Reduce field contention during dump() (496ebf67) · Commits · e / os / android_frameworks_base

core/java/android/util/NtpTrustedTime.java

+46 −23

Original line number	Diff line number	Diff line
		@@ -216,19 +216,36 @@ public abstract class NtpTrustedTime implements TrustedTime {

		private static NtpTrustedTime sSingleton;

		/** A lock to prevent multiple refreshes taking place at the same time. */
		private final Object mRefreshLock = new Object();

		/** A lock to ensure safe read/writes to configuration. */
		private final Object mConfigLock = new Object();

		/** An in-memory config override for use during tests. */
		@GuardedBy("this")
		@GuardedBy("mConfigLock")
		@Nullable
		private NtpConfig mNtpConfigForTests;

		@GuardedBy("this")
		/**
		* The latest time result.
		*
		* <p>Written when holding {@link #mRefreshLock} but declared volatile and can be read outside
		* synchronized blocks to avoid blocking dump() during {@link #forceRefresh}.
		*/
		@Nullable
		private URI mLastSuccessfulNtpServerUri;

		// Declared volatile and accessed outside synchronized blocks to avoid blocking reads during
		// forceRefresh().
		private volatile TimeResult mTimeResult;

		/**
		* The last successful NTP server URI, i.e. the one used to obtain {@link #mTimeResult} when it
		* is non-null.
		*
		* <p>Written when holding {@link #mRefreshLock} but declared volatile and can be read outside
		* synchronized blocks to avoid blocking dump() during {@link #forceRefresh}.
		*/
		@Nullable
		private volatile URI mLastSuccessfulNtpServerUri;

		protected NtpTrustedTime() {
		}

		@@ -246,7 +263,7 @@ public abstract class NtpTrustedTime implements TrustedTime {
		* test value, i.e. so the normal value will be used next time.
		*/
		public void setServerConfigForTests(@NonNull NtpConfig ntpConfig) {
		synchronized (this) {
		synchronized (mConfigLock) {
		mNtpConfigForTests = ntpConfig;
		}
		}
		@@ -254,7 +271,7 @@ public abstract class NtpTrustedTime implements TrustedTime {
		/** Forces a refresh using the default network. */
		@UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
		public boolean forceRefresh() {
		synchronized (this) {
		synchronized (mRefreshLock) {
		Network network = getDefaultNetwork();
		if (network == null) {
		if (LOGD) Log.d(TAG, "forceRefresh: no network available");
		@@ -269,12 +286,13 @@ public abstract class NtpTrustedTime implements TrustedTime {
		public boolean forceRefresh(@NonNull Network network) {
		Objects.requireNonNull(network);

		synchronized (this) {
		synchronized (mRefreshLock) {
		// Prevent concurrent refreshes.
		return forceRefreshLocked(network);
		}
		}

		@GuardedBy("this")
		@GuardedBy("mRefreshLock")
		private boolean forceRefreshLocked(@NonNull Network network) {
		Objects.requireNonNull(network);

		@@ -349,13 +367,14 @@ public abstract class NtpTrustedTime implements TrustedTime {
		return false;
		}

		@GuardedBy("this")
		private NtpConfig getNtpConfig() {
		synchronized (mConfigLock) {
		if (mNtpConfigForTests != null) {
		return mNtpConfigForTests;
		}
		return getNtpConfigInternal();
		}
		}

		/**
		* Returns the {@link NtpConfig} to use during an NTP query. This method can return {@code null}
		@@ -363,6 +382,7 @@ public abstract class NtpTrustedTime implements TrustedTime {
		*
		* <p>This method has been made public for easy replacement during tests.
		*/
		@GuardedBy("mConfigLock")
		@VisibleForTesting
		@Nullable
		public abstract NtpConfig getNtpConfigInternal();
		@@ -479,14 +499,14 @@ public abstract class NtpTrustedTime implements TrustedTime {

		/** Sets the last received NTP time. Intended for use during tests. */
		public void setCachedTimeResult(TimeResult timeResult) {
		synchronized (this) {
		synchronized (mRefreshLock) {
		mTimeResult = timeResult;
		}
		}

		/** Clears the last received NTP time. Intended for use during tests. */
		public void clearCachedTimeResult() {
		synchronized (this) {
		synchronized (mRefreshLock) {
		mTimeResult = null;
		}
		}
		@@ -585,15 +605,18 @@ public abstract class NtpTrustedTime implements TrustedTime {

		/** Prints debug information. */
		public void dump(PrintWriter pw) {
		synchronized (this) {
		synchronized (mConfigLock) {
		pw.println("getNtpConfig()=" + getNtpConfig());
		pw.println("mNtpConfigForTests=" + mNtpConfigForTests);
		}

		pw.println("mLastSuccessfulNtpServerUri=" + mLastSuccessfulNtpServerUri);
		pw.println("mTimeResult=" + mTimeResult);
		if (mTimeResult != null) {

		TimeResult timeResult = mTimeResult;
		pw.println("mTimeResult=" + timeResult);
		if (timeResult != null) {
		pw.println("mTimeResult.getAgeMillis()="
		+ Duration.ofMillis(mTimeResult.getAgeMillis()));
		}
		+ Duration.ofMillis(timeResult.getAgeMillis()));
		}
		}