Hello hackers,
Couple of years ago Victor Wagner presented a patch [1] that introduced
multiple hosts capability and also hostorder and failover_timeout
parameters for libpq. Subsequently multi-host feature was reimplemented
by Robert Haas and committed. Later target_session_attrs parameter was
also added. In this thread I want to revisit hostorder and
failover_timeout proposal.
'hostorder' defines the order in which postgres instances listed in
connection string will be tried. Possible values are:
* sequential (default)
* random
Random order can be used, for instance, for maintaining load balancing
(which is particularly useful in multi-master cluster, but also can be
used to load-balance read-only connections to standbys).
'failover_timeout' specifies time span (in seconds) during which libpq
would continue attempts to connect to the hosts listed in connection
string. If failover_timeout is specified then libpq will loop over hosts
again and again until either it successfully connects to one of the
hosts or it runs out of time.
I reimplemented 'hostorder' and 'failover_timeout' parameters in the
attached patch. I also took some documentation pieces from Victor
Wagner's original patch. I'll be glad to see any comments and
suggestions. Thanks!
[1]
https://www.postgresql.org/message-id/flat/20150818041850.GA5092%40wagner.pp.ru
--
Ildar Musin
i.mu...@postgrespro.ru
diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index 800e68a..a9ba534 100644
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -845,7 +845,7 @@ postgresql://localhost/mydb
postgresql://user@localhost
postgresql://user:secret@localhost
postgresql://other@localhost/otherdb?connect_timeout=10&application_name=myapp
-postgresql://host1:123,host2:456/somedb?target_session_attrs=any&application_name=myapp
+postgresql://host1:123,host2:456/somedb?hostorder=random&target_session_attrs=any&application_name=myapp
</programlisting>
Components of the hierarchical part of the <acronym>URI</acronym> can also
be given as parameters. For example:
@@ -910,14 +910,15 @@ postgresql://%2Fvar%2Flib%2Fpostgresql/dbname
<title>Specifying Multiple Hosts</title>
<para>
- It is possible to specify multiple hosts to connect to, so that they are
- tried in the given order. In the Keyword/Value format, the <literal>host</literal>,
- <literal>hostaddr</literal>, and <literal>port</literal> options accept a comma-separated
- list of values. The same number of elements must be given in each option, such
- that e.g. the first <literal>hostaddr</literal> corresponds to the first host name,
- the second <literal>hostaddr</literal> corresponds to the second host name, and so
- forth. As an exception, if only one <literal>port</literal> is specified, it
- applies to all the hosts.
+ It is possible to specify multiple hosts to connect to. In the Keyword/Value
+ format, the <literal>host</literal>, <literal>hostaddr</literal>, and
+ <literal>port</literal> options accept a comma-separated list of values.
+ The same number of elements must be given in each option, such that e.g. the
+ first <literal>hostaddr</literal> corresponds to the first host name, the second
+ <literal>hostaddr</literal> corresponds to the second host name, and so
+ forth. As an exception, if only one <literal>port</literal> is specified,
+ it applies to all the hosts. The order in which hosts are tried may be
+ specified by <xref linkend="libpq-connect-hostorder"/> parameter.
</para>
<para>
@@ -968,8 +969,7 @@ postgresql://%2Fvar%2Flib%2Fpostgresql/dbname
Unix-domain sockets, the default is to connect to <literal>localhost</literal>.
</para>
<para>
- A comma-separated list of host names is also accepted, in which case
- each host name in the list is tried in order. See
+ A comma-separated list of host names is also accepted. See
<xref linkend="libpq-multiple-hosts"/> for details.
</para>
</listitem>
@@ -1039,6 +1039,30 @@ postgresql://%2Fvar%2Flib%2Fpostgresql/dbname
</listitem>
</varlistentry>
+ <varlistentry id="libpq-connect-hostorder" xreflabel="hostorder">
+ <term><literal>hostorder</literal></term>
+ <listitem>
+ <para>
+ Specifies the order in which hosts from the list of hosts
+ specified by the <xref linkend="libpq-connect-host"/> parameter are
+ tried.
+ </para>
+ <para>
+ If the value of this argument is <literal>sequential</literal> (the
+ default) connections to the hosts will be attempted in the order in
+ which they are given.
+ </para>
+ <para>
+ If the value is <literal>random</literal>, the host to connect to
+ will be randomly picked from the list. It allows load balacing between
+ several cluster nodes. However, PostgreSQL doesn't currently support
+ multimaster clusters. So, without the use of third-party products,
+ only read-only connections can take advantage from load-balancing.
+ See <xref linkend="libpq-connect-target-session-attrs"/>
+ </para>
+ </listitem>
+ </varlistentry>
+
<varlistentry id="libpq-connect-port" xreflabel="port">
<term><literal>port</literal></term>
<listitem>
@@ -1115,6 +1139,29 @@ postgresql://%2Fvar%2Flib%2Fpostgresql/dbname
</listitem>
</varlistentry>
+ <varlistentry id="libpq-connect-falover-timeout" xreflabel="failover_timeout">
+ <term><literal>failover_timeout</literal></term>
+ <listitem>
+ <para>
+ Maximum time to cyclically retry all the hosts in the connection string.
+ (as decimal integer number of seconds). If not specified, then
+ hosts are tried just once.
+ </para>
+ <para>
+ If we have replicating cluster, and master node fails, it might
+ take some time to promote one of the standby nodes to the new master.
+ So clients which detect failure to connect to the master might
+ abandon attempts to reestablish a connection before the new master
+ becomes available.
+ </para>
+ <para>
+ Setting this parameter to a value that takes into account the amount of
+ time needed for failover to complete will ensure attempts to connect
+ to hosts continue to be made until the new master becomes available.
+ </para>
+ </listitem>
+ </varlistentry>
+
<varlistentry id="libpq-connect-client-encoding" xreflabel="client_encoding">
<term><literal>client_encoding</literal></term>
<listitem>
diff --git a/src/interfaces/libpq/Makefile b/src/interfaces/libpq/Makefile
index abe0a50..18b6a78 100644
--- a/src/interfaces/libpq/Makefile
+++ b/src/interfaces/libpq/Makefile
@@ -35,8 +35,8 @@ OBJS= fe-auth.o fe-auth-scram.o fe-connect.o fe-exec.o fe-misc.o fe-print.o fe-l
fe-protocol2.o fe-protocol3.o pqexpbuffer.o fe-secure.o \
libpq-events.o
# libpgport C files we always use
-OBJS += chklocale.o inet_net_ntop.o noblock.o pgstrcasecmp.o pqsignal.o \
- thread.o
+OBJS += chklocale.o inet_net_ntop.o noblock.o pgsleep.o pgstrcasecmp.o \
+ pqsignal.o thread.o
# libpgport C files that are needed if identified by configure
OBJS += $(filter crypt.o getaddrinfo.o getpeereid.o inet_aton.o open.o system.o snprintf.o strerror.o strlcpy.o strnlen.o win32error.o win32setlocale.o, $(LIBOBJS))
@@ -78,7 +78,7 @@ endif
# shared library link. (The order in which you list them here doesn't
# matter.)
ifneq ($(PORTNAME), win32)
-SHLIB_LINK += $(filter -lcrypt -ldes -lcom_err -lcrypto -lk5crypto -lkrb5 -lgssapi_krb5 -lgss -lgssapi -lssl -lsocket -lnsl -lresolv -lintl, $(LIBS)) $(LDAP_LIBS_FE) $(PTHREAD_LIBS)
+SHLIB_LINK += $(filter -lcrypt -ldes -lcom_err -lcrypto -lk5crypto -lkrb5 -lgssapi_krb5 -lgss -lgssapi -lssl -lsocket -lnsl -lresolv -lintl -lrt, $(LIBS)) $(LDAP_LIBS_FE) $(PTHREAD_LIBS)
else
SHLIB_LINK += $(filter -lcrypt -ldes -lcom_err -lcrypto -lk5crypto -lkrb5 -lgssapi32 -lssl -lsocket -lnsl -lresolv -lintl $(PTHREAD_LIBS), $(LIBS)) $(LDAP_LIBS_FE)
endif
diff --git a/src/interfaces/libpq/fe-auth.c b/src/interfaces/libpq/fe-auth.c
index 3b2073a..f908a32 100644
--- a/src/interfaces/libpq/fe-auth.c
+++ b/src/interfaces/libpq/fe-auth.c
@@ -44,6 +44,9 @@
#include "fe-auth.h"
+#define CURRENT_HOST(conn) \
+ ((conn)->connhost[(conn)->connaddr[(conn)->whichaddr].hostidx])
+
#ifdef ENABLE_GSS
/*
* GSSAPI authentication system.
@@ -558,7 +561,7 @@ pg_SASL_init(PGconn *conn, int payloadlen)
* password, so we can just go ahead here without further distinction.
*/
conn->password_needed = true;
- password = conn->connhost[conn->whichhost].password;
+ password = CURRENT_HOST(conn).password;
if (password == NULL)
password = conn->pgpass;
if (password == NULL || password[0] == '\0')
@@ -967,7 +970,7 @@ pg_fe_sendauth(AuthRequest areq, int payloadlen, PGconn *conn)
char *password;
conn->password_needed = true;
- password = conn->connhost[conn->whichhost].password;
+ password = CURRENT_HOST(conn).password;
if (password == NULL)
password = conn->pgpass;
if (password == NULL || password[0] == '\0')
diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index f3057e9..07ea7e5 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -75,6 +75,8 @@ static int ldapServiceLookup(const char *purl, PQconninfoOption *options,
#include "mb/pg_wchar.h"
#include "port/pg_bswap.h"
+#include "portability/instr_time.h"
+
#ifndef WIN32
#define PGPASSFILE ".pgpass"
@@ -123,6 +125,7 @@ static int ldapServiceLookup(const char *purl, PQconninfoOption *options,
#define DefaultOption ""
#define DefaultAuthtype ""
#define DefaultTargetSessionAttrs "any"
+#define DefaultHostorder "sequential"
#define DefaultSCRAMChannelBinding SCRAM_CHANNEL_BINDING_TLS_UNIQUE
#ifdef USE_SSL
#define DefaultSSLMode "prefer"
@@ -130,6 +133,11 @@ static int ldapServiceLookup(const char *purl, PQconninfoOption *options,
#define DefaultSSLMode "disable"
#endif
+#define CURRENT_HOST(conn) \
+ ((conn)->connhost[(conn)->connaddr[(conn)->whichaddr].hostidx])
+#define SHOULD_TRY_NEXT_ADDR(conn) \
+ ((conn)->whichaddr + 1 < (conn)->nconnaddr || (conn)->failover_timeout)
+
/* ----------
* Definition of the conninfo parameters and their fallback resources.
*
@@ -330,6 +338,14 @@ static const internalPQconninfoOption PQconninfoOptions[] = {
"Target-Session-Attrs", "", 11, /* sizeof("read-write") = 11 */
offsetof(struct pg_conn, target_session_attrs)},
+ {"hostorder", NULL, DefaultHostorder, NULL,
+ "Hostorder", "", 10, /* sizeof("sequential") = 10 */
+ offsetof(struct pg_conn, hostorder)},
+
+ {"failover_timeout", NULL, NULL, NULL,
+ "Failover Timeout", "", 10,
+ offsetof(struct pg_conn, failover_timeout)},
+
/* Terminating entry --- MUST BE LAST */
{NULL, NULL, NULL, NULL,
NULL, NULL, 0}
@@ -410,6 +426,7 @@ static char *passwordFromFile(const char *hostname, const char *port, const char
const char *username, const char *pgpassfile);
static void pgpassfileWarning(PGconn *conn);
static void default_threadlock(int acquire);
+static void displayed_host_port(PGconn *conn, char **displayed_host, char **displayed_port);
/* global variable because fe-auth.c needs to access it */
@@ -906,7 +923,7 @@ connectOptions2(PGconn *conn)
* try to connect. For that, count the number of elements in the hostaddr
* or host options. If neither is given, assume one host.
*/
- conn->whichhost = 0;
+ conn->whichaddr = 0;
if (conn->pghostaddr && conn->pghostaddr[0] != '\0')
conn->nconnhost = count_comma_separated_elems(conn->pghostaddr);
else if (conn->pghost && conn->pghost[0] != '\0')
@@ -935,6 +952,7 @@ connectOptions2(PGconn *conn)
goto oom_error;
conn->connhost[i].type = CHT_HOST_ADDRESS;
+ conn->connhost[i].readonly = false;
}
/*
@@ -967,6 +985,7 @@ connectOptions2(PGconn *conn)
conn->connhost[i].type = CHT_UNIX_SOCKET;
#endif
}
+ conn->connhost[i].readonly = false;
}
if (more || i != conn->nconnhost)
{
@@ -992,6 +1011,7 @@ connectOptions2(PGconn *conn)
conn->connhost[0].host = strdup(DefaultHost);
conn->connhost[0].type = CHT_HOST_NAME;
#endif
+ conn->connhost[0].readonly = false;
if (conn->connhost[0].host == NULL)
goto oom_error;
}
@@ -1195,6 +1215,22 @@ connectOptions2(PGconn *conn)
}
/*
+ * Validate hostorder option.
+ */
+ if (conn->hostorder)
+ {
+ if (strcmp(conn->hostorder, "sequential") != 0
+ && strcmp(conn->hostorder, "random") != 0)
+ {
+ conn->status = CONNECTION_BAD;
+ printfPQExpBuffer(&conn->errorMessage,
+ libpq_gettext("invalid hostorder value: \"%s\"\n"),
+ conn->hostorder);
+ return false;
+ }
+ }
+
+ /*
* Only if we get this far is it appropriate to try to connect. (We need a
* state flag, rather than just the boolean result of this function, in
* case someone tries to PQreset() the PGconn.)
@@ -1445,17 +1481,17 @@ connectFailureMessage(PGconn *conn, int errorno)
else
#endif /* HAVE_UNIX_SOCKETS */
{
- char host_addr[NI_MAXHOST];
- const char *displayed_host;
- const char *displayed_port;
+ char host_addr[NI_MAXHOST];
+ char *displayed_host;
+ char *displayed_port;
struct sockaddr_storage *addr = &conn->raddr.addr;
/*
* Optionally display the network address with the hostname. This is
* useful to distinguish between IPv4 and IPv6 connections.
*/
- if (conn->connhost[conn->whichhost].type == CHT_HOST_ADDRESS)
- strlcpy(host_addr, conn->connhost[conn->whichhost].hostaddr, NI_MAXHOST);
+ if (CURRENT_HOST(conn).type == CHT_HOST_ADDRESS)
+ strlcpy(host_addr, CURRENT_HOST(conn).hostaddr, NI_MAXHOST);
else if (addr->ss_family == AF_INET)
{
if (inet_net_ntop(AF_INET,
@@ -1478,20 +1514,14 @@ connectFailureMessage(PGconn *conn, int errorno)
strcpy(host_addr, "???");
/* To which host and port were we actually connecting? */
- if (conn->connhost[conn->whichhost].type == CHT_HOST_ADDRESS)
- displayed_host = conn->connhost[conn->whichhost].hostaddr;
- else
- displayed_host = conn->connhost[conn->whichhost].host;
- displayed_port = conn->connhost[conn->whichhost].port;
- if (displayed_port == NULL || displayed_port[0] == '\0')
- displayed_port = DEF_PGPORT_STR;
+ displayed_host_port(conn, &displayed_host, &displayed_port);
/*
* If the user did not supply an IP address using 'hostaddr', and
* 'host' was missing or does not match our lookup, display the
* looked-up IP address.
*/
- if (conn->connhost[conn->whichhost].type != CHT_HOST_ADDRESS &&
+ if (CURRENT_HOST(conn).type != CHT_HOST_ADDRESS &&
strcmp(displayed_host, host_addr) != 0)
appendPQExpBuffer(&conn->errorMessage,
libpq_gettext("could not connect to server: %s\n"
@@ -1691,6 +1721,9 @@ connectDBStart(PGconn *conn)
int ret;
int i;
+ pg_conn_address addrs[1024]; /* TODO */
+ int naddrs = 0;
+
if (!conn)
return 0;
@@ -1794,6 +1827,60 @@ connectDBStart(PGconn *conn)
conn->options_valid = false;
goto connect_errReturn;
}
+
+ if (ch->addrlist)
+ {
+ struct addrinfo *addr;
+
+ for (addr = ch->addrlist; addr != NULL; addr = addr->ai_next)
+ {
+ addrs[naddrs].info = addr;
+ addrs[naddrs++].hostidx = i;
+ }
+ }
+ }
+
+ if (naddrs)
+ {
+ Size connaddr_sz = sizeof(pg_conn_address) * naddrs;
+
+ conn->connaddr = malloc(connaddr_sz);
+ if (!conn->connaddr)
+ {
+ printfPQExpBuffer(&conn->errorMessage,
+ libpq_gettext("out of memory\n"));
+ goto connect_errReturn;
+ }
+ memcpy((char *) conn->connaddr, (char *) addrs, connaddr_sz);
+ conn->nconnaddr = naddrs;
+
+ /*
+ * If random hostorder is specified then permutate original
+ * addresses array
+ */
+ if (conn->hostorder != NULL
+ && strcmp(conn->hostorder, "random") == 0)
+ {
+ int i;
+ instr_time t;
+
+ INSTR_TIME_SET_CURRENT(t);
+ srandom((unsigned int) INSTR_TIME_GET_MICROSEC(t));
+
+ for (i = 0; i < naddrs; i++)
+ {
+ long r1 = random() % naddrs,
+ r2 = random() % naddrs;
+ pg_conn_address tmp;
+
+ if (r1 == r2)
+ continue;
+
+ tmp = conn->connaddr[r1];
+ conn->connaddr[r1] = conn->connaddr[r2];
+ conn->connaddr[r2] = tmp;
+ }
+ }
}
#ifdef USE_SSL
@@ -1807,11 +1894,15 @@ connectDBStart(PGconn *conn)
/*
* Set up to try to connect, with protocol 3.0 as the first attempt.
*/
- conn->whichhost = 0;
- conn->addr_cur = conn->connhost[0].addrlist;
+ conn->whichaddr = 0;
conn->pversion = PG_PROTOCOL(3, 0);
conn->send_appname = true;
conn->status = CONNECTION_NEEDED;
+ if (conn->failover_timeout)
+ conn->failover_finish_time = time(NULL) + atoi(conn->failover_timeout);
+ else
+ conn->failover_finish_time = (time_t) 0; /* it is in past, so its
+ * ok */
/*
* The code for processing CONNECTION_NEEDED state is in PQconnectPoll(),
@@ -1914,9 +2005,9 @@ connectDBComplete(PGconn *conn)
* If there are no more hosts, return (the error message is
* already set)
*/
- if (++conn->whichhost >= conn->nconnhost)
+ if (conn->whichaddr + 1 >= conn->nconnaddr)
{
- conn->whichhost = 0;
+ conn->whichaddr = 0;
conn->status = CONNECTION_BAD;
return 0;
}
@@ -1926,7 +2017,6 @@ connectDBComplete(PGconn *conn)
* connect_timeout timer
*/
pqDropConnection(conn, true);
- conn->addr_cur = conn->connhost[conn->whichhost].addrlist;
conn->status = CONNECTION_NEEDED;
if (conn->connect_timeout != NULL)
finish_time = time(NULL) + timeout;
@@ -2071,30 +2161,56 @@ keep_going: /* We will come back to here until there is
{
/*
* Try to initiate a connection to one of the addresses
- * returned by pg_getaddrinfo_all(). conn->addr_cur is the
- * next one to try. We fail when we run out of addresses.
+ * returned by pg_getaddrinfo_all(). conn->whichaddr is the
+ * index in conn->connaddrs which points to the next address
+ * to try. We fail when we run out of addresses.
*/
for (;;)
{
struct addrinfo *addr_cur;
- /*
- * Advance to next possible host, if we've tried all of
- * the addresses for the current host.
- */
- if (conn->addr_cur == NULL)
+ /* No more addresses */
+ if (conn->whichaddr >= conn->nconnaddr)
{
- if (++conn->whichhost >= conn->nconnhost)
+ if (time(NULL) < conn->failover_finish_time)
{
- conn->whichhost = 0;
- break;
+ /*
+ * If failover timeout is set, retry list of hosts
+ * from the beginning
+ */
+ pg_usleep(1000000);
+ conn->whichaddr = 0;
+
+ /*
+ * Reset readonly flag for all hosts as one of
+ * them might have been promoted
+ */
+ if (strcmp(conn->target_session_attrs, "read-write") == 0)
+ {
+ int i;
+
+ for (i = 0; i < conn->nconnhost; i++)
+ conn->connhost[i].readonly = false;
+ }
}
- conn->addr_cur =
- conn->connhost[conn->whichhost].addrlist;
+ else
+ break; /* Stop trying */
+ }
+
+ /*
+ * If read-write connection is required check whether
+ * host was already marked as read-only
+ */
+ if (conn->target_session_attrs != NULL
+ && strcmp(conn->target_session_attrs, "read-write") == 0
+ && CURRENT_HOST(conn).readonly)
+ {
+ conn->whichaddr++;
+ continue;
}
/* Remember current address for possible error msg */
- addr_cur = conn->addr_cur;
+ addr_cur = conn->connaddr[conn->whichaddr].info;
memcpy(&conn->raddr.addr, addr_cur->ai_addr,
addr_cur->ai_addrlen);
conn->raddr.salen = addr_cur->ai_addrlen;
@@ -2106,10 +2222,9 @@ keep_going: /* We will come back to here until there is
* ignore socket() failure if we have more addresses
* to try
*/
- if (addr_cur->ai_next != NULL ||
- conn->whichhost + 1 < conn->nconnhost)
+ if (SHOULD_TRY_NEXT_ADDR(conn))
{
- conn->addr_cur = addr_cur->ai_next;
+ conn->whichaddr++;
continue;
}
appendPQExpBuffer(&conn->errorMessage,
@@ -2128,7 +2243,7 @@ keep_going: /* We will come back to here until there is
if (!connectNoDelay(conn))
{
pqDropConnection(conn, true);
- conn->addr_cur = addr_cur->ai_next;
+ conn->whichaddr++;
continue;
}
}
@@ -2138,7 +2253,7 @@ keep_going: /* We will come back to here until there is
libpq_gettext("could not set socket to nonblocking mode: %s\n"),
SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
pqDropConnection(conn, true);
- conn->addr_cur = addr_cur->ai_next;
+ conn->whichaddr++;
continue;
}
@@ -2149,7 +2264,7 @@ keep_going: /* We will come back to here until there is
libpq_gettext("could not set socket to close-on-exec mode: %s\n"),
SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
pqDropConnection(conn, true);
- conn->addr_cur = addr_cur->ai_next;
+ conn->whichaddr++;
continue;
}
#endif /* F_SETFD */
@@ -2197,7 +2312,7 @@ keep_going: /* We will come back to here until there is
if (err)
{
pqDropConnection(conn, true);
- conn->addr_cur = addr_cur->ai_next;
+ conn->whichaddr++;
continue;
}
}
@@ -2286,9 +2401,9 @@ keep_going: /* We will come back to here until there is
pqDropConnection(conn, true);
/*
- * Try the next address, if any.
+ * Advance to next address
*/
- conn->addr_cur = addr_cur->ai_next;
+ conn->whichaddr++;
} /* loop over addresses */
/*
@@ -2334,10 +2449,9 @@ keep_going: /* We will come back to here until there is
* If more addresses remain, keep trying, just as in the
* case where connect() returned failure immediately.
*/
- if (conn->addr_cur->ai_next != NULL ||
- conn->whichhost + 1 < conn->nconnhost)
+ if (SHOULD_TRY_NEXT_ADDR(conn))
{
- conn->addr_cur = conn->addr_cur->ai_next;
+ conn->whichaddr++;
conn->status = CONNECTION_NEEDED;
goto keep_going;
}
@@ -3099,8 +3213,8 @@ keep_going: /* We will come back to here until there is
}
case CONNECTION_CHECK_WRITABLE:
{
- const char *displayed_host;
- const char *displayed_port;
+ char *displayed_host;
+ char *displayed_port;
if (!saveErrorMessage(conn, &savedMessage))
goto error_return;
@@ -3128,16 +3242,11 @@ keep_going: /* We will come back to here until there is
val = PQgetvalue(res, 0, 0);
if (strncmp(val, "on", 2) == 0)
{
- const char *displayed_host;
- const char *displayed_port;
+ char *displayed_host;
+ char *displayed_port;
- if (conn->connhost[conn->whichhost].type == CHT_HOST_ADDRESS)
- displayed_host = conn->connhost[conn->whichhost].hostaddr;
- else
- displayed_host = conn->connhost[conn->whichhost].host;
- displayed_port = conn->connhost[conn->whichhost].port;
- if (displayed_port == NULL || displayed_port[0] == '\0')
- displayed_port = DEF_PGPORT_STR;
+ CURRENT_HOST(conn).readonly = true;
+ displayed_host_port(conn, &displayed_host, &displayed_port);
PQclear(res);
restoreErrorMessage(conn, &savedMessage);
@@ -3152,10 +3261,9 @@ keep_going: /* We will come back to here until there is
sendTerminateConn(conn);
pqDropConnection(conn, true);
- /* Skip any remaining addresses for this host. */
- conn->addr_cur = NULL;
- if (conn->whichhost + 1 < conn->nconnhost)
+ if (SHOULD_TRY_NEXT_ADDR(conn))
{
+ conn->whichaddr++;
conn->status = CONNECTION_NEEDED;
goto keep_going;
}
@@ -3185,13 +3293,7 @@ keep_going: /* We will come back to here until there is
PQclear(res);
restoreErrorMessage(conn, &savedMessage);
- if (conn->connhost[conn->whichhost].type == CHT_HOST_ADDRESS)
- displayed_host = conn->connhost[conn->whichhost].hostaddr;
- else
- displayed_host = conn->connhost[conn->whichhost].host;
- displayed_port = conn->connhost[conn->whichhost].port;
- if (displayed_port == NULL || displayed_port[0] == '\0')
- displayed_port = DEF_PGPORT_STR;
+ displayed_host_port(conn, &displayed_host, &displayed_port);
appendPQExpBuffer(&conn->errorMessage,
libpq_gettext("test \"SHOW transaction_read_only\" failed "
"on server \"%s:%s\"\n"),
@@ -3200,10 +3302,9 @@ keep_going: /* We will come back to here until there is
sendTerminateConn(conn);
pqDropConnection(conn, true);
- if (conn->addr_cur->ai_next != NULL ||
- conn->whichhost + 1 < conn->nconnhost)
+ if (SHOULD_TRY_NEXT_ADDR(conn))
{
- conn->addr_cur = conn->addr_cur->ai_next;
+ conn->whichaddr++;
conn->status = CONNECTION_NEEDED;
goto keep_going;
}
@@ -3438,6 +3539,8 @@ freePGconn(PGconn *conn)
free(conn->connhost);
}
+ if (conn->connaddr)
+ free(conn->connaddr);
if (conn->client_encoding_initial)
free(conn->client_encoding_initial);
if (conn->events)
@@ -3547,7 +3650,6 @@ release_all_addrinfo(PGconn *conn)
conn->connhost[i].addrlist = NULL;
}
}
- conn->addr_cur = NULL;
}
/*
@@ -6002,8 +6104,8 @@ PQpass(const PGconn *conn)
if (!conn)
return NULL;
- if (conn->connhost != NULL)
- password = conn->connhost[conn->whichhost].password;
+ if (conn->connhost != NULL && conn->connaddr != NULL)
+ password = CURRENT_HOST(conn).password;
if (password == NULL)
password = conn->pgpass;
/* Historically we've returned "" not NULL for no password specified */
@@ -6020,12 +6122,12 @@ PQhost(const PGconn *conn)
if (conn->connhost != NULL)
{
- if (conn->connhost[conn->whichhost].host != NULL &&
- conn->connhost[conn->whichhost].host[0] != '\0')
- return conn->connhost[conn->whichhost].host;
- else if (conn->connhost[conn->whichhost].hostaddr != NULL &&
- conn->connhost[conn->whichhost].hostaddr[0] != '\0')
- return conn->connhost[conn->whichhost].hostaddr;
+ if (CURRENT_HOST(conn).host != NULL &&
+ CURRENT_HOST(conn).host[0] != '\0')
+ return CURRENT_HOST(conn).host;
+ else if (CURRENT_HOST(conn).hostaddr != NULL &&
+ CURRENT_HOST(conn).hostaddr[0] != '\0')
+ return CURRENT_HOST(conn).hostaddr;
}
return "";
@@ -6038,7 +6140,7 @@ PQport(const PGconn *conn)
return NULL;
if (conn->connhost != NULL)
- return conn->connhost[conn->whichhost].port;
+ return CURRENT_HOST(conn).port;
return "";
}
@@ -6615,3 +6717,17 @@ PQregisterThreadLock(pgthreadlock_t newhandler)
return prev;
}
+
+static void
+displayed_host_port(PGconn *conn, char **displayed_host, char **displayed_port)
+{
+ pg_conn_host *h = &CURRENT_HOST(conn);
+
+ if (h->type == CHT_HOST_ADDRESS)
+ *displayed_host = h->hostaddr;
+ else
+ *displayed_host = h->host;
+ *displayed_port = h->port;
+ if (*displayed_port == NULL || *displayed_port[0] == '\0')
+ *displayed_port = DEF_PGPORT_STR;
+}
diff --git a/src/interfaces/libpq/libpq-int.h b/src/interfaces/libpq/libpq-int.h
index eba23dc..4e46766 100644
--- a/src/interfaces/libpq/libpq-int.h
+++ b/src/interfaces/libpq/libpq-int.h
@@ -313,8 +313,15 @@ typedef struct pg_conn_host
* password file. only set if the PGconn's
* pgpass field is NULL. */
struct addrinfo *addrlist; /* list of possible backend addresses */
+ bool readonly; /* true if host is proved to be read-only */
} pg_conn_host;
+typedef struct pg_conn_address
+{
+ struct addrinfo *info;
+ int hostidx; /* host index in connhost array */
+} pg_conn_address;
+
/*
* PGconn stores all the state data associated with a single connection
* to a backend.
@@ -365,6 +372,12 @@ struct pg_conn
/* Type of connection to make. Possible values: any, read-write. */
char *target_session_attrs;
+ /* Connection order. Possible values: sequential, random */
+ char *hostorder;
+
+ char *failover_timeout;
+ time_t failover_finish_time;
+
/* Optional file to write trace info to */
FILE *Pfdebug;
@@ -394,8 +407,10 @@ struct pg_conn
/* Support for multiple hosts in connection string */
int nconnhost; /* # of possible hosts */
- int whichhost; /* host we're currently considering */
pg_conn_host *connhost; /* details about each possible host */
+ int nconnaddr; /* # of possible addresses */
+ int whichaddr; /* address we're currently considering */
+ pg_conn_address *connaddr; /* plain array of all addresses */
/* Connection data */
pgsocket sock; /* FD for socket, PGINVALID_SOCKET if
@@ -411,7 +426,6 @@ struct pg_conn
bool sigpipe_flag; /* can we mask SIGPIPE via MSG_NOSIGNAL? */
/* Transient state needed while establishing connection */
- struct addrinfo *addr_cur; /* backend address currently being tried */
PGSetenvStatusType setenv_state; /* for 2.0 protocol only */
const PQEnvironmentOption *next_eo;
bool send_appname; /* okay to send application_name? */
