gate fixes

Author: roberttoyonaga

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jfr/JfrThrottler.java

@@ -218,7 +218,7 @@ public void configure() {
             // This effectively means we reset the debt count upon reconfiguration
             accumulatedDebtCarryCount = accumulatedDebtCarryLimit;
             avgPopulationSize = 0;
-            ewmaPopulationSizeAlpha = (double) 1 / windowLookback(next);
+            ewmaPopulationSizeAlpha = 1.0 / windowLookback(next);
             reconfigure = false;
         }
 

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jfr/JfrThrottlerSupport.java

@@ -32,10 +32,12 @@
 import com.oracle.svm.core.locks.VMMutex;
 
 /**
- * Each event that supports throttling has its own throttler that can be accessed through this class.
+ * Each event that supports throttling has its own throttler that can be accessed through this
+ * class.
  */
 public class JfrThrottlerSupport {
     JfrThrottler objectAllocationSampleThrottler;
+
     @Platforms(Platform.HOSTED_ONLY.class)
     JfrThrottlerSupport() {
         if (HasJfrSupport.get()) {

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jfr/JfrThrottlerWindow.java

@@ -83,13 +83,13 @@ public long samplesExpected() {
         return samplesPerWindow + debt;
     }
 
-    public void configure(long debt, double projectedPopSize) {
-        this.debt = debt;
+    public void configure(long newDebt, double projectedPopSize) {
+        this.debt = newDebt;
         if (projectedPopSize <= samplesExpected()) {
             samplingInterval = 1;
         } else {
 
-            double projectedProbability = (double) samplesExpected() / projectedPopSize;
+            double projectedProbability = samplesExpected() / projectedPopSize;
             samplingInterval = nextGeometric(projectedProbability, Math.random());
         }
 
@@ -110,12 +110,13 @@ public void configure(long debt, double projectedPopSize) {
      * This method is essentially the same as jfrAdaptiveSampler::next_geometric(double, double) in
      * the OpenJDK.
      */
-    private long nextGeometric(double p, double u) {
-        if (u == 0.0) {
-            u = 0.01;
+    private static long nextGeometric(double probability, double u) {
+        double randomVar = u;
+        if (randomVar == 0.0) {
+            randomVar = 0.01;
         }
         // Inverse CDF for the geometric distribution.
-        return (long) Math.ceil(log(1.0 - u) / log(1.0 - p));
+        return (long) Math.ceil(log(1.0 - randomVar) / log(1.0 - probability));
     }
 
     public boolean isExpired() {

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jfr/SubstrateJVM.java

@@ -648,7 +648,6 @@ public boolean shouldCommit(JfrEvent event) {
         return jfrThrottlerSupport.shouldCommit(event.getId());
     }
 
-    @Uninterruptible(reason = "Called from uninterruptible code.", mayBeInlined = true)
     public boolean setThrottle(long eventTypeId, long eventSampleSize, long periodMs) {
         return jfrThrottlerSupport.setThrottle(eventTypeId, eventSampleSize, periodMs);
     }

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jfr/events/JfrAllocationEvents.java

@@ -56,8 +56,7 @@ public static void emit(long startTicks, Class<?> clazz, UnsignedWord allocation
 
     /**
      * This method exists as a slight optimization to avoid entering the sampler code if
-     * unnecessary. We'll have to check {@link JfrEvent.shouldEmit()} again if a sample ends up
-     * being taken.
+     * unnecessary. This is required because the sampler code is interruptible.
      */
     @Uninterruptible(reason = "Needed for JfrEvent.shouldEmit().")
     private static boolean shouldEmitObjectAllocationSample() {

substratevm/src/com.oracle.svm.test/src/com/oracle/svm/test/jfr/TestThrottler.java

@@ -324,7 +324,7 @@ public void testDistributionLateBurst() { // *** I think its [NOT] bursting ever
      * This is a more involved test that checks the sample distribution. It has been adapted from
      * JfrGTestAdaptiveSampling in the OpenJDK.
      */
-    private void testDistribution(IncomingPopulation incomingPopulation, int samplePointsPerWindow, double errorFactor) {
+    private static void testDistribution(IncomingPopulation incomingPopulation, int samplePointsPerWindow, double errorFactor) {
         final int distributionSlots = 100;
         final int windowDurationMs = 100;
         final int windowCount = 10000;