Optimize FastReader.readUntil() with scan+arraycopy pattern

Split the inner loop into a read-only delimiter scan followed by
a bulk System.arraycopy, allowing the JIT to optimize the tight
scan loop independently from the memory write.

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

Author: jdereg

pom.xml

@@ -5,7 +5,7 @@
     <groupId>com.cedarsoftware</groupId>
     <artifactId>java-util</artifactId>
     <packaging>bundle</packaging>
-    <version>4.97.0-SNAPSHOT</version>
+    <version>4.97.0</version>
     <description>Java Utilities</description>
     <url>https://github.com/jdereg/java-util</url>
 
@@ -32,7 +32,7 @@
         <version.junit-jupiter-params>5.14.2</version.junit-jupiter-params>
         <version.mockito-junit-jupiter>4.11.0</version.mockito-junit-jupiter>   <!-- can't update until they have JDK support -->
         <version.assertj-core>3.27.7</version.assertj-core>
-        <version.json-io>4.94.0</version.json-io>
+        <version.json-io>4.96.0</version.json-io>
         <version.agrona>1.22.0</version.agrona> <!-- do not increase past 1.22.0 until abandoning JDK 8 support, class file format 52 -->
         <version.commons-collections4>4.5.0</version.commons-collections4>
         <version.guava>33.5.0-jre</version.guava>

src/main/java/com/cedarsoftware/util/FastReader.java

@@ -220,22 +220,26 @@ public int readUntil(final char[] dest, int off, int maxLen, char delim1, char d
                 return totalRead > 0 ? totalRead : -1;
             }
 
-            // Single-pass loop with position localized to avoid per-char field write
+            // Scan for delimiter in a tight loop (reads only, no writes),
+            // then bulk-copy with System.arraycopy (JVM intrinsic).
             int pos = position;
             int end = pos + Math.min(limit - pos, maxLen - totalRead);
-            while (pos < end) {
-                char c = locBuf[pos];
-                if (c == delim1 || c == delim2) {
-                    // Found delimiter — don't consume it
-                    totalRead += pos - position;
-                    position = pos;
-                    return totalRead;
-                }
-                dest[off++] = c;
-                pos++;
+            int scanPos = pos;
+            while (scanPos < end && locBuf[scanPos] != delim1 && locBuf[scanPos] != delim2) {
+                scanPos++;
+            }
+            int copyLen = scanPos - pos;
+            if (copyLen > 0) {
+                System.arraycopy(locBuf, pos, dest, off, copyLen);
+                off += copyLen;
+                totalRead += copyLen;
+            }
+            if (scanPos < end) {
+                // Found delimiter — don't consume it
+                position = scanPos;
+                return totalRead;
             }
-            totalRead += pos - position;
-            position = pos;
+            position = scanPos;
         }
 
         return totalRead;