Added three histograms to track the following TCP connection latency

intervals.

a) t <= 10ms
b) 10ms < t <= 20ms
c) 20ms < t (or no previous time)

R=jar@chromium.org

Review URL: https://codereview.chromium.org/68793007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235652 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 59 insertions, 22 deletions

diff --git a/net/socket/transport_client_socket_pool.cc b/net/socket/transport_client_socket_pool.cc
index 6da3b45..ec56dcb 100644
--- a/net/socket/transport_client_socket_pool.cc
+++ b/net/socket/transport_client_socket_pool.cc
@@ -96,7 +96,7 @@ TransportConnectJob::TransportConnectJob(
       client_socket_factory_(client_socket_factory),
       resolver_(host_resolver),
       next_state_(STATE_NONE),
-      less_than_20ms_since_connect_(true) {
+      interval_between_connects_(CONNECT_INTERVAL_GT_20MS) {
 }
 
 TransportConnectJob::~TransportConnectJob() {
@@ -204,11 +204,16 @@ int TransportConnectJob::DoTransportConnect() {
     last_connect_time = g_last_connect_time.Get();
     *g_last_connect_time.Pointer() = now;
   }
-  if (last_connect_time.is_null() ||
-      (now - last_connect_time).InMilliseconds() < 20) {
-    less_than_20ms_since_connect_ = true;
+  if (last_connect_time.is_null()) {
+    interval_between_connects_ = CONNECT_INTERVAL_GT_20MS;
   } else {
-    less_than_20ms_since_connect_ = false;
+    int64 interval = (now - last_connect_time).InMilliseconds();
+    if (interval <= 10)
+      interval_between_connects_ = CONNECT_INTERVAL_LE_10MS;
+    else if (interval <= 20)
+      interval_between_connects_ = CONNECT_INTERVAL_LE_20MS;
+    else
+      interval_between_connects_ = CONNECT_INTERVAL_GT_20MS;
   }
 
   next_state_ = STATE_TRANSPORT_CONNECT_COMPLETE;
@@ -247,20 +252,34 @@ int TransportConnectJob::DoTransportConnectComplete(int result) {
         base::TimeDelta::FromMinutes(10),
         100);
 
-    if (less_than_20ms_since_connect_) {
-      UMA_HISTOGRAM_CUSTOM_TIMES(
-          "Net.TCP_Connection_Latency_Interval_20ms_Minus",
-          connect_duration,
-          base::TimeDelta::FromMilliseconds(1),
-          base::TimeDelta::FromMinutes(10),
-          100);
-    } else {
-      UMA_HISTOGRAM_CUSTOM_TIMES(
-          "Net.TCP_Connection_Latency_Interval_20ms_Plus",
-          connect_duration,
-          base::TimeDelta::FromMilliseconds(1),
-          base::TimeDelta::FromMinutes(10),
-          100);
+    switch (interval_between_connects_) {
+      case CONNECT_INTERVAL_LE_10MS:
+        UMA_HISTOGRAM_CUSTOM_TIMES(
+            "Net.TCP_Connection_Latency_Interval_LessThanOrEqual_10ms",
+            connect_duration,
+            base::TimeDelta::FromMilliseconds(1),
+            base::TimeDelta::FromMinutes(10),
+            100);
+        break;
+      case CONNECT_INTERVAL_LE_20MS:
+        UMA_HISTOGRAM_CUSTOM_TIMES(
+            "Net.TCP_Connection_Latency_Interval_LessThanOrEqual_20ms",
+            connect_duration,
+            base::TimeDelta::FromMilliseconds(1),
+            base::TimeDelta::FromMinutes(10),
+            100);
+        break;
+      case CONNECT_INTERVAL_GT_20MS:
+        UMA_HISTOGRAM_CUSTOM_TIMES(
+            "Net.TCP_Connection_Latency_Interval_GreaterThan_20ms",
+            connect_duration,
+            base::TimeDelta::FromMilliseconds(1),
+            base::TimeDelta::FromMinutes(10),
+            100);
+        break;
+      default:
+        NOTREACHED();
+        break;
     }
 
     if (is_ipv4) {
diff --git a/net/socket/transport_client_socket_pool.h b/net/socket/transport_client_socket_pool.h
index 95b51c3..1c22bf2 100644
--- a/net/socket/transport_client_socket_pool.h
+++ b/net/socket/transport_client_socket_pool.h
@@ -93,6 +93,12 @@ class NET_EXPORT_PRIVATE TransportConnectJob : public ConnectJob {
     STATE_NONE,
   };
 
+  enum ConnectInterval {
+    CONNECT_INTERVAL_LE_10MS,
+    CONNECT_INTERVAL_LE_20MS,
+    CONNECT_INTERVAL_GT_20MS,
+  };
+
   void OnIOComplete(int result);
 
   // Runs the state transition loop.
@@ -125,9 +131,8 @@ class NET_EXPORT_PRIVATE TransportConnectJob : public ConnectJob {
   base::TimeTicks fallback_connect_start_time_;
   base::OneShotTimer<TransportConnectJob> fallback_timer_;
 
-  // If the interval between this connect and previous connect is less than
-  // 20ms, then |less_than_20ms_since_connect_| is set to true.
-  bool less_than_20ms_since_connect_;
+  // Track the interval between this connect and previous connect.
+  ConnectInterval interval_between_connects_;
 
   DISALLOW_COPY_AND_ASSIGN(TransportConnectJob);
 };
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 603e5ad..c572e7d 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -30280,6 +30280,11 @@ other types of suffix sets.
   <affected-histogram name="Instant.SessionsStorageNamespace"/>
 </fieldtrial>
 
+<fieldtrial name="Interval" separator="_">
+  <group name="Interval" label="Interval between two consecutive connects is"/>
+  <affected-histogram name="Net.TCP_Connection_Latency"/>
+</fieldtrial>
+
 <fieldtrial name="Interval_20ms_plus_and_minus" separator="_">
   <group name="Interval_20ms_Minus"
       label="Interval between two consecutive connects is less than 20ms."/>
@@ -30289,6 +30294,14 @@ other types of suffix sets.
   <affected-histogram name="Net.TCP_Connection_Latency"/>
 </fieldtrial>
 
+<fieldtrial name="Interval_lt_gt_20ms" separator="_">
+  <group name="LessThanOrEqual_10ms" label="less than or equal to 10ms."/>
+  <group name="LessThanOrEqual_20ms"
+      label="more than 10ms, and less than or equal to 20ms."/>
+  <group name="GreaterThan_20ms" label="greater than 20ms."/>
+  <affected-histogram name="Net.TCP_Connection_Latency_Interval"/>
+</fieldtrial>
+
 <fieldtrial name="IPv6_Probe">
   <group name="IPv6_probe_skipped"
       label="with IPv6 not probed, and default OS settings used"/>