Fix race condition in nextInsertBatch() causing off-by-1 doc count

has_next_create() and next() were separate non-atomic operations, allowing
two threads to both pass the boundary check at create_e and produce one
extra document beyond the intended range.

Fix: atomically claim the index with getAndIncrement() first, then break
if the claimed index is out of bounds — eliminating the check-then-act gap.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: ShivamPaliwal1

src/main/java/utils/docgen/DocumentGenerator.java

@@ -350,23 +350,26 @@ public WorkLoadSettings get_work_load_settings() {
         return this.ws;
     }
 
-    public Tuple2<String, Object> next() {
-        long temp = this.ws.dr.createItr.getAndIncrement();
+    private Tuple2<String, Object> nextCreateAt(long idx) {
         String k = null;
         Object v = null;
-            try {
-                if (this.target_vbuckets != null && this.target_vbuckets.length > 0) {
-                    k = this.generated_create_keys.get(temp);
-                } else {
-                    k = (String) this.keyMethod.invoke(this.keys, temp);
-                }
-                v = (Object) this.valMethod.invoke(this.vals, k);
-            } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e1) {
-                e1.printStackTrace();
+        try {
+            if (this.target_vbuckets != null && this.target_vbuckets.length > 0) {
+                k = this.generated_create_keys.get(idx);
+            } else {
+                k = (String) this.keyMethod.invoke(this.keys, idx);
             }
+            v = (Object) this.valMethod.invoke(this.vals, k);
+        } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e1) {
+            e1.printStackTrace();
+        }
         return Tuples.of(k, v);
     }
 
+    public Tuple2<String, Object> next() {
+        return nextCreateAt(this.ws.dr.createItr.getAndIncrement());
+    }
+
     public Tuple2<String, Object> nextRead() {
         long temp = this.ws.dr.readItr.getAndIncrement();
         String k = null;
@@ -464,8 +467,10 @@ public Tuple2<String, Object> nextExpiry() {
     public List<Tuple2<String, Object>> nextInsertBatch() {
         List<Tuple2<String, Object>> docs = new ArrayList<Tuple2<String,Object>>();
         int count = 0;
-        while (this.has_next_create() && count<ws.batchSize*ws.creates/100) {
-            docs.add(this.next());
+        while (count < ws.batchSize * ws.creates / 100) {
+            long idx = this.ws.dr.createItr.getAndIncrement();
+            if (idx >= this.ws.dr.create_e) break;
+            docs.add(nextCreateAt(idx));
             count += 1;
         }
         return docs;