Use Durations everywhere, drop unused constructors, and add tests.

service/src/main/java/org/whispersystems/textsecuregcm/limits/CardinalityRateLimiter.java

@@ -59,7 +59,8 @@ public class CardinalityRateLimiter {
     });
 
     if (rateLimitExceeded) {
-      throw new RateLimitExceededException();
+      // Using the TTL as the "retry after" time isn't EXACTLY right, but it's a reasonable approximation
+      throw new RateLimitExceededException(ttl);
     }
   }
 

service/src/main/java/org/whispersystems/textsecuregcm/limits/LeakyBucket.java

@@ -9,6 +9,7 @@ import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
 import java.io.IOException;
+import java.time.Duration;
 
 public class LeakyBucket {
 
@@ -48,15 +49,15 @@ public class LeakyBucket {
                     (int)Math.floor(this.spaceRemaining + (elapsedTime * this.leakRatePerMillis)));
   }
 
-  public long getMillisUntilSpace(double amount) {
+  public Duration getTimeUntilSpaceAvailable(int amount) {
     int currentSpaceRemaining = getUpdatedSpaceRemaining();
     if (currentSpaceRemaining >= amount) {
-      return 0;
+      return Duration.ZERO;
     } else if (amount > this.bucketSize) {
       // This shouldn't happen today but if so we should bubble this to the clients somehow
-      return -1;
+      throw new IllegalArgumentException("Requested permits exceed maximum bucket size");
     } else {
-      return (long)Math.ceil(amount - currentSpaceRemaining / this.leakRatePerMillis);
+      return Duration.ofMillis((long)Math.ceil((double)(amount - currentSpaceRemaining) / this.leakRatePerMillis));
     }
   }
 

service/src/main/java/org/whispersystems/textsecuregcm/limits/LockingRateLimiter.java

@@ -13,6 +13,8 @@ import org.whispersystems.textsecuregcm.controllers.RateLimitExceededException;
 import org.whispersystems.textsecuregcm.redis.FaultTolerantRedisCluster;
 import org.whispersystems.textsecuregcm.util.Constants;
 
+import java.time.Duration;
+
 import static com.codahale.metrics.MetricRegistry.name;
 
 public class LockingRateLimiter extends RateLimiter {
@@ -30,7 +32,7 @@ public class LockingRateLimiter extends RateLimiter {
   public void validate(String key, int amount) throws RateLimitExceededException {
     if (!acquireLock(key)) {
       meter.mark();
-      throw new RateLimitExceededException("Locked");
+      throw new RateLimitExceededException("Locked", Duration.ZERO);
     }
 
     try {

service/src/main/java/org/whispersystems/textsecuregcm/limits/RateLimiter.java

@@ -19,6 +19,7 @@ import org.whispersystems.textsecuregcm.util.Constants;
 import org.whispersystems.textsecuregcm.util.SystemMapper;
 
 import java.io.IOException;
+import java.time.Duration;
 
 import static com.codahale.metrics.MetricRegistry.name;
 
@@ -28,7 +29,7 @@ public class RateLimiter {
   private final ObjectMapper mapper = SystemMapper.getMapper();
 
   private   final Meter                     meter;
-  protected final Timer                     validateTimer;
+  private   final Timer                     validateTimer;
   protected final FaultTolerantRedisCluster cacheCluster;
   protected final String                    name;
   private   final int                       bucketSize;
@@ -66,7 +67,7 @@ public class RateLimiter {
         setBucket(key, bucket);
       } else {
         meter.mark();
-        throw new RateLimitExceededException(key + " , " + amount, bucket.getMillisUntilSpace(amount));
+        throw new RateLimitExceededException(key + " , " + amount, bucket.getTimeUntilSpaceAvailable(amount));
       }
     }
   }
@@ -87,7 +88,7 @@ public class RateLimiter {
     return leakRatePerMinute;
   }
 
-  protected void setBucket(String key, LeakyBucket bucket) {
+  private void setBucket(String key, LeakyBucket bucket) {
     try {
       final String serialized = bucket.serialize(mapper);
 
@@ -97,7 +98,7 @@ public class RateLimiter {
     }
   }
 
-  protected LeakyBucket getBucket(String key) {
+  private LeakyBucket getBucket(String key) {
     try {
       final String serialized = cacheCluster.withCluster(connection -> connection.sync().get(getBucketName(key)));