Allow simplification fetch to have noWait with or without expires. (n…

…ats-io#1089)

src/main/java/io/nats/client/BaseConsumeOptions.java

@@ -13,6 +13,8 @@
 
 package io.nats.client;
 
+import io.nats.client.api.ConsumerConfiguration;
+
 /**
  * Base Consume Options are provided to customize the way the consume and
  * fetch operate. It is the base class for ConsumeOptions and FetchConsumeOptions.
@@ -23,6 +25,7 @@ public class BaseConsumeOptions {
     public static final int DEFAULT_THRESHOLD_PERCENT = 25;
     public static final long DEFAULT_EXPIRES_IN_MILLIS = 30000;
     public static final long MIN_EXPIRES_MILLS = 1000;
+    public static final long MIN_NOWAIT_EXPIRES_MILLS = 100;
     public static final long MAX_HEARTBEAT_MILLIS = 30000;
     public static final int MAX_IDLE_HEARTBEAT_PERCENT = 50;
 
@@ -31,6 +34,7 @@ public class BaseConsumeOptions {
     protected final long expiresIn;
     protected final long idleHeartbeat;
     protected final int thresholdPercent;
+    protected final boolean noWait;
 
     @SuppressWarnings("rawtypes") // Don't need the type of the builder to get its vars
     protected BaseConsumeOptions(Builder b) {
@@ -45,6 +49,7 @@ protected BaseConsumeOptions(Builder b) {
         // validation handled in builder
         thresholdPercent = b.thresholdPercent;
         expiresIn = b.expiresIn;
+        noWait = b.noWait;
 
         // calculated
         idleHeartbeat = Math.min(MAX_HEARTBEAT_MILLIS, expiresIn * MAX_IDLE_HEARTBEAT_PERCENT / 100);
@@ -67,6 +72,7 @@ protected static abstract class Builder<B, CO> {
         protected long bytes = 0;
         protected int thresholdPercent = DEFAULT_THRESHOLD_PERCENT;
         protected long expiresIn = DEFAULT_EXPIRES_IN_MILLIS;
+        protected boolean noWait = false;
 
         protected abstract B getThis();
 
@@ -90,11 +96,23 @@ protected B bytes(long bytes) {
          * @return the builder
          */
         public B expiresIn(long expiresInMillis) {
-            if (expiresInMillis < 1) {
-                expiresIn = DEFAULT_EXPIRES_IN_MILLIS;
+            if (expiresInMillis < 1) { // this is way to clear or reset, just a code guard really
+                if (noWait) {
+                    expiresIn = ConsumerConfiguration.LONG_UNSET;
+                }
+                else {
+                    expiresIn = DEFAULT_EXPIRES_IN_MILLIS;
+                }
             }
             else if (expiresInMillis < MIN_EXPIRES_MILLS) {
-                throw new IllegalArgumentException("Expires must be greater than or equal to " + MIN_EXPIRES_MILLS);
+                if (noWait) {
+                    if (expiresInMillis < MIN_NOWAIT_EXPIRES_MILLS) {
+                        throw new IllegalArgumentException("Expires when No Wait must be greater than or equal to " + MIN_NOWAIT_EXPIRES_MILLS);
+                    }
+                }
+                else {
+                    throw new IllegalArgumentException("Expires must be greater than or equal to " + MIN_EXPIRES_MILLS);
+                }
             }
             else {
                 expiresIn = expiresInMillis;

src/main/java/io/nats/client/FetchConsumeOptions.java

@@ -13,6 +13,8 @@
 
 package io.nats.client;
 
+import io.nats.client.api.ConsumerConfiguration;
+
 /**
  * Fetch Consume Options are provided to customize the fetch operation.
  */
@@ -39,6 +41,8 @@ public long getMaxBytes() {
         return bytes;
     }
 
+    public boolean isNoWait() { return noWait; }
+
     public static Builder builder() {
         return new Builder();
     }
@@ -92,6 +96,27 @@ public Builder max(int maxBytes, int maxMessages) {
             return bytes(maxBytes);
         }
 
+        /**
+         * Set no wait to true
+         * @return the builder
+         */
+        public Builder noWait() {
+            this.noWait = true;
+            expiresIn = ConsumerConfiguration.LONG_UNSET;
+            return this;
+        }
+
+        /**
+         * Set no wait to true with an expiration, special behavior.
+         * @param expiresInMillis the expiration time in milliseconds
+         * @return the builder
+         */
+        public Builder noWaitExpiresIn(long expiresInMillis) {
+            this.noWait = true;
+            expiresIn(expiresInMillis);
+            return this;
+        }
+
         /**
          * Build the FetchConsumeOptions.
          * @return a FetchConsumeOptions instance

src/main/java/io/nats/client/impl/NatsFetchConsumer.java

@@ -18,7 +18,11 @@
 
 import java.io.IOException;
 
+import static io.nats.client.BaseConsumeOptions.MIN_EXPIRES_MILLS;
+import static io.nats.client.BaseConsumeOptions.MIN_NOWAIT_EXPIRES_MILLS;
+
 class NatsFetchConsumer extends NatsMessageConsumerBase implements FetchConsumer, PullManagerObserver {
+    private final boolean isNoWait;
     private final long maxWaitNanos;
     private final String pullSubject;
     private long startNanos;
@@ -29,13 +33,22 @@ class NatsFetchConsumer extends NatsMessageConsumerBase implements FetchConsumer
     {
         super(cachedConsumerInfo);
 
+        isNoWait = fetchConsumeOptions.isNoWait();
         long expiresInMillis = fetchConsumeOptions.getExpiresInMillis();
-        maxWaitNanos = expiresInMillis * 1_000_000;
-        long inactiveThreshold = expiresInMillis * 110 / 100; // ten % longer than the wait
+        long inactiveThreshold;
+        if (expiresInMillis <= MIN_NOWAIT_EXPIRES_MILLS ) { // can be for noWait
+            maxWaitNanos = MIN_NOWAIT_EXPIRES_MILLS * 1_000_000;
+            inactiveThreshold = MIN_EXPIRES_MILLS; // no need to do the 10% longer
+        }
+        else {
+            maxWaitNanos = expiresInMillis * 1_000_000;
+            inactiveThreshold = expiresInMillis * 110 / 100; // 10% longer than the wait
+        }
         PullRequestOptions pro = PullRequestOptions.builder(fetchConsumeOptions.getMaxMessages())
             .maxBytes(fetchConsumeOptions.getMaxBytes())
-            .expiresIn(fetchConsumeOptions.getExpiresInMillis())
+            .expiresIn(expiresInMillis)
             .idleHeartbeat(fetchConsumeOptions.getIdleHeartbeat())
+            .noWait(isNoWait)
             .build();
         initSub(subscriptionMaker.subscribe(null, null, null, inactiveThreshold));
         pullSubject = sub._pull(pro, false, this);
@@ -82,7 +95,12 @@ public Message nextMessage() throws InterruptedException, JetStreamStatusChecked
             // if the timer has run out, don't allow waiting
             // this might happen once, but it should already be noMorePending
             if (timeLeftMillis < 1) {
-                return sub._nextUnmanagedNoWait(pullSubject); // null means don't wait
+                Message m = sub._nextUnmanagedNoWait(pullSubject); // null means don't wait
+                if (m == null && isNoWait) {
+                    finished.set(true);
+                    lenientClose();
+                }
+                return m;
             }
 
             return sub._nextUnmanaged(timeLeftMillis, pullSubject);

src/main/java/io/nats/client/impl/NatsJetStreamMetaData.java

@@ -35,22 +35,22 @@ public class NatsJetStreamMetaData {
     private final long consumerSeq;
     private final ZonedDateTime timestamp;
     private final long pending;
-
     @Override
     public String toString() {
         return "NatsJetStreamMetaData{" +
-                "prefix='" + prefix + '\'' +
-                ", domain='" + domain + '\'' +
-                ", stream='" + stream + '\'' +
-                ", consumer='" + consumer + '\'' +
-                ", delivered=" + delivered +
-                ", streamSeq=" + streamSeq +
-                ", consumerSeq=" + consumerSeq +
-                ", timestamp=" + timestamp +
-                ", pending=" + pending +
-                '}';
+            "prefix='" + prefix + '\'' +
+            ", domain='" + domain + '\'' +
+            ", stream='" + stream + '\'' +
+            ", consumer='" + consumer + '\'' +
+            ", delivered=" + delivered +
+            ", streamSeq=" + streamSeq +
+            ", consumerSeq=" + consumerSeq +
+            ", timestamp=" + timestamp +
+            ", pending=" + pending +
+            '}';
     }
 
+
     /*
     v0 <prefix>.ACK.<stream name>.<consumer name>.<num delivered>.<stream sequence>.<consumer sequence>.<timestamp>
     v1 <prefix>.ACK.<stream name>.<consumer name>.<num delivered>.<stream sequence>.<consumer sequence>.<timestamp>.<num pending>