Reduce redundant network probing and prevent probing loop

NetworkMonitor did not limit the probe usage on a non-metered
network for data stall detection verification. As NM polls TCP
information with certain timer(10s for now), NM may get legacy
information if the data stall suspicion comes from other
signals, e.g. DNS. It may cause false alarm probing on the
network. The first tcp polling event will be 10s later. It may
cause a loop due to dns result received w/o latest tcp info.
Hence, start first polling while entering validated state.

Bug: 145275899
Bug: 147673885
Test: atest NetworkStackTests NetworkStackNextTests
Test: Manually test with such network and observe the probe
      behavior

Change-Id: Icb56ebe9d8304880d4f9f4fa8153b6e3727000fb

2 files changed, 18 insertions, 7 deletions

diff --git a/src/com/android/networkstack/netlink/TcpSocketTracker.java b/src/com/android/networkstack/netlink/TcpSocketTracker.java
index 8929cdb..78813bd 100644
--- a/src/com/android/networkstack/netlink/TcpSocketTracker.java
+++ b/src/com/android/networkstack/netlink/TcpSocketTracker.java
@@ -311,7 +311,7 @@ public class TcpSocketTracker {
             }
         }
         final SocketInfo info = new SocketInfo(tcpInfo, family, mark, time);
-        log("pollSocketsInfo, " + info);
+        log("parseSockInfo, " + info);
         return info;
     }
 
diff --git a/src/com/android/server/connectivity/NetworkMonitor.java b/src/com/android/server/connectivity/NetworkMonitor.java
index f950b47..a991156 100644
--- a/src/com/android/server/connectivity/NetworkMonitor.java
+++ b/src/com/android/server/connectivity/NetworkMonitor.java
@@ -752,9 +752,20 @@ public class NetworkMonitor extends StateMachine {
             }
             mEvaluationState.reportEvaluationResult(result, null /* redirectUrl */);
             mValidations++;
+            initSocketTrackingIfRequired();
+            // start periodical polling.
             sendTcpPollingEvent();
         }
 
+        private void initSocketTrackingIfRequired() {
+            if (!isValidationRequired()) return;
+
+            final TcpSocketTracker tst = getTcpSocketTracker();
+            if (tst != null) {
+                tst.pollSocketsInfo();
+            }
+        }
+
         @Override
         public boolean processMessage(Message message) {
             switch (message.what) {
@@ -2229,7 +2240,7 @@ public class NetworkMonitor extends StateMachine {
     @VisibleForTesting
     protected boolean isDataStall() {
         Boolean result = null;
-        final StringJoiner msg = VDBG_STALL ? new StringJoiner(", ") : null;
+        final StringJoiner msg = (DBG || VDBG_STALL) ? new StringJoiner(", ") : null;
         // Reevaluation will generate traffic. Thus, set a minimal reevaluation timer to limit the
         // possible traffic cost in metered network.
         if (!mNetworkCapabilities.hasCapability(NET_CAPABILITY_NOT_METERED)
@@ -2247,9 +2258,9 @@ public class NetworkMonitor extends StateMachine {
             } else if (tst.isDataStallSuspected()) {
                 result = true;
             }
-            if (VDBG_STALL) {
+            if (DBG || VDBG_STALL) {
                 msg.add("tcp packets received=" + tst.getLatestReceivedCount())
-                     .add("tcp fail rate=" + tst.getLatestPacketFailPercentage());
+                    .add("latest tcp fail rate=" + tst.getLatestPacketFailPercentage());
             }
         }
 
@@ -2262,13 +2273,13 @@ public class NetworkMonitor extends StateMachine {
                 result = true;
                 logNetworkEvent(NetworkEvent.NETWORK_CONSECUTIVE_DNS_TIMEOUT_FOUND);
             }
-            if (VDBG_STALL) {
+            if (DBG || VDBG_STALL) {
                 msg.add("consecutive dns timeout count="
                         + mDnsStallDetector.getConsecutiveTimeoutCount());
             }
         }
-
-        if (VDBG_STALL) {
+        // log only data stall suspected.
+        if ((DBG && Boolean.TRUE.equals(result)) || VDBG_STALL) {
             log("isDataStall: result=" + result + ", " + msg);
         }