if (set_config(conn, "synchronous_commit", "local") == false)
{
if (exit_on_error)
{
PQfinish(conn);
exit(ERR_DB_CON);
}
}
return conn;
}
/*
* Establish a database connection, optionally exit on error
*/
PGconn *
establish_db_connection(const char *conninfo, const bool exit_on_error)
{
return _establish_db_connection(conninfo, exit_on_error, false, false);
}
/*
* Attempt to establish a database connection, never exit on error, only
* output error messages if --verbose option used
*/
PGconn *
establish_db_connection_quiet(const char *conninfo)
{
return _establish_db_connection(conninfo, false, false, true);
}
/*
* Attempt to establish a database connection, never exit on error,
* output connection error messages as NOTICE (useful when connection
* failure is expected)
*/
PGconn *
test_db_connection(const char *conninfo)
{
return _establish_db_connection(conninfo, false, true, false);
}
PGconn *
establish_db_connection_by_params(const char *keywords[], const char *values[],
const bool exit_on_error)
{
PGconn *conn;
bool replication_connection = false;
int i;
/* Connect to the database using the provided parameters */
conn = PQconnectdbParams(keywords, values, true);
/* Check to see that the backend connection was successfully made */
if ((PQstatus(conn) != CONNECTION_OK))
{
log_err(_("connection to database failed: %s\n"),
PQerrorMessage(conn));
if (exit_on_error)
{
PQfinish(conn);
exit(ERR_DB_CON);
}
}
else
{
/*
* set "synchronous_commit" to "local" in case synchronous replication is in
* use (provided this is not a replication connection)
*/
for (i = 0; keywords[i]; i++)
{
if (strcmp(keywords[i], "replication") == 0)
replication_connection = true;
}
if (replication_connection == false && set_config(conn, "synchronous_commit", "local") == false)
{
if (exit_on_error)
{
PQfinish(conn);
exit(ERR_DB_CON);
}
}
}
return conn;
}
bool
begin_transaction(PGconn *conn)
{
PGresult *res;
log_verbose(LOG_DEBUG, "begin_transaction()\n");
res = PQexec(conn, "BEGIN");
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
log_err(_("Unable to begin transaction: %s\n"),
PQerrorMessage(conn));
PQclear(res);
return false;
}
PQclear(res);
return true;
}
bool
commit_transaction(PGconn *conn)
{
PGresult *res;
log_verbose(LOG_DEBUG, "commit_transaction()\n");
res = PQexec(conn, "COMMIT");
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
log_err(_("Unable to commit transaction: %s\n"),
PQerrorMessage(conn));
PQclear(res);
return false;
}
PQclear(res);
return true;
}
bool
rollback_transaction(PGconn *conn)
{
PGresult *res;
log_verbose(LOG_DEBUG, "rollback_transaction()\n");
res = PQexec(conn, "ROLLBACK");
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
log_err(_("Unable to rollback transaction: %s\n"),
PQerrorMessage(conn));
PQclear(res);
return false;
}
PQclear(res);
return true;
}
bool
check_cluster_schema(PGconn *conn)
{
PGresult *res;
char sqlquery[QUERY_STR_LEN];
sqlquery_snprintf(sqlquery,
"SELECT 1 FROM pg_catalog.pg_namespace WHERE nspname = '%s'",
get_repmgr_schema());
log_verbose(LOG_DEBUG, "check_cluster_schema(): %s\n", sqlquery);
res = PQexec(conn, sqlquery);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_err(_("check_cluster_schema(): unable to check cluster schema: %s\n"),
PQerrorMessage(conn));
PQclear(res);
return false;
}
if (PQntuples(res) == 0)
{
/* schema doesn't exist */
log_debug(_("check_cluster_schema(): schema '%s' doesn't exist\n"), get_repmgr_schema());
PQclear(res);
return false;
}
PQclear(res);
return true;
}
int
is_standby(PGconn *conn)
{
PGresult *res;
int result = 0;
char *sqlquery = "SELECT pg_catalog.pg_is_in_recovery()";
log_verbose(LOG_DEBUG, "is_standby(): %s\n", sqlquery);
res = PQexec(conn, sqlquery);
if (res == NULL || PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_err(_("Unable to query server mode: %s\n"),
PQerrorMessage(conn));
result = -1;
}
else if (PQntuples(res) == 1 && strcmp(PQgetvalue(res, 0, 0), "t") == 0)
{
result = 1;
}
PQclear(res);
return result;
}
/* check the PQStatus and try to 'select 1' to confirm good connection */
bool
is_pgup(PGconn *conn, int timeout)
{
char sqlquery[QUERY_STR_LEN];
/* Check the connection status twice in case it changes after reset */
bool twice = false;
for (;;)
{
if (PQstatus(conn) != CONNECTION_OK)
{
if (twice)
return false;
PQreset(conn); /* reconnect */
twice = true;
}
else
{
/*
* Send a SELECT 1 just to check if the connection is OK
*/
if (!cancel_query(conn, timeout))
goto failed;
if (wait_connection_availability(conn, timeout) != 1)
goto failed;
sqlquery_snprintf(sqlquery, "SELECT 1");
if (PQsendQuery(conn, sqlquery) == 0)
{
log_warning(_("PQsendQuery: Query could not be sent to primary. %s\n"),
PQerrorMessage(conn));
goto failed;
}
if (wait_connection_availability(conn, timeout) != 1)
goto failed;
break;
failed:
/*
* we need to retry, because we might just have lost the
* connection once
*/
if (twice)
return false;
PQreset(conn); /* reconnect */
twice = true;
}
}
return true;
}
/*
* Return the id of the active master node, or NODE_NOT_FOUND if no
* record available.
*
* This reports the value stored in the database only and
* does not verify whether the node is actually available
*/
int
get_master_node_id(PGconn *conn, char *cluster)
{
char sqlquery[QUERY_STR_LEN];
PGresult *res;
int retval;
sqlquery_snprintf(sqlquery,
"SELECT id "
" FROM %s.repl_nodes "
" WHERE cluster = '%s' "
" AND type = 'master' "
" AND active IS TRUE ",
get_repmgr_schema_quoted(conn),
cluster);
log_verbose(LOG_DEBUG, "get_master_node_id():\n%s\n", sqlquery);
res = PQexec(conn, sqlquery);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_err(_("get_master_node_id(): query failed\n%s\n"),
PQerrorMessage(conn));
retval = NODE_NOT_FOUND;
}
else if (PQntuples(res) == 0)
{
log_verbose(LOG_WARNING, _("get_master_node_id(): no active primary found\n"));
retval = NODE_NOT_FOUND;
}
else
{
retval = atoi(PQgetvalue(res, 0, 0));
}
PQclear(res);
return retval;
}
/*
* Return the server version number for the connection provided
*/
int
get_server_version(PGconn *conn, char *server_version)
{
PGresult *res;
res = PQexec(conn,
"SELECT current_setting('server_version_num'), "
" current_setting('server_version')");
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_err(_("unable to determine server version number:\n%s"),
PQerrorMessage(conn));
PQclear(res);
return -1;
}
if (server_version != NULL)
strcpy(server_version, PQgetvalue(res, 0, 0));
return atoi(PQgetvalue(res, 0, 0));
}
int
guc_set(PGconn *conn, const char *parameter, const char *op,
const char *value)
{
PGresult *res;
char sqlquery[QUERY_STR_LEN];
int retval = 1;
sqlquery_snprintf(sqlquery,
"SELECT true FROM pg_catalog.pg_settings "
" WHERE name = '%s' AND setting %s '%s'",
parameter, op, value);
log_verbose(LOG_DEBUG, "guc_set():\n%s\n", sqlquery);
res = PQexec(conn, sqlquery);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_err(_("guc_set(): unable to execute query\n%s\n"),
PQerrorMessage(conn));
retval = -1;
}
else if (PQntuples(res) == 0)
{
retval = 0;
}
PQclear(res);
return retval;
}
/**
* Just like guc_set except with an extra parameter containing the name of
* the pg datatype so that the comparison can be done properly.
*/
int
guc_set_typed(PGconn *conn, const char *parameter, const char *op,
const char *value, const char *datatype)
{
PGresult *res;
char sqlquery[QUERY_STR_LEN];
int retval = 1;
sqlquery_snprintf(sqlquery,
"SELECT true FROM pg_catalog.pg_settings "
" WHERE name = '%s' AND setting::%s %s '%s'::%s",
parameter, datatype, op, value, datatype);
log_verbose(LOG_DEBUG, "guc_set_typed():\n%s\n", sqlquery);
res = PQexec(conn, sqlquery);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_err(_("guc_set_typed(): unable to execute query\n%s\n"),
PQerrorMessage(conn));
retval = -1;
}
else if (PQntuples(res) == 0)
{
retval = 0;
}
PQclear(res);
return retval;
}
bool
get_cluster_size(PGconn *conn, char *size)
{
PGresult *res;
char sqlquery[QUERY_STR_LEN];
sqlquery_snprintf(sqlquery,
"SELECT pg_catalog.pg_size_pretty(SUM(pg_catalog.pg_database_size(oid))::bigint) "
" FROM pg_catalog.pg_database ");
log_verbose(LOG_DEBUG, "get_cluster_size():\n%s\n", sqlquery);
res = PQexec(conn, sqlquery);
if (res == NULL || PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_err(_("get_cluster_size(): unable to execute query\n%s\n"),
PQerrorMessage(conn));
PQclear(res);
return false;
}
strncpy(size, PQgetvalue(res, 0, 0), MAXLEN);
PQclear(res);
return true;
}
bool
get_pg_setting(PGconn *conn, const char *setting, char *output)
{
char sqlquery[QUERY_STR_LEN];
PGresult *res;
int i;
bool success = false;
sqlquery_snprintf(sqlquery,
"SELECT name, setting "
" FROM pg_catalog.pg_settings WHERE name = '%s'",
setting);
log_verbose(LOG_DEBUG, "get_pg_setting(): %s\n", sqlquery);
res = PQexec(conn, sqlquery);
if (res == NULL || PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_err(_("get_pg_setting() - PQexec failed: %s"),
PQerrorMessage(conn));
PQclear(res);
return false;
}
for (i = 0; i < PQntuples(res); i++)
{
if (strcmp(PQgetvalue(res, i, 0), setting) == 0)
{
strncpy(output, PQgetvalue(res, i, 1), MAXLEN);
success = true;
break;
}
else
{
/* XXX highly unlikely this would ever happen */
log_err(_("get_pg_setting(): unknown parameter \"%s\""), PQgetvalue(res, i, 0));
}
}
if (success == true)
{
log_verbose(LOG_DEBUG, _("get_pg_setting(): returned value is \"%s\"\n"), output);
}
PQclear(res);
return success;
}
/*
* get_conninfo_value()
*
* Extract the value represented by 'keyword' in 'conninfo' and copy
* it to the 'output' buffer.
*
* Returns true on success, or false on failure (conninfo string could
* not be parsed, or provided keyword not found).
*/
bool
get_conninfo_value(const char *conninfo, const char *keyword, char *output)
{
PQconninfoOption *conninfo_options;
PQconninfoOption *conninfo_option;
conninfo_options = PQconninfoParse(conninfo, NULL);
if (conninfo_options == NULL)
{
log_err(_("Unable to parse provided conninfo string \"%s\""), conninfo);
return false;
}
for (conninfo_option = conninfo_options; conninfo_option->keyword != NULL; conninfo_option++)
{
if (strcmp(conninfo_option->keyword, keyword) == 0)
{
if (conninfo_option->val != NULL && conninfo_option->val[0] != '\0')
{
strncpy(output, conninfo_option->val, MAXLEN);
break;
}
}
}
PQconninfoFree(conninfo_options);
return true;
}
/*
* get_upstream_connection()
*
* Returns connection to node's upstream node
*
* NOTE: will attempt to connect even if node is marked as inactive
*/
PGconn *
get_upstream_connection(PGconn *standby_conn, char *cluster, int node_id,
int *upstream_node_id_ptr, char *upstream_conninfo_out)
{
PGconn *upstream_conn = NULL;
PGresult *res;
char sqlquery[QUERY_STR_LEN];
char upstream_conninfo_stack[MAXCONNINFO];
char *upstream_conninfo = &*upstream_conninfo_stack;
/*
* If the caller wanted to get a copy of the connection info string, sub
* out the local stack pointer for the pointer passed by the caller.
*/
if (upstream_conninfo_out != NULL)
upstream_conninfo = upstream_conninfo_out;
sqlquery_snprintf(sqlquery,
" SELECT un.conninfo, un.id "
" FROM %s.repl_nodes un "
"INNER JOIN %s.repl_nodes n "
" ON (un.id = n.upstream_node_id AND un.cluster = n.cluster)"
" WHERE n.cluster = '%s' "
" AND n.id = %i ",
get_repmgr_schema_quoted(standby_conn),
get_repmgr_schema_quoted(standby_conn),
cluster,
node_id);
log_verbose(LOG_DEBUG, "get_upstream_connection():\n%s\n", sqlquery);
res = PQexec(standby_conn, sqlquery);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_err(_("error when attempting to find upstream server\n%s\n"),
PQerrorMessage(standby_conn));
PQclear(res);
return NULL;
}
if (!PQntuples(res))
{
PQclear(res);
log_debug("no record found for upstream server\n");
sqlquery_snprintf(sqlquery,
" SELECT un.conninfo, un.id "
" FROM %s.repl_nodes un "
" WHERE un.cluster = '%s' "
" AND un.type='master' "
" AND un.active IS TRUE",
get_repmgr_schema_quoted(standby_conn),
cluster);
res = PQexec(standby_conn, sqlquery);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_err(_("error when attempting to find active master server\n%s\n"),
PQerrorMessage(standby_conn));
PQclear(res);
return NULL;
}
if (!PQntuples(res))
{
PQclear(res);
log_notice(_("no record found for active master server\n"));
return NULL;
}
log_debug("record found for active master server\n");
}
strncpy(upstream_conninfo, PQgetvalue(res, 0, 0), MAXCONNINFO);
if (upstream_node_id_ptr != NULL)
*upstream_node_id_ptr = atoi(PQgetvalue(res, 0, 1));
PQclear(res);
log_verbose(LOG_DEBUG, "get_upstream_connection(): conninfo is \"%s\"\n", upstream_conninfo);
upstream_conn = establish_db_connection(upstream_conninfo, false);
if (PQstatus(upstream_conn) != CONNECTION_OK)
{
log_err(_("unable to connect to upstream node: %s\n"),
PQerrorMessage(upstream_conn));
return NULL;
}
return upstream_conn;
}
/*
* Read the node list from the local node and attempt to connect to each node
* in turn to definitely establish if it's the cluster primary.
*
* The node list is returned in the order which makes it likely that the
* current primary will be returned first, reducing the number of speculative
* connections which need to be made to other nodes.
*
* If master_conninfo_out points to allocated memory of MAXCONNINFO in length,
* the primary server's conninfo string will be copied there.
*/
PGconn *
get_master_connection(PGconn *standby_conn, char *cluster,
int *master_id, char *master_conninfo_out)
{
PGconn *remote_conn = NULL;
PGresult *res;
char sqlquery[QUERY_STR_LEN];
char remote_conninfo_stack[MAXCONNINFO];
char *remote_conninfo = &*remote_conninfo_stack;
int i,
node_id;
/*
* If the caller wanted to get a copy of the connection info string, sub
* out the local stack pointer for the pointer passed by the caller.
*/
if (master_conninfo_out != NULL)
remote_conninfo = master_conninfo_out;
if (master_id != NULL)
{
*master_id = NODE_NOT_FOUND;
}
/* find all nodes belonging to this cluster */
log_info(_("retrieving node list for cluster '%s'\n"),
cluster);
sqlquery_snprintf(sqlquery,
" SELECT id, conninfo, "
" CASE WHEN type = 'master' THEN 1 ELSE 2 END AS type_priority"
" FROM %s.repl_nodes "
" WHERE cluster = '%s' "
" AND type != 'witness' "
"ORDER BY active DESC, type_priority, priority, id",
get_repmgr_schema_quoted(standby_conn),
cluster);
log_verbose(LOG_DEBUG, "get_master_connection():\n%s\n", sqlquery);
res = PQexec(standby_conn, sqlquery);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_err(_("unable to retrieve node records: %s\n"),
PQerrorMessage(standby_conn));
PQclear(res);
return NULL;
}
for (i = 0; i < PQntuples(res); i++)
{
int is_node_standby;
/* initialize with the values of the current node being processed */
node_id = atoi(PQgetvalue(res, i, 0));
strncpy(remote_conninfo, PQgetvalue(res, i, 1), MAXCONNINFO);
log_verbose(LOG_INFO,
_("checking role of cluster node '%i'\n"),
node_id);
remote_conn = establish_db_connection(remote_conninfo, false);
if (PQstatus(remote_conn) != CONNECTION_OK)
continue;
is_node_standby = is_standby(remote_conn);
if (is_node_standby == -1)
{
log_err(_("unable to retrieve recovery state from node %i:\n%s\n"),
node_id,
PQerrorMessage(remote_conn));
PQfinish(remote_conn);
continue;
}
/* if is_standby() returns 0, queried node is the master */
if (is_node_standby == 0)
{
PQclear(res);
log_debug(_("get_master_connection(): current master node is %i\n"), node_id);
if (master_id != NULL)
{
*master_id = node_id;
}
return remote_conn;
}
/* if it is a standby, clear connection info and continue*/
PQfinish(remote_conn);
}
/*
* If we finish this loop without finding a master then we doesn't have
* the info or the master has failed (or we reached max_connections or
* superuser_reserved_connections, anything else I'm missing?).
*
* Probably we will need to check the error to know if we need to start
* failover procedure or just fix some situation on the standby.
*/
PQclear(res);
return NULL;
}
/*
* wait until current query finishes ignoring any results, this could be an
* async command or a cancelation of a query
* return 1 if Ok; 0 if any error ocurred; -1 if timeout reached
*/
int
wait_connection_availability(PGconn *conn, long long timeout)
{
PGresult *res;
fd_set read_set;
int sock = PQsocket(conn);
struct timeval tmout,
before,
after;
struct timezone tz;
/* recalc to microseconds */
timeout *= 1000000;
while (timeout > 0)
{
if (PQconsumeInput(conn) == 0)
{
log_warning(_("wait_connection_availability(): could not receive data from connection. %s\n"),
PQerrorMessage(conn));
return 0;
}
if (PQisBusy(conn) == 0)
{
do
{
res = PQgetResult(conn);
PQclear(res);
} while (res != NULL);
break;
}
tmout.tv_sec = 0;
tmout.tv_usec = 250000;
FD_ZERO(&read_set);
FD_SET(sock, &read_set);
gettimeofday(&before, &tz);
if (select(sock, &read_set, NULL, NULL, &tmout) == -1)
{
log_warning(
_("wait_connection_availability(): select() returned with error\n%s\n"),
strerror(errno));
return -1;
}
gettimeofday(&after, &tz);
timeout -= (after.tv_sec * 1000000 + after.tv_usec) -
(before.tv_sec * 1000000 + before.tv_usec);
}
if (timeout >= 0)
{
return 1;
}
log_warning(_("wait_connection_availability(): timeout reached"));
return -1;
}
bool
cancel_query(PGconn *conn, int timeout)
{
char errbuf[ERRBUFF_SIZE];
PGcancel *pgcancel;
if (wait_connection_availability(conn, timeout) != 1)
return false;
pgcancel = PQgetCancel(conn);
if (pgcancel == NULL)
return false;
/*
* PQcancel can only return 0 if socket()/connect()/send() fails, in any
* of those cases we can assume something bad happened to the connection
*/
if (PQcancel(pgcancel, errbuf, ERRBUFF_SIZE) == 0)
{
log_warning(_("Can't stop current query: %s\n"), errbuf);
PQfreeCancel(pgcancel);
return false;
}
PQfreeCancel(pgcancel);
return true;
}
/* Return the repmgr schema as an unmodified string
* This is useful for displaying the schema name in log messages,
* however inclusion in SQL statements, get_repmgr_schema_quoted() should
* always be used.
*/
char *
get_repmgr_schema(void)
{
return repmgr_schema;
}
char *
get_repmgr_schema_quoted(PGconn *conn)
{
if (strcmp(repmgr_schema_quoted, "") == 0)
{
char *identifier = PQescapeIdentifier(conn, repmgr_schema,
strlen(repmgr_schema));
maxlen_snprintf(repmgr_schema_quoted, "%s", identifier);
PQfreemem(identifier);
}
return repmgr_schema_quoted;
}
bool
create_replication_slot(PGconn *conn, char *slot_name, int server_version_num, PQExpBufferData *error_msg)
{
char sqlquery[QUERY_STR_LEN];
int query_res;
PGresult *res;
t_replication_slot slot_info;