From 7a75e50facf86d59d16e1cf924580fc81fe489d6 Mon Sep 17 00:00:00 2001
From: Ling Ma <linggm@google.com>
Date: Sun, 23 Oct 2022 13:47:35 -0700
Subject: [PATCH] Reevaluate condition on handover retry

This change reevaluate conditions on handover retry attempts.

Bug: 254023175
Test: atest + basic voice call + data browsing
Change-Id: I50efebe9e8047fbc32396a7abbc7e171e94686a8
---
 .../telephony/data/DataNetworkController.java | 73 +++++++++++--------
 .../data/DataNetworkControllerTest.java       | 17 +++++
 2 files changed, 61 insertions(+), 29 deletions(-)

diff --git a/src/java/com/android/internal/telephony/data/DataNetworkController.java b/src/java/com/android/internal/telephony/data/DataNetworkController.java
index c6fba7c838..ffecad39b9 100644
--- a/src/java/com/android/internal/telephony/data/DataNetworkController.java
+++ b/src/java/com/android/internal/telephony/data/DataNetworkController.java
@@ -1858,11 +1858,6 @@ public class DataNetworkController extends Handler {
             return dataEvaluation;
         }
 
-        if (mDataRetryManager.isAnyHandoverRetryScheduled(dataNetwork)) {
-            dataEvaluation.addDataDisallowedReason(DataDisallowedReason.RETRY_SCHEDULED);
-            return dataEvaluation;
-        }
-
         // If enhanced handover check is enabled, perform extra checks.
         if (mDataConfigManager.isEnhancedIwlanHandoverCheckEnabled()) {
             int targetTransport = DataUtils.getTargetTransport(dataNetwork.getTransport());
@@ -2687,7 +2682,7 @@ public class DataNetworkController extends Handler {
         logl("onDataNetworkHandoverRetry: Start handover " + dataNetwork + " to "
                 + AccessNetworkConstants.transportTypeToString(preferredTransport)
                 + ", " + dataHandoverRetryEntry);
-        dataNetwork.startHandover(preferredTransport, dataHandoverRetryEntry);
+        tryHandoverDataNetwork(dataNetwork, preferredTransport, dataHandoverRetryEntry);
     }
 
     /**
@@ -2964,33 +2959,53 @@ public class DataNetworkController extends Handler {
                     continue;
                 }
 
-                DataEvaluation dataEvaluation = evaluateDataNetworkHandover(dataNetwork);
-                log("onEvaluatePreferredTransport: " + dataEvaluation + ", " + dataNetwork);
-                if (!dataEvaluation.containsDisallowedReasons()) {
-                    logl("Start handover " + dataNetwork + " to "
-                            + AccessNetworkConstants.transportTypeToString(preferredTransport));
-                    dataNetwork.startHandover(preferredTransport, null);
-                } else if (dataEvaluation.containsAny(DataDisallowedReason.NOT_ALLOWED_BY_POLICY,
-                        DataDisallowedReason.NOT_IN_SERVICE,
-                        DataDisallowedReason.VOPS_NOT_SUPPORTED)) {
-                    logl("onEvaluatePreferredTransport: Handover not allowed. Tear "
-                            + "down " + dataNetwork + " so a new network can be setup on "
-                            + AccessNetworkConstants.transportTypeToString(preferredTransport)
-                            + ".");
-                    tearDownGracefully(dataNetwork,
-                            DataNetwork.TEAR_DOWN_REASON_HANDOVER_NOT_ALLOWED);
-                } else if (dataEvaluation.containsAny(DataDisallowedReason.ILLEGAL_STATE,
-                        DataDisallowedReason.RETRY_SCHEDULED)) {
-                    logl("onEvaluatePreferredTransport: Handover not allowed. " + dataNetwork
-                            + " will remain on " + AccessNetworkConstants.transportTypeToString(
-                                    dataNetwork.getTransport()));
-                } else {
-                    loge("onEvaluatePreferredTransport: Unexpected handover evaluation result.");
-                }
+                tryHandoverDataNetwork(dataNetwork, preferredTransport, null/*handoverRetryEntry*/);
             }
         }
     }
 
+    /**
+     * Perform data network handover if condition allows, otherwise tear down the network to allow
+     * new network setup on the target transport.
+     *
+     * @param dataNetwork The network on which the handover occurs
+     * @param targetTransport The target transport of the handover
+     * @param dataHandoverRetryEntry {@code null} if the handover attempt is not due to scheduled
+     *                                           retry
+     */
+    private void tryHandoverDataNetwork(@NonNull DataNetwork dataNetwork,
+            @TransportType int targetTransport,
+            @Nullable DataHandoverRetryEntry dataHandoverRetryEntry) {
+        if (dataHandoverRetryEntry == null // This handover is a new request
+                && mDataRetryManager.isAnyHandoverRetryScheduled(dataNetwork)) {
+            log("tryHandoverDataNetwork: retry scheduled for" + dataNetwork
+                    + ", ignore this attempt");
+            return;
+        }
+        DataEvaluation dataEvaluation = evaluateDataNetworkHandover(dataNetwork);
+        log("tryHandoverDataNetwork: " + dataEvaluation + ", " + dataNetwork);
+        if (!dataEvaluation.containsDisallowedReasons()) {
+            logl("Start handover " + dataNetwork + " to "
+                    + AccessNetworkConstants.transportTypeToString(targetTransport));
+            dataNetwork.startHandover(targetTransport, dataHandoverRetryEntry);
+        } else if (dataEvaluation.containsAny(DataDisallowedReason.NOT_ALLOWED_BY_POLICY,
+                DataDisallowedReason.NOT_IN_SERVICE,
+                DataDisallowedReason.VOPS_NOT_SUPPORTED)) {
+            logl("tryHandoverDataNetwork: Handover not allowed. Tear down"
+                    + dataNetwork + " so a new network can be setup on "
+                    + AccessNetworkConstants.transportTypeToString(targetTransport));
+            tearDownGracefully(dataNetwork,
+                    DataNetwork.TEAR_DOWN_REASON_HANDOVER_NOT_ALLOWED);
+        } else if (dataEvaluation.containsAny(DataDisallowedReason.ILLEGAL_STATE,
+                DataDisallowedReason.RETRY_SCHEDULED)) {
+            logl("tryHandoverDataNetwork: Handover not allowed. " + dataNetwork
+                    + " will remain on " + AccessNetworkConstants.transportTypeToString(
+                    dataNetwork.getTransport()));
+        } else {
+            loge("tryHandoverDataNetwork: Unexpected handover evaluation result.");
+        }
+    }
+
     /**
      * Update {@link SubscriptionPlan}s from {@link NetworkPolicyManager}.
      */
diff --git a/tests/telephonytests/src/com/android/internal/telephony/data/DataNetworkControllerTest.java b/tests/telephonytests/src/com/android/internal/telephony/data/DataNetworkControllerTest.java
index 7b2cf4107d..895be101c1 100644
--- a/tests/telephonytests/src/com/android/internal/telephony/data/DataNetworkControllerTest.java
+++ b/tests/telephonytests/src/com/android/internal/telephony/data/DataNetworkControllerTest.java
@@ -2074,9 +2074,26 @@ public class DataNetworkControllerTest extends TelephonyTest {
         assertThat(dataNetwork.getTransport()).isEqualTo(
                 AccessNetworkConstants.TRANSPORT_TYPE_WWAN);
 
+        // Set target transport OOS
+        serviceStateChanged(TelephonyManager.NETWORK_TYPE_UNKNOWN,
+                NetworkRegistrationInfo.REGISTRATION_STATE_HOME, /* data */
+                NetworkRegistrationInfo.REGISTRATION_STATE_HOME, /* voice */
+                NetworkRegistrationInfo.REGISTRATION_STATE_NOT_REGISTERED_OR_SEARCHING, /* iwlan */
+                null);
         setSuccessfulSetupDataResponse(mMockedWlanDataServiceManager, 1);
 
         processAllFutureMessages();
+        // Verify that data network is still on cellular
+        assertThat(dataNetwork.getTransport()).isEqualTo(
+                AccessNetworkConstants.TRANSPORT_TYPE_WWAN);
+
+        // Set target transport back to service
+        serviceStateChanged(TelephonyManager.NETWORK_TYPE_UNKNOWN,
+                NetworkRegistrationInfo.REGISTRATION_STATE_HOME, /* data */
+                NetworkRegistrationInfo.REGISTRATION_STATE_HOME, /* voice */
+                NetworkRegistrationInfo.REGISTRATION_STATE_HOME, /* iwlan */
+                null);
+        processAllFutureMessages();
 
         dataNetwork = getDataNetworks().get(0);
         // Verify that data network is handovered to IWLAN
-- 
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