1 /*
2 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package jdk.nashorn.internal.runtime.linker;
27
28 import static jdk.nashorn.internal.codegen.CompilerConstants.staticCallNoLookup;
29
30 import java.lang.invoke.CallSite;
31 import java.lang.invoke.MethodHandle;
32 import java.lang.invoke.MethodHandles;
33 import java.lang.invoke.MethodHandles.Lookup;
34 import java.lang.invoke.MethodType;
35 import jdk.internal.dynalink.CallSiteDescriptor;
36 import jdk.internal.dynalink.DynamicLinker;
37 import jdk.internal.dynalink.DynamicLinkerFactory;
38 import jdk.internal.dynalink.beans.BeansLinker;
39 import jdk.internal.dynalink.linker.GuardedInvocation;
40 import jdk.internal.dynalink.linker.LinkerServices;
41 import jdk.nashorn.internal.codegen.CompilerConstants.Call;
42 import jdk.nashorn.internal.codegen.RuntimeCallSite;
43 import jdk.nashorn.internal.runtime.options.Options;
44
45 /**
46 * This class houses bootstrap method for invokedynamic instructions generated by compiler.
47 */
48 public final class Bootstrap {
49 /** Reference to the seed boostrap function */
50 public static final Call BOOTSTRAP = staticCallNoLookup(Bootstrap.class, "bootstrap", CallSite.class, Lookup.class, String.class, MethodType.class, int.class);
51
52 // do not create me!!
53 private Bootstrap() {
54 }
55
56 private static final DynamicLinker dynamicLinker;
57 static {
58 final DynamicLinkerFactory factory = new DynamicLinkerFactory();
59 factory.setPrioritizedLinkers(new NashornLinker(), new NashornPrimitiveLinker(), new NashornStaticClassLinker(),
60 new JSObjectLinker(), new ReflectionCheckLinker());
61 factory.setFallbackLinkers(new BeansLinker(), new NashornBottomLinker());
62 factory.setSyncOnRelink(true);
63 final int relinkThreshold = Options.getIntProperty("nashorn.unstable.relink.threshold", -1);
64 if (relinkThreshold > -1) {
65 factory.setUnstableRelinkThreshold(relinkThreshold);
66 }
67 dynamicLinker = factory.createLinker();
68 }
69
70 /**
71 * Create a call site and link it for Nashorn. This version of the method conforms to the invokedynamic bootstrap
72 * method expected signature and is referenced from Nashorn generated bytecode as the bootstrap method for all
73 * invokedynamic instructions.
74 * @param lookup MethodHandle lookup. Ignored as Nashorn only uses public lookup.
75 * @param opDesc Dynalink dynamic operation descriptor.
76 * @param type Method type.
77 * @param flags flags for call type, trace/profile etc.
78 * @return CallSite with MethodHandle to appropriate method or null if not found.
79 */
80 public static CallSite bootstrap(final Lookup lookup, final String opDesc, final MethodType type, final int flags) {
81 return dynamicLinker.link(LinkerCallSite.newLinkerCallSite(opDesc, type, flags));
82 }
83
84 /**
85 * Bootstrapper for a specialized Runtime call
86 *
87 * @param lookup lookup
88 * @param initialName initial name for callsite
89 * @param type method type for call site
90 *
91 * @return callsite for a runtime node
92 */
93 public static CallSite runtimeBootstrap(final MethodHandles.Lookup lookup, final String initialName, final MethodType type) {
94 return new RuntimeCallSite(type, initialName);
95 }
96
97
98 /**
99 * Returns a dynamic invoker for a specified dynamic operation. You can use this method to create a method handle
100 * that when invoked acts completely as if it were a Nashorn-linked call site. An overview of available dynamic
101 * operations can be found in the <a href="https://github.com/szegedi/dynalink/wiki/User-Guide-0.4">Dynalink User Guide</a>,
102 * but we'll show few examples here:
103 * <ul>
104 * <li>Get a named property with fixed name:
105 * <pre>
106 * MethodHandle getColor = Boostrap.createDynamicInvoker("dyn:getProp:color", Object.class, Object.class);
107 * Object obj = ...; // somehow obtain the object
108 * Object color = getColor.invokeExact(obj);
109 * </pre>
110 * </li>
111 * <li>Get a named property with variable name:
112 * <pre>
113 * MethodHandle getProperty = Boostrap.createDynamicInvoker("dyn:getElem", Object.class, Object.class, String.class);
114 * Object obj = ...; // somehow obtain the object
115 * Object color = getProperty.invokeExact(obj, "color");
116 * Object shape = getProperty.invokeExact(obj, "shape");
117 * MethodHandle getNumProperty = Boostrap.createDynamicInvoker("dyn:getElem", Object.class, Object.class, int.class);
118 * Object elem42 = getNumProperty.invokeExact(obj, 42);
119 * </pre>
120 * </li>
121 * <li>Set a named property with fixed name:
122 * <pre>
123 * MethodHandle setColor = Boostrap.createDynamicInvoker("dyn:setProp:color", void.class, Object.class, Object.class);
124 * Object obj = ...; // somehow obtain the object
125 * setColor.invokeExact(obj, Color.BLUE);
126 * </pre>
127 * </li>
128 * <li>Set a property with variable name:
129 * <pre>
130 * MethodHandle setProperty = Boostrap.createDynamicInvoker("dyn:setElem", void.class, Object.class, String.class, Object.class);
131 * Object obj = ...; // somehow obtain the object
132 * setProperty.invokeExact(obj, "color", Color.BLUE);
133 * setProperty.invokeExact(obj, "shape", Shape.CIRCLE);
134 * </pre>
135 * </li>
136 * <li>Call a function on an object; two-step variant. This is the actual variant used by Nashorn-generated code:
137 * <pre>
138 * MethodHandle findFooFunction = Boostrap.createDynamicInvoker("dyn:getMethod:foo", Object.class, Object.class);
139 * Object obj = ...; // somehow obtain the object
140 * Object foo_fn = findFooFunction.invokeExact(obj);
141 * MethodHandle callFunctionWithTwoArgs = Boostrap.createDynamicInvoker("dyn:call", Object.class, Object.class, Object.class, Object.class, Object.class);
142 * // Note: "call" operation takes a function, then a "this" value, then the arguments:
143 * Object foo_retval = callFunctionWithTwoArgs.invokeExact(foo_fn, obj, arg1, arg2);
144 * </pre>
145 * </li>
146 * <li>Call a function on an object; single-step variant. Although Nashorn doesn't use this variant and never
147 * emits any INVOKEDYNAMIC instructions with {@code dyn:getMethod}, it still supports this standard Dynalink
148 * operation:
149 * <pre>
150 * MethodHandle callFunctionFooWithTwoArgs = Boostrap.createDynamicInvoker("dyn:callMethod:foo", Object.class, Object.class, Object.class, Object.class);
151 * Object obj = ...; // somehow obtain the object
152 * Object foo_retval = callFunctionFooWithTwoArgs.invokeExact(obj, arg1, arg2);
153 * </pre>
154 * </li>
155 * </ul>
156 * Few additional remarks:
157 * <ul>
158 * <li>Just as Nashorn works with any Java object, the invokers returned from this method can also be applied to
159 * arbitrary Java objects in addition to Nashorn JavaScript objects.</li>
160 * <li>For invoking a named function on an object, you can also use the {@link InvokeByName} convenience class.</li>
161 * <li>For Nashorn objects {@code getElem}, {@code getProp}, and {@code getMethod} are handled almost identically,
162 * since JavaScript doesn't distinguish between different kinds of properties on an object. Either can be used with
163 * fixed property name or a variable property name. The only significant difference is handling of missing
164 * properties: {@code getMethod} for a missing member will link to a potential invocation of
165 * {@code __noSuchMethod__} on the object, {@code getProp} for a missing member will link to a potential invocation
166 * of {@code __noSuchProperty__}, while {@code getElem} for a missing member will link to an empty getter.</li>
167 * <li>In similar vein, {@code setElem} and {@code setProp} are handled identically on Nashorn objects.</li>
168 * <li>There's no rule that the variable property identifier has to be a {@code String} for {@code getProp/setProp}
169 * and {@code int} for {@code getElem/setElem}. You can declare their type to be {@code int}, {@code double},
170 * {@code Object}, and so on regardless of the kind of the operation.</li>
171 * <li>You can be as specific in parameter types as you want. E.g. if you know that the receiver of the operation
172 * will always be {@code ScriptObject}, you can pass {@code ScriptObject.class} as its parameter type. If you happen
173 * to link to a method that expects different types, (you can use these invokers on POJOs too, after all, and end up
174 * linking with their methods that have strongly-typed signatures), all necessary conversions allowed by either Java
175 * or JavaScript will be applied: if invoked methods specify either primitive or wrapped Java numeric types, or
176 * {@code String} or {@code boolean/Boolean}, then the parameters might be subjected to standard ECMAScript
177 * {@code ToNumber}, {@code ToString}, and {@code ToBoolean} conversion, respectively. Less obviously, if the
178 * expected parameter type is a SAM type, and you pass a JavaScript function, a proxy object implementing the SAM
179 * type and delegating to the function will be passed. Linkage can often be optimized when linkers have more
180 * specific type information than "everything can be an object".</li>
181 * <li>You can also be as specific in return types as you want. For return types any necessary type conversion
182 * available in either Java or JavaScript will be automatically applied, similar to the process described for
183 * parameters, only in reverse direction: if you specify any either primitive or wrapped Java numeric type, or
184 * {@code String} or {@code boolean/Boolean}, then the return values will be subjected to standard ECMAScript
185 * {@code ToNumber}, {@code ToString}, and {@code ToBoolean} conversion, respectively. Less obviously, if the return
186 * type is a SAM type, and the return value is a JavaScript function, a proxy object implementing the SAM type and
187 * delegating to the function will be returned.</li>
188 * </ul>
189 * @param opDesc Dynalink dynamic operation descriptor.
190 * @param rtype the return type for the operation
191 * @param ptypes the parameter types for the operation
192 * @return MethodHandle for invoking the operation.
193 */
194 public static MethodHandle createDynamicInvoker(final String opDesc, final Class<?> rtype, final Class<?>... ptypes) {
195 return createDynamicInvoker(opDesc, MethodType.methodType(rtype, ptypes));
196 }
197
198 /**
199 * Returns a dynamic invoker for a specified dynamic operation. Similar to
200 * {@link #createDynamicInvoker(String, Class, Class...)} but with return and parameter types composed into a
201 * method type in the signature. See the discussion of that method for details.
202 * @param opDesc Dynalink dynamic operation descriptor.
203 * @param type the method type for the operation
204 * @return MethodHandle for invoking the operation.
205 */
206 public static MethodHandle createDynamicInvoker(final String opDesc, final MethodType type) {
207 return bootstrap(null, opDesc, type, 0).dynamicInvoker();
208 }
209
210 /**
211 * Returns the Nashorn's internally used dynamic linker's services object. Note that in code that is processing a
212 * linking request, you will normally use the {@code LinkerServices} object passed by whatever top-level linker
213 * invoked the linking (if the call site is in Nashorn-generated code, you'll get this object anyway). You should
214 * only resort to retrieving a linker services object using this method when you need some linker services (e.g.
215 * type converter method handles) outside of a code path that is linking a call site.
216 * @return Nashorn's internal dynamic linker's services object.
217 */
218 public static LinkerServices getLinkerServices() {
219 return dynamicLinker.getLinkerServices();
220 }
221
222 /**
223 * Takes a guarded invocation, and ensures its method and guard conform to the type of the call descriptor, using
224 * all type conversions allowed by the linker's services. This method is used by Nashorn's linkers as a last step
225 * before returning guarded invocations to the callers. Most of the code used to produce the guarded invocations
226 * does not make an effort to coordinate types of the methods, and so a final type adjustment before a guarded
227 * invocation is returned is the responsibility of the linkers themselves.
228 * @param inv the guarded invocation that needs to be type-converted. Can be null.
229 * @param linkerServices the linker services object providing the type conversions.
230 * @param desc the call site descriptor to whose method type the invocation needs to conform.
231 * @return the type-converted guarded invocation. If input is null, null is returned. If the input invocation
232 * already conforms to the requested type, it is returned unchanged.
233 */
234 static GuardedInvocation asType(final GuardedInvocation inv, final LinkerServices linkerServices, final CallSiteDescriptor desc) {
235 return inv == null ? null : inv.asType(linkerServices, desc.getMethodType());
236 }
237 }
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