1.1 --- a/rt/emul/compact/src/main/java/java/lang/invoke/CallSite.java Sun Aug 17 20:09:05 2014 +0200
1.2 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000
1.3 @@ -1,339 +0,0 @@
1.4 -/*
1.5 - * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
1.6 - * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 - *
1.8 - * This code is free software; you can redistribute it and/or modify it
1.9 - * under the terms of the GNU General Public License version 2 only, as
1.10 - * published by the Free Software Foundation. Oracle designates this
1.11 - * particular file as subject to the "Classpath" exception as provided
1.12 - * by Oracle in the LICENSE file that accompanied this code.
1.13 - *
1.14 - * This code is distributed in the hope that it will be useful, but WITHOUT
1.15 - * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.16 - * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.17 - * version 2 for more details (a copy is included in the LICENSE file that
1.18 - * accompanied this code).
1.19 - *
1.20 - * You should have received a copy of the GNU General Public License version
1.21 - * 2 along with this work; if not, write to the Free Software Foundation,
1.22 - * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.23 - *
1.24 - * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.25 - * or visit www.oracle.com if you need additional information or have any
1.26 - * questions.
1.27 - */
1.28 -
1.29 -package java.lang.invoke;
1.30 -
1.31 -import sun.invoke.empty.Empty;
1.32 -import static java.lang.invoke.MethodHandleStatics.*;
1.33 -import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
1.34 -
1.35 -/**
1.36 - * A {@code CallSite} is a holder for a variable {@link MethodHandle},
1.37 - * which is called its {@code target}.
1.38 - * An {@code invokedynamic} instruction linked to a {@code CallSite} delegates
1.39 - * all calls to the site's current target.
1.40 - * A {@code CallSite} may be associated with several {@code invokedynamic}
1.41 - * instructions, or it may be "free floating", associated with none.
1.42 - * In any case, it may be invoked through an associated method handle
1.43 - * called its {@linkplain #dynamicInvoker dynamic invoker}.
1.44 - * <p>
1.45 - * {@code CallSite} is an abstract class which does not allow
1.46 - * direct subclassing by users. It has three immediate,
1.47 - * concrete subclasses that may be either instantiated or subclassed.
1.48 - * <ul>
1.49 - * <li>If a mutable target is not required, an {@code invokedynamic} instruction
1.50 - * may be permanently bound by means of a {@linkplain ConstantCallSite constant call site}.
1.51 - * <li>If a mutable target is required which has volatile variable semantics,
1.52 - * because updates to the target must be immediately and reliably witnessed by other threads,
1.53 - * a {@linkplain VolatileCallSite volatile call site} may be used.
1.54 - * <li>Otherwise, if a mutable target is required,
1.55 - * a {@linkplain MutableCallSite mutable call site} may be used.
1.56 - * </ul>
1.57 - * <p>
1.58 - * A non-constant call site may be <em>relinked</em> by changing its target.
1.59 - * The new target must have the same {@linkplain MethodHandle#type() type}
1.60 - * as the previous target.
1.61 - * Thus, though a call site can be relinked to a series of
1.62 - * successive targets, it cannot change its type.
1.63 - * <p>
1.64 - * Here is a sample use of call sites and bootstrap methods which links every
1.65 - * dynamic call site to print its arguments:
1.66 -<blockquote><pre>{@code
1.67 -static void test() throws Throwable {
1.68 - // THE FOLLOWING LINE IS PSEUDOCODE FOR A JVM INSTRUCTION
1.69 - InvokeDynamic[#bootstrapDynamic].baz("baz arg", 2, 3.14);
1.70 -}
1.71 -private static void printArgs(Object... args) {
1.72 - System.out.println(java.util.Arrays.deepToString(args));
1.73 -}
1.74 -private static final MethodHandle printArgs;
1.75 -static {
1.76 - MethodHandles.Lookup lookup = MethodHandles.lookup();
1.77 - Class thisClass = lookup.lookupClass(); // (who am I?)
1.78 - printArgs = lookup.findStatic(thisClass,
1.79 - "printArgs", MethodType.methodType(void.class, Object[].class));
1.80 -}
1.81 -private static CallSite bootstrapDynamic(MethodHandles.Lookup caller, String name, MethodType type) {
1.82 - // ignore caller and name, but match the type:
1.83 - return new ConstantCallSite(printArgs.asType(type));
1.84 -}
1.85 -}</pre></blockquote>
1.86 - * @author John Rose, JSR 292 EG
1.87 - */
1.88 -abstract
1.89 -public class CallSite {
1.90 - static { MethodHandleImpl.initStatics(); }
1.91 -
1.92 - // The actual payload of this call site:
1.93 - /*package-private*/
1.94 - MethodHandle target; // Note: This field is known to the JVM. Do not change.
1.95 -
1.96 - /**
1.97 - * Make a blank call site object with the given method type.
1.98 - * An initial target method is supplied which will throw
1.99 - * an {@link IllegalStateException} if called.
1.100 - * <p>
1.101 - * Before this {@code CallSite} object is returned from a bootstrap method,
1.102 - * it is usually provided with a more useful target method,
1.103 - * via a call to {@link CallSite#setTarget(MethodHandle) setTarget}.
1.104 - * @throws NullPointerException if the proposed type is null
1.105 - */
1.106 - /*package-private*/
1.107 - CallSite(MethodType type) {
1.108 - target = type.invokers().uninitializedCallSite();
1.109 - }
1.110 -
1.111 - /**
1.112 - * Make a call site object equipped with an initial target method handle.
1.113 - * @param target the method handle which will be the initial target of the call site
1.114 - * @throws NullPointerException if the proposed target is null
1.115 - */
1.116 - /*package-private*/
1.117 - CallSite(MethodHandle target) {
1.118 - target.type(); // null check
1.119 - this.target = target;
1.120 - }
1.121 -
1.122 - /**
1.123 - * Make a call site object equipped with an initial target method handle.
1.124 - * @param targetType the desired type of the call site
1.125 - * @param createTargetHook a hook which will bind the call site to the target method handle
1.126 - * @throws WrongMethodTypeException if the hook cannot be invoked on the required arguments,
1.127 - * or if the target returned by the hook is not of the given {@code targetType}
1.128 - * @throws NullPointerException if the hook returns a null value
1.129 - * @throws ClassCastException if the hook returns something other than a {@code MethodHandle}
1.130 - * @throws Throwable anything else thrown by the hook function
1.131 - */
1.132 - /*package-private*/
1.133 - CallSite(MethodType targetType, MethodHandle createTargetHook) throws Throwable {
1.134 - this(targetType);
1.135 - ConstantCallSite selfCCS = (ConstantCallSite) this;
1.136 - MethodHandle boundTarget = (MethodHandle) createTargetHook.invokeWithArguments(selfCCS);
1.137 - checkTargetChange(this.target, boundTarget);
1.138 - this.target = boundTarget;
1.139 - }
1.140 -
1.141 - /**
1.142 - * Returns the type of this call site's target.
1.143 - * Although targets may change, any call site's type is permanent, and can never change to an unequal type.
1.144 - * The {@code setTarget} method enforces this invariant by refusing any new target that does
1.145 - * not have the previous target's type.
1.146 - * @return the type of the current target, which is also the type of any future target
1.147 - */
1.148 - public MethodType type() {
1.149 - // warning: do not call getTarget here, because CCS.getTarget can throw IllegalStateException
1.150 - return target.type();
1.151 - }
1.152 -
1.153 - /**
1.154 - * Returns the target method of the call site, according to the
1.155 - * behavior defined by this call site's specific class.
1.156 - * The immediate subclasses of {@code CallSite} document the
1.157 - * class-specific behaviors of this method.
1.158 - *
1.159 - * @return the current linkage state of the call site, its target method handle
1.160 - * @see ConstantCallSite
1.161 - * @see VolatileCallSite
1.162 - * @see #setTarget
1.163 - * @see ConstantCallSite#getTarget
1.164 - * @see MutableCallSite#getTarget
1.165 - * @see VolatileCallSite#getTarget
1.166 - */
1.167 - public abstract MethodHandle getTarget();
1.168 -
1.169 - /**
1.170 - * Updates the target method of this call site, according to the
1.171 - * behavior defined by this call site's specific class.
1.172 - * The immediate subclasses of {@code CallSite} document the
1.173 - * class-specific behaviors of this method.
1.174 - * <p>
1.175 - * The type of the new target must be {@linkplain MethodType#equals equal to}
1.176 - * the type of the old target.
1.177 - *
1.178 - * @param newTarget the new target
1.179 - * @throws NullPointerException if the proposed new target is null
1.180 - * @throws WrongMethodTypeException if the proposed new target
1.181 - * has a method type that differs from the previous target
1.182 - * @see CallSite#getTarget
1.183 - * @see ConstantCallSite#setTarget
1.184 - * @see MutableCallSite#setTarget
1.185 - * @see VolatileCallSite#setTarget
1.186 - */
1.187 - public abstract void setTarget(MethodHandle newTarget);
1.188 -
1.189 - void checkTargetChange(MethodHandle oldTarget, MethodHandle newTarget) {
1.190 - MethodType oldType = oldTarget.type();
1.191 - MethodType newType = newTarget.type(); // null check!
1.192 - if (!newType.equals(oldType))
1.193 - throw wrongTargetType(newTarget, oldType);
1.194 - }
1.195 -
1.196 - private static WrongMethodTypeException wrongTargetType(MethodHandle target, MethodType type) {
1.197 - return new WrongMethodTypeException(String.valueOf(target)+" should be of type "+type);
1.198 - }
1.199 -
1.200 - /**
1.201 - * Produces a method handle equivalent to an invokedynamic instruction
1.202 - * which has been linked to this call site.
1.203 - * <p>
1.204 - * This method is equivalent to the following code:
1.205 - * <blockquote><pre>{@code
1.206 - * MethodHandle getTarget, invoker, result;
1.207 - * getTarget = MethodHandles.publicLookup().bind(this, "getTarget", MethodType.methodType(MethodHandle.class));
1.208 - * invoker = MethodHandles.exactInvoker(this.type());
1.209 - * result = MethodHandles.foldArguments(invoker, getTarget)
1.210 - * }</pre></blockquote>
1.211 - *
1.212 - * @return a method handle which always invokes this call site's current target
1.213 - */
1.214 - public abstract MethodHandle dynamicInvoker();
1.215 -
1.216 - /*non-public*/ MethodHandle makeDynamicInvoker() {
1.217 - MethodHandle getTarget = GET_TARGET.bindReceiver(this);
1.218 - MethodHandle invoker = MethodHandles.exactInvoker(this.type());
1.219 - return MethodHandles.foldArguments(invoker, getTarget);
1.220 - }
1.221 -
1.222 - private static final MethodHandle GET_TARGET;
1.223 - static {
1.224 - try {
1.225 - GET_TARGET = IMPL_LOOKUP.
1.226 - findVirtual(CallSite.class, "getTarget", MethodType.methodType(MethodHandle.class));
1.227 - } catch (ReflectiveOperationException e) {
1.228 - throw newInternalError(e);
1.229 - }
1.230 - }
1.231 -
1.232 - /** This guy is rolled into the default target if a MethodType is supplied to the constructor. */
1.233 - /*package-private*/
1.234 - static Empty uninitializedCallSite() {
1.235 - throw new IllegalStateException("uninitialized call site");
1.236 - }
1.237 -
1.238 - /*package-private*/
1.239 - void setTargetNormal(MethodHandle newTarget) {
1.240 - MethodHandleNatives.setCallSiteTargetNormal(this, newTarget);
1.241 - }
1.242 - /*package-private*/
1.243 - MethodHandle getTargetVolatile() {
1.244 - return target;
1.245 - }
1.246 - /*package-private*/
1.247 - void setTargetVolatile(MethodHandle newTarget) {
1.248 - MethodHandleNatives.setCallSiteTargetVolatile(this, newTarget);
1.249 - }
1.250 -
1.251 - // this implements the upcall from the JVM, MethodHandleNatives.makeDynamicCallSite:
1.252 - static CallSite makeSite(MethodHandle bootstrapMethod,
1.253 - // Callee information:
1.254 - String name, MethodType type,
1.255 - // Extra arguments for BSM, if any:
1.256 - Object info,
1.257 - // Caller information:
1.258 - Class<?> callerClass) {
1.259 - MethodHandles.Lookup caller = IMPL_LOOKUP.in(callerClass);
1.260 - CallSite site;
1.261 - try {
1.262 - Object binding;
1.263 - info = maybeReBox(info);
1.264 - if (info == null) {
1.265 - binding = bootstrapMethod.invoke(caller, name, type);
1.266 - } else if (!info.getClass().isArray()) {
1.267 - binding = bootstrapMethod.invoke(caller, name, type, info);
1.268 - } else {
1.269 - Object[] argv = (Object[]) info;
1.270 - maybeReBoxElements(argv);
1.271 - switch (argv.length) {
1.272 - case 0:
1.273 - binding = bootstrapMethod.invoke(caller, name, type);
1.274 - break;
1.275 - case 1:
1.276 - binding = bootstrapMethod.invoke(caller, name, type,
1.277 - argv[0]);
1.278 - break;
1.279 - case 2:
1.280 - binding = bootstrapMethod.invoke(caller, name, type,
1.281 - argv[0], argv[1]);
1.282 - break;
1.283 - case 3:
1.284 - binding = bootstrapMethod.invoke(caller, name, type,
1.285 - argv[0], argv[1], argv[2]);
1.286 - break;
1.287 - case 4:
1.288 - binding = bootstrapMethod.invoke(caller, name, type,
1.289 - argv[0], argv[1], argv[2], argv[3]);
1.290 - break;
1.291 - case 5:
1.292 - binding = bootstrapMethod.invoke(caller, name, type,
1.293 - argv[0], argv[1], argv[2], argv[3], argv[4]);
1.294 - break;
1.295 - case 6:
1.296 - binding = bootstrapMethod.invoke(caller, name, type,
1.297 - argv[0], argv[1], argv[2], argv[3], argv[4], argv[5]);
1.298 - break;
1.299 - default:
1.300 - final int NON_SPREAD_ARG_COUNT = 3; // (caller, name, type)
1.301 - if (NON_SPREAD_ARG_COUNT + argv.length > MethodType.MAX_MH_ARITY)
1.302 - throw new BootstrapMethodError("too many bootstrap method arguments");
1.303 - MethodType bsmType = bootstrapMethod.type();
1.304 - MethodType invocationType = MethodType.genericMethodType(NON_SPREAD_ARG_COUNT + argv.length);
1.305 - MethodHandle typedBSM = bootstrapMethod.asType(invocationType);
1.306 - MethodHandle spreader = invocationType.invokers().spreadInvoker(NON_SPREAD_ARG_COUNT);
1.307 - binding = spreader.invokeExact(typedBSM, (Object)caller, (Object)name, (Object)type, argv);
1.308 - }
1.309 - }
1.310 - //System.out.println("BSM for "+name+type+" => "+binding);
1.311 - if (binding instanceof CallSite) {
1.312 - site = (CallSite) binding;
1.313 - } else {
1.314 - throw new ClassCastException("bootstrap method failed to produce a CallSite");
1.315 - }
1.316 - if (!site.getTarget().type().equals(type))
1.317 - throw new WrongMethodTypeException("wrong type: "+site.getTarget());
1.318 - } catch (Throwable ex) {
1.319 - BootstrapMethodError bex;
1.320 - if (ex instanceof BootstrapMethodError)
1.321 - bex = (BootstrapMethodError) ex;
1.322 - else
1.323 - bex = new BootstrapMethodError("call site initialization exception", ex);
1.324 - throw bex;
1.325 - }
1.326 - return site;
1.327 - }
1.328 -
1.329 - private static Object maybeReBox(Object x) {
1.330 - if (x instanceof Integer) {
1.331 - int xi = (int) x;
1.332 - if (xi == (byte) xi)
1.333 - x = xi; // must rebox; see JLS 5.1.7
1.334 - }
1.335 - return x;
1.336 - }
1.337 - private static void maybeReBoxElements(Object[] xa) {
1.338 - for (int i = 0; i < xa.length; i++) {
1.339 - xa[i] = maybeReBox(xa[i]);
1.340 - }
1.341 - }
1.342 -}