8187443: Forest Consolidation: Move files to unified layout

Reviewed-by: darcy, ihse

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

@@ -0,0 +1,401 @@
+/*
+ * Copyright (c) 2008, 2016, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package java.lang.invoke;
+
+import static java.lang.invoke.MethodHandleStatics.*;
+import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
+
+import jdk.internal.vm.annotation.Stable;
+
+/**
+ * A {@code CallSite} is a holder for a variable {@link MethodHandle},
+ * which is called its {@code target}.
+ * An {@code invokedynamic} instruction linked to a {@code CallSite} delegates
+ * all calls to the site's current target.
+ * A {@code CallSite} may be associated with several {@code invokedynamic}
+ * instructions, or it may be "free floating", associated with none.
+ * In any case, it may be invoked through an associated method handle
+ * called its {@linkplain #dynamicInvoker dynamic invoker}.
+ * <p>
+ * {@code CallSite} is an abstract class which does not allow
+ * direct subclassing by users.  It has three immediate,
+ * concrete subclasses that may be either instantiated or subclassed.
+ * <ul>
+ * <li>If a mutable target is not required, an {@code invokedynamic} instruction
+ * may be permanently bound by means of a {@linkplain ConstantCallSite constant call site}.
+ * <li>If a mutable target is required which has volatile variable semantics,
+ * because updates to the target must be immediately and reliably witnessed by other threads,
+ * a {@linkplain VolatileCallSite volatile call site} may be used.
+ * <li>Otherwise, if a mutable target is required,
+ * a {@linkplain MutableCallSite mutable call site} may be used.
+ * </ul>
+ * <p>
+ * A non-constant call site may be <em>relinked</em> by changing its target.
+ * The new target must have the same {@linkplain MethodHandle#type() type}
+ * as the previous target.
+ * Thus, though a call site can be relinked to a series of
+ * successive targets, it cannot change its type.
+ * <p>
+ * Here is a sample use of call sites and bootstrap methods which links every
+ * dynamic call site to print its arguments:
+<blockquote><pre>{@code
+static void test() throws Throwable {
+    // THE FOLLOWING LINE IS PSEUDOCODE FOR A JVM INSTRUCTION
+    InvokeDynamic[#bootstrapDynamic].baz("baz arg", 2, 3.14);
+}
+private static void printArgs(Object... args) {
+  System.out.println(java.util.Arrays.deepToString(args));
+}
+private static final MethodHandle printArgs;
+static {
+  MethodHandles.Lookup lookup = MethodHandles.lookup();
+  Class thisClass = lookup.lookupClass();  // (who am I?)
+  printArgs = lookup.findStatic(thisClass,
+      "printArgs", MethodType.methodType(void.class, Object[].class));
+}
+private static CallSite bootstrapDynamic(MethodHandles.Lookup caller, String name, MethodType type) {
+  // ignore caller and name, but match the type:
+  return new ConstantCallSite(printArgs.asType(type));
+}
+}</pre></blockquote>
+ * @author John Rose, JSR 292 EG
+ * @since 1.7
+ */
+abstract
+public class CallSite {
+
+    // The actual payload of this call site:
+    /*package-private*/
+    MethodHandle target;    // Note: This field is known to the JVM.  Do not change.
+
+    /**
+     * Make a blank call site object with the given method type.
+     * An initial target method is supplied which will throw
+     * an {@link IllegalStateException} if called.
+     * <p>
+     * Before this {@code CallSite} object is returned from a bootstrap method,
+     * it is usually provided with a more useful target method,
+     * via a call to {@link CallSite#setTarget(MethodHandle) setTarget}.
+     * @throws NullPointerException if the proposed type is null
+     */
+    /*package-private*/
+    CallSite(MethodType type) {
+        target = makeUninitializedCallSite(type);
+    }
+
+    /**
+     * Make a call site object equipped with an initial target method handle.
+     * @param target the method handle which will be the initial target of the call site
+     * @throws NullPointerException if the proposed target is null
+     */
+    /*package-private*/
+    CallSite(MethodHandle target) {
+        target.type();  // null check
+        this.target = target;
+    }
+
+    /**
+     * Make a call site object equipped with an initial target method handle.
+     * @param targetType the desired type of the call site
+     * @param createTargetHook a hook which will bind the call site to the target method handle
+     * @throws WrongMethodTypeException if the hook cannot be invoked on the required arguments,
+     *         or if the target returned by the hook is not of the given {@code targetType}
+     * @throws NullPointerException if the hook returns a null value
+     * @throws ClassCastException if the hook returns something other than a {@code MethodHandle}
+     * @throws Throwable anything else thrown by the hook function
+     */
+    /*package-private*/
+    CallSite(MethodType targetType, MethodHandle createTargetHook) throws Throwable {
+        this(targetType);
+        ConstantCallSite selfCCS = (ConstantCallSite) this;
+        MethodHandle boundTarget = (MethodHandle) createTargetHook.invokeWithArguments(selfCCS);
+        checkTargetChange(this.target, boundTarget);
+        this.target = boundTarget;
+    }
+
+    /**
+     * {@code CallSite} dependency context.
+     * JVM uses CallSite.context to store nmethod dependencies on the call site target.
+     */
+    private final MethodHandleNatives.CallSiteContext context = MethodHandleNatives.CallSiteContext.make(this);
+
+    /**
+     * Returns the type of this call site's target.
+     * Although targets may change, any call site's type is permanent, and can never change to an unequal type.
+     * The {@code setTarget} method enforces this invariant by refusing any new target that does
+     * not have the previous target's type.
+     * @return the type of the current target, which is also the type of any future target
+     */
+    public MethodType type() {
+        // warning:  do not call getTarget here, because CCS.getTarget can throw IllegalStateException
+        return target.type();
+    }
+
+    /**
+     * Returns the target method of the call site, according to the
+     * behavior defined by this call site's specific class.
+     * The immediate subclasses of {@code CallSite} document the
+     * class-specific behaviors of this method.
+     *
+     * @return the current linkage state of the call site, its target method handle
+     * @see ConstantCallSite
+     * @see VolatileCallSite
+     * @see #setTarget
+     * @see ConstantCallSite#getTarget
+     * @see MutableCallSite#getTarget
+     * @see VolatileCallSite#getTarget
+     */
+    public abstract MethodHandle getTarget();
+
+    /**
+     * Updates the target method of this call site, according to the
+     * behavior defined by this call site's specific class.
+     * The immediate subclasses of {@code CallSite} document the
+     * class-specific behaviors of this method.
+     * <p>
+     * The type of the new target must be {@linkplain MethodType#equals equal to}
+     * the type of the old target.
+     *
+     * @param newTarget the new target
+     * @throws NullPointerException if the proposed new target is null
+     * @throws WrongMethodTypeException if the proposed new target
+     *         has a method type that differs from the previous target
+     * @see CallSite#getTarget
+     * @see ConstantCallSite#setTarget
+     * @see MutableCallSite#setTarget
+     * @see VolatileCallSite#setTarget
+     */
+    public abstract void setTarget(MethodHandle newTarget);
+
+    void checkTargetChange(MethodHandle oldTarget, MethodHandle newTarget) {
+        MethodType oldType = oldTarget.type();
+        MethodType newType = newTarget.type();  // null check!
+        if (!newType.equals(oldType))
+            throw wrongTargetType(newTarget, oldType);
+    }
+
+    private static WrongMethodTypeException wrongTargetType(MethodHandle target, MethodType type) {
+        return new WrongMethodTypeException(String.valueOf(target)+" should be of type "+type);
+    }
+
+    /**
+     * Produces a method handle equivalent to an invokedynamic instruction
+     * which has been linked to this call site.
+     * <p>
+     * This method is equivalent to the following code:
+     * <blockquote><pre>{@code
+     * MethodHandle getTarget, invoker, result;
+     * getTarget = MethodHandles.publicLookup().bind(this, "getTarget", MethodType.methodType(MethodHandle.class));
+     * invoker = MethodHandles.exactInvoker(this.type());
+     * result = MethodHandles.foldArguments(invoker, getTarget)
+     * }</pre></blockquote>
+     *
+     * @return a method handle which always invokes this call site's current target
+     */
+    public abstract MethodHandle dynamicInvoker();
+
+    /*non-public*/ MethodHandle makeDynamicInvoker() {
+        MethodHandle getTarget = getTargetHandle().bindArgumentL(0, this);
+        MethodHandle invoker = MethodHandles.exactInvoker(this.type());
+        return MethodHandles.foldArguments(invoker, getTarget);
+    }
+
+    private static @Stable MethodHandle GET_TARGET;
+    private static MethodHandle getTargetHandle() {
+        MethodHandle handle = GET_TARGET;
+        if (handle != null) {
+            return handle;
+        }
+        try {
+            return GET_TARGET = IMPL_LOOKUP.
+                    findVirtual(CallSite.class, "getTarget",
+                                MethodType.methodType(MethodHandle.class));
+        } catch (ReflectiveOperationException e) {
+            throw newInternalError(e);
+        }
+    }
+
+    private static @Stable MethodHandle THROW_UCS;
+    private static MethodHandle uninitializedCallSiteHandle() {
+        MethodHandle handle = THROW_UCS;
+        if (handle != null) {
+            return handle;
+        }
+        try {
+            return THROW_UCS = IMPL_LOOKUP.
+                findStatic(CallSite.class, "uninitializedCallSite",
+                           MethodType.methodType(Object.class, Object[].class));
+        } catch (ReflectiveOperationException e) {
+            throw newInternalError(e);
+        }
+    }
+
+    /** This guy is rolled into the default target if a MethodType is supplied to the constructor. */
+    private static Object uninitializedCallSite(Object... ignore) {
+        throw new IllegalStateException("uninitialized call site");
+    }
+
+    private MethodHandle makeUninitializedCallSite(MethodType targetType) {
+        MethodType basicType = targetType.basicType();
+        MethodHandle invoker = basicType.form().cachedMethodHandle(MethodTypeForm.MH_UNINIT_CS);
+        if (invoker == null) {
+            invoker = uninitializedCallSiteHandle().asType(basicType);
+            invoker = basicType.form().setCachedMethodHandle(MethodTypeForm.MH_UNINIT_CS, invoker);
+        }
+        // unchecked view is OK since no values will be received or returned
+        return invoker.viewAsType(targetType, false);
+    }
+
+    // unsafe stuff:
+    private static @Stable long TARGET_OFFSET;
+    private static long getTargetOffset() {
+        long offset = TARGET_OFFSET;
+        if (offset > 0) {
+            return offset;
+        }
+        offset = TARGET_OFFSET = UNSAFE.objectFieldOffset(CallSite.class, "target");
+        assert(offset > 0);
+        return offset;
+    }
+
+    /*package-private*/
+    void setTargetNormal(MethodHandle newTarget) {
+        MethodHandleNatives.setCallSiteTargetNormal(this, newTarget);
+    }
+    /*package-private*/
+    MethodHandle getTargetVolatile() {
+        return (MethodHandle) UNSAFE.getObjectVolatile(this, getTargetOffset());
+    }
+    /*package-private*/
+    void setTargetVolatile(MethodHandle newTarget) {
+        MethodHandleNatives.setCallSiteTargetVolatile(this, newTarget);
+    }
+
+    // this implements the upcall from the JVM, MethodHandleNatives.linkCallSite:
+    static CallSite makeSite(MethodHandle bootstrapMethod,
+                             // Callee information:
+                             String name, MethodType type,
+                             // Extra arguments for BSM, if any:
+                             Object info,
+                             // Caller information:
+                             Class<?> callerClass) {
+        MethodHandles.Lookup caller = IMPL_LOOKUP.in(callerClass);
+        CallSite site;
+        try {
+            Object binding;
+            info = maybeReBox(info);
+            if (info == null) {
+                binding = bootstrapMethod.invoke(caller, name, type);
+            } else if (!info.getClass().isArray()) {
+                binding = bootstrapMethod.invoke(caller, name, type, info);
+            } else {
+                Object[] argv = (Object[]) info;
+                maybeReBoxElements(argv);
+                switch (argv.length) {
+                    case 0:
+                        binding = bootstrapMethod.invoke(caller, name, type);
+                        break;
+                    case 1:
+                        binding = bootstrapMethod.invoke(caller, name, type,
+                                                         argv[0]);
+                        break;
+                    case 2:
+                        binding = bootstrapMethod.invoke(caller, name, type,
+                                                         argv[0], argv[1]);
+                        break;
+                    case 3:
+                        binding = bootstrapMethod.invoke(caller, name, type,
+                                                         argv[0], argv[1], argv[2]);
+                        break;
+                    case 4:
+                        binding = bootstrapMethod.invoke(caller, name, type,
+                                                         argv[0], argv[1], argv[2], argv[3]);
+                        break;
+                    case 5:
+                        binding = bootstrapMethod.invoke(caller, name, type,
+                                                         argv[0], argv[1], argv[2], argv[3], argv[4]);
+                        break;
+                    case 6:
+                        binding = bootstrapMethod.invoke(caller, name, type,
+                                                         argv[0], argv[1], argv[2], argv[3], argv[4], argv[5]);
+                        break;
+                    default:
+                        final int NON_SPREAD_ARG_COUNT = 3;  // (caller, name, type)
+                        if (NON_SPREAD_ARG_COUNT + argv.length > MethodType.MAX_MH_ARITY)
+                            throw new BootstrapMethodError("too many bootstrap method arguments");
+
+                        MethodType invocationType = MethodType.genericMethodType(NON_SPREAD_ARG_COUNT + argv.length);
+                        MethodHandle typedBSM = bootstrapMethod.asType(invocationType);
+                        MethodHandle spreader = invocationType.invokers().spreadInvoker(NON_SPREAD_ARG_COUNT);
+                        binding = spreader.invokeExact(typedBSM, (Object) caller, (Object) name, (Object) type, argv);
+                }
+            }
+            if (binding instanceof CallSite) {
+                site = (CallSite) binding;
+            } else {
+                // See the "Linking Exceptions" section for the invokedynamic
+                // instruction in JVMS 6.5.
+                // Throws a runtime exception defining the cause that is then
+                // in the "catch (Throwable ex)" a few lines below wrapped in
+                // BootstrapMethodError
+                throw new ClassCastException("bootstrap method failed to produce a CallSite");
+            }
+            if (!site.getTarget().type().equals(type)) {
+                // See the "Linking Exceptions" section for the invokedynamic
+                // instruction in JVMS 6.5.
+                // Throws a runtime exception defining the cause that is then
+                // in the "catch (Throwable ex)" a few lines below wrapped in
+                // BootstrapMethodError
+                throw wrongTargetType(site.getTarget(), type);
+            }
+        } catch (Error e) {
+            // Pass through an Error, including BootstrapMethodError, any other
+            // form of linkage error, such as IllegalAccessError if the bootstrap
+            // method is inaccessible, or say ThreadDeath/OutOfMemoryError
+            // See the "Linking Exceptions" section for the invokedynamic
+            // instruction in JVMS 6.5.
+            throw e;
+        } catch (Throwable ex) {
+            // Wrap anything else in BootstrapMethodError
+            throw new BootstrapMethodError("call site initialization exception", ex);
+        }
+        return site;
+    }
+
+    private static Object maybeReBox(Object x) {
+        if (x instanceof Integer) {
+            int xi = (int) x;
+            if (xi == (byte) xi)
+                x = xi;  // must rebox; see JLS 5.1.7
+        }
+        return x;
+    }
+    private static void maybeReBoxElements(Object[] xa) {
+        for (int i = 0; i < xa.length; i++) {
+            xa[i] = maybeReBox(xa[i]);
+        }
+    }
+}