Merge "Remove some usages of NitzData.isDst()" (f5ea5f61) · Commits · e / os / android_frameworks_opt_telephony

src/java/com/android/internal/telephony/NitzData.java

+25 −3

Original line number	Diff line number	Diff line
		@@ -26,7 +26,7 @@ import java.util.Calendar;
		import java.util.TimeZone;

		/**
		* Represents NITZ data. Various static methods are provided to help with parsing and intepretation
		* Represents NITZ data. Various static methods are provided to help with parsing and interpretation
		* of NITZ data.
		*
		* {@hide}
		@@ -153,7 +153,11 @@ public final class NitzData {

		/**
		* Returns the total offset to apply to the {@link #getCurrentTimeInMillis()} to arrive at a
		* local time.
		* local time. NITZ is limited in only being able to express total offsets in multiples of 15
		* minutes.
		*
		* <p>Note that some time zones change offset during the year for reasons other than "daylight
		* savings", e.g. for Ramadan. This is not well handled by most date / time APIs.
		*/
		public int getLocalOffsetMillis() {
		return mZoneOffset;
		@@ -162,7 +166,25 @@ public final class NitzData {
		/**
		* Returns the offset (already included in {@link #getLocalOffsetMillis()}) associated with
		* Daylight Savings Time (DST). This field is optional: {@code null} means the DST offset is
		* unknown.
		* unknown. NITZ is limited in only being able to express DST offsets in positive multiples of
		* one or two hours.
		*
		* <p>Callers should remember that standard time / DST is a matter of convention: it has
		* historically been assumed by NITZ and many date/time APIs that DST happens in the summer and
		* the "raw" offset will increase during this time, usually by one hour. However, the tzdb
		* maintainers have moved to different conventions on a country-by-country basis so that some
		* summer times are considered the "standard" time (i.e. in this model winter time is the "DST"
		* and a negative adjustment, usually of (negative) one hour.
		*
		* <p>There is nothing that says NITZ and tzdb need to treat DST conventions the same.
		*
		* <p>At the time of writing Android date/time APIs are sticking with the historic tzdb
		* convention that DST is used in summer time and is <em>always</em> a positive offset but this
		* could change in future. If Android or carriers change the conventions used then it might make
		* NITZ comparisons with tzdb information more error-prone.
		*
		* <p>See also {@link #getLocalOffsetMillis()} for other reasons besides DST that a local offset
		* may change.
		*/
		public Integer getDstAdjustmentMillis() {
		return mDstOffset;

src/java/com/android/internal/telephony/NitzStateMachineImpl.java

+1 −1

Original line number	Diff line number	Diff line
		@@ -263,7 +263,7 @@ public final class NitzStateMachineImpl implements NitzStateMachine {
		}

		NitzData newNitzData = nitzSignal.getValue();
		boolean zeroOffsetNitz = newNitzData.getLocalOffsetMillis() == 0 && !newNitzData.isDst();
		boolean zeroOffsetNitz = newNitzData.getLocalOffsetMillis() == 0;
		return zeroOffsetNitz && !countryUsesUtc(isoCountryCode, nitzSignal);
		}

src/java/com/android/internal/telephony/TimeZoneLookupHelper.java

+36 −13

Original line number	Diff line number	Diff line
		@@ -23,7 +23,6 @@ import libcore.timezone.CountryTimeZones;
		import libcore.timezone.CountryTimeZones.TimeZoneMapping;
		import libcore.timezone.TimeZoneFinder;

		import java.util.Date;
		import java.util.List;
		import java.util.Objects;

		@@ -314,30 +313,36 @@ public class TimeZoneLookupHelper {

		private static OffsetResult lookupByNitzStatic(NitzData nitzData) {
		int utcOffsetMillis = nitzData.getLocalOffsetMillis();
		boolean isDst = nitzData.isDst();
		long timeMillis = nitzData.getCurrentTimeInMillis();

		// Android NITZ time zone matching doesn't try to do a precise match using the DST offset
		// supplied by the carrier. It only considers whether or not the carrier suggests local time
		// is DST (if known). NITZ is limited in only being able to express DST offsets in whole
		// hours and the DST info is optional.
		Integer dstAdjustmentMillis = nitzData.getDstAdjustmentMillis();
		Boolean isDst = dstAdjustmentMillis == null ? null : dstAdjustmentMillis != 0;

		OffsetResult match = lookupByInstantOffsetDst(timeMillis, utcOffsetMillis, isDst);
		if (match == null) {
		// Couldn't find a proper timezone. Perhaps the DST data is wrong.
		match = lookupByInstantOffsetDst(timeMillis, utcOffsetMillis, !isDst);
		if (match == null && isDst != null) {
		// This branch is extremely unlikely and could probably be removed. The match above will
		// have searched the entire tzdb for a zone with the same total offset and isDst state.
		// Here we try another match but use "null" for isDst to indicate that only the total
		// offset should be considered. If, by the end of this, there isn't a match then the
		// current offset suggested by the carrier must be highly unusual.
		match = lookupByInstantOffsetDst(timeMillis, utcOffsetMillis, null /* isDst */);
		}
		return match;
		}

		private static OffsetResult lookupByInstantOffsetDst(long timeMillis, int utcOffsetMillis,
		boolean isDst) {
		int rawOffset = utcOffsetMillis;
		if (isDst) {
		rawOffset -= MS_PER_HOUR;
		}
		String[] zones = TimeZone.getAvailableIDs(rawOffset);
		Boolean isDst) {

		String[] zones = TimeZone.getAvailableIDs();
		TimeZone match = null;
		Date d = new Date(timeMillis);
		boolean isOnlyMatch = true;
		for (String zone : zones) {
		TimeZone tz = TimeZone.getFrozenTimeZone(zone);
		if (tz.getOffset(timeMillis) == utcOffsetMillis && tz.inDaylightTime(d) == isDst) {
		if (offsetMatchesAtTime(tz, utcOffsetMillis, isDst, timeMillis)) {
		if (match == null) {
		match = tz;
		} else {
		@@ -353,6 +358,24 @@ public class TimeZoneLookupHelper {
		return new OffsetResult(match, isOnlyMatch);
		}

		/**
		* Returns {@code true} if the specified {@code totalOffset} and {@code isDst} would be valid in
		* the {@code timeZone} at time {@code whenMillis}. {@code totalOffetMillis} is always matched.
		* If {@code isDst} is {@code null} this means the DST state is unknown so DST state is ignored.
		* If {@code isDst} is not {@code null} then it is also matched.
		*/
		private static boolean offsetMatchesAtTime(TimeZone timeZone, int totalOffsetMillis,
		Boolean isDst, long whenMillis) {
		int[] offsets = new int[2];
		timeZone.getOffset(whenMillis, false /* local */, offsets);

		if (totalOffsetMillis != (offsets[0] + offsets[1])) {
		return false;
		}

		return isDst == null \|\| isDst == (offsets[1] != 0);
		}

		/**
		* Returns {@code true} if the supplied (lower-case) ISO country code is for a country known to
		* use a raw offset of zero from UTC at the time specified.