Intern common TimeValue constants (#107985)

The values `30s` and `1m` are used as defaults in various places in ES,
there's no need to create a new `TimeValue` instance each time they
appear. Moreover we already have constants for `0` and `-1`, but we
don't use these constants when reading the values off the wire.

This commit adds constants for `30s` and `1m` and adjusts the
deserialization code to avoid unnecessary allocation for common
`TimeValue` instances.

Relates #107984

libs/core/src/main/java/org/elasticsearch/core/TimeValue.java

@@ -17,9 +17,11 @@ public class TimeValue implements Comparable<TimeValue> {
     /** How many nano-seconds in one milli-second */
     public static final long NSEC_PER_MSEC = TimeUnit.NANOSECONDS.convert(1, TimeUnit.MILLISECONDS);
 
-    public static final TimeValue MINUS_ONE = timeValueMillis(-1);
-    public static final TimeValue ZERO = timeValueMillis(0);
-    public static final TimeValue MAX_VALUE = TimeValue.timeValueNanos(Long.MAX_VALUE);
+    public static final TimeValue MINUS_ONE = new TimeValue(-1, TimeUnit.MILLISECONDS);
+    public static final TimeValue ZERO = new TimeValue(0, TimeUnit.MILLISECONDS);
+    public static final TimeValue MAX_VALUE = new TimeValue(Long.MAX_VALUE, TimeUnit.NANOSECONDS);
+    public static final TimeValue THIRTY_SECONDS = new TimeValue(30, TimeUnit.SECONDS);
+    public static final TimeValue ONE_MINUTE = new TimeValue(1, TimeUnit.MINUTES);
 
     private static final long C0 = 1L;
     private static final long C1 = C0 * 1000L;
@@ -49,14 +51,28 @@ public class TimeValue implements Comparable<TimeValue> {
     }
 
     public static TimeValue timeValueMillis(long millis) {
+        if (millis == 0) {
+            return ZERO;
+        }
+        if (millis == -1) {
+            return MINUS_ONE;
+        }
         return new TimeValue(millis, TimeUnit.MILLISECONDS);
     }
 
     public static TimeValue timeValueSeconds(long seconds) {
+        if (seconds == 30) {
+            // common value, no need to allocate each time
+            return THIRTY_SECONDS;
+        }
         return new TimeValue(seconds, TimeUnit.SECONDS);
     }
 
     public static TimeValue timeValueMinutes(long minutes) {
+        if (minutes == 1) {
+            // common value, no need to allocate each time
+            return ONE_MINUTE;
+        }
         return new TimeValue(minutes, TimeUnit.MINUTES);
     }
 
@@ -355,18 +371,18 @@ public class TimeValue implements Comparable<TimeValue> {
         }
         final String normalized = sValue.toLowerCase(Locale.ROOT).trim();
         if (normalized.endsWith("nanos")) {
-            return new TimeValue(parse(sValue, normalized, "nanos", settingName), TimeUnit.NANOSECONDS);
+            return TimeValue.timeValueNanos(parse(sValue, normalized, "nanos", settingName));
         } else if (normalized.endsWith("micros")) {
             return new TimeValue(parse(sValue, normalized, "micros", settingName), TimeUnit.MICROSECONDS);
         } else if (normalized.endsWith("ms")) {
-            return new TimeValue(parse(sValue, normalized, "ms", settingName), TimeUnit.MILLISECONDS);
+            return TimeValue.timeValueMillis(parse(sValue, normalized, "ms", settingName));
         } else if (normalized.endsWith("s")) {
-            return new TimeValue(parse(sValue, normalized, "s", settingName), TimeUnit.SECONDS);
+            return TimeValue.timeValueSeconds(parse(sValue, normalized, "s", settingName));
         } else if (sValue.endsWith("m")) {
             // parsing minutes should be case-sensitive as 'M' means "months", not "minutes"; this is the only special case.
-            return new TimeValue(parse(sValue, normalized, "m", settingName), TimeUnit.MINUTES);
+            return TimeValue.timeValueMinutes(parse(sValue, normalized, "m", settingName));
         } else if (normalized.endsWith("h")) {
-            return new TimeValue(parse(sValue, normalized, "h", settingName), TimeUnit.HOURS);
+            return TimeValue.timeValueHours(parse(sValue, normalized, "h", settingName));
         } else if (normalized.endsWith("d")) {
             return new TimeValue(parse(sValue, normalized, "d", settingName), TimeUnit.DAYS);
         } else if (normalized.matches("-0*1")) {

libs/core/src/test/java/org/elasticsearch/common/unit/TimeValueTests.java

@@ -242,4 +242,16 @@ public class TimeValueTests extends ESTestCase {
             TimeUnit.DAYS
         );
     }
+
+    public void testInternedValues() {
+        assertSame(TimeValue.timeValueMillis(-1), TimeValue.MINUS_ONE);
+        assertSame(TimeValue.timeValueMillis(0), TimeValue.ZERO);
+        assertSame(TimeValue.timeValueSeconds(30), TimeValue.THIRTY_SECONDS);
+        assertSame(TimeValue.timeValueMinutes(1), TimeValue.ONE_MINUTE);
+
+        assertSame(TimeValue.parseTimeValue("-1", getTestName()), TimeValue.MINUS_ONE);
+        assertSame(TimeValue.parseTimeValue("0", getTestName()), TimeValue.ZERO);
+        assertSame(TimeValue.parseTimeValue("30s", getTestName()), TimeValue.THIRTY_SECONDS);
+        assertSame(TimeValue.parseTimeValue("1m", getTestName()), TimeValue.ONE_MINUTE);
+    }
 }