From 9bef2d1610647dec18f9e81cbac3dddbbf99dd6d Mon Sep 17 00:00:00 2001
From: Erik Gahlin <egahlin@openjdk.org>
Date: Tue, 15 Jul 2025 20:33:24 +0000
Subject: [PATCH] 8361640: JFR: RandomAccessFile::readLine emits events for
 each character

Reviewed-by: rriggs, alanb, mgronlun
---
 .../classes/java/io/RandomAccessFile.java     | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/java.base/share/classes/java/io/RandomAccessFile.java b/src/java.base/share/classes/java/io/RandomAccessFile.java
index 339030e022c..a7aa3ea358b 100644
--- a/src/java.base/share/classes/java/io/RandomAccessFile.java
+++ b/src/java.base/share/classes/java/io/RandomAccessFile.java
@@ -1030,17 +1030,32 @@ public class RandomAccessFile implements DataOutput, DataInput, Closeable {
      */
 
     public final String readLine() throws IOException {
+        if (jfrTracing && FileReadEvent.enabled()) {
+            long bytesRead = 0;
+            long start = FileReadEvent.timestamp();
+            try {
+                String result = implReadLine();
+                bytesRead = result == null ? 0 : result.length();
+                return result;
+            } finally {
+                FileReadEvent.offer(start, path, bytesRead);
+            }
+        }
+        return implReadLine();
+    }
+
+    private final String implReadLine() throws IOException {
         StringBuilder input = new StringBuilder();
         int c = -1;
         boolean eol = false;
 
         while (!eol) {
-            switch (c = read()) {
+            switch (c = read0()) {
                 case -1, '\n' -> eol = true;
                 case '\r'     -> {
                     eol = true;
                     long cur = getFilePointer();
-                    if ((read()) != '\n') {
+                    if ((read0()) != '\n') {
                         seek(cur);
                     }
                 }