Add a mode for cell radios unable to time share
Upon changing the default SIM card, the radio will create a
new connection to the new subscription. If that subscription
works correctly, the stack will prefer it to the old one as
the new subscription will be marked with a Primary policy
flag it its score.
Normally, at this point the old network lingers to give apps
an opportunity to gracefully migrate their connections. But
with some radios, this may have a dramatic effect on the
performance of the new connection.
This patch introduces a flag so that devices with such radios
can be marked. In this case the stack will move to a degraded
mode and eschew the grace delay for apps and give them a hard
break instead, so that the new network can reach a good
performance immediately. Apps with existing connections will
suffer a worse experience.
If there is a request that can only be served by the old
connection, still keep it, as arguably the user still
expects their MMS be sent on the old connection, even if the
new connection doesn't work well until it's done.
Test: new test in this patch, and add relevant tests in both modes
also manually change the value of the flag and run
FrameworksNetTests and CtsNetTestCasesLatestSdk
Bug: 200226979
Change-Id: I4ace82f90e873bf06298cc689bb1d794ed5124bd
diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index 9f63191..c69af06 100644
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -80,6 +80,7 @@
import static android.net.NetworkCapabilities.TRANSPORT_VPN;
import static android.net.NetworkCapabilities.TRANSPORT_WIFI;
import static android.net.NetworkRequest.Type.LISTEN_FOR_BEST;
+import static android.net.NetworkScore.POLICY_TRANSPORT_PRIMARY;
import static android.net.OemNetworkPreferences.OEM_NETWORK_PREFERENCE_TEST;
import static android.net.OemNetworkPreferences.OEM_NETWORK_PREFERENCE_TEST_ONLY;
import static android.net.shared.NetworkMonitorUtils.isPrivateDnsValidationRequired;
@@ -335,6 +336,9 @@
protected int mLingerDelayMs; // Can't be final, or test subclass constructors can't change it.
@VisibleForTesting
protected int mNascentDelayMs;
+ // True if the cell radio of the device is capable of time-sharing.
+ @VisibleForTesting
+ protected boolean mCellularRadioTimesharingCapable = true;
// How long to delay to removal of a pending intent based request.
// See ConnectivitySettingsManager.CONNECTIVITY_RELEASE_PENDING_INTENT_DELAY_MS
@@ -1375,6 +1379,12 @@
NetworkCapabilities.NET_CAPABILITY_VEHICLE_INTERNAL,
NetworkRequest.Type.BACKGROUND_REQUEST);
+ mLingerDelayMs = mSystemProperties.getInt(LINGER_DELAY_PROPERTY, DEFAULT_LINGER_DELAY_MS);
+ // TODO: Consider making the timer customizable.
+ mNascentDelayMs = DEFAULT_NASCENT_DELAY_MS;
+ mCellularRadioTimesharingCapable =
+ mResources.get().getBoolean(R.bool.config_cellular_radio_timesharing_capable);
+
mHandlerThread = mDeps.makeHandlerThread();
mHandlerThread.start();
mHandler = new InternalHandler(mHandlerThread.getLooper());
@@ -1385,10 +1395,6 @@
mReleasePendingIntentDelayMs = Settings.Secure.getInt(context.getContentResolver(),
ConnectivitySettingsManager.CONNECTIVITY_RELEASE_PENDING_INTENT_DELAY_MS, 5_000);
- mLingerDelayMs = mSystemProperties.getInt(LINGER_DELAY_PROPERTY, DEFAULT_LINGER_DELAY_MS);
- // TODO: Consider making the timer customizable.
- mNascentDelayMs = DEFAULT_NASCENT_DELAY_MS;
-
mStatsManager = mContext.getSystemService(NetworkStatsManager.class);
mPolicyManager = mContext.getSystemService(NetworkPolicyManager.class);
mDnsResolver = Objects.requireNonNull(dnsresolver, "missing IDnsResolver");
@@ -7824,6 +7830,30 @@
bundle.putParcelable(t.getClass().getSimpleName(), t);
}
+ /**
+ * Returns whether reassigning a request from an NAI to another can be done gracefully.
+ *
+ * When a request should be assigned to a new network, it is normally lingered to give
+ * time for apps to gracefully migrate their connections. When both networks are on the same
+ * radio, but that radio can't do time-sharing efficiently, this may end up being
+ * counter-productive because any traffic on the old network may drastically reduce the
+ * performance of the new network.
+ * The stack supports a configuration to let modem vendors state that their radio can't
+ * do time-sharing efficiently. If this configuration is set, the stack assumes moving
+ * from one cell network to another can't be done gracefully.
+ *
+ * @param oldNai the old network serving the request
+ * @param newNai the new network serving the request
+ * @return whether the switch can be graceful
+ */
+ private boolean canSupportGracefulNetworkSwitch(@NonNull final NetworkAgentInfo oldSatisfier,
+ @NonNull final NetworkAgentInfo newSatisfier) {
+ if (mCellularRadioTimesharingCapable) return true;
+ return !oldSatisfier.networkCapabilities.hasSingleTransport(TRANSPORT_CELLULAR)
+ || !newSatisfier.networkCapabilities.hasSingleTransport(TRANSPORT_CELLULAR)
+ || !newSatisfier.getScore().hasPolicy(POLICY_TRANSPORT_PRIMARY);
+ }
+
private void teardownUnneededNetwork(NetworkAgentInfo nai) {
if (nai.numRequestNetworkRequests() != 0) {
for (int i = 0; i < nai.numNetworkRequests(); i++) {
@@ -8084,7 +8114,13 @@
log(" accepting network in place of " + previousSatisfier.toShortString());
}
previousSatisfier.removeRequest(previousRequest.requestId);
- previousSatisfier.lingerRequest(previousRequest.requestId, now);
+ if (canSupportGracefulNetworkSwitch(previousSatisfier, newSatisfier)) {
+ // If this network switch can't be supported gracefully, the request is not
+ // lingered. This allows letting go of the network sooner to reclaim some
+ // performance on the new network, since the radio can't do both at the same
+ // time while preserving good performance.
+ previousSatisfier.lingerRequest(previousRequest.requestId, now);
+ }
} else {
if (VDBG || DDBG) log(" accepting network in place of null");
}