8068730: Increase the precision of the implementation of java.time.Clock.systemUTC()
Summary: Changes the implementation of java.time.Clock.systemUTC() to take advantage of the maximum resolution of the underlying native clock on which System.currentTimeMillis() is based.
Reviewed-by: dholmes, rriggs, scolebourne, sla
--- a/hotspot/make/aix/makefiles/mapfile-vers-debug Wed Jan 28 09:27:49 2015 +0100
+++ b/hotspot/make/aix/makefiles/mapfile-vers-debug Wed Jan 28 17:52:48 2015 +0100
@@ -1,5 +1,5 @@
#
-# Copyright (c) 2002, 2014, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2002, 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
@@ -132,6 +132,7 @@
JVM_GetMethodIxSignatureUTF;
JVM_GetMethodParameters;
JVM_GetMethodTypeAnnotations;
+ JVM_GetNanoTimeAdjustment;
JVM_GetPrimitiveArrayElement;
JVM_GetProtectionDomain;
JVM_GetStackAccessControlContext;
--- a/hotspot/make/aix/makefiles/mapfile-vers-product Wed Jan 28 09:27:49 2015 +0100
+++ b/hotspot/make/aix/makefiles/mapfile-vers-product Wed Jan 28 17:52:48 2015 +0100
@@ -1,5 +1,5 @@
#
-# Copyright (c) 2002, 2014, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2002, 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
@@ -130,6 +130,7 @@
JVM_GetMethodIxNameUTF;
JVM_GetMethodIxSignatureUTF;
JVM_GetMethodParameters;
+ JVM_GetNanoTimeAdjustment;
JVM_GetPrimitiveArrayElement;
JVM_GetProtectionDomain;
JVM_GetStackAccessControlContext;
--- a/hotspot/make/bsd/makefiles/mapfile-vers-darwin-debug Wed Jan 28 09:27:49 2015 +0100
+++ b/hotspot/make/bsd/makefiles/mapfile-vers-darwin-debug Wed Jan 28 17:52:48 2015 +0100
@@ -1,5 +1,5 @@
#
-# Copyright (c) 2002, 2014, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2002, 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
@@ -130,6 +130,7 @@
_JVM_GetMethodIxSignatureUTF
_JVM_GetMethodParameters
_JVM_GetMethodTypeAnnotations
+ _JVM_GetNanoTimeAdjustment
_JVM_GetPrimitiveArrayElement
_JVM_GetProtectionDomain
_JVM_GetStackAccessControlContext
--- a/hotspot/make/bsd/makefiles/mapfile-vers-darwin-product Wed Jan 28 09:27:49 2015 +0100
+++ b/hotspot/make/bsd/makefiles/mapfile-vers-darwin-product Wed Jan 28 17:52:48 2015 +0100
@@ -1,5 +1,5 @@
#
-# Copyright (c) 2002, 2014, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2002, 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
@@ -130,6 +130,7 @@
_JVM_GetMethodIxSignatureUTF
_JVM_GetMethodParameters
_JVM_GetMethodTypeAnnotations
+ _JVM_GetNanoTimeAdjustment
_JVM_GetPrimitiveArrayElement
_JVM_GetProtectionDomain
_JVM_GetStackAccessControlContext
--- a/hotspot/make/bsd/makefiles/mapfile-vers-debug Wed Jan 28 09:27:49 2015 +0100
+++ b/hotspot/make/bsd/makefiles/mapfile-vers-debug Wed Jan 28 17:52:48 2015 +0100
@@ -1,5 +1,5 @@
#
-# Copyright (c) 2002, 2014, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2002, 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
@@ -132,6 +132,7 @@
JVM_GetMethodIxSignatureUTF;
JVM_GetMethodParameters;
JVM_GetMethodTypeAnnotations;
+ JVM_GetNanoTimeAdjustment;
JVM_GetPrimitiveArrayElement;
JVM_GetProtectionDomain;
JVM_GetStackAccessControlContext;
--- a/hotspot/make/bsd/makefiles/mapfile-vers-product Wed Jan 28 09:27:49 2015 +0100
+++ b/hotspot/make/bsd/makefiles/mapfile-vers-product Wed Jan 28 17:52:48 2015 +0100
@@ -1,5 +1,5 @@
#
-# Copyright (c) 2002, 2014, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2002, 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
@@ -132,6 +132,7 @@
JVM_GetMethodIxSignatureUTF;
JVM_GetMethodParameters;
JVM_GetMethodTypeAnnotations;
+ JVM_GetNanoTimeAdjustment;
JVM_GetPrimitiveArrayElement;
JVM_GetProtectionDomain;
JVM_GetStackAccessControlContext;
--- a/hotspot/make/linux/makefiles/mapfile-vers-debug Wed Jan 28 09:27:49 2015 +0100
+++ b/hotspot/make/linux/makefiles/mapfile-vers-debug Wed Jan 28 17:52:48 2015 +0100
@@ -1,5 +1,5 @@
#
-# Copyright (c) 2002, 2014, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2002, 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
@@ -132,6 +132,7 @@
JVM_GetMethodIxSignatureUTF;
JVM_GetMethodParameters;
JVM_GetMethodTypeAnnotations;
+ JVM_GetNanoTimeAdjustment;
JVM_GetPrimitiveArrayElement;
JVM_GetProtectionDomain;
JVM_GetStackAccessControlContext;
--- a/hotspot/make/linux/makefiles/mapfile-vers-product Wed Jan 28 09:27:49 2015 +0100
+++ b/hotspot/make/linux/makefiles/mapfile-vers-product Wed Jan 28 17:52:48 2015 +0100
@@ -1,5 +1,5 @@
#
-# Copyright (c) 2002, 2014, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2002, 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
@@ -132,6 +132,7 @@
JVM_GetMethodIxSignatureUTF;
JVM_GetMethodParameters;
JVM_GetMethodTypeAnnotations;
+ JVM_GetNanoTimeAdjustment;
JVM_GetPrimitiveArrayElement;
JVM_GetProtectionDomain;
JVM_GetStackAccessControlContext;
--- a/hotspot/make/solaris/makefiles/mapfile-vers Wed Jan 28 09:27:49 2015 +0100
+++ b/hotspot/make/solaris/makefiles/mapfile-vers Wed Jan 28 17:52:48 2015 +0100
@@ -1,5 +1,5 @@
#
-# Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2000, 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
@@ -132,6 +132,7 @@
JVM_GetMethodIxSignatureUTF;
JVM_GetMethodParameters;
JVM_GetMethodTypeAnnotations;
+ JVM_GetNanoTimeAdjustment;
JVM_GetPrimitiveArrayElement;
JVM_GetProtectionDomain;
JVM_GetStackAccessControlContext;
--- a/hotspot/src/os/aix/vm/os_aix.cpp Wed Jan 28 09:27:49 2015 +0100
+++ b/hotspot/src/os/aix/vm/os_aix.cpp Wed Jan 28 17:52:48 2015 +0100
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 1999, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2015, Oracle and/or its affiliates. All rights reserved.
* Copyright 2012, 2014 SAP AG. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
@@ -1115,6 +1115,15 @@
return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000);
}
+void os::javaTimeSystemUTC(jlong &seconds, jlong &nanos) {
+ timeval time;
+ int status = gettimeofday(&time, NULL);
+ assert(status != -1, "aix error at gettimeofday()");
+ seconds = jlong(time.tv_sec);
+ nanos = jlong(time.tv_usec) * 1000;
+}
+
+
// We need to manually declare mread_real_time,
// because IBM didn't provide a prototype in time.h.
// (they probably only ever tested in C, not C++)
--- a/hotspot/src/os/bsd/vm/os_bsd.cpp Wed Jan 28 09:27:49 2015 +0100
+++ b/hotspot/src/os/bsd/vm/os_bsd.cpp Wed Jan 28 17:52:48 2015 +0100
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 1999, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 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
@@ -984,6 +984,14 @@
return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000);
}
+void os::javaTimeSystemUTC(jlong &seconds, jlong &nanos) {
+ timeval time;
+ int status = gettimeofday(&time, NULL);
+ assert(status != -1, "bsd error");
+ seconds = jlong(time.tv_sec);
+ nanos = jlong(time.tv_usec) * 1000;
+}
+
#ifndef __APPLE__
#ifndef CLOCK_MONOTONIC
#define CLOCK_MONOTONIC (1)
--- a/hotspot/src/os/linux/vm/os_linux.cpp Wed Jan 28 09:27:49 2015 +0100
+++ b/hotspot/src/os/linux/vm/os_linux.cpp Wed Jan 28 17:52:48 2015 +0100
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 1999, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 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
@@ -1322,6 +1322,15 @@
return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000);
}
+void os::javaTimeSystemUTC(jlong &seconds, jlong &nanos) {
+ timeval time;
+ int status = gettimeofday(&time, NULL);
+ assert(status != -1, "linux error");
+ seconds = jlong(time.tv_sec);
+ nanos = jlong(time.tv_usec) * 1000;
+}
+
+
#ifndef CLOCK_MONOTONIC
#define CLOCK_MONOTONIC (1)
#endif
--- a/hotspot/src/os/solaris/vm/os_solaris.cpp Wed Jan 28 09:27:49 2015 +0100
+++ b/hotspot/src/os/solaris/vm/os_solaris.cpp Wed Jan 28 17:52:48 2015 +0100
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 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
@@ -1475,6 +1475,16 @@
return jlong(t.tv_sec) * 1000 + jlong(t.tv_usec) / 1000;
}
+void os::javaTimeSystemUTC(jlong &seconds, jlong &nanos) {
+ timeval t;
+ if (gettimeofday(&t, NULL) == -1) {
+ fatal(err_msg("os::javaTimeSystemUTC: gettimeofday (%s)", strerror(errno)));
+ }
+ seconds = jlong(t.tv_sec);
+ nanos = jlong(t.tv_usec) * 1000;
+}
+
+
jlong os::javaTimeNanos() {
return (jlong)getTimeNanos();
}
--- a/hotspot/src/os/windows/vm/os_windows.cpp Wed Jan 28 09:27:49 2015 +0100
+++ b/hotspot/src/os/windows/vm/os_windows.cpp Wed Jan 28 17:52:48 2015 +0100
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 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
@@ -839,6 +839,12 @@
return (a - offset()) / 10000;
}
+// Returns time ticks in (10th of micro seconds)
+jlong windows_to_time_ticks(FILETIME wt) {
+ jlong a = jlong_from(wt.dwHighDateTime, wt.dwLowDateTime);
+ return (a - offset());
+}
+
FILETIME java_to_windows_time(jlong l) {
jlong a = (l * 10000) + offset();
FILETIME result;
@@ -874,6 +880,15 @@
}
}
+void os::javaTimeSystemUTC(jlong &seconds, jlong &nanos) {
+ FILETIME wt;
+ GetSystemTimeAsFileTime(&wt);
+ jlong ticks = windows_to_time_ticks(wt); // 10th of micros
+ jlong secs = jlong(ticks / 10000000); // 10000 * 1000
+ seconds = secs;
+ nanos = jlong(ticks - (secs*10000000)) * 100;
+}
+
jlong os::javaTimeNanos() {
if (!win32::_has_performance_count) {
return javaTimeMillis() * NANOSECS_PER_MILLISEC; // the best we can do.
--- a/hotspot/src/share/vm/prims/jvm.cpp Wed Jan 28 09:27:49 2015 +0100
+++ b/hotspot/src/share/vm/prims/jvm.cpp Wed Jan 28 17:52:48 2015 +0100
@@ -300,6 +300,48 @@
return os::javaTimeNanos();
JVM_END
+// The function below is actually exposed by sun.misc.VM and not
+// java.lang.System, but we choose to keep it here so that it stays next
+// to JVM_CurrentTimeMillis and JVM_NanoTime
+
+const jlong MAX_DIFF_SECS = 0x0100000000; // 2^32
+const jlong MIN_DIFF_SECS = -MAX_DIFF_SECS; // -2^32
+
+JVM_LEAF(jlong, JVM_GetNanoTimeAdjustment(JNIEnv *env, jclass ignored, jlong offset_secs))
+ JVMWrapper("JVM_GetNanoTimeAdjustment");
+ jlong seconds;
+ jlong nanos;
+
+ os::javaTimeSystemUTC(seconds, nanos);
+
+ // We're going to verify that the result can fit in a long.
+ // For that we need the difference in seconds between 'seconds'
+ // and 'offset_secs' to be such that:
+ // |seconds - offset_secs| < (2^63/10^9)
+ // We're going to approximate 10^9 ~< 2^30 (1000^3 ~< 1024^3)
+ // which makes |seconds - offset_secs| < 2^33
+ // and we will prefer +/- 2^32 as the maximum acceptable diff
+ // as 2^32 has a more natural feel than 2^33...
+ //
+ // So if |seconds - offset_secs| >= 2^32 - we return a special
+ // sentinel value (-1) which the caller should take as an
+ // exception value indicating that the offset given to us is
+ // too far from range of the current time - leading to too big
+ // a nano adjustment. The caller is expected to recover by
+ // computing a more accurate offset and calling this method
+ // again. (For the record 2^32 secs is ~136 years, so that
+ // should rarely happen)
+ //
+ jlong diff = seconds - offset_secs;
+ if (diff >= MAX_DIFF_SECS || diff <= MIN_DIFF_SECS) {
+ return -1; // sentinel value: the offset is too far off the target
+ }
+
+ // return the adjustment. If you compute a time by adding
+ // this number of nanoseconds along with the number of seconds
+ // in the offset you should get the current UTC time.
+ return (diff * (jlong)1000000000) + nanos;
+JVM_END
JVM_ENTRY(void, JVM_ArrayCopy(JNIEnv *env, jclass ignored, jobject src, jint src_pos,
jobject dst, jint dst_pos, jint length))
--- a/hotspot/src/share/vm/prims/jvm.h Wed Jan 28 09:27:49 2015 +0100
+++ b/hotspot/src/share/vm/prims/jvm.h Wed Jan 28 17:52:48 2015 +0100
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 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
@@ -131,6 +131,9 @@
JNIEXPORT jlong JNICALL
JVM_NanoTime(JNIEnv *env, jclass ignored);
+JNIEXPORT jlong JNICALL
+JVM_GetNanoTimeAdjustment(JNIEnv *env, jclass ignored, jlong offset_secs);
+
JNIEXPORT void JNICALL
JVM_ArrayCopy(JNIEnv *env, jclass ignored, jobject src, jint src_pos,
jobject dst, jint dst_pos, jint length);
--- a/hotspot/src/share/vm/runtime/os.hpp Wed Jan 28 09:27:49 2015 +0100
+++ b/hotspot/src/share/vm/runtime/os.hpp Wed Jan 28 17:52:48 2015 +0100
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 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
@@ -172,10 +172,10 @@
static jlong javaTimeMillis();
static jlong javaTimeNanos();
static void javaTimeNanos_info(jvmtiTimerInfo *info_ptr);
+ static void javaTimeSystemUTC(jlong &seconds, jlong &nanos);
static void run_periodic_checks();
static bool supports_monotonic_clock();
-
// Returns the elapsed time in seconds since the vm started.
static double elapsedTime();