(lucene) 03/03: Override single byte writes to OutputStreamIndexOutput to remove locking (#13543)

[jp...@apache.org]

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jpountz pushed a commit to branch branch_9x
in repository https://gitbox.apache.org/repos/asf/lucene.git

commit 35de1ead82d1344d660ea6a148b788e39c4a1d5a
Author: Armin Braun <me...@obrown.io>
AuthorDate: Mon Jul 8 10:59:50 2024 +0200

    Override single byte writes to OutputStreamIndexOutput to remove locking (#13543)
    
    Single byte writes to BufferedOutputStream show up pretty hot in
    indexing benchmarks. We can save the locking overhead introduced by
    JEP374 by overriding and providing a no-lock fastpath.
---
 .../org/apache/lucene/store/OutputStreamIndexOutput.java   | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/lucene/core/src/java/org/apache/lucene/store/OutputStreamIndexOutput.java b/lucene/core/src/java/org/apache/lucene/store/OutputStreamIndexOutput.java
index 5c3b4dbd88a..14b56a67e8a 100644
--- a/lucene/core/src/java/org/apache/lucene/store/OutputStreamIndexOutput.java
+++ b/lucene/core/src/java/org/apache/lucene/store/OutputStreamIndexOutput.java
@@ -135,5 +135,19 @@ public class OutputStreamIndexOutput extends IndexOutput {
       BitUtil.VH_LE_LONG.set(buf, count, i);
       count += Long.BYTES;
     }
+
+    @Override
+    public void write(int b) throws IOException {
+      // override single byte write to avoid synchronization overhead now that JEP374 removed biased
+      // locking
+      byte[] buffer = buf;
+      int count = this.count;
+      if (count >= buffer.length) {
+        super.write(b);
+      } else {
+        buffer[count] = (byte) b;
+        this.count = count + 1;
+      }
+    }
   }
 }