Relax synchronization on class transformation

Fixes btraceio#369
elex-fu · Nov 11, 2018 · e601842 · e601842
1 parent 5dc1408
commit e601842
Showing 1 changed file with 63 additions and 45 deletions.
diff --git a/src/share/classes/com/sun/btrace/runtime/BTraceTransformer.java b/src/share/classes/com/sun/btrace/runtime/BTraceTransformer.java
@@ -33,6 +33,7 @@
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
 import java.util.regex.Pattern;
 
 /**
@@ -130,24 +131,35 @@ public Result matchClass(String className) {
         }
     }
     private final DebugSupport debug;
+    private final ReentrantReadWriteLock setupLock = new ReentrantReadWriteLock();
     private final Collection<BTraceProbe> probes = new ArrayList<>(3);
     private final Filter filter = new Filter();
 
     public BTraceTransformer(DebugSupport d) {
         debug = d;
     }
 
-    public final synchronized void register(BTraceProbe p) {
-        probes.add(p);
-        for(OnMethod om : p.onmethods()) {
-            filter.add(om);
+    public final void register(BTraceProbe p) {
+        try {
+            setupLock.writeLock().lock();
+            probes.add(p);
+            for(OnMethod om : p.onmethods()) {
+                filter.add(om);
+            }
+        } finally {
+            setupLock.writeLock().unlock();
         }
     }
 
-    public final synchronized void unregister(BTraceProbe p) {
-        probes.remove(p);
-        for(OnMethod om : p.onmethods()) {
-            filter.remove(om);
+    public final void unregister(BTraceProbe p) {
+        try {
+            setupLock.writeLock().lock();
+            probes.remove(p);
+            for(OnMethod om : p.onmethods()) {
+                filter.remove(om);
+            }
+        } finally {
+            setupLock.writeLock().unlock();
         }
     }
 
@@ -156,54 +168,60 @@ Filter getFilter() {
     }
 
     @Override
-    public synchronized byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
-        if (probes.isEmpty()) return null;
+    public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
+        try {
+            setupLock.readLock().lock();
+            if (probes.isEmpty()) return null;
 
-        className = className != null ? className : "<anonymous>";
+            className = className != null ? className : "<anonymous>";
 
-        if ((loader == null || loader.equals(ClassLoader.getSystemClassLoader())) && isSensitiveClass(className)) {
-            if (isDebug()) {
-                debugPrint("skipping transform for BTrace class " + className); // NOI18N
+            if ((loader == null || loader.equals(ClassLoader.getSystemClassLoader())) && isSensitiveClass(className)) {
+                if (isDebug()) {
+                    debugPrint("skipping transform for BTrace class " + className); // NOI18N
+                }
+                return null;
             }
-            return null;
-        }
 
-        if (filter.matchClass(className) == Filter.Result.FALSE) return null;
+            if (filter.matchClass(className) == Filter.Result.FALSE) return null;
 
-        boolean entered = BTraceRuntime.enter();
-        try {
-            if (isDebug()) {
-                debug.dumpClass(className.replace('.', '/') + "_orig", classfileBuffer);
-            }
-            BTraceClassReader cr = InstrumentUtils.newClassReader(loader, classfileBuffer);
-            BTraceClassWriter cw = InstrumentUtils.newClassWriter(cr);
-            for(BTraceProbe p : probes) {
-                p.notifyTransform(className);
-                cw.addInstrumentor(p, loader);
-            }
-            byte[] transformed = cw.instrument();
-            if (transformed == null) {
-                // no instrumentation necessary
+            boolean entered = BTraceRuntime.enter();
+            try {
                 if (isDebug()) {
-                    debugPrint("skipping class " + cr.getJavaClassName());
+                    debug.dumpClass(className.replace('.', '/') + "_orig", classfileBuffer);
                 }
-                return classfileBuffer;
-            } else {
-                if (isDebug()) {
-                    debugPrint("transformed class " + cr.getJavaClassName());
+                BTraceClassReader cr = InstrumentUtils.newClassReader(loader, classfileBuffer);
+                BTraceClassWriter cw = InstrumentUtils.newClassWriter(cr);
+                for(BTraceProbe p : probes) {
+                    p.notifyTransform(className);
+                    cw.addInstrumentor(p, loader);
+                }
+                byte[] transformed = cw.instrument();
+                if (transformed == null) {
+                    // no instrumentation necessary
+                    if (isDebug()) {
+                        debugPrint("skipping class " + cr.getJavaClassName());
+                    }
+                    return classfileBuffer;
+                } else {
+                    if (isDebug()) {
+                        debugPrint("transformed class " + cr.getJavaClassName());
+                    }
+                    if (debug.isDumpClasses()) {
+                        debug.dumpClass(className.replace('.', '/'), transformed);
+                    }
                 }
-                if (debug.isDumpClasses()) {
-                    debug.dumpClass(className.replace('.', '/'), transformed);
+                return transformed;
+            } catch (Throwable th) {
+                debugPrint(th);
+                throw th;
+            } finally {
+                if (entered) {
+                    BTraceRuntime.leave();
                 }
+                System.err.println("*** <<< Thread: " + Thread.currentThread().getName());
             }
-            return transformed;
-        } catch (Throwable th) {
-            debugPrint(th);
-            throw th;
         } finally {
-            if (entered) {
-                BTraceRuntime.leave();
-            }
+            setupLock.readLock().unlock();
         }
     }