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Commit da86336b authored by Cody Kesting's avatar Cody Kesting
Browse files

Remove use of locks in VcnGatewayConnection. 

This CL updates VcnGatewayConnection to not use locking for accesses to
its TelephonySubscriptionSnapshot field. Instead, it will verify that
the caller is running on the VCN-Looper. Because VcnGatewayConnection
also runs on the VCN-Looper, this check guarantees that accesses to that
field are safe even when not explicitly in a Handler event.

Bug: 177364490
Test: atest FrameworksVcnTests
Change-Id: I128a894cead739b88a77e37f4d829d33f6bfb26a
parent 204a2fed

services/core/java/com/android/server/vcn/VcnGatewayConnection.java

+4 −13
Original line number Diff line number Diff line
@@ -61,7 +61,6 @@ import android.os.ParcelUuid; 
import android.util.ArraySet;

import android.util.Slog;



import com.android.internal.annotations.GuardedBy;

import com.android.internal.annotations.VisibleForTesting;

import com.android.internal.annotations.VisibleForTesting.Visibility;

import com.android.internal.util.State;
@@ -404,9 +403,6 @@ public class VcnGatewayConnection extends StateMachine { 
    @NonNull

    final RetryTimeoutState mRetryTimeoutState = new RetryTimeoutState();



    @NonNull private final Object mLock = new Object();



    @GuardedBy("mLock")

    @NonNull private TelephonySubscriptionSnapshot mLastSnapshot;



    @NonNull private final VcnContext mVcnContext;
@@ -516,9 +512,7 @@ public class VcnGatewayConnection extends StateMachine { 
                Objects.requireNonNull(gatewayStatusCallback, "Missing gatewayStatusCallback");

        mDeps = Objects.requireNonNull(deps, "Missing deps");



        synchronized (mLock) {

        mLastSnapshot = Objects.requireNonNull(snapshot, "Missing snapshot");

        }



        mUnderlyingNetworkTrackerCallback = new VcnUnderlyingNetworkTrackerCallback();
@@ -589,13 +583,10 @@ public class VcnGatewayConnection extends StateMachine { 
     */

    public void updateSubscriptionSnapshot(@NonNull TelephonySubscriptionSnapshot snapshot) {

        Objects.requireNonNull(snapshot, "Missing snapshot");

        mVcnContext.ensureRunningOnLooperThread();



        // Vcn is the only user of this method and runs on the same Thread, but lock around

        // mLastSnapshot to be technically correct.

        synchronized (mLock) {

        mLastSnapshot = snapshot;

        mUnderlyingNetworkTracker.updateSubscriptionSnapshot(mLastSnapshot);

        }



        sendMessage(EVENT_SUBSCRIPTIONS_CHANGED, TOKEN_ALL);

    }