+ * If only the value is given, it must name a subclass of {@link CallSite}
+ * with a constructor which accepts a class, string, and method type.
+ * If the value and name are both given, there must be
+ * a static method in the given class of the given name which accepts a class, string,
+ * and method type, and returns a reference coercible to {@link CallSite}.
+ *
+ * This annotation can be placed either on the return type of a single {@link InvokeDynamic} + * call (see examples) or else it can be placed on an enclosing class or method, where it + * determines a default bootstrap method for any {@link InvokeDynamic} calls which are not + * specifically annotated with a bootstrap method. + * Every {@link InvokeDynamic} call must be given a bootstrap method. + *
+ * Examples: +
+@BootstrapMethod(value=MyLanguageRuntime.class, name="bootstrapDynamic")
+String x = (String) InvokeDynamic.greet();
+//BSM => MyLanguageRuntime.bootstrapDynamic(Here.class, "greet", methodType(String.class))
+@BootstrapMethod(MyCallSite.class)
+void example() throws Throwable {
+ InvokeDynamic.greet();
+ //BSM => new MyCallSite(Here.class, "greet", methodType(void.class))
+}
++ */ +@Target({ElementType.TYPE_USE, + // For defaulting every indy site within a class or method; cf. @SuppressWarnings: + ElementType.TYPE, ElementType.METHOD, ElementType.CONSTRUCTOR + }) +@Retention(RetentionPolicy.SOURCE) +public @interface BootstrapMethod { + /** The class containing the bootstrap method. */ + Class value(); + + /** The name of the bootstrap method. + * If this is the empty string, an instance of the bootstrap class is created, + * and a constructor is invoked. + * Otherwise, there must be a static method of the required name. + */ + String name() default ""; // empty string denotes a constructor with 'new' + + /** The argument types of the bootstrap method, as passed out by the JVM. + * There is usually no reason to override the default. + */ + Class[] arguments() default {Class.class, String.class, MethodType.class}; +} diff --git a/jdk/src/share/classes/java/dyn/CallSite.java b/jdk/src/share/classes/java/dyn/CallSite.java index b8335774851..c3b7962911f 100644 --- a/jdk/src/share/classes/java/dyn/CallSite.java +++ b/jdk/src/share/classes/java/dyn/CallSite.java @@ -25,56 +25,26 @@ package java.dyn; -import sun.dyn.Access; -import sun.dyn.MemberName; -import sun.dyn.CallSiteImpl; +import sun.dyn.*; +import java.util.Collection; /** - * A {@code CallSite} reifies an {@code invokedynamic} instruction from bytecode, - * and controls its linkage. - * Every linked {@code CallSite} object corresponds to a distinct instance - * of the {@code invokedynamic} instruction, and vice versa. + * A {@code CallSite} is a holder for a variable {@link MethodHandle}, + * which is called its {@code target}. + * Every call to a {@code CallSite} is delegated to the site's current target. *
- * Every linked {@code CallSite} object has one state variable, - * a {@link MethodHandle} reference called the {@code target}. - * This reference is never null. Though it can change its value - * successive values must always have exactly the {@link MethodType method type} - * called for by the bytecodes of the associated {@code invokedynamic} instruction + * A call site is initially created in an unlinked state, + * which is distinguished by a null target variable. + * Before the call site may be invoked (and before certain other + * operations are attempted), the call site must be linked to + * a non-null target. *
- * It is the responsibility of each class's - * {@link Linkage#registerBootstrapMethod(Class, MethodHandle) bootstrap method} - * to produce call sites which have been pre-linked to an initial target method. - * The required {@link MethodType type} for the target method is a parameter - * to each bootstrap method call. - *
- * The bootstrap method may elect to produce call sites of a - * language-specific subclass of {@code CallSite}. In such a case, - * the subclass may claim responsibility for initializing its target to - * a non-null value, by overriding {@link #initialTarget}. - *
- * An {@code invokedynamic} instruction which has not yet been executed - * is said to be unlinked. When an unlinked call site is executed, - * the containing class's bootstrap method is called to manufacture a call site, - * for the instruction. If the bootstrap method does not assign a non-null - * value to the new call site's target variable, the method {@link #initialTarget} - * is called to produce the new call site's first target method. - *
- * A freshly-created {@code CallSite} object is not yet in a linked state. - * An unlinked {@code CallSite} object reports null for its {@code callerClass}. - * When the JVM receives a {@code CallSite} object from a bootstrap method, - * it first ensures that its target is non-null and of the correct type. - * The JVM then links the {@code CallSite} object to the call site instruction, - * enabling the {@code callerClass} to return the class in which the instruction occurs. - *
- * Next, the JVM links the instruction to the {@code CallSite}, at which point - * any further execution of the {@code invokedynamic} instruction implicitly - * invokes the current target of the {@code CallSite} object. - * After this two-way linkage, both the instruction and the {@code CallSite} - * object are said to be linked. - *
- * This state of linkage continues until the method containing the - * dynamic call site is garbage collected, or the dynamic call site - * is invalidated by an explicit request. + * A call site may be relinked by changing its target. + * The new target must be non-null and 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. *
* Linkage happens once in the lifetime of any given {@code CallSite} object. * Because of call site invalidation, this linkage can be repeated for @@ -87,6 +57,10 @@ import sun.dyn.CallSiteImpl; * Here is a sample use of call sites and bootstrap methods which links every * dynamic call site to print its arguments:
+@BootstrapMethod(value=PrintArgsDemo.class, name="bootstrapDynamic")
+static void test() throws Throwable {
+ InvokeDynamic.baz("baz arg", 2, 3.14);
+}
private static void printArgs(Object... args) {
System.out.println(java.util.Arrays.deepToString(args));
}
@@ -96,17 +70,16 @@ static {
Class thisClass = lookup.lookupClass(); // (who am I?)
printArgs = lookup.findStatic(thisClass,
"printArgs", MethodType.methodType(void.class, Object[].class));
- Linkage.registerBootstrapMethod("bootstrapDynamic");
}
private static CallSite bootstrapDynamic(Class caller, String name, MethodType type) {
// ignore caller and name, but match the type:
return new CallSite(MethodHandles.collectArguments(printArgs, type));
}
If this call site is a {@link ConstantCallSite}, this method + * simply returns the call site's target, since that will not change. + *
Otherwise, this method is equivalent to the following code: + *
+ * @return a method handle which always invokes this call site's current target + */ + public final MethodHandle dynamicInvoker() { + if (this instanceof ConstantCallSite) + return getTarget(); // will not change dynamically + MethodHandle getCSTarget = GET_TARGET; + if (getCSTarget == null) + GET_TARGET = getCSTarget = MethodHandles.Lookup.IMPL_LOOKUP. + findVirtual(CallSite.class, "getTarget", MethodType.methodType(MethodHandle.class)); + MethodHandle getTarget = MethodHandleImpl.bindReceiver(IMPL_TOKEN, getCSTarget, this); + MethodHandle invoker = MethodHandles.exactInvoker(this.type()); + return MethodHandles.foldArguments(invoker, getTarget); + } + private static MethodHandle GET_TARGET = null; // link this lazily, not eagerly + + /** Implementation of {@link MethodHandleProvider} which returns {@code this.dynamicInvoker()}. */ + public final MethodHandle asMethodHandle() { return dynamicInvoker(); } + + /** Implementation of {@link MethodHandleProvider}, which returns {@code this.dynamicInvoker().asType(type)}. */ + public final MethodHandle asMethodHandle(MethodType type) { return dynamicInvoker().asType(type); } } diff --git a/jdk/src/share/classes/java/dyn/ConstantCallSite.java b/jdk/src/share/classes/java/dyn/ConstantCallSite.java new file mode 100644 index 00000000000..e03fa8d3368 --- /dev/null +++ b/jdk/src/share/classes/java/dyn/ConstantCallSite.java @@ -0,0 +1,43 @@ +/* + * Copyright (c) 2010, 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.dyn; + +/** + * A {@code ConstantCallSite} is a {@link CallSite} whose target is permanent, and can never be changed. + * The only way to relink an {@code invokedynamic} instruction bound to a {@code ConstantCallSite} is + * to invalidate the instruction as a whole. + * @author John Rose, JSR 292 EG + */ +public class ConstantCallSite extends CallSite { + /** Create a call site with a permanent target. */ + public ConstantCallSite(MethodHandle target) { + super(target); + } + /** Throw an {@link IllegalArgumentException}, because this kind of call site cannot change its target. */ + @Override public final void setTarget(MethodHandle ignore) { + throw new IllegalArgumentException("ConstantCallSite"); + } +} diff --git a/jdk/src/share/classes/java/dyn/InvokeDynamic.java b/jdk/src/share/classes/java/dyn/InvokeDynamic.java index 021e75a1ea7..4406363a990 100644 --- a/jdk/src/share/classes/java/dyn/InvokeDynamic.java +++ b/jdk/src/share/classes/java/dyn/InvokeDynamic.java @@ -35,7 +35,7 @@ package java.dyn; * The target method is a property of the reified {@linkplain CallSite call site object} * which is linked to each active {@code invokedynamic} instruction. * The call site object is initially produced by a - * {@linkplain java.dyn.Linkage#registerBootstrapMethod(Class, MethodHandle) bootstrap method} + * {@linkplain BootstrapMethod bootstrap method} * associated with the class whose bytecodes include the dynamic call site. *+ * MethodHandle getTarget, invoker, result; + * getTarget = MethodHandles.lookup().bind(this, "getTarget", MethodType.methodType(MethodHandle.class)); + * invoker = MethodHandles.exactInvoker(this.type()); + * result = MethodHandles.foldArguments(invoker, getTarget) + *
* The type {@code InvokeDynamic} has no particular meaning as a @@ -45,22 +45,31 @@ package java.dyn; * It may be imported for ease of use. *
* Here are some examples: - *
- * Object x; String s; int i;
- * x = InvokeDynamic.greet("world"); // greet(Ljava/lang/String;)Ljava/lang/Object;
- * s = InvokeDynamic.<String>hail(x); // hail(Ljava/lang/Object;)Ljava/lang/String;
- * InvokeDynamic.<void>cogito(); // cogito()V
- * i = InvokeDynamic.<int>#"op:+"(2, 3); // "op:+"(II)I
- *
+@BootstrapMethod(value=Here.class, name="bootstrapDynamic")
+static void example() throws Throwable {
+ Object x; String s; int i;
+ x = InvokeDynamic.greet("world"); // greet(Ljava/lang/String;)Ljava/lang/Object;
+ s = (String) InvokeDynamic.hail(x); // hail(Ljava/lang/Object;)Ljava/lang/String;
+ InvokeDynamic.cogito(); // cogito()V
+ i = (int) InvokeDynamic.#"op:+"(2, 3); // "op:+"(II)I
+}
+static MethodHandle bootstrapDynamic(Class caller, String name, MethodType type) { ... }
+* The argument types are taken directly from the actual arguments, - * while the return type is taken from the type parameter. - * (This type parameter may be a primtive, and it defaults to {@code Object}.) + * while the return type corresponds to the target of the assignment. + * (Currently, the return type must be given as a false type parameter. + * This type parameter is an irregular use of the generic type syntax, + * and is likely to change in favor of a convention based on target typing.) + *
* The final example uses a special syntax for uttering non-Java names. * Any name legal to the JVM may be given between the double quotes. + *
* None of these calls is complete without a bootstrap method, - * which must be registered by the static initializer of the enclosing class. + * which must be declared for the enclosing class or method. * @author John Rose, JSR 292 EG */ @MethodHandle.PolymorphicSignature diff --git a/jdk/src/share/classes/java/dyn/InvokeDynamicBootstrapError.java b/jdk/src/share/classes/java/dyn/InvokeDynamicBootstrapError.java index 83ebcd464b4..be1bc8a5970 100644 --- a/jdk/src/share/classes/java/dyn/InvokeDynamicBootstrapError.java +++ b/jdk/src/share/classes/java/dyn/InvokeDynamicBootstrapError.java @@ -28,15 +28,11 @@ package java.dyn; /** * Thrown to indicate that an {@code invokedynamic} instruction has * failed to find its - * {@linkplain Linkage#registerBootstrapMethod(Class, MethodHandle) bootstrap method}, + * {@linkplain BootstrapMethod bootstrap method}, * or the bootstrap method has * failed to provide a * {@linkplain CallSite} call site with a non-null {@linkplain MethodHandle target} * of the correct {@linkplain MethodType method type}. - *
- * The bootstrap method must have been declared during a class's initialization - * by a call to one of the overloadings of - * {@link Linkage#registerBootstrapMethod registerBootstrapMethod}. * * @author John Rose, JSR 292 EG */ diff --git a/jdk/src/share/classes/java/dyn/Linkage.java b/jdk/src/share/classes/java/dyn/Linkage.java index d65ae41c31c..98eedbbabfb 100644 --- a/jdk/src/share/classes/java/dyn/Linkage.java +++ b/jdk/src/share/classes/java/dyn/Linkage.java @@ -25,7 +25,6 @@ package java.dyn; -import java.lang.annotation.Annotation; import java.dyn.MethodHandles.Lookup; import java.util.WeakHashMap; import sun.dyn.Access; @@ -56,11 +55,7 @@ public class Linkage { *
@@ -86,6 +81,7 @@ public class Linkage { * or is already running in another thread * @exception SecurityException if there is a security manager installed, * and a {@link LinkagePermission} check fails for "registerBootstrapMethod" + * @deprecated Use @{@link BootstrapMethod} annotations instead */ public static void registerBootstrapMethod(Class callerClass, MethodHandle bootstrapMethod) { @@ -97,14 +93,9 @@ public class Linkage { static private void checkBSM(MethodHandle mh) { if (mh == null) throw newIllegalArgumentException("null bootstrap method"); - if (mh.type() == BOOTSTRAP_METHOD_TYPE_2) - // For now, always pass an empty array for the Annotations argument - mh = MethodHandles.insertArguments(mh, BOOTSTRAP_METHOD_TYPE_2.parameterCount()-1, - (Object)NO_ANNOTATIONS); if (mh.type() == BOOTSTRAP_METHOD_TYPE) return; throw new WrongMethodTypeException(mh.toString()); } - static private final Annotation[] NO_ANNOTATIONS = { }; /** * PROVISIONAL API, WORK IN PROGRESS: @@ -115,6 +106,7 @@ public class Linkage { * @throws NoSuchMethodException if there is no such method * @throws IllegalStateException if the caller class's static initializer * has already run, or is already running in another thread + * @deprecated Use @{@link BootstrapMethod} annotations instead */ public static void registerBootstrapMethod(Class runtime, String name) { @@ -131,6 +123,7 @@ public class Linkage { * @throws IllegalArgumentException if there is no such method * @throws IllegalStateException if the caller class's static initializer * has already run, or is already running in another thread + * @deprecated Use @{@link BootstrapMethod} annotations instead */ public static void registerBootstrapMethod(String name) { @@ -142,18 +135,10 @@ public class Linkage { void registerBootstrapMethodLookup(Class callerClass, Class runtime, String name) { Lookup lookup = new Lookup(IMPL_TOKEN, callerClass); MethodHandle bootstrapMethod; - // Try both types. TBD try { - bootstrapMethod = lookup.findStatic(runtime, name, BOOTSTRAP_METHOD_TYPE_2); + bootstrapMethod = lookup.findStatic(runtime, name, BOOTSTRAP_METHOD_TYPE); } catch (NoAccessException ex) { - bootstrapMethod = null; - } - if (bootstrapMethod == null) { - try { - bootstrapMethod = lookup.findStatic(runtime, name, BOOTSTRAP_METHOD_TYPE); - } catch (NoAccessException ex) { - throw new IllegalArgumentException("no such bootstrap method in "+runtime+": "+name, ex); - } + throw new IllegalArgumentException("no such bootstrap method in "+runtime+": "+name, ex); } checkBSM(bootstrapMethod); MethodHandleImpl.registerBootstrap(IMPL_TOKEN, callerClass, bootstrapMethod); @@ -172,6 +157,7 @@ public class Linkage { * and the immediate caller of this method is not in the same * package as the caller class * and a {@link LinkagePermission} check fails for "getBootstrapMethod" + * @deprecated */ public static MethodHandle getBootstrapMethod(Class callerClass) { @@ -188,10 +174,6 @@ public class Linkage { public static final MethodType BOOTSTRAP_METHOD_TYPE = MethodType.methodType(CallSite.class, Class.class, String.class, MethodType.class); - static final MethodType BOOTSTRAP_METHOD_TYPE_2 - = MethodType.methodType(CallSite.class, - Class.class, String.class, MethodType.class, - Annotation[].class); /** * PROVISIONAL API, WORK IN PROGRESS: diff --git a/jdk/src/share/classes/java/dyn/LinkagePermission.java b/jdk/src/share/classes/java/dyn/LinkagePermission.java index 4478d959853..9f1c35e85e0 100644 --- a/jdk/src/share/classes/java/dyn/LinkagePermission.java +++ b/jdk/src/share/classes/java/dyn/LinkagePermission.java @@ -1,5 +1,5 @@ /* - * Copyright (c) 2008, 2009, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2008, 2010, 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 @@ -31,6 +31,7 @@ import java.util.Hashtable; import java.util.StringTokenizer; /** + * PROVISIONAL API, WORK IN PROGRESS: * This class is for managing runtime permission checking for * operations performed by methods in the {@link Linkage} class. * Like a {@link RuntimePermission}, on which it is modeled, @@ -52,13 +53,6 @@ import java.util.StringTokenizer; * * *
ISSUE: Is this still needed? * - * @see java.security.RuntimePermission + * @see java.lang.RuntimePermission * @see java.lang.SecurityManager * * @author John Rose, JSR 292 EG @@ -84,7 +79,7 @@ public final class LinkagePermission extends BasicPermission { /** * Create a new LinkagePermission with the given name. * The name is the symbolic name of the LinkagePermission, such as - * "registerBootstrapMethod", "invalidateCallerClass.*", etc. An asterisk + * "invalidateCallerClass.*", etc. An asterisk * may appear at the end of the name, following a ".", or by itself, to * signify a wildcard match. * diff --git a/jdk/src/share/classes/java/dyn/MethodHandle.java b/jdk/src/share/classes/java/dyn/MethodHandle.java index 20387ca6859..4904e975306 100644 --- a/jdk/src/share/classes/java/dyn/MethodHandle.java +++ b/jdk/src/share/classes/java/dyn/MethodHandle.java @@ -1,5 +1,5 @@ /* - * Copyright (c) 2008, 2009, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2008, 2010, 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 @@ -36,11 +36,13 @@ import static sun.dyn.MemberName.newIllegalArgumentException; // utility /** * A method handle is a typed, directly executable reference to a method, * constructor, field, or similar low-level operation, with optional - * conversion or substitution of arguments or return values. + * transformations of arguments or return values. + * (These transformations include conversion, insertion, deletion, + * substitution. See the methods of this class and of {@link MethodHandles}.) *
* Method handles are strongly typed according to signature. * They are not distinguished by method name or enclosing class. - * A method handle must be invoked under a signature which exactly matches + * A method handle must be invoked under a signature which matches * the method handle's own {@link MethodType method type}. *
* Every method handle confesses its type via the {@code type} accessor. @@ -174,9 +176,10 @@ assert(i == 3); * merely a documentation convention. These type parameters do * not play a role in type-checking method handle invocations. *
- * Note: Like classes and strings, method handles that correspond directly - * to fields and methods can be represented directly as constants to be - * loaded by {@code ldc} bytecodes. + * Like classes and strings, method handles that correspond to accessible + * fields, methods, and constructors can be represented directly + * in a class file's constant pool as constants to be loaded by {@code ldc} bytecodes. + * Loading such a constant causes the component classes of its type to be loaded as necessary. * * @see MethodType * @see MethodHandles @@ -186,6 +189,7 @@ public abstract class MethodHandle // Note: This is an implementation inheritance hack, and will be removed // with a JVM change which moves the required hidden state onto this class. extends MethodHandleImpl + implements MethodHandleProvider { private static Access IMPL_TOKEN = Access.getToken(); @@ -197,7 +201,7 @@ public abstract class MethodHandle * those methods which are signature polymorphic. */ @java.lang.annotation.Target({java.lang.annotation.ElementType.METHOD,java.lang.annotation.ElementType.TYPE}) - @java.lang.annotation.Retention(java.lang.annotation.RetentionPolicy.CLASS) + @java.lang.annotation.Retention(java.lang.annotation.RetentionPolicy.RUNTIME) @interface PolymorphicSignature { } private MethodType type; @@ -274,10 +278,14 @@ public abstract class MethodHandle * and performing simple conversions for arguments and return types. * The signature at the call site of {@code invokeGeneric} must * have the same arity as this method handle's {@code type}. - * The same conversions are allowed on arguments or return values as are supported by - * by {@link MethodHandles#convertArguments}. + *
* If the call site signature exactly matches this method handle's {@code type}, * the call proceeds as if by {@link #invokeExact}. + *
+ * Otherwise, the call proceeds as if this method handle were first
+ * adjusted by calling {@link #asType} to adjust this method handle
+ * to the required type, and then the call proceeds as if by
+ * {@link #invokeExact} on the adjusted method handle.
*/
public final native @PolymorphicSignature
+ * The type {@link MethodHandle} is a concrete class whose implementation
+ * hierarchy (if any) may be tightly coupled to the underlying JVM implementation.
+ * It cannot also serve as a base type for user-defined functional APIs.
+ * For this reason, {@code MethodHandle} cannot be subclassed to add new
+ * behavior to method handles. But this interface can be used to provide
+ * a link between a user-defined function and the {@code invokedynamic}
+ * instruction and the method handle API.
+ */
+public interface MethodHandleProvider {
+ /** Produce a method handle which will serve as a behavioral proxy for the current object.
+ * The type and invocation behavior of the proxy method handle are user-defined,
+ * and should have some relation to the intended meaning of the original object itself.
+ *
+ * The current object may have a changeable behavior.
+ * For example, {@link CallSite} has a {@code setTarget} method which changes its invocation.
+ * In such a case, it is incorrect for {@code asMethodHandle} to return
+ * a method handle whose behavior may diverge from that of the current object.
+ * Rather, the returned method handle must stably and permanently access
+ * the behavior of the current object, even if that behavior is changeable.
+ *
+ * The reference identity of the proxy method handle is not guaranteed to
+ * have any particular relation to the reference identity of the object.
+ * In particular, several objects with the same intended meaning could
+ * share a common method handle, or the same object could return different
+ * method handles at different times. In the latter case, the different
+ * method handles should have the same type and invocation behavior,
+ * and be usable from any thread at any time.
+ * In particular, if a MethodHandleProvider is bound to an
+ * The type {@link MethodHandle} itself implements {@code MethodHandleProvider}, and
+ * for this method simply returns {@code this}.
+ */
+ public MethodHandle asMethodHandle();
+
+ /** Produce a method handle of a given type which will serve as a behavioral proxy for the current object.
+ * As for the no-argument version {@link #asMethodHandle()}, the invocation behavior of the
+ * proxy method handle is user-defined. But the type must be the given type,
+ * or else a {@link WrongMethodTypeException} must be thrown.
+ *
+ * If the current object somehow represents a variadic or overloaded behavior,
+ * the method handle returned for a given type might represent only a subset of
+ * the current object's repertoire of behaviors, which correspond to that type.
+ */
+ public MethodHandle asMethodHandle(MethodType type) throws WrongMethodTypeException;
+}
diff --git a/jdk/src/share/classes/java/dyn/package-info.java b/jdk/src/share/classes/java/dyn/package-info.java
index 7a285b75d22..37555be14b4 100644
--- a/jdk/src/share/classes/java/dyn/package-info.java
+++ b/jdk/src/share/classes/java/dyn/package-info.java
@@ -40,20 +40,18 @@
* The JVM links any such call (regardless of signature) to a dynamically
* typed method handle invocation. In the case of {@code invokeGeneric},
* argument and return value conversions are applied.
+ * invokedynamic
+ * call site, the proxy method handle extracted at the time of binding
+ * will be used for an unlimited time, until the call site is rebound.
+ *
+ * Each instance of an {@code invokedynamic} instruction is called a dynamic call site. + * Multiple instances of an {@code invokedynamic} instruction can share a single + * {@code CONSTANT_InvokeDynamic} entry. + * In any case, distinct call sites always have distinct linkage state. + *
+ * Moreover, for the purpose of distinguishing dynamic call sites, + * the JVM is allowed (but not required) to make internal copies + * of {@code invokedynamic} instructions, each one + * constituting a separate dynamic call site with its own linkage state. + * Such copying, if it occurs, cannot be observed except indirectly via + * execution of bootstrap methods and target methods. + *
+ * A dynamic call site is originally in an unlinked state. In this state, there is + * no target method for the call site to invoke. + * A dynamic call site is linked by means of a bootstrap method, + * as described below. + *
+ * (Historic Note: Some older JVMs may allow the index of a {@code CONSTANT_NameAndType} + * instead of a {@code CONSTANT_InvokeDynamic}. In earlier, obsolete versions of this API, the + * bootstrap method was specified dynamically, in a per-class basis, during class initialization.) + * + *
+ * The JVM will ensure that on first + * execution of an {@code ldc} instruction for this entry, a {@link java.dyn.MethodType MethodType} * will be created which represents the signature. * Any classes mentioned in the {@code MethodType} will be loaded if necessary, * but not initialized. @@ -86,12 +116,15 @@ *
* The JVM will ensure that on first execution of an {@code ldc} instruction - * for this entry, a {@link java.dyn.MethodHandle} will be created which represents + * for this entry, a {@link java.dyn.MethodHandle MethodHandle} will be created which represents * the field or method reference, according to the specific mode implied by the subtag. *
* As with {@code CONSTANT_Class} and {@code CONSTANT_MethodType} constants, @@ -126,6 +159,129 @@ * Method handles for subtags {@code REF_getStatic}, {@code REF_putStatic}, and {@code REF_invokeStatic} * may force class initialization on their first invocation, just like the corresponding bytecodes. * + *
+ * Each {@code invokedynamic} instruction statically specifies its own + * bootstrap method as a constant pool reference. + * The constant pool reference also specifies the call site's name and type signature, + * just like {@code invokevirtual} and the other invoke instructions. + *
+ * Linking starts with resolving the constant pool entry for the + * bootstrap method, and resolving a {@link java.dyn.MethodType MethodType} object for + * the type signature of the dynamic call site. + * This resolution process may trigger class loading. + * It may therefore throw an error if a class fails to load. + * This error becomes the abnormal termination of the dynamic + * call site execution. + * Linkage does not trigger class initialization. + *
+ * Next, the bootstrap method call is started, with four values being stacked: + *
invokeGeneric method}.
+ * The returned result must be a {@link java.dyn.CallSite CallSite}, a {@link java.dyn.MethodHandle MethodHandle},
+ * or another {@link java.dyn.MethodHandleProvider MethodHandleProvider} value.
+ * The method {@linkplain java.dyn.MethodHandleProvider#asMethodHandle asMethodHandle}
+ * is then called on the returned value. The result of that second
+ * call is the {@code MethodHandle} which becomes the
+ * permanent binding for the dynamic call site.
+ * That method handle's type must be exactly equal to the type
+ * derived from the dynamic call site signature and passed to
+ * the bootstrap method.
+ * + * After resolution, the linkage process may fail in a variety of ways. + * All failures are reported by an {@link java.dyn.InvokeDynamicBootstrapError InvokeDynamicBootstrapError}, + * which is thrown as the abnormal termination of the dynamic call + * site execution. + * The following circumstances will cause this: + *
+ * If there are several such threads, the JVM picks one thread + * and runs the bootstrap method while the others wait for the + * invocation to terminate normally or abnormally. + *
+ * After a bootstrap method is called and a method handle target + * successfully extracted, the JVM attempts to link the instruction + * being executed to the target method handle. + * This may fail if there has been intervening linkage + * or invalidation event for the same instruction. + * If such a failure occurs, the dynamic call site must be + * re-executed from the beginning, either re-linking it + * (if it has been invalidated) or invoking the target + * (if it the instruction has been linked by some other means). + *
+ * If the instruction is linked successfully, the target method + * handle is invoked to complete the instruction execution. + * The state of linkage continues until the method containing the + * dynamic call site is garbage collected, or the dynamic call site + * is invalidated by an explicit request, + * such as {@link java.dyn.Linkage#invalidateCallerClass Linkage.invalidateCallerClass}. + *
+ * In an application which requires dynamic call sites with individually + * mutable behaviors, their bootstrap methods should produce distinct + * {@link java.dyn.CallSite CallSite} objects, one for each linkage request. + *
+ * If a class containing {@code invokedynamic} instructions + * is {@linkplain java.dyn.Linkage#invalidateCallerClass(Class) invalidated}, + * subsequent execution of those {@code invokedynamic} instructions + * will require linking. + * It is as if they had never been executed in the first place. + * (However, invalidation does not cause constant pool entries to be + * resolved a second time.) + *
+ * Invalidation events and bootstrap method calls for a particular + * dynamic call site are globally ordered relative to each other. + * When an invokedynamic instruction is invalidated, if there is + * simultaneously a bootstrap method invocation in process + * (in the same thread or a different thread), the result + * eventually returned must not be used to link the call site. + * Put another way, when a call site is invalidated, its + * subsequent linkage (if any) must be performed by a bootstrap method + * call initiated after the invalidation occurred. + *
+ * If several threads simultaneously execute a bootstrap method for a single dynamic + * call site, the JVM must choose one target object and installs it visibly to + * all threads. Any other bootstrap method calls are allowed to complete, but their + * results are ignored, and their dynamic call site invocations proceed with the originally + * chosen target object. + *
+ * The JVM is free to duplicate dynamic call sites. + * This means that, even if a class contains just one {@code invokedynamic} + * instruction, its bootstrap method may be executed several times, + * once for each duplicate. Thus, bootstrap method code should not + * assume an exclusive one-to-one correspondence between particular occurrences + * of {@code invokedynamic} bytecodes in class files and linkage events. + *
+ * In principle, each individual execution of an {@code invokedynamic}
+ * instruction could be deemed (by a conforming implementation) to be a separate
+ * duplicate, requiring its own execution of the bootstrap method.
+ * However, implementations are expected to perform code duplication
+ * (if at all) in order to improve performance, not make it worse.
+ *
* @author John Rose, JSR 292 EG
*/
diff --git a/jdk/src/share/classes/sun/dyn/CallSiteImpl.java b/jdk/src/share/classes/sun/dyn/CallSiteImpl.java
index 2e02e74ebd0..90d004b6b1a 100644
--- a/jdk/src/share/classes/sun/dyn/CallSiteImpl.java
+++ b/jdk/src/share/classes/sun/dyn/CallSiteImpl.java
@@ -49,18 +49,21 @@ public class CallSiteImpl {
}
CallSite site;
try {
- if (bootstrapMethod.type().parameterCount() == 3)
- site = bootstrapMethod.