Changeset: 85b7a3eb0880 for MonetDB
URL: http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=85b7a3eb0880
Modified Files:
tools/merovingian/daemon/multiplex-funnel.c
tools/merovingian/daemon/multiplex-funnel.h
Branch: default
Log Message:
multiplex: defer cycling connections until not in use
Under full stress, mapi would not be too happy when operations are
executed on a Mapi handle, that from another thread is being destroyed.
Obviously this leads to segfaults. To avoid connection switch overs
during queries to result in segfaults, delay the actually switch made
effective until the point we know noone is using the connection.
On a high-stress environment, this now happily keeps on running
correctly with switches allover.
diffs (124 lines):
diff --git a/tools/merovingian/daemon/multiplex-funnel.c
b/tools/merovingian/daemon/multiplex-funnel.c
--- a/tools/merovingian/daemon/multiplex-funnel.c
+++ b/tools/merovingian/daemon/multiplex-funnel.c
@@ -155,9 +155,9 @@
Mfprintf(stderr, "target %s can no longer "
"be resolved\n",
m->dbcv[i]->database);
-
m->dbcv[i]->conn = NULL;
-
mapi_disconnect(tm);
-
mapi_destroy(tm);
+ /* schedule to
drop connection */
+
m->dbcv[i]->newconn = NULL;
+
m->dbcv[i]->connupdate = 1;
continue;
}
/* walk all
connections, in an attempt to
@@ -171,7 +171,6 @@
break;
}
if (walk == NULL) {
- Mapi ttm;
snprintf(buf,
sizeof(buf), "%s%s",
stats->conns->val, stats->dbname);
Mfprintf(stdout, "changing multiplexer target %s: %s->%s\n",
@@ -185,20 +184,17 @@
m->dbcv[i]->database,
mapi_error_str(tm));
mapi_destroy(tm);
- tm =
m->dbcv[i]->conn;
-
m->dbcv[i]->conn = NULL;
-
mapi_disconnect(tm);
-
mapi_destroy(tm);
+ /*
schedule connection for removal */
+
m->dbcv[i]->newconn = NULL;
+
m->dbcv[i]->connupdate = 1;
msab_freeStatus(&stats);
continue;
}
mapi_cache_limit(tm, -1); /* don't page */
- /* set the new
connection live */
- ttm =
m->dbcv[i]->conn;
-
m->dbcv[i]->conn = tm;
-
mapi_disconnect(ttm);
-
mapi_destroy(ttm);
+ /* let the new
connection go live */
+
m->dbcv[i]->newconn = tm;
+
m->dbcv[i]->connupdate = 1;
}
msab_freeStatus(&stats);
}
@@ -298,6 +294,8 @@
*p = '\0';
m->dbcv[i]->database = p + 1;
m->dbcv[i]->conn = NULL;
+ m->dbcv[i]->newconn = NULL;
+ m->dbcv[i]->connupdate = 0;
i++;
p = q + 1;
@@ -332,6 +330,8 @@
*p = '\0';
m->dbcv[i]->database = p + 1;
m->dbcv[i]->conn = NULL;
+ m->dbcv[i]->newconn = NULL;
+ m->dbcv[i]->connupdate = 0;
}
}
@@ -507,7 +507,7 @@
multiplex_client *c;
int msock = -1;
char buf[BLOCK + 1];
- int r;
+ int r, i;
/* select on upstream clients, on new data, read query, forward,
* union all results, send back, and restart cycle. */
@@ -520,10 +520,29 @@
if (c->sock > msock)
msock = c->sock;
}
- /* wait up to 5 seconds. */
- tv.tv_sec = 5;
+
+ /* wait up to 1 second. */
+ tv.tv_sec = 1;
tv.tv_usec = 0;
r = select(msock + 1, &fds, NULL, NULL, &tv);
+
+ /* evaluate if connections have to be switched */
+ for (i = 0; i < m->dbcc; i++) {
+ if (m->dbcv[i]->connupdate) {
+ /* put new connection live */
+ Mfprintf(stdout, "performing deferred
connection cycle "
+ "for %s from %s to %s",
+ m->dbcv[i]->database,
+ mapi_get_uri(m->dbcv[i]->conn),
+
mapi_get_uri(m->dbcv[i]->newconn));
+ mapi_disconnect(m->dbcv[i]->conn);
+ mapi_destroy(m->dbcv[i]->conn);
+ m->dbcv[i]->conn = m->dbcv[i]->newconn;
+ m->dbcv[i]->newconn = NULL;
+ m->dbcv[i]->connupdate = 0;
+ }
+ }
+
/* nothing interesting has happened */
if (r == 0)
continue;
diff --git a/tools/merovingian/daemon/multiplex-funnel.h
b/tools/merovingian/daemon/multiplex-funnel.h
--- a/tools/merovingian/daemon/multiplex-funnel.h
+++ b/tools/merovingian/daemon/multiplex-funnel.h
@@ -27,7 +27,9 @@
#include "merovingian.h"
typedef struct _multiplex_database {
- Mapi conn;
+ Mapi conn; /* current connection in use */
+ Mapi newconn; /* new connection we should set live (or NULL)
*/
+ char connupdate; /* if set, we have to cycle newconn into conn */
char *user;
char *pass;
char *database;
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