[net/dns] Instrument DnsConfigService to measure performance and failures.

net/dns/dns_config_service.cc

Index: net/dns/dns_config_service.cc
diff --git a/net/dns/dns_config_service.cc b/net/dns/dns_config_service.cc
index bff1fc709f8df5d1b9f1e26f75dccf8e73b97573..fe8386e776d7dee2cbae43cc4cea40899e54464b 100644
--- a/net/dns/dns_config_service.cc
+++ b/net/dns/dns_config_service.cc
@@ -5,6 +5,7 @@
 #include "net/dns/dns_config_service.h"
 
 #include "base/logging.h"
+#include "base/metrics/histogram.h"
 #include "base/values.h"
 #include "net/base/ip_endpoint.h"
 
@@ -104,6 +105,12 @@ void DnsConfigService::Watch(const CallbackType& callback) {
 
 void DnsConfigService::InvalidateConfig() {
   DCHECK(CalledOnValidThread());
+  base::TimeTicks now = base::TimeTicks::Now();
+  if (!last_invalidate_config_time_.is_null()) {
+    UMA_HISTOGRAM_LONG_TIMES("AsyncDNS.ConfigNotifyPeriod",

[cbentzel, 2012/06/15 20:29:36]

ConfigNotifyIntervval perhaps?

[szym, 2012/06/15 21:22:19]

Done.

+                             now - last_invalidate_config_time_);
+  }
+  last_invalidate_config_time_ = now;
   if (!have_config_)
     return;
   have_config_ = false;
@@ -112,6 +119,12 @@ void DnsConfigService::InvalidateConfig() {
 
 void DnsConfigService::InvalidateHosts() {
   DCHECK(CalledOnValidThread());
+  base::TimeTicks now = base::TimeTicks::Now();
+  if (!last_invalidate_hosts_time_.is_null()) {
+    UMA_HISTOGRAM_LONG_TIMES("AsyncDNS.HostsNotifyPeriod",
+                             now - last_invalidate_hosts_time_);
+  }
+  last_invalidate_hosts_time_ = now;
   if (!have_hosts_)
     return;
   have_hosts_ = false;
@@ -122,10 +135,13 @@ void DnsConfigService::OnConfigRead(const DnsConfig& config) {
   DCHECK(CalledOnValidThread());
   DCHECK(config.IsValid());
 
+  bool changed = false;
   if (!config.EqualsIgnoreHosts(dns_config_)) {
     dns_config_.CopyIgnoreHosts(config);
     need_update_ = true;
+    changed = true;
   }
+  UMA_HISTOGRAM_BOOLEAN("AsyncDNS.ConfigChange", changed);
 
   have_config_ = true;
   if (have_hosts_)
@@ -135,10 +151,13 @@ void DnsConfigService::OnConfigRead(const DnsConfig& config) {
 void DnsConfigService::OnHostsRead(const DnsHosts& hosts) {
   DCHECK(CalledOnValidThread());
 
+  bool changed = false;
   if (hosts != dns_config_.hosts) {
     dns_config_.hosts = hosts;
     need_update_ = true;
+    changed = true;
   }
+  UMA_HISTOGRAM_BOOLEAN("AsyncDNS.HostsChange", changed);
 
   have_hosts_ = true;
   if (have_config_)