diff --git a/services/core/java/com/android/server/pm/DumpState.java b/services/core/java/com/android/server/pm/DumpState.java
index ec79483e0f34b..ed00609cd8abb 100644
--- a/services/core/java/com/android/server/pm/DumpState.java
+++ b/services/core/java/com/android/server/pm/DumpState.java
@@ -58,6 +58,7 @@ public final class DumpState {
     private boolean mTitlePrinted;
     private boolean mFullPreferred;
     private boolean mCheckIn;
+    private boolean mBrief;
 
     private String mTargetPackageName;
 
@@ -128,4 +129,12 @@ public final class DumpState {
     public void setCheckIn(boolean checkIn) {
         mCheckIn = checkIn;
     }
+
+    public boolean isBrief() {
+        return mBrief;
+    }
+
+    public void setBrief(boolean brief) {
+        mBrief = brief;
+    }
 }
diff --git a/services/core/java/com/android/server/pm/KeySetManagerService.java b/services/core/java/com/android/server/pm/KeySetManagerService.java
index 2015c78e0817e..34caaf52b2154 100644
--- a/services/core/java/com/android/server/pm/KeySetManagerService.java
+++ b/services/core/java/com/android/server/pm/KeySetManagerService.java
@@ -30,6 +30,7 @@ import android.util.TypedXmlPullParser;
 import android.util.TypedXmlSerializer;
 
 import com.android.server.pm.parsing.pkg.AndroidPackage;
+import com.android.server.utils.WatchedArrayMap;
 
 import org.xmlpull.v1.XmlPullParser;
 import org.xmlpull.v1.XmlPullParserException;
@@ -65,7 +66,7 @@ public class KeySetManagerService {
 
     protected final LongSparseArray<ArraySet<Long>> mKeySetMapping;
 
-    private final ArrayMap<String, PackageSetting> mPackages;
+    private final WatchedArrayMap<String, PackageSetting> mPackages;
 
     private long lastIssuedKeySetId = 0;
 
@@ -114,7 +115,7 @@ public class KeySetManagerService {
         }
     }
 
-    public KeySetManagerService(ArrayMap<String, PackageSetting> packages) {
+    public KeySetManagerService(WatchedArrayMap<String, PackageSetting> packages) {
         mKeySets = new LongSparseArray<KeySetHandle>();
         mPublicKeys = new LongSparseArray<PublicKeyHandle>();
         mKeySetMapping = new LongSparseArray<ArraySet<Long>>();
diff --git a/services/core/java/com/android/server/pm/PackageManagerService.java b/services/core/java/com/android/server/pm/PackageManagerService.java
index 679042ff40c9d..882d8e64c8cc4 100644
--- a/services/core/java/com/android/server/pm/PackageManagerService.java
+++ b/services/core/java/com/android/server/pm/PackageManagerService.java
@@ -1309,14 +1309,17 @@ public class PackageManagerService extends IPackageManager.Stub
             // Avoid invalidation-thrashing by preventing cache invalidations from causing property
             // writes if the cache isn't enabled yet.  We re-enable writes later when we're
             // done initializing.
-            sSnapshotCorked = true;
+            sSnapshotCorked.incrementAndGet();
             PackageManager.corkPackageInfoCache();
         }
 
         @Override
         public void enablePackageCaches() {
             // Uncork cache invalidations and allow clients to cache package information.
-            sSnapshotCorked = false;
+            int corking = sSnapshotCorked.decrementAndGet();
+            if (TRACE_SNAPSHOTS && corking == 0) {
+                Log.i(TAG, "snapshot: corking returns to 0");
+            }
             PackageManager.uncorkPackageInfoCache();
         }
     }
@@ -1588,6 +1591,7 @@ public class PackageManagerService extends IPackageManager.Stub
     static final int INTEGRITY_VERIFICATION_COMPLETE = 25;
     static final int CHECK_PENDING_INTEGRITY_VERIFICATION = 26;
     static final int DOMAIN_VERIFICATION = 27;
+    static final int SNAPSHOT_UNCORK = 28;
 
     static final int DEFERRED_NO_KILL_POST_DELETE_DELAY_MS = 3 * 1000;
     static final int DEFERRED_NO_KILL_INSTALL_OBSERVER_DELAY_MS = 500;
@@ -4874,12 +4878,16 @@ public class PackageManagerService extends IPackageManager.Stub
     // A lock-free cache for frequently called functions.
     private volatile Computer mSnapshotComputer;
     // If true, the snapshot is invalid (stale).  The attribute is static since it may be
-    // set from outside classes.
-    private static volatile boolean sSnapshotInvalid = true;
+    // set from outside classes.  The attribute may be set to true anywhere, although it
+    // should only be set true while holding mLock.  However, the attribute id guaranteed
+    // to be set false only while mLock and mSnapshotLock are both held.
+    private static AtomicBoolean sSnapshotInvalid = new AtomicBoolean(true);
+    // The package manager that is using snapshots.
+    private static PackageManagerService sSnapshotConsumer = null;
     // If true, the snapshot is corked.  Do not create a new snapshot but use the live
     // computer.  This throttles snapshot creation during periods of churn in Package
     // Manager.
-    private static volatile boolean sSnapshotCorked = false;
+    private static AtomicInteger sSnapshotCorked = new AtomicInteger(0);
 
     /**
      * This lock is used to make reads from {@link #sSnapshotInvalid} and
@@ -4899,6 +4907,9 @@ public class PackageManagerService extends IPackageManager.Stub
     // and an image with the flag set false does not use snapshots.
     private static final boolean SNAPSHOT_ENABLED = false;
 
+    // The default auto-cork delay for snapshots.  This is 1s.
+    private static final long SNAPSHOT_AUTOCORK_DELAY_MS = TimeUnit.SECONDS.toMillis(1);
+
     // The per-instance snapshot disable/enable flag.  This is generally set to false in
     // test instances and set to SNAPSHOT_ENABLED in operational instances.
     private final boolean mSnapshotEnabled;
@@ -4922,15 +4933,16 @@ public class PackageManagerService extends IPackageManager.Stub
             // If the current thread holds mLock then it may have modified state but not
             // yet invalidated the snapshot.  Always give the thread the live computer.
             return mLiveComputer;
+        } else if (sSnapshotCorked.get() > 0) {
+            // Snapshots are corked, which means new ones should not be built right now.
+            mSnapshotStatistics.corked();
+            return mLiveComputer;
         }
         synchronized (mSnapshotLock) {
+            // This synchronization block serializes access to the snapshot computer and
+            // to the code that samples mSnapshotInvalid.
             Computer c = mSnapshotComputer;
-            if (sSnapshotCorked && (c != null)) {
-                // Snapshots are corked, which means new ones should not be built right now.
-                c.use();
-                return c;
-            }
-            if (sSnapshotInvalid || (c == null)) {
+            if (sSnapshotInvalid.getAndSet(false) || (c == null)) {
                 // The snapshot is invalid if it is marked as invalid or if it is null.  If it
                 // is null, then it is currently being rebuilt by rebuildSnapshot().
                 synchronized (mLock) {
@@ -4938,9 +4950,7 @@ public class PackageManagerService extends IPackageManager.Stub
                     // invalidated as it is rebuilt.  However, the snapshot is still
                     // self-consistent (the lock is being held) and is current as of the time
                     // this function is entered.
-                    if (sSnapshotInvalid) {
-                        rebuildSnapshot();
-                    }
+                    rebuildSnapshot();
 
                     // Guaranteed to be non-null.  mSnapshotComputer is only be set to null
                     // temporarily in rebuildSnapshot(), which is guarded by mLock().  Since
@@ -4958,12 +4968,11 @@ public class PackageManagerService extends IPackageManager.Stub
      * Rebuild the cached computer.  mSnapshotComputer is temporarily set to null to block other
      * threads from using the invalid computer until it is rebuilt.
      */
-    @GuardedBy("mLock")
+    @GuardedBy({ "mLock", "mSnapshotLock"})
     private void rebuildSnapshot() {
         final long now = SystemClock.currentTimeMicro();
         final int hits = mSnapshotComputer == null ? -1 : mSnapshotComputer.getUsed();
         mSnapshotComputer = null;
-        sSnapshotInvalid = false;
         final Snapshot args = new Snapshot(Snapshot.SNAPPED);
         mSnapshotComputer = new ComputerEngine(args);
         final long done = SystemClock.currentTimeMicro();
@@ -4971,6 +4980,30 @@ public class PackageManagerService extends IPackageManager.Stub
         mSnapshotStatistics.rebuild(now, done, hits);
     }
 
+    /**
+     * Create a new snapshot.  Used for testing only.  This does collect statistics or
+     * update the snapshot used by other actors.  It does not alter the invalidation
+     * flag.  This method takes the mLock internally.
+     */
+    private Computer createNewSnapshot() {
+        synchronized (mLock) {
+            final Snapshot args = new Snapshot(Snapshot.SNAPPED);
+            return new ComputerEngine(args);
+        }
+    }
+
+    /**
+     * Cork snapshots.  This times out after the programmed delay.
+     */
+    private void corkSnapshots(int multiplier) {
+        int corking = sSnapshotCorked.getAndIncrement();
+        if (TRACE_SNAPSHOTS && corking == 0) {
+            Log.i(TAG, "snapshot: corking goes positive");
+        }
+        Message message = mHandler.obtainMessage(SNAPSHOT_UNCORK);
+        mHandler.sendMessageDelayed(message, SNAPSHOT_AUTOCORK_DELAY_MS * multiplier);
+    }
+
     /**
      * Create a live computer
      */
@@ -4986,9 +5019,9 @@ public class PackageManagerService extends IPackageManager.Stub
      */
     public static void onChange(@Nullable Watchable what) {
         if (TRACE_SNAPSHOTS) {
-            Log.e(TAG, "snapshot: onChange(" + what + ")");
+            Log.i(TAG, "snapshot: onChange(" + what + ")");
         }
-        sSnapshotInvalid = true;
+        sSnapshotInvalid.set(true);
     }
 
     /**
@@ -5367,6 +5400,13 @@ public class PackageManagerService extends IPackageManager.Stub
                     mDomainVerificationManager.runMessage(messageCode, object);
                     break;
                 }
+                case SNAPSHOT_UNCORK: {
+                    int corking = sSnapshotCorked.decrementAndGet();
+                    if (TRACE_SNAPSHOTS && corking == 0) {
+                        Log.e(TAG, "snapshot: corking goes to zero in message handler");
+                    }
+                    break;
+                }
             }
         }
     }
@@ -6383,12 +6423,13 @@ public class PackageManagerService extends IPackageManager.Stub
             // constructor, at which time the invalidation method updates it.  The cache is
             // corked initially to ensure a cached computer is not built until the end of the
             // constructor.
-            mSnapshotEnabled = SNAPSHOT_ENABLED;
-            sSnapshotCorked = true;
-            sSnapshotInvalid = true;
             mSnapshotStatistics = new SnapshotStatistics();
+            sSnapshotConsumer = this;
+            sSnapshotCorked.set(1);
+            sSnapshotInvalid.set(true);
             mLiveComputer = createLiveComputer();
             mSnapshotComputer = null;
+            mSnapshotEnabled = SNAPSHOT_ENABLED;
             registerObserver();
         }
 
@@ -18521,7 +18562,7 @@ public class PackageManagerService extends IPackageManager.Stub
         }
     }
 
-    @GuardedBy({"mInstallLock", "mLock"})
+    @GuardedBy("mInstallLock")
     private void installPackagesTracedLI(List<InstallRequest> requests) {
         try {
             Trace.traceBegin(TRACE_TAG_PACKAGE_MANAGER, "installPackages");
@@ -24018,6 +24059,15 @@ public class PackageManagerService extends IPackageManager.Stub
                 dumpState.setDump(DumpState.DUMP_PER_UID_READ_TIMEOUTS);
             } else if ("snapshot".equals(cmd)) {
                 dumpState.setDump(DumpState.DUMP_SNAPSHOT_STATISTICS);
+                if (opti < args.length) {
+                    if ("--full".equals(args[opti])) {
+                        dumpState.setBrief(false);
+                        opti++;
+                    } else if ("--brief".equals(args[opti])) {
+                        dumpState.setBrief(true);
+                        opti++;
+                    }
+                }
             } else if ("write".equals(cmd)) {
                 synchronized (mLock) {
                     writeSettingsLPrTEMP();
@@ -24353,13 +24403,14 @@ public class PackageManagerService extends IPackageManager.Stub
                 pw.println("  Snapshots disabled");
             } else {
                 int hits = 0;
+                int level = sSnapshotCorked.get();
                 synchronized (mSnapshotLock) {
                     if (mSnapshotComputer != null) {
                         hits = mSnapshotComputer.getUsed();
                     }
                 }
                 final long now = SystemClock.currentTimeMicro();
-                mSnapshotStatistics.dump(pw, "  ", now, hits, true);
+                mSnapshotStatistics.dump(pw, "  ", now, hits, level, dumpState.isBrief());
             }
         }
     }
diff --git a/services/core/java/com/android/server/pm/Settings.java b/services/core/java/com/android/server/pm/Settings.java
index 1b8eee3925a5f..e14c9871ea853 100644
--- a/services/core/java/com/android/server/pm/Settings.java
+++ b/services/core/java/com/android/server/pm/Settings.java
@@ -351,6 +351,7 @@ public final class Settings implements Watchable, Snappable {
 
     private final PackageManagerTracedLock mLock;
 
+    @Watched(manual = true)
     private final RuntimePermissionPersistence mRuntimePermissionsPersistence;
 
     private final File mSettingsFilename;
@@ -435,6 +436,7 @@ public final class Settings implements Watchable, Snappable {
     }
 
     /** Device identity for the purpose of package verification. */
+    @Watched(manual = true)
     private VerifierDeviceIdentity mVerifierDeviceIdentity;
 
     // The user's preferred activities associated with particular intent
@@ -462,10 +464,12 @@ public final class Settings implements Watchable, Snappable {
     private final WatchedSparseArray<SettingBase> mOtherAppIds;
 
     // For reading/writing settings file.
-    private final ArrayList<Signature> mPastSignatures =
-            new ArrayList<Signature>();
-    private final ArrayMap<Long, Integer> mKeySetRefs =
-            new ArrayMap<Long, Integer>();
+    @Watched
+    private final WatchedArrayList<Signature> mPastSignatures =
+            new WatchedArrayList<Signature>();
+    @Watched
+    private final WatchedArrayMap<Long, Integer> mKeySetRefs =
+            new WatchedArrayMap<Long, Integer>();
 
     // Packages that have been renamed since they were first installed.
     // Keys are the new names of the packages, values are the original
@@ -495,18 +499,22 @@ public final class Settings implements Watchable, Snappable {
      * TODO: make this just a local variable that is passed in during package
      * scanning to make it less confusing.
      */
-    private final ArrayList<PackageSetting> mPendingPackages = new ArrayList<>();
+    @Watched
+    private final WatchedArrayList<PackageSetting> mPendingPackages = new WatchedArrayList<>();
 
     private final File mSystemDir;
 
-    public final KeySetManagerService mKeySetManagerService =
-            new KeySetManagerService(mPackages.untrackedStorage());
+    private final KeySetManagerService mKeySetManagerService =
+            new KeySetManagerService(mPackages);
 
     /** Settings and other information about permissions */
+    @Watched(manual = true)
     final LegacyPermissionSettings mPermissions;
 
+    @Watched(manual = true)
     private final LegacyPermissionDataProvider mPermissionDataProvider;
 
+    @Watched(manual = true)
     private final DomainVerificationManagerInternal mDomainVerificationManager;
 
     /**
@@ -532,6 +540,27 @@ public final class Settings implements Watchable, Snappable {
             }};
     }
 
+    private void registerObservers() {
+        mPackages.registerObserver(mObserver);
+        mInstallerPackages.registerObserver(mObserver);
+        mKernelMapping.registerObserver(mObserver);
+        mDisabledSysPackages.registerObserver(mObserver);
+        mBlockUninstallPackages.registerObserver(mObserver);
+        mVersion.registerObserver(mObserver);
+        mPreferredActivities.registerObserver(mObserver);
+        mPersistentPreferredActivities.registerObserver(mObserver);
+        mCrossProfileIntentResolvers.registerObserver(mObserver);
+        mSharedUsers.registerObserver(mObserver);
+        mAppIds.registerObserver(mObserver);
+        mOtherAppIds.registerObserver(mObserver);
+        mRenamedPackages.registerObserver(mObserver);
+        mNextAppLinkGeneration.registerObserver(mObserver);
+        mDefaultBrowserApp.registerObserver(mObserver);
+        mPendingPackages.registerObserver(mObserver);
+        mPastSignatures.registerObserver(mObserver);
+        mKeySetRefs.registerObserver(mObserver);
+    }
+
     @VisibleForTesting(visibility = VisibleForTesting.Visibility.PRIVATE)
     public Settings(Map<String, PackageSetting> pkgSettings) {
         mLock = new PackageManagerTracedLock();
@@ -549,22 +578,8 @@ public final class Settings implements Watchable, Snappable {
         mBackupStoppedPackagesFilename = null;
         mKernelMappingFilename = null;
         mDomainVerificationManager = null;
-        mPackages.registerObserver(mObserver);
-        mInstallerPackages.registerObserver(mObserver);
-        mKernelMapping.registerObserver(mObserver);
-        mDisabledSysPackages.registerObserver(mObserver);
-        mBlockUninstallPackages.registerObserver(mObserver);
-        mVersion.registerObserver(mObserver);
-        mPreferredActivities.registerObserver(mObserver);
-        mPersistentPreferredActivities.registerObserver(mObserver);
-        mCrossProfileIntentResolvers.registerObserver(mObserver);
-        mSharedUsers.registerObserver(mObserver);
-        mAppIds.registerObserver(mObserver);
-        mOtherAppIds.registerObserver(mObserver);
-        mRenamedPackages.registerObserver(mObserver);
-        mNextAppLinkGeneration.registerObserver(mObserver);
-        mDefaultBrowserApp.registerObserver(mObserver);
 
+        registerObservers();
         Watchable.verifyWatchedAttributes(this, mObserver);
 
         mSnapshot = makeCache();
@@ -602,22 +617,7 @@ public final class Settings implements Watchable, Snappable {
 
         mDomainVerificationManager = domainVerificationManager;
 
-        mPackages.registerObserver(mObserver);
-        mInstallerPackages.registerObserver(mObserver);
-        mKernelMapping.registerObserver(mObserver);
-        mDisabledSysPackages.registerObserver(mObserver);
-        mBlockUninstallPackages.registerObserver(mObserver);
-        mVersion.registerObserver(mObserver);
-        mPreferredActivities.registerObserver(mObserver);
-        mPersistentPreferredActivities.registerObserver(mObserver);
-        mCrossProfileIntentResolvers.registerObserver(mObserver);
-        mSharedUsers.registerObserver(mObserver);
-        mAppIds.registerObserver(mObserver);
-        mOtherAppIds.registerObserver(mObserver);
-        mRenamedPackages.registerObserver(mObserver);
-        mNextAppLinkGeneration.registerObserver(mObserver);
-        mDefaultBrowserApp.registerObserver(mObserver);
-
+        registerObservers();
         Watchable.verifyWatchedAttributes(this, mObserver);
 
         mSnapshot = makeCache();
@@ -629,7 +629,6 @@ public final class Settings implements Watchable, Snappable {
      * are changed by PackageManagerService APIs are deep-copied
      */
     private Settings(Settings r) {
-        final int mPackagesSize = r.mPackages.size();
         mPackages.putAll(r.mPackages);
 
         // The following assignments satisfy Java requirements but are not
@@ -662,20 +661,23 @@ public final class Settings implements Watchable, Snappable {
         mSharedUsers.putAll(r.mSharedUsers);
         mAppIds = r.mAppIds.snapshot();
         mOtherAppIds = r.mOtherAppIds.snapshot();
-        mPastSignatures.addAll(r.mPastSignatures);
-        mKeySetRefs.putAll(r.mKeySetRefs);
+        WatchedArrayList.snapshot(
+                mPastSignatures, r.mPastSignatures);
+        WatchedArrayMap.snapshot(
+                mKeySetRefs, r.mKeySetRefs);
         mRenamedPackages.snapshot(r.mRenamedPackages);
         mNextAppLinkGeneration.snapshot(r.mNextAppLinkGeneration);
         mDefaultBrowserApp.snapshot(r.mDefaultBrowserApp);
         // mReadMessages
-        mPendingPackages.addAll(r.mPendingPackages);
+        WatchedArrayList.snapshot(
+                mPendingPackages, r.mPendingPackages);
         mSystemDir = null;
         // mKeySetManagerService;
         mPermissions = r.mPermissions;
         mPermissionDataProvider = r.mPermissionDataProvider;
 
         // Do not register any Watchables and do not create a snapshot cache.
-        mSnapshot = null;
+        mSnapshot = new SnapshotCache.Sealed();
     }
 
     /**
@@ -2326,7 +2328,7 @@ public final class Settings implements Watchable, Snappable {
                 serializer.startTag(null, "shared-user");
                 serializer.attribute(null, ATTR_NAME, usr.name);
                 serializer.attributeInt(null, "userId", usr.userId);
-                usr.signatures.writeXml(serializer, "sigs", mPastSignatures);
+                usr.signatures.writeXml(serializer, "sigs", mPastSignatures.untrackedStorage());
                 serializer.endTag(null, "shared-user");
             }
 
@@ -2736,11 +2738,11 @@ public final class Settings implements Watchable, Snappable {
 
         writeUsesStaticLibLPw(serializer, pkg.usesStaticLibraries, pkg.usesStaticLibrariesVersions);
 
-        pkg.signatures.writeXml(serializer, "sigs", mPastSignatures);
+        pkg.signatures.writeXml(serializer, "sigs", mPastSignatures.untrackedStorage());
 
         if (installSource.initiatingPackageSignatures != null) {
             installSource.initiatingPackageSignatures.writeXml(
-                    serializer, "install-initiator-sigs", mPastSignatures);
+                    serializer, "install-initiator-sigs", mPastSignatures.untrackedStorage());
         }
 
         writeSigningKeySetLPr(serializer, pkg.keySetData);
@@ -2909,7 +2911,7 @@ public final class Settings implements Watchable, Snappable {
                 } else if (TAG_READ_EXTERNAL_STORAGE.equals(tagName)) {
                     // No longer used.
                 } else if (tagName.equals("keyset-settings")) {
-                    mKeySetManagerService.readKeySetsLPw(parser, mKeySetRefs);
+                    mKeySetManagerService.readKeySetsLPw(parser, mKeySetRefs.untrackedStorage());
                 } else if (TAG_VERSION.equals(tagName)) {
                     final String volumeUuid = XmlUtils.readStringAttribute(parser,
                             ATTR_VOLUME_UUID);
@@ -3697,7 +3699,7 @@ public final class Settings implements Watchable, Snappable {
                 } else if (tagName.equals(TAG_ENABLED_COMPONENTS)) {
                     readEnabledComponentsLPw(packageSetting, parser, 0);
                 } else if (tagName.equals("sigs")) {
-                    packageSetting.signatures.readXml(parser, mPastSignatures);
+                    packageSetting.signatures.readXml(parser, mPastSignatures.untrackedStorage());
                 } else if (tagName.equals(TAG_PERMISSIONS)) {
                     readInstallPermissionsLPr(parser,
                             packageSetting.getLegacyPermissionState(), users);
@@ -3728,7 +3730,7 @@ public final class Settings implements Watchable, Snappable {
                     packageSetting.keySetData.addDefinedKeySet(id, alias);
                 } else if (tagName.equals("install-initiator-sigs")) {
                     final PackageSignatures signatures = new PackageSignatures();
-                    signatures.readXml(parser, mPastSignatures);
+                    signatures.readXml(parser, mPastSignatures.untrackedStorage());
                     packageSetting.installSource =
                             packageSetting.installSource.setInitiatingPackageSignatures(signatures);
                 } else if (tagName.equals(TAG_DOMAIN_VERIFICATION)) {
@@ -3923,7 +3925,7 @@ public final class Settings implements Watchable, Snappable {
 
                 String tagName = parser.getName();
                 if (tagName.equals("sigs")) {
-                    su.signatures.readXml(parser, mPastSignatures);
+                    su.signatures.readXml(parser, mPastSignatures.untrackedStorage());
                 } else if (tagName.equals("perms")) {
                     readInstallPermissionsLPr(parser, su.getLegacyPermissionState(), users);
                 } else {
diff --git a/services/core/java/com/android/server/pm/SnapshotStatistics.java b/services/core/java/com/android/server/pm/SnapshotStatistics.java
index c425bad50ae87..7bf00603f1321 100644
--- a/services/core/java/com/android/server/pm/SnapshotStatistics.java
+++ b/services/core/java/com/android/server/pm/SnapshotStatistics.java
@@ -23,6 +23,7 @@ import android.os.Message;
 import android.os.SystemClock;
 import android.text.TextUtils;
 
+import com.android.internal.annotations.GuardedBy;
 import com.android.server.EventLogTags;
 
 import java.io.PrintWriter;
@@ -238,6 +239,11 @@ public class SnapshotStatistics {
          */
         public int mTotalUsed = 0;
 
+        /**
+         * The total number of times a snapshot was bypassed because corking was in effect.
+         */
+        public int mTotalCorked = 0;
+
         /**
          * The total number of builds that count as big, which means they took longer than
          * SNAPSHOT_BIG_BUILD_TIME_NS.
@@ -291,6 +297,13 @@ public class SnapshotStatistics {
             }
         }
 
+        /**
+         * Record a cork.
+         */
+        private void corked() {
+            mTotalCorked++;
+        }
+
         private Stats(long now) {
             mStartTimeUs = now;
             mTimes = new int[mTimeBins.count()];
@@ -308,6 +321,7 @@ public class SnapshotStatistics {
             mUsed = Arrays.copyOf(orig.mUsed, orig.mUsed.length);
             mTotalBuilds = orig.mTotalBuilds;
             mTotalUsed = orig.mTotalUsed;
+            mTotalCorked = orig.mTotalCorked;
             mBigBuilds = orig.mBigBuilds;
             mShortLived = orig.mShortLived;
             mTotalTimeUs = orig.mTotalTimeUs;
@@ -365,6 +379,7 @@ public class SnapshotStatistics {
          * Dump the summary statistics record.  Choose the header or the data.
          *    number of builds
          *    number of uses
+         *    number of corks
          *    number of big builds
          *    number of short lifetimes
          *    cumulative build time, in seconds
@@ -373,13 +388,13 @@ public class SnapshotStatistics {
         private void dumpStats(PrintWriter pw, String indent, long now, boolean header) {
             dumpPrefix(pw, indent, now, header, "Summary stats");
             if (header) {
-                pw.format(Locale.US, "  %10s  %10s  %10s  %10s  %10s  %10s",
-                          "TotBlds", "TotUsed", "BigBlds", "ShortLvd",
+                pw.format(Locale.US, "  %10s  %10s  %10s  %10s  %10s  %10s  %10s",
+                          "TotBlds", "TotUsed", "TotCork", "BigBlds", "ShortLvd",
                           "TotTime", "MaxTime");
             } else {
                 pw.format(Locale.US,
-                        "  %10d  %10d  %10d  %10d  %10d  %10d",
-                        mTotalBuilds, mTotalUsed, mBigBuilds, mShortLived,
+                        "  %10d  %10d  %10d  %10d  %10d  %10d  %10d",
+                        mTotalBuilds, mTotalUsed, mTotalCorked, mBigBuilds, mShortLived,
                         mTotalTimeUs / 1000, mMaxBuildTimeUs / 1000);
             }
             pw.println();
@@ -516,7 +531,7 @@ public class SnapshotStatistics {
      * @param done The time at which the snapshot rebuild completed, in ns.
      * @param hits The number of times the previous snapshot was used.
      */
-    public void rebuild(long now, long done, int hits) {
+    public final void rebuild(long now, long done, int hits) {
         // The duration has a span of about 2000s
         final int duration = (int) (done - now);
         boolean reportEvent = false;
@@ -543,10 +558,21 @@ public class SnapshotStatistics {
         }
     }
 
+    /**
+     * Record a corked snapshot request.
+     */
+    public final void corked() {
+        synchronized (mLock) {
+            mShort[0].corked();
+            mLong[0].corked();
+        }
+    }
+
     /**
      * Roll a stats array.  Shift the elements up an index and create a new element at
      * index zero.  The old element zero is completed with the specified time.
      */
+    @GuardedBy("mLock")
     private void shift(Stats[] s, long now) {
         s[0].complete(now);
         for (int i = s.length - 1; i > 0; i--) {
@@ -598,7 +624,8 @@ public class SnapshotStatistics {
      * Dump the statistics.  The format is compatible with the PackageManager dumpsys
      * output.
      */
-    public void dump(PrintWriter pw, String indent, long now, int unrecorded, boolean full) {
+    public void dump(PrintWriter pw, String indent, long now, int unrecorded,
+                     int corkLevel, boolean full) {
         // Grab the raw statistics under lock, but print them outside of the lock.
         Stats[] l;
         Stats[] s;
@@ -608,7 +635,8 @@ public class SnapshotStatistics {
             s = Arrays.copyOf(mShort, mShort.length);
             s[0] = new Stats(s[0]);
         }
-        pw.format(Locale.US, "%s Unrecorded hits %d", indent, unrecorded);
+        pw.format(Locale.US, "%s Unrecorded-hits: %d  Cork-level: %d", indent,
+                  unrecorded, corkLevel);
         pw.println();
         dump(pw, indent, now, l, s, "stats");
         if (!full) {
diff --git a/services/core/java/com/android/server/utils/SnapshotCache.java b/services/core/java/com/android/server/utils/SnapshotCache.java
index b4b8835ac0269..68eb4b09b3ab5 100644
--- a/services/core/java/com/android/server/utils/SnapshotCache.java
+++ b/services/core/java/com/android/server/utils/SnapshotCache.java
@@ -40,10 +40,10 @@ public abstract class SnapshotCache<T> extends Watcher{
     protected final T mSource;
 
     // The cached snapshot
-    private T mSnapshot = null;
+    private volatile T mSnapshot = null;
 
     // True if the snapshot is sealed and may not be modified.
-    private boolean mSealed = false;
+    private volatile boolean mSealed = false;
 
     /**
      * Create a cache with a source object for rebuilding snapshots and a
@@ -69,7 +69,7 @@ public abstract class SnapshotCache<T> extends Watcher{
      * Notify the object that the source object has changed.  If the local object is sealed then
      * IllegalStateException is thrown.  Otherwise, the cache is cleared.
      */
-    public void onChange(@Nullable Watchable what) {
+    public final void onChange(@Nullable Watchable what) {
         if (mSealed) {
             throw new IllegalStateException("attempt to change a sealed object");
         }
@@ -79,7 +79,7 @@ public abstract class SnapshotCache<T> extends Watcher{
     /**
      * Seal the cache.  Attempts to modify the cache will generate an exception.
      */
-    public void seal() {
+    public final void seal() {
         mSealed = true;
     }
 
@@ -88,7 +88,7 @@ public abstract class SnapshotCache<T> extends Watcher{
      * new snapshot and saves it in the cache.
      * @return A snapshot as returned by createSnapshot() and possibly cached.
      */
-    public T snapshot() {
+    public final T snapshot() {
         T s = mSnapshot;
         if (s == null || !ENABLED) {
             s = createSnapshot();
diff --git a/services/tests/servicestests/src/com/android/server/pm/KeySetManagerServiceTest.java b/services/tests/servicestests/src/com/android/server/pm/KeySetManagerServiceTest.java
index 709b009c2feb8..1b6bddc158b8b 100644
--- a/services/tests/servicestests/src/com/android/server/pm/KeySetManagerServiceTest.java
+++ b/services/tests/servicestests/src/com/android/server/pm/KeySetManagerServiceTest.java
@@ -25,6 +25,7 @@ import android.util.ArraySet;
 import android.util.LongSparseArray;
 
 import com.android.internal.util.ArrayUtils;
+import com.android.server.utils.WatchedArrayMap;
 
 import java.io.File;
 import java.io.IOException;
@@ -33,7 +34,7 @@ import java.security.cert.CertificateException;
 
 public class KeySetManagerServiceTest extends AndroidTestCase {
 
-    private ArrayMap<String, PackageSetting> mPackagesMap;
+    private WatchedArrayMap<String, PackageSetting> mPackagesMap;
     private KeySetManagerService mKsms;
 
     public PackageSetting generateFakePackageSetting(String name) {
@@ -46,7 +47,7 @@ public class KeySetManagerServiceTest extends AndroidTestCase {
     @Override
     public void setUp() throws Exception {
         super.setUp();
-        mPackagesMap = new ArrayMap<String, PackageSetting>();
+        mPackagesMap = new WatchedArrayMap<String, PackageSetting>();
         mKsms = new KeySetManagerService(mPackagesMap);
     }
 
@@ -94,7 +95,8 @@ public class KeySetManagerServiceTest extends AndroidTestCase {
     }
 
     public void testEncodePublicKey() throws IOException {
-        ArrayMap<String, PackageSetting> packagesMap = new ArrayMap<String, PackageSetting>();
+        WatchedArrayMap<String, PackageSetting> packagesMap =
+                new WatchedArrayMap<String, PackageSetting>();
         KeySetManagerService ksms = new KeySetManagerService(packagesMap);
 
         PublicKey keyA = PackageParser.parsePublicKey(KeySetStrings.ctsKeySetPublicKeyA);
diff --git a/services/tests/servicestests/src/com/android/server/pm/PackageManagerSettingsTests.java b/services/tests/servicestests/src/com/android/server/pm/PackageManagerSettingsTests.java
index a2311690744e3..29f4aa976ef61 100644
--- a/services/tests/servicestests/src/com/android/server/pm/PackageManagerSettingsTests.java
+++ b/services/tests/servicestests/src/com/android/server/pm/PackageManagerSettingsTests.java
@@ -47,7 +47,6 @@ import android.os.BaseBundle;
 import android.os.PersistableBundle;
 import android.os.Process;
 import android.os.UserHandle;
-import android.util.ArrayMap;
 import android.util.ArraySet;
 import android.util.AtomicFile;
 import android.util.Log;
@@ -64,6 +63,7 @@ import com.android.server.pm.parsing.pkg.ParsedPackage;
 import com.android.server.pm.permission.LegacyPermissionDataProvider;
 import com.android.server.pm.verify.domain.DomainVerificationManagerInternal;
 import com.android.server.utils.WatchableTester;
+import com.android.server.utils.WatchedArrayMap;
 
 import com.google.common.truth.Truth;
 
@@ -1202,9 +1202,8 @@ public class PackageManagerSettingsTests {
 
     private void verifyKeySetMetaData(Settings settings)
             throws ReflectiveOperationException, IllegalAccessException {
-        ArrayMap<String, PackageSetting> packages =
-                settings.mPackages.untrackedStorage();
-        KeySetManagerService ksms = settings.mKeySetManagerService;
+        WatchedArrayMap<String, PackageSetting> packages = settings.mPackages;
+        KeySetManagerService ksms = settings.getKeySetManagerService();
 
         /* verify keyset and public key ref counts */
         assertThat(KeySetUtils.getKeySetRefCount(ksms, 1), is(2));