Fix VirtualThread pinning with RealSpan and zipkin2.reporter by switc…

…hing from synchronized to ReentrantLock

Signed-off-by: Andriy Redko <[email protected]>

brave/src/main/java/brave/RealSpan.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2020 The OpenZipkin Authors
+ * Copyright 2013-2024 The OpenZipkin Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
@@ -13,12 +13,15 @@
  */
 package brave;
 
+import java.util.concurrent.locks.ReentrantLock;
+
 import brave.handler.MutableSpan;
 import brave.internal.recorder.PendingSpans;
 import brave.propagation.TraceContext;
 
 /** This wraps the public api and guards access to a mutable span. */
 final class RealSpan extends Span {
+  final ReentrantLock lock = new ReentrantLock();
   final TraceContext context;
   final PendingSpans pendingSpans;
   final MutableSpan state;
@@ -139,17 +142,30 @@ final class RealSpan extends Span {
   }
 
   @Override public void finish(long timestamp) {
-    synchronized (state) {
+    lock.lock();
+    try {
       pendingSpans.finish(context, timestamp);
+    } finally {
+      lock.unlock();
     }
   }
 
   @Override public void abandon() {
-    pendingSpans.abandon(context);
+    lock.lock();
+    try {
+      pendingSpans.abandon(context);
+    } finally {
+      lock.unlock();
+    }
   }
 
   @Override public void flush() {
-    pendingSpans.flush(context);
+    lock.lock();
+    try {
+      pendingSpans.flush(context);
+    } finally {
+      lock.unlock();
+    }
   }
 
   @Override public String toString() {

brave/src/main/java/brave/internal/Platform.java

@@ -21,6 +21,7 @@
 import java.security.SecureRandom;
 import java.util.Enumeration;
 import java.util.Random;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.logging.Level;
 import java.util.logging.LogRecord;
 import java.util.logging.Logger;
@@ -35,6 +36,7 @@
 public abstract class Platform implements Clock {
   private static final Platform PLATFORM = findPlatform();
 
+  private final ReentrantLock lock = new ReentrantLock();
   volatile String linkLocalIp;
 
   /** Returns the same value as {@link System#nanoTime()}. */
@@ -47,10 +49,13 @@ public abstract class Platform implements Clock {
   @Nullable public String linkLocalIp() {
     // uses synchronized variant of double-checked locking as getting the endpoint can be expensive
     if (linkLocalIp != null) return linkLocalIp;
-    synchronized (this) {
+    lock.lock();
+    try {
       if (linkLocalIp == null) {
         linkLocalIp = produceLinkLocalIp();
       }
+    } finally {
+      lock.unlock();
     }
     return linkLocalIp;
   }

brave/src/main/java/brave/internal/extra/Extra.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2020 The OpenZipkin Authors
+ * Copyright 2013-2024 The OpenZipkin Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
@@ -17,6 +17,7 @@
 import brave.propagation.TraceContext;
 import brave.propagation.TraceContextOrSamplingFlags;
 import java.util.Arrays;
+import java.util.concurrent.locks.ReentrantLock;
 
 /**
  * Holds extended state in {@link TraceContext#extra()} or {@link TraceContextOrSamplingFlags#extra()}.
@@ -39,7 +40,7 @@ public abstract class Extra<E extends Extra<E, F>, F extends ExtraFactory<E, F>>
    * Updates like {@link #tryToClaim(long, long)} lock on this object, as should any non-atomic
    * {@link #state} updates.
    */
-  protected final Object lock = new Object();
+  protected final ReentrantLock lock = new ReentrantLock();
   /**
    * Lock on {@link #lock} when comparing existing values for a state update that happens after
    * {@link #mergeStateKeepingOursOnConflict(Extra)}.
@@ -74,13 +75,16 @@ protected Extra(F factory) {
 
   /** Fields are extracted before a context is created. We need to lazy set the context */
   final boolean tryToClaim(long traceId, long spanId) {
-    synchronized (lock) {
+    lock.lock();
+    try {
       if (this.traceId == 0L) {
         this.traceId = traceId;
         this.spanId = spanId;
         return true;
       }
       return this.traceId == traceId && this.spanId == spanId;
+    } finally {
+      lock.unlock();
     }
   }
 

brave/src/main/java/brave/internal/extra/MapExtra.java

@@ -92,7 +92,8 @@ protected boolean put(K key, @Nullable V value) {
       return false;
     }
 
-    synchronized (lock) {
+    lock.lock();
+    try {
       Object[] prior = state();
 
       // double-check lost race in dynamic case
@@ -105,6 +106,8 @@ protected boolean put(K key, @Nullable V value) {
       newState[i + 1] = value;
       this.state = newState;
       return true;
+    } finally {
+        lock.unlock();
     }
   }