Automatic merge of jdk:master into master

Author: duke

src/hotspot/os/linux/os_linux.cpp

@@ -1376,18 +1376,35 @@ double os::elapsedVTime() {
 }
 
 jlong os::javaTimeMillis() {
-  timeval time;
-  int status = gettimeofday(&time, NULL);
-  assert(status != -1, "linux error");
-  return jlong(time.tv_sec) * 1000  +  jlong(time.tv_usec / 1000);
+  if (os::Posix::supports_clock_gettime()) {
+    struct timespec ts;
+    int status = os::Posix::clock_gettime(CLOCK_REALTIME, &ts);
+    assert_status(status == 0, status, "gettime error");
+    return jlong(ts.tv_sec) * MILLIUNITS +
+           jlong(ts.tv_nsec) / NANOUNITS_PER_MILLIUNIT;
+  } else {
+    timeval time;
+    int status = gettimeofday(&time, NULL);
+    assert(status != -1, "linux error");
+    return jlong(time.tv_sec) * MILLIUNITS  +
+           jlong(time.tv_usec) / (MICROUNITS / MILLIUNITS);
+  }
 }
 
 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;
+  if (os::Posix::supports_clock_gettime()) {
+    struct timespec ts;
+    int status = os::Posix::clock_gettime(CLOCK_REALTIME, &ts);
+    assert_status(status == 0, status, "gettime error");
+    seconds = jlong(ts.tv_sec);
+    nanos = jlong(ts.tv_nsec);
+  } else {
+    timeval time;
+    int status = gettimeofday(&time, NULL);
+    assert(status != -1, "linux error");
+    seconds = jlong(time.tv_sec);
+    nanos = jlong(time.tv_usec) * (NANOUNITS / MICROUNITS);
+  }
 }
 
 void os::Linux::fast_thread_clock_init() {

src/hotspot/os/posix/os_posix.cpp

@@ -1638,6 +1638,8 @@ void os::Posix::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
 int (*os::Posix::_clock_gettime)(clockid_t, struct timespec *) = NULL;
 int (*os::Posix::_clock_getres)(clockid_t, struct timespec *) = NULL;
 
+bool os::Posix::_supports_monotonic_clock = false;
+
 static int (*_pthread_condattr_setclock)(pthread_condattr_t *, clockid_t) = NULL;
 
 static bool _use_clock_monotonic_condattr = false;
@@ -1653,7 +1655,7 @@ void os::Posix::init(void) {
 
   void* handle = NULL;
 
-  // For linux we need librt, for other OS we can find
+  // For older linux we need librt, for other OS we can find
   // this function in regular libc.
 #ifdef NEEDS_LIBRT
   // We do dlopen's in this particular order due to bug in linux
@@ -1673,22 +1675,16 @@ void os::Posix::init(void) {
   int (*clock_gettime_func)(clockid_t, struct timespec*) =
     (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime");
   if (clock_getres_func != NULL && clock_gettime_func != NULL) {
+    _clock_gettime = clock_gettime_func;
+    _clock_getres = clock_getres_func;
     // We assume that if both clock_gettime and clock_getres support
     // CLOCK_MONOTONIC then the OS provides true high-res monotonic clock.
     struct timespec res;
     struct timespec tp;
     if (clock_getres_func(CLOCK_MONOTONIC, &res) == 0 &&
         clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) {
       // Yes, monotonic clock is supported.
-      _clock_gettime = clock_gettime_func;
-      _clock_getres = clock_getres_func;
-    } else {
-#ifdef NEEDS_LIBRT
-      // Close librt if there is no monotonic clock.
-      if (handle != RTLD_DEFAULT) {
-        dlclose(handle);
-      }
-#endif
+      _supports_monotonic_clock = true;
     }
   }
 

src/hotspot/os/posix/os_posix.hpp

@@ -128,18 +128,18 @@ class Posix {
 #ifdef SUPPORTS_CLOCK_MONOTONIC
 
 private:
+  static bool _supports_monotonic_clock;
   // These need to be members so we can access them from inline functions
   static int (*_clock_gettime)(clockid_t, struct timespec *);
   static int (*_clock_getres)(clockid_t, struct timespec *);
 public:
   static bool supports_monotonic_clock();
+  static bool supports_clock_gettime();
   static int clock_gettime(clockid_t clock_id, struct timespec *tp);
   static int clock_getres(clockid_t clock_id, struct timespec *tp);
-
 #else
-
   static bool supports_monotonic_clock() { return false; }
-
+  static bool supports_clock_gettime() { return false; }
 #endif
 
   static void to_RTC_abstime(timespec* abstime, int64_t millis);

src/hotspot/os/posix/os_posix.inline.hpp

@@ -32,6 +32,10 @@
 // Exported clock functionality
 
 inline bool os::Posix::supports_monotonic_clock() {
+  return _supports_monotonic_clock;
+}
+
+inline bool os::Posix::supports_clock_gettime() {
   return _clock_gettime != NULL;
 }
 

test/jdk/java/time/test/java/time/TestClock_System.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2020, 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
@@ -177,7 +177,8 @@ public void test_ClockResolution() {
                         + formatTime("\n\thighest1", highest1));
             }
 
-            int count=0;
+            int countBetterThanMillisPrecision = 0;
+            int countBetterThanMicrosPrecision = 0;
             // let's preheat the system a bit:
             int lastNanos = 0;
             for (int i = 0; i < 1000 ; i++) {
@@ -191,7 +192,10 @@ public void test_ClockResolution() {
                 lastNanos = nanos;
 
                 if ((nanos % 1000000) > 0) {
-                    count++; // we have micro seconds
+                    countBetterThanMillisPrecision++; // we have microseconds
+                }
+                if ((nanos % 1000) > 0) {
+                    countBetterThanMicrosPrecision++; // we have nanoseconds
                 }
                 if ((sysnan % 1000000) > 0) {
                     throw new RuntimeException("Expected only millisecconds "
@@ -200,13 +204,17 @@ public void test_ClockResolution() {
                 }
             }
             System.out.println("\nNumber of time stamps which had better than"
-                    + " millisecond precision: "+count+"/"+1000);
+                               + " millisecond precision: "
+                               + countBetterThanMillisPrecision + "/" + 1000);
+            System.out.println("\nNumber of time stamps which had better than"
+                               + " microsecond precision: "
+                               + countBetterThanMicrosPrecision + "/" + 1000);
             System.out.println(formatTime("\nsystemUTC            ", system1));
             System.out.println(formatTime("highestResolutionUTC ", highest1));
-            if (count == 0) {
+            if (countBetterThanMillisPrecision == 0) {
                 System.err.println("Something is strange: no microsecond "
-                        + "precision with highestResolutionUTC?");
-                throw new RuntimeException("Micro second preccision not reached");
+                                   + "precision with highestResolutionUTC?");
+                throw new RuntimeException("Micro second precision not reached");
             }
 
             // check again

test/micro/org/openjdk/bench/java/lang/Systems.java test/micro/org/openjdk/bench/java/lang/SystemTime.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2020, 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
@@ -27,11 +27,12 @@
 import org.openjdk.jmh.annotations.Mode;
 import org.openjdk.jmh.annotations.OutputTimeUnit;
 
+import java.time.Instant;
 import java.util.concurrent.TimeUnit;
 
 @BenchmarkMode(Mode.AverageTime)
 @OutputTimeUnit(TimeUnit.NANOSECONDS)
-public class Systems {
+public class SystemTime {
 
     @Benchmark
     public long currentTimeMillis() {
@@ -43,4 +44,9 @@ public long nanoTime() {
         return System.nanoTime();
     }
 
+    @Benchmark
+    public long instantNowAsEpochNanos() {
+        Instant now = Instant.now();
+        return now.getEpochSecond() * 1_000_000_000L + now.getNano();
+    }
 }