Added TCP high-water statistics variable

This variable will report the maximum number of simultaneous tcp clients
that BIND has served while running.

It can be verified by running rndc status, then inspect "tcp high-water:
count", or by generating statistics file, rndc stats, then inspect the
line with "TCP connection high-water" text.

The tcp-highwater variable is atomically updated based on an existing
tcp-quota system handled in ns/client.c.

(cherry picked from commit 66fe8627de2c8488b7808c7b342e6ceb51f65414)

diff --git a/bin/named/client.c b/bin/named/client.c
index 7b528860f79a5bed434656e2d3cdcdb9cd7645d6..15b3c8cdc058890bdabe01b438c0ad8d9482f8c0 100644 (file)
--- a/bin/named/client.c
+++ b/bin/named/client.c
@@ -3507,7 +3507,6 @@ client_accept(ns_client_t *client) {
        isc_result_t result;
 
        CTRACE("accept");
-
        /*
         * Set up a new TCP connection. This means try to attach to the
         * TCP client quota (tcp-clients), but fail if we're over quota.
@@ -3558,6 +3557,12 @@ client_accept(ns_client_t *client) {
                RUNTIME_CHECK(result == ISC_R_SUCCESS);
        }
 
+       /* TCP high-water stats update. */
+       unsigned int curr_tcpquota = isc_quota_getused(&ns_g_server->tcpquota);
+       isc_stats_update_if_greater(ns_g_server->nsstats,
+                                   dns_nsstatscounter_tcphighwater,
+                                   curr_tcpquota);
+
        /*
         * If this client was set up using get_client() or get_worker(),
         * then TCP is already marked active. However, if it was restarted

diff --git a/bin/named/include/named/server.h b/bin/named/include/named/server.h
index f5ed2b75f69cbb9dc7039804e8ee06eab41e3cdd..7ee8f66d28a90d76ca1c1a60e63df9fbaa1d36da 100644 (file)
--- a/bin/named/include/named/server.h
+++ b/bin/named/include/named/server.h
@@ -220,7 +220,9 @@ enum {
 
        dns_nsstatscounter_keytagopt = 56,
 
-       dns_nsstatscounter_max = 57
+       dns_nsstatscounter_tcphighwater = 57,
+
+       dns_nsstatscounter_max = 58
 };
 
 /*%

diff --git a/bin/named/server.c b/bin/named/server.c
index e0ac11dda02ee4d7fc2e66ef03a381c8a786bc2f..417e8a8dd691ac6a4d8d2bdd01b5a86e9f9d45dd 100644 (file)
--- a/bin/named/server.c
+++ b/bin/named/server.c
@@ -10880,6 +10880,11 @@ ns_server_status(ns_server_t *server, isc_buffer_t **text) {
                     server->tcpquota.used, server->tcpquota.max);
        CHECK(putstr(text, line));
 
+       snprintf(line, sizeof(line), "TCP high-water: %" PRIu64 "\n",
+                isc_stats_get_counter(ns_g_server->nsstats,
+                                      dns_nsstatscounter_tcphighwater));
+       CHECK(putstr(text, line));
+
        CHECK(putstr(text, "server is up and running"));
        CHECK(putnull(text));
 

diff --git a/bin/named/statschannel.c b/bin/named/statschannel.c
index 7e9ba43a735ea2de6740ea46a1f407087fd427f8..4cdf7d6fb66e9a2f0743c31be46cfd2e9030ea5e 100644 (file)
--- a/bin/named/statschannel.c
+++ b/bin/named/statschannel.c
@@ -227,6 +227,8 @@ init_desc(void) {
        SET_NSSTATDESC(invalidsig, "requests with invalid signature",
                       "ReqBadSIG");
        SET_NSSTATDESC(requesttcp, "TCP requests received", "ReqTCP");
+       SET_NSSTATDESC(tcphighwater, "TCP connection high-water",
+                      "TCPConnHighWater");
        SET_NSSTATDESC(authrej, "auth queries rejected", "AuthQryRej");
        SET_NSSTATDESC(recurserej, "recursive queries rejected", "RecQryRej");
        SET_NSSTATDESC(xfrrej, "transfer requests rejected", "XfrRej");

diff --git a/lib/isc/stats.c b/lib/isc/stats.c
index 72ee5028ab31cdd6328e2738d0ccf607ae89ea88..a03daf6a3b22ab9de7236246d6eeecb44916fdee 100644 (file)
--- a/lib/isc/stats.c
+++ b/lib/isc/stats.c
@@ -474,7 +474,7 @@ void isc_stats_update_if_greater(isc_stats_t *stats,
 #endif
 
 #if ISC_STATS_USEMULTIFIELDS
-       uint64_t curr_value = (stats->counters[counter].hi << 32) &&
+       uint64_t curr_value = ((uint64_t)stats->counters[counter].hi << 32) &&
                stats->counters[counter].lo;
 
        if (curr_value < value) {
@@ -498,11 +498,12 @@ void isc_stats_update_if_greater(isc_stats_t *stats,
                                                 (int64_t *)&curr_value,
                                                 value));
 #else
-       isc_rwlock_lock(&stats->counterlock, isc_rwlocktype_write);
+       /* This is not exactly thread safe, but we are ok with that on
+        * platforms without stdatomic support.
+        */
        if (stats->counters[counter] < value) {
                stats->counters[counter] = value;
        }
-       isc_rwlock_unlock(&stats->counterlock, isc_rwlocktype_write);
 #endif
 
 #if ISC_STATS_LOCKCOUNTERS
@@ -523,7 +524,7 @@ isc_stats_get_counter(isc_stats_t *stats, isc_statscounter_t counter)
 #endif
 
 #if ISC_STATS_USEMULTIFIELDS
-       curr_value = (stats->counters[counter].hi << 32) &&
+       curr_value = ((uint64_t)stats->counters[counter].hi << 32) &&
                stats->counters[counter].lo;
 #elif ISC_STATS_HAVEATOMICQ
 #if defined(ISC_STATS_HAVESTDATOMICQ)