src/java.base/share/classes/java/lang/invoke/BoundMethodHandle.java

@@ -32,11 +32,13 @@
 
 import java.lang.invoke.LambdaForm.NamedFunction;
 import java.lang.invoke.MethodHandles.Lookup;
 import java.lang.reflect.Field;
 import java.util.Arrays;
-import java.util.HashMap;
+import java.util.function.Function;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.ConcurrentHashMap;
 
 import sun.invoke.util.ValueConversions;
 import sun.invoke.util.Wrapper;
 
 import jdk.internal.org.objectweb.asm.ClassWriter;

@@ -353,30 +355,18 @@
 
         private void initForBootstrap() {
             assert(!INIT_DONE);
             if (constructor() == null) {
                 String types = typeChars;
+                CACHE.put(types, this);
                 Factory.makeCtors(clazz, types, this.constructor);
                 Factory.makeGetters(clazz, types, this.getters);
                 Factory.makeNominalGetters(types, this.nominalGetters, this.getters);
             }
         }
 
-        private SpeciesData(String typeChars) {
-            // Placeholder only.
-            this.typeChars = typeChars;
-            this.typeCodes = basicTypes(typeChars);
-            this.clazz = null;
-            this.constructor = null;
-            this.getters = null;
-            this.nominalGetters = null;
-            this.extensions = null;
-        }
-        private boolean isPlaceholder() { return clazz == null; }
-
-        private static final HashMap<String, SpeciesData> CACHE = new HashMap<>();
-        static { CACHE.put("", EMPTY); }  // make bootstrap predictable
+        private static final ConcurrentMap<String, SpeciesData> CACHE = new ConcurrentHashMap<>();
         private static final boolean INIT_DONE;  // set after <clinit> finishes...
 
         SpeciesData extendWith(byte type) {
             return extendWith(BasicType.basicType(type));
         }

@@ -388,66 +378,57 @@
             extensions[ord] = d = get(typeChars+type.basicTypeChar());
             return d;
         }
 
         private static SpeciesData get(String types) {
-            // Acquire cache lock for query.
-            SpeciesData d = lookupCache(types);
-            if (!d.isPlaceholder())
-                return d;
-            synchronized (d) {
-                // Use synch. on the placeholder to prevent multiple instantiation of one species.
-                // Creating this class forces a recursive call to getForClass.
-                if (lookupCache(types).isPlaceholder())
-                    Factory.generateConcreteBMHClass(types);
-            }
-            // Reacquire cache lock.
-            d = lookupCache(types);
-            // Class loading must have upgraded the cache.
-            assert(d != null && !d.isPlaceholder());
+            SpeciesData d = CACHE.get(types);
+            if (d == null) {
+                Class<? extends BoundMethodHandle> bmhcl = Factory.getConcreteBMHClass(types);
+                // obtain value of SPECIES_DATA static field.
+                // This triggers class initialization which might fail!
+                d = Factory.speciesDataFromConcreteBMHClass(bmhcl);
+                SpeciesData d2 = CACHE.putIfAbsent(types, d);
+                assert d2 == null || d2 == d;
+            }
             return d;
         }
+
+        // a call-back from generated BMH subclass' <clinit>
         static SpeciesData getForClass(String types, Class<? extends BoundMethodHandle> clazz) {
             // clazz is a new class which is initializing its SPECIES_DATA field
-            return updateCache(types, new SpeciesData(types, clazz));
-        }
-        private static synchronized SpeciesData lookupCache(String types) {
-            SpeciesData d = CACHE.get(types);
-            if (d != null)  return d;
-            d = new SpeciesData(types);
-            assert(d.isPlaceholder());
-            CACHE.put(types, d);
-            return d;
-        }
-        private static synchronized SpeciesData updateCache(String types, SpeciesData d) {
-            SpeciesData d2;
-            assert((d2 = CACHE.get(types)) == null || d2.isPlaceholder());
-            assert(!d.isPlaceholder());
-            CACHE.put(types, d);
-            return d;
+            return new SpeciesData(types, clazz);
         }
 
-        static {
-            // pre-fill the BMH speciesdata cache with BMH's inner classes
-            final Class<BoundMethodHandle> rootCls = BoundMethodHandle.class;
+        /**
+         * This is to be called when assertions are enabled. It checks whether SpeciesData for all of the statically
+         * defined species subclasses of BoundMethodHandle has been added to the SpeciesData cache. See below in the
+         * static initializer for
+         */
+        static boolean speciesDataCachePopulated() {
+            Class<BoundMethodHandle> rootCls = BoundMethodHandle.class;
             try {
                 for (Class<?> c : rootCls.getDeclaredClasses()) {
                     if (rootCls.isAssignableFrom(c)) {
                         final Class<? extends BoundMethodHandle> cbmh = c.asSubclass(BoundMethodHandle.class);
                         SpeciesData d = Factory.speciesDataFromConcreteBMHClass(cbmh);
                         assert(d != null) : cbmh.getName();
                         assert(d.clazz == cbmh);
-                        assert(d == lookupCache(d.typeChars));
+                        assert(CACHE.get(d.typeChars) == d);
                     }
                 }
             } catch (Throwable e) {
                 throw newInternalError(e);
             }
-
-            for (SpeciesData d : CACHE.values()) {
-                d.initForBootstrap();
+            return true;
             }
+
+        static {
+            // Pre-fill the BMH species-data cache with EMPTY and all BMH's inner subclasses.
+            EMPTY.initForBootstrap();
+            Species_L.SPECIES_DATA.initForBootstrap();
+            // check that all static SpeciesData instances have been initialized
+            assert speciesDataCachePopulated();
             // Note:  Do not simplify this, because INIT_DONE must not be
             // a compile-time constant during bootstrapping.
             INIT_DONE = Boolean.TRUE;
         }
     }

@@ -491,10 +472,30 @@
 
         static final String SIG_INCIPIT = "(Ljava/lang/invoke/MethodType;Ljava/lang/invoke/LambdaForm;";
 
         static final String[] E_THROWABLE = new String[] { "java/lang/Throwable" };
 
+        static final ConcurrentMap<String, Class<? extends BoundMethodHandle>> CLASS_CACHE = new ConcurrentHashMap<>();
+
+        /**
+         * Get a concrete subclass of BMH for a given combination of bound types.
+         *
+         * @param types the type signature, wherein reference types are erased to 'L'
+         * @return the concrete BMH class
+         */
+        static Class<? extends BoundMethodHandle> getConcreteBMHClass(String types) {
+            // CHM.computeIfAbsent ensures generateConcreteBMHClass is called
+            // only once per key.
+            return CLASS_CACHE.computeIfAbsent(
+                types, new Function<String, Class<? extends BoundMethodHandle>>() {
+                    @Override
+                    public Class<? extends BoundMethodHandle> apply(String types) {
+                        return generateConcreteBMHClass(types);
+                    }
+                });
+        }
+
         /**
          * Generate a concrete subclass of BMH for a given combination of bound types.
          *
          * A concrete BMH species adheres to the following schema:
          *

@@ -713,11 +714,10 @@
             Class<? extends BoundMethodHandle> bmhClass =
                 //UNSAFE.defineAnonymousClass(BoundMethodHandle.class, classFile, null).asSubclass(BoundMethodHandle.class);
                 UNSAFE.defineClass(className, classFile, 0, classFile.length,
                                    BoundMethodHandle.class.getClassLoader(), null)
                     .asSubclass(BoundMethodHandle.class);
-            UNSAFE.ensureClassInitialized(bmhClass);
 
             return bmhClass;
         }
 
         private static int typeLoadOp(char t) {