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jdk/src/java.base/share/classes/sun/misc/VM.java
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@@ -1,7 +1,7 @@
/*
- * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2015, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
@@ -400,10 +400,40 @@
* Returns the effective group ID of the calling process,
* or -1 if the value is not available.
*/
public static native long getegid();
+ /**
+ * Get a nanosecond time stamp adjustment in the form of a single long.
+ *
+ * This value can be used to create an instant using
+ * {@link java.time.Instant#ofEpochSecond(long, long)
+ * java.time.Instant.ofEpochSecond(offsetInSeconds,
+ * getNanoTimeAdjustment(offsetInSeconds))}.
+ * <p>
+ * The value returned has the best resolution available to the JVM on
+ * the current system.
+ * This is usually down to microseconds - or tenth of microseconds -
+ * depending on the OS/Hardware and the JVM implementation.
+ *
+ * @param offsetInSeconds The offset in seconds from which the nanosecond
+ * time stamp should be computed.
+ *
+ * @apiNote The offset should be recent enough - so that
+ * {@code offsetInSeconds} is within {@code +/- 2^32} seconds of the
+ * current UTC time. If the offset is too far off, {@code -1} will be
+ * returned. As such, {@code -1} must not be considered as a valid
+ * nano time adjustment, but as an exception value indicating
+ * that an offset closer to the current time should be used.
+ *
+ * @return A nanosecond time stamp adjustment in the form of a single long.
+ * If the offset is too far off the current time, this method returns -1.
+ * In that case, the caller should call this method again, passing a
+ * more accurate offset.
+ */
+ public static native long getNanoTimeAdjustment(long offsetInSeconds);
+
static {
initialize();
}
private native static void initialize();
}
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