8235741: Inappropriate uses of os::javaTimeMillis()

Reviewed-by: rehn, kbarrett, egahlin, shade

src/hotspot/os/aix/os_perf_aix.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2019, 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
@@ -371,19 +371,21 @@ static int get_boot_time(uint64_t* time) {
 
 static int perf_context_switch_rate(double* rate) {
   static pthread_mutex_t contextSwitchLock = PTHREAD_MUTEX_INITIALIZER;
-  static uint64_t      lastTime;
+  static uint64_t      bootTime;
+  static uint64_t      lastTimeNanos;
   static uint64_t      lastSwitches;
   static double        lastRate;
 
-  uint64_t lt = 0;
+  uint64_t bt = 0;
   int res = 0;
 
-  if (lastTime == 0) {
+  // First time through bootTime will be zero.
+  if (bootTime == 0) {
     uint64_t tmp;
     if (get_boot_time(&tmp) < 0) {
       return OS_ERR;
     }
-    lt = tmp * 1000;
+    bt = tmp * 1000;
   }
 
   res = OS_OK;
@@ -394,20 +396,29 @@ static int perf_context_switch_rate(double* rate) {
     uint64_t sw;
     s8 t, d;
 
-    if (lastTime == 0) {
-      lastTime = lt;
+    if (bootTime == 0) {
+      // First interval is measured from boot time which is
+      // seconds since the epoch. Thereafter we measure the
+      // elapsed time using javaTimeNanos as it is monotonic-
+      // non-decreasing.
+      lastTimeNanos = os::javaTimeNanos();
+      t = os::javaTimeMillis();
+      d = t - bt;
+      // keep bootTime zero for now to use as a first-time-through flag
+    } else {
+      t = os::javaTimeNanos();
+      d = nanos_to_millis(t - lastTimeNanos);
     }
 
-    t = os::javaTimeMillis();
-    d = t - lastTime;
-
     if (d == 0) {
       *rate = lastRate;
-    } else if (!get_noof_context_switches(&sw)) {
+    } else if (get_noof_context_switches(&sw) == 0) {
       *rate      = ( (double)(sw - lastSwitches) / d ) * 1000;
       lastRate     = *rate;
       lastSwitches = sw;
-      lastTime     = t;
+      if (bootTime != 0) {
+        lastTimeNanos = t;
+      }
     } else {
       *rate = 0;
       res   = OS_ERR;
@@ -416,6 +427,10 @@ static int perf_context_switch_rate(double* rate) {
       *rate = 0;
       lastRate = 0;
     }
+
+    if (bootTime == 0) {
+      bootTime = bt;
+    }
   }
   pthread_mutex_unlock(&contextSwitchLock);
 

src/hotspot/os/bsd/semaphore_bsd.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 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
@@ -76,17 +76,17 @@ bool OSXSemaphore::timedwait(int64_t millis) {
   // kernel semaphores take a relative timeout
   mach_timespec_t waitspec;
   int secs = millis / MILLIUNITS;
-  int nsecs = (millis % MILLIUNITS) * NANOSECS_PER_MILLISEC;
+  int nsecs = millis_to_nanos(millis % MILLIUNITS);
   waitspec.tv_sec = secs;
   waitspec.tv_nsec = nsecs;
 
-  int64_t starttime = os::javaTimeMillis() * NANOSECS_PER_MILLISEC;
+  int64_t starttime = os::javaTimeNanos();
 
   kr = semaphore_timedwait(_semaphore, waitspec);
   while (kr == KERN_ABORTED) {
     // reduce the timout and try again
-    int64_t totalwait = millis * NANOSECS_PER_MILLISEC;
-    int64_t current = os::javaTimeMillis() * NANOSECS_PER_MILLISEC;
+    int64_t totalwait = millis_to_nanos(millis);
+    int64_t current = os::javaTimeNanos();
     int64_t passedtime = current - starttime;
 
     if (passedtime >= totalwait) {

src/hotspot/os/linux/os_perf_linux.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2019, 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
@@ -431,19 +431,21 @@ static int get_boot_time(uint64_t* time) {
 
 static int perf_context_switch_rate(double* rate) {
   static pthread_mutex_t contextSwitchLock = PTHREAD_MUTEX_INITIALIZER;
-  static uint64_t      lastTime;
+  static uint64_t      bootTime;
+  static uint64_t      lastTimeNanos;
   static uint64_t      lastSwitches;
   static double        lastRate;
 
-  uint64_t lt = 0;
+  uint64_t bt = 0;
   int res = 0;
 
-  if (lastTime == 0) {
+  // First time through bootTime will be zero.
+  if (bootTime == 0) {
     uint64_t tmp;
     if (get_boot_time(&tmp) < 0) {
       return OS_ERR;
     }
-    lt = tmp * 1000;
+    bt = tmp * 1000;
   }
 
   res = OS_OK;
@@ -454,20 +456,29 @@ static int perf_context_switch_rate(double* rate) {
     uint64_t sw;
     s8 t, d;
 
-    if (lastTime == 0) {
-      lastTime = lt;
+    if (bootTime == 0) {
+      // First interval is measured from boot time which is
+      // seconds since the epoch. Thereafter we measure the
+      // elapsed time using javaTimeNanos as it is monotonic-
+      // non-decreasing.
+      lastTimeNanos = os::javaTimeNanos();
+      t = os::javaTimeMillis();
+      d = t - bt;
+      // keep bootTime zero for now to use as a first-time-through flag
+    } else {
+      t = os::javaTimeNanos();
+      d = nanos_to_millis(t - lastTimeNanos);
     }
 
-    t = os::javaTimeMillis();
-    d = t - lastTime;
-
     if (d == 0) {
       *rate = lastRate;
-    } else if (!get_noof_context_switches(&sw)) {
+    } else if (get_noof_context_switches(&sw) == 0) {
       *rate      = ( (double)(sw - lastSwitches) / d ) * 1000;
       lastRate     = *rate;
       lastSwitches = sw;
-      lastTime     = t;
+      if (bootTime != 0) {
+        lastTimeNanos = t;
+      }
     } else {
       *rate = 0;
       res   = OS_ERR;
@@ -476,6 +487,10 @@ static int perf_context_switch_rate(double* rate) {
       *rate = 0;
       lastRate = 0;
     }
+
+    if (bootTime == 0) {
+      bootTime = bt;
+    }
   }
   pthread_mutex_unlock(&contextSwitchLock);
 

src/hotspot/os/posix/os_posix.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 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
@@ -681,7 +681,7 @@ void os::naked_short_nanosleep(jlong ns) {
 
 void os::naked_short_sleep(jlong ms) {
   assert(ms < MILLIUNITS, "Un-interruptable sleep, short time use only");
-  os::naked_short_nanosleep(ms * (NANOUNITS / MILLIUNITS));
+  os::naked_short_nanosleep(millis_to_nanos(ms));
   return;
 }
 
@@ -1833,18 +1833,18 @@ static void unpack_abs_time(timespec* abstime, jlong deadline, jlong now_sec) {
     abstime->tv_nsec = 0;
   } else {
     abstime->tv_sec = seconds;
-    abstime->tv_nsec = millis * (NANOUNITS / MILLIUNITS);
+    abstime->tv_nsec = millis_to_nanos(millis);
   }
 }
 
-static jlong millis_to_nanos(jlong millis) {
+static jlong millis_to_nanos_bounded(jlong millis) {
   // We have to watch for overflow when converting millis to nanos,
   // but if millis is that large then we will end up limiting to
   // MAX_SECS anyway, so just do that here.
   if (millis / MILLIUNITS > MAX_SECS) {
     millis = jlong(MAX_SECS) * MILLIUNITS;
   }
-  return millis * (NANOUNITS / MILLIUNITS);
+  return millis_to_nanos(millis);
 }
 
 static void to_abstime(timespec* abstime, jlong timeout,
@@ -1897,7 +1897,7 @@ static void to_abstime(timespec* abstime, jlong timeout,
 // Create an absolute time 'millis' milliseconds in the future, using the
 // real-time (time-of-day) clock. Used by PosixSemaphore.
 void os::Posix::to_RTC_abstime(timespec* abstime, int64_t millis) {
-  to_abstime(abstime, millis_to_nanos(millis),
+  to_abstime(abstime, millis_to_nanos_bounded(millis),
              false /* not absolute */,
              true  /* use real-time clock */);
 }
@@ -1992,7 +1992,7 @@ int os::PlatformEvent::park(jlong millis) {
 
   if (v == 0) { // Do this the hard way by blocking ...
     struct timespec abst;
-    to_abstime(&abst, millis_to_nanos(millis), false, false);
+    to_abstime(&abst, millis_to_nanos_bounded(millis), false, false);
 
     int ret = OS_TIMEOUT;
     int status = pthread_mutex_lock(_mutex);
@@ -2318,7 +2318,7 @@ int os::PlatformMonitor::wait(jlong millis) {
     if (millis / MILLIUNITS > MAX_SECS) {
       millis = jlong(MAX_SECS) * MILLIUNITS;
     }
-    to_abstime(&abst, millis * (NANOUNITS / MILLIUNITS), false, false);
+    to_abstime(&abst, millis_to_nanos(millis), false, false);
 
     int ret = OS_TIMEOUT;
     int status = pthread_cond_timedwait(cond(), mutex(), &abst);

src/hotspot/os/windows/os_perf_windows.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2019, 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
@@ -97,7 +97,7 @@ static const int min_update_interval_millis = 500;
 */
 typedef struct {
   HQUERY query;
-  s8     lastUpdate; // Last time query was updated (current millis).
+  s8     lastUpdate; // Last time query was updated.
 } UpdateQueryS, *UpdateQueryP;
 
 
@@ -287,8 +287,8 @@ static OSReturn add_process_counter(MultiCounterQueryP query, int slot_index, co
 
 static int collect_query_data(UpdateQueryP update_query) {
   assert(update_query != NULL, "invariant");
-  const s8 now = os::javaTimeMillis();
-  if (now - update_query->lastUpdate > min_update_interval_millis) {
+  const s8 now = os::javaTimeNanos();
+  if (nanos_to_millis(now - update_query->lastUpdate) > min_update_interval_millis) {
     if (PdhDll::PdhCollectQueryData(update_query->query) != ERROR_SUCCESS) {
       return OS_ERR;
     }

src/hotspot/share/compiler/compilationPolicy.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 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
@@ -289,14 +289,14 @@ class CounterDecay : public AllStatic {
 public:
   static void decay();
   static bool is_decay_needed() {
-    return (os::javaTimeMillis() - _last_timestamp) > CounterDecayMinIntervalLength;
+    return nanos_to_millis(os::javaTimeNanos() - _last_timestamp) > CounterDecayMinIntervalLength;
   }
 };
 
 jlong CounterDecay::_last_timestamp = 0;
 
 void CounterDecay::decay() {
-  _last_timestamp = os::javaTimeMillis();
+  _last_timestamp = os::javaTimeNanos();
 
   // This operation is going to be performed only at the end of a safepoint
   // and hence GC's will not be going on, all Java mutators are suspended

src/hotspot/share/compiler/tieredThresholdPolicy.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2010, 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
@@ -304,7 +304,7 @@ void TieredThresholdPolicy::initialize() {
 #endif
 
   set_increase_threshold_at_ratio();
-  set_start_time(os::javaTimeMillis());
+  set_start_time(nanos_to_millis(os::javaTimeNanos()));
 }
 
 
@@ -404,7 +404,7 @@ CompileTask* TieredThresholdPolicy::select_task(CompileQueue* compile_queue) {
   CompileTask *max_blocking_task = NULL;
   CompileTask *max_task = NULL;
   Method* max_method = NULL;
-  jlong t = os::javaTimeMillis();
+  jlong t = nanos_to_millis(os::javaTimeNanos());
   // Iterate through the queue and find a method with a maximum rate.
   for (CompileTask* task = compile_queue->first(); task != NULL;) {
     CompileTask* next_task = task->next();
@@ -596,7 +596,7 @@ void TieredThresholdPolicy::compile(const methodHandle& mh, int bci, CompLevel l
       print_event(COMPILE, mh(), mh(), bci, level);
     }
     int hot_count = (bci == InvocationEntryBci) ? mh->invocation_count() : mh->backedge_count();
-    update_rate(os::javaTimeMillis(), mh());
+    update_rate(nanos_to_millis(os::javaTimeNanos()), mh());
     CompileBroker::compile_method(mh, bci, level, mh, hot_count, CompileTask::Reason_Tiered, thread);
   }
 }
@@ -616,7 +616,7 @@ void TieredThresholdPolicy::update_rate(jlong t, Method* m) {
 
   // We don't update the rate if we've just came out of a safepoint.
   // delta_s is the time since last safepoint in milliseconds.
-  jlong delta_s = t - SafepointTracing::end_of_last_safepoint_epoch_ms();
+  jlong delta_s = t - SafepointTracing::end_of_last_safepoint_ms();
   jlong delta_t = t - (m->prev_time() != 0 ? m->prev_time() : start_time()); // milliseconds since the last measurement
   // How many events were there since the last time?
   int event_count = m->invocation_count() + m->backedge_count();
@@ -641,7 +641,7 @@ void TieredThresholdPolicy::update_rate(jlong t, Method* m) {
 // Check if this method has been stale for a given number of milliseconds.
 // See select_task().
 bool TieredThresholdPolicy::is_stale(jlong t, jlong timeout, Method* m) {
-  jlong delta_s = t - SafepointTracing::end_of_last_safepoint_epoch_ms();
+  jlong delta_s = t - SafepointTracing::end_of_last_safepoint_ms();
   jlong delta_t = t - m->prev_time();
   if (delta_t > timeout && delta_s > timeout) {
     int event_count = m->invocation_count() + m->backedge_count();

src/hotspot/share/gc/shenandoah/shenandoahHeapRegionCounters.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2019, Red Hat, Inc. All rights reserved.
+ * Copyright (c) 2016, 2020, Red Hat, Inc. 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
@@ -75,7 +75,7 @@ ShenandoahHeapRegionCounters::~ShenandoahHeapRegionCounters() {
 
 void ShenandoahHeapRegionCounters::update() {
   if (ShenandoahRegionSampling) {
-    jlong current = os::javaTimeMillis();
+    jlong current = nanos_to_millis(os::javaTimeNanos());
     jlong last = _last_sample_millis;
     if (current - last > ShenandoahRegionSamplingRate &&
             Atomic::cmpxchg(&_last_sample_millis, last, current) == last) {

src/hotspot/share/jfr/recorder/repository/jfrChunk.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2019, 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
@@ -37,6 +37,8 @@ static const u2 JFR_VERSION_MINOR = 1;
 // strictly monotone
 static jlong nanos_now() {
   static jlong last = 0;
+  // We use javaTimeMillis so this can be correlated with
+  // external timestamps.
   const jlong now = os::javaTimeMillis() * JfrTimeConverter::NANOS_PER_MILLISEC;
   if (now > last) {
     last = now;