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SntpClient periodically re-syncs the offset to NTP server #697

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stevemayhew wants to merge 2 commits into from
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SntpClient periodically re-syncs the offset to NTP server #697

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068482e
SntpClient periodically re-syncs the offset to NTP server
stevemayhew Oct 4, 2023
1bdf9de
Merge branch 'androidx:release' into p-fix-ntp-time-update
stevemayhew Jul 22, 2024
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12 changes: 12 additions & 0 deletions libraries/exoplayer/src/main/java/androidx/media3/exoplayer/util/SntpClient.java
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Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,9 @@ public final class SntpClient {
/** The default NTP host address used to retrieve {@link #getElapsedRealtimeOffsetMs()}. */
public static final String DEFAULT_NTP_HOST = "time.android.com";

/** Max time to allow before re-initializing with NTP server, default is 10 minutes */
private static final long MAX_ELAPSED_MS_TILL_UPDATE = 60 * 10 * 1_000L;

/** Callback for calls to {@link #initialize(Loader, InitializationCallback)}. */
public interface InitializationCallback {

Expand Down Expand Up @@ -88,6 +91,9 @@ public interface InitializationCallback {
@GuardedBy("valueLock")
private static String ntpHost = DEFAULT_NTP_HOST;

@GuardedBy("valueLock")
private static long lastUpdateElapsedRealtime = C.TIME_UNSET;

private SntpClient() {}

/** Returns the NTP host address used to retrieve {@link #getElapsedRealtimeOffsetMs()}. */
Expand All @@ -112,6 +118,7 @@ public static void setNtpHost(String ntpHost) {
if (!SntpClient.ntpHost.equals(ntpHost)) {
SntpClient.ntpHost = ntpHost;
isInitialized = false;
lastUpdateElapsedRealtime = C.TIME_UNSET;
}
}
}
Expand All @@ -124,6 +131,10 @@ public static void setNtpHost(String ntpHost) {
*/
public static boolean isInitialized() {
synchronized (valueLock) {
if (lastUpdateElapsedRealtime != C.TIME_UNSET) {
long deltaLastUpdate = SystemClock.elapsedRealtime() - lastUpdateElapsedRealtime;
isInitialized = isInitialized && deltaLastUpdate < MAX_ELAPSED_MS_TILL_UPDATE;
}
return isInitialized;
}
}
Expand Down Expand Up @@ -299,6 +310,7 @@ public void load() throws IOException {
}
long offsetMs = loadNtpTimeOffsetMs();
synchronized (valueLock) {
lastUpdateElapsedRealtime = SystemClock.elapsedRealtime();
elapsedRealtimeOffsetMs = offsetMs;
isInitialized = true;
}
Expand Down