Fix bad precondition check

Author: elandau

concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/limiter/DefaultLimiter.java

@@ -83,7 +83,7 @@ public Builder limit(Limit limit) {
         }
 
         public Builder minWindowTime(long minWindowTime, TimeUnit units) {
-            Preconditions.checkArgument(minWindowTime >= units.toMillis(100), "minWindowTime must be >= 100 ms");
+            Preconditions.checkArgument(units.toMillis(minWindowTime) >= 100, "minWindowTime must be >= 100 ms");
             this.minWindowTime = units.toNanos(minWindowTime);
             return this;
         }
@@ -130,14 +130,13 @@ private DefaultLimiter(Builder builder, Strategy<ContextT> strategy) {
 
     @Override
     public Optional<Listener> acquire(final ContextT context) {
-        final long startTime = nanoClock.get();
-        
         // Did we exceed the limit
         final Token token = strategy.tryAcquire(context);
         if (!token.isAcquired()) {
             return Optional.empty();
         }
 
+        final long startTime = nanoClock.get();
         int currentMaxInFlight = inFlight.incrementAndGet();
 
         return Optional.of(new Listener() {

concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/limiter/ImmutableSample.java

@@ -1,5 +1,7 @@
 package com.netflix.concurrency.limits.limiter;
 
+import java.util.concurrent.TimeUnit;
+
 import com.netflix.concurrency.limits.Limit;
 
 /**
@@ -56,4 +58,12 @@ public int getSampleCount() {
     public boolean didDrop() {
         return didDrop;
     }
+
+    @Override
+    public String toString() {
+        return "ImmutableSample [minRtt=" + TimeUnit.NANOSECONDS.toMillis(minRtt) 
+                + ", maxInFlight=" + maxInFlight 
+                + ", sampleCount=" + sampleCount
+                + ", didDrop=" + didDrop + "]";
+    }
 }