Data stall detection using DNS event

If dns resolver on a network get consecutively timeout then it
is a strong signal that the network is no longer usable.
Reevaluate the network once it's data stall suspected

Test: 1. runtest frameworks-net
      2. SettingsBackupTest passes
      2. Run on wifi w/o internet capability
Bug: 112653893, 113916551

Change-Id: I74287b174d933f97a91fa1529b1809856ac3b38d
diff --git a/core/java/android/net/metrics/NetworkEvent.java b/core/java/android/net/metrics/NetworkEvent.java
index 1999e78..cb82fbe 100644
--- a/core/java/android/net/metrics/NetworkEvent.java
+++ b/core/java/android/net/metrics/NetworkEvent.java
@@ -44,6 +44,8 @@
     public static final int NETWORK_FIRST_VALIDATION_PORTAL_FOUND = 10;
     public static final int NETWORK_REVALIDATION_PORTAL_FOUND     = 11;
 
+    public static final int NETWORK_CONSECUTIVE_DNS_TIMEOUT_FOUND = 12;
+
     @IntDef(value = {
             NETWORK_CONNECTED,
             NETWORK_VALIDATED,
@@ -56,6 +58,7 @@
             NETWORK_REVALIDATION_SUCCESS,
             NETWORK_FIRST_VALIDATION_PORTAL_FOUND,
             NETWORK_REVALIDATION_PORTAL_FOUND,
+            NETWORK_CONSECUTIVE_DNS_TIMEOUT_FOUND,
     })
     @Retention(RetentionPolicy.SOURCE)
     public @interface EventType {}
diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index 916676a..4b656f8 100644
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -10436,6 +10436,41 @@
         public static final String CAPTIVE_PORTAL_USER_AGENT = "captive_portal_user_agent";
 
         /**
+         * The threshold value for the number of consecutive dns timeout events received to be a
+         * signal of data stall. Set the value to 0 or less than 0 to disable. Note that the value
+         * should be larger than 0 if the DNS data stall detection is enabled.
+         *
+         * @hide
+         */
+        public static final String DATA_STALL_CONSECUTIVE_DNS_TIMEOUT_THRESHOLD =
+                "data_stall_consecutive_dns_timeout_threshold";
+
+        /**
+         * The minimal time interval in milliseconds for data stall reevaluation.
+         *
+         * @hide
+         */
+        public static final String DATA_STALL_MIN_EVALUATE_INTERVAL =
+                "data_stall_min_evaluate_interval";
+
+        /**
+         * DNS timeouts older than this timeout (in milliseconds) are not considered for detecting
+         * a data stall.
+         *
+         * @hide
+         */
+        public static final String DATA_STALL_VALID_DNS_TIME_THRESHOLD =
+                "data_stall_valid_dns_time_threshold";
+
+        /**
+         * Which data stall detection signal to use. Possible values are a union of the powers of 2
+         * of DATA_STALL_EVALUATION_TYPE_*.
+         *
+         * @hide
+         */
+        public static final String DATA_STALL_EVALUATION_TYPE = "data_stall_evaluation_type";
+
+        /**
          * Whether network service discovery is enabled.
          *
          * @hide
diff --git a/core/tests/coretests/src/android/provider/SettingsBackupTest.java b/core/tests/coretests/src/android/provider/SettingsBackupTest.java
index d498268..66f5f1f 100644
--- a/core/tests/coretests/src/android/provider/SettingsBackupTest.java
+++ b/core/tests/coretests/src/android/provider/SettingsBackupTest.java
@@ -185,6 +185,10 @@
                     Settings.Global.DATA_ROAMING,
                     Settings.Global.DATA_STALL_ALARM_AGGRESSIVE_DELAY_IN_MS,
                     Settings.Global.DATA_STALL_ALARM_NON_AGGRESSIVE_DELAY_IN_MS,
+                    Settings.Global.DATA_STALL_CONSECUTIVE_DNS_TIMEOUT_THRESHOLD,
+                    Settings.Global.DATA_STALL_EVALUATION_TYPE,
+                    Settings.Global.DATA_STALL_MIN_EVALUATE_INTERVAL,
+                    Settings.Global.DATA_STALL_VALID_DNS_TIME_THRESHOLD,
                     Settings.Global.DEBUG_APP,
                     Settings.Global.DEBUG_VIEW_ATTRIBUTES,
                     Settings.Global.DEFAULT_DNS_SERVER,