JDK8/Java8源码在线阅读
/*
* Copyright (c) 2008, 2013, 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
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package java.lang.invoke;
import java.lang.reflect.Array;
import java.util.Arrays;
import static java.lang.invoke.MethodHandleStatics.*;
import static java.lang.invoke.MethodHandleNatives.Constants.*;
import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
import static java.lang.invoke.LambdaForm.*;
/**
* Construction and caching of often-used invokers.
* @author jrose
*/
class Invokers {
// exact type (sans leading taget MH) for the outgoing call
private final MethodType targetType;
// Cached adapter information:
private final @Stable MethodHandle[] invokers = new MethodHandle[INV_LIMIT];
// Indexes into invokers:
static final int
INV_EXACT = 0, // MethodHandles.exactInvoker
INV_GENERIC = 1, // MethodHandles.invoker (generic invocation)
INV_BASIC = 2, // MethodHandles.basicInvoker
INV_LIMIT = 3;
/** Compute and cache information common to all collecting adapters
* that implement members of the erasure-family of the given erased type.
*/
/*non-public*/ Invokers(MethodType targetType) {
this.targetType = targetType;
}
/*non-public*/ MethodHandle exactInvoker() {
MethodHandle invoker = cachedInvoker(INV_EXACT);
if (invoker != null) return invoker;
invoker = makeExactOrGeneralInvoker(true);
return setCachedInvoker(INV_EXACT, invoker);
}
/*non-public*/ MethodHandle genericInvoker() {
MethodHandle invoker = cachedInvoker(INV_GENERIC);
if (invoker != null) return invoker;
invoker = makeExactOrGeneralInvoker(false);
return setCachedInvoker(INV_GENERIC, invoker);
}
/*non-public*/ MethodHandle basicInvoker() {
MethodHandle invoker = cachedInvoker(INV_BASIC);
if (invoker != null) return invoker;
MethodType basicType = targetType.basicType();
if (basicType != targetType) {
// double cache; not used significantly
return setCachedInvoker(INV_BASIC, basicType.invokers().basicInvoker());
}
invoker = basicType.form().cachedMethodHandle(MethodTypeForm.MH_BASIC_INV);
if (invoker == null) {
MemberName method = invokeBasicMethod(basicType);
invoker = DirectMethodHandle.make(method);
assert(checkInvoker(invoker));
invoker = basicType.form().setCachedMethodHandle(MethodTypeForm.MH_BASIC_INV, invoker);
}
return setCachedInvoker(INV_BASIC, invoker);
}
private MethodHandle cachedInvoker(int idx) {
return invokers[idx];
}
private synchronized MethodHandle setCachedInvoker(int idx, final MethodHandle invoker) {
// Simulate a CAS, to avoid racy duplication of results.
MethodHandle prev = invokers[idx];
if (prev != null) return prev;
return invokers[idx] = invoker;
}
private MethodHandle makeExactOrGeneralInvoker(boolean isExact) {
MethodType mtype = targetType;
MethodType invokerType = mtype.invokerType();
int which = (isExact ? MethodTypeForm.LF_EX_INVOKER : MethodTypeForm.LF_GEN_INVOKER);
LambdaForm lform = invokeHandleForm(mtype, false, which);
MethodHandle invoker = BoundMethodHandle.bindSingle(invokerType, lform, mtype);
String whichName = (isExact ? "invokeExact" : "invoke");
invoker = invoker.withInternalMemberName(MemberName.makeMethodHandleInvoke(whichName, mtype), false);
assert(checkInvoker(invoker));
maybeCompileToBytecode(invoker);
return invoker;
}
/** If the target type seems to be common enough, eagerly compile the invoker to bytecodes. */
private void maybeCompileToBytecode(MethodHandle invoker) {
final int EAGER_COMPILE_ARITY_LIMIT = 10;
if (targetType == targetType.erase() &&
targetType.parameterCount() < EAGER_COMPILE_ARITY_LIMIT) {
invoker.form.compileToBytecode();
}
}
// This next one is called from LambdaForm.NamedFunction.<init>.
/*non-public*/ static MemberName invokeBasicMethod(MethodType basicType) {
assert(basicType == basicType.basicType());
try {
//Lookup.findVirtual(MethodHandle.class, name, type);
return IMPL_LOOKUP.resolveOrFail(REF_invokeVirtual, MethodHandle.class, "invokeBasic", basicType);
} catch (ReflectiveOperationException ex) {
throw newInternalError("JVM cannot find invoker for "+basicType, ex);
}
}
private boolean checkInvoker(MethodHandle invoker) {
assert(targetType.invokerType().equals(invoker.type()))
: java.util.Arrays.asList(targetType, targetType.invokerType(), invoker);
assert(invoker.internalMemberName() == null ||
invoker.internalMemberName().getMethodType().equals(targetType));
assert(!invoker.isVarargsCollector());
return true;
}
/**
* Find or create an invoker which passes unchanged a given number of arguments
* and spreads the rest from a trailing array argument.
* The invoker target type is the post-spread type {@code (TYPEOF(uarg*), TYPEOF(sarg*))=>RT}.
* All the {@code sarg}s must have a common type {@code C}. (If there are none, {@code Object} is assumed.}
* @param leadingArgCount the number of unchanged (non-spread) arguments
* @return {@code invoker.invokeExact(mh, uarg*, C[]{sarg*}) := (RT)mh.invoke(uarg*, sarg*)}
*/
/*non-public*/ MethodHandle spreadInvoker(int leadingArgCount) {
int spreadArgCount = targetType.parameterCount() - leadingArgCount;
MethodType postSpreadType = targetType;
Class<?> argArrayType = impliedRestargType(postSpreadType, leadingArgCount);
if (postSpreadType.parameterSlotCount() <= MethodType.MAX_MH_INVOKER_ARITY) {
return genericInvoker().asSpreader(argArrayType, spreadArgCount);
}
// Cannot build a generic invoker here of type ginvoker.invoke(mh, a*[254]).
// Instead, factor sinvoker.invoke(mh, a) into ainvoker.invoke(filter(mh), a)
// where filter(mh) == mh.asSpreader(Object[], spreadArgCount)
MethodType preSpreadType = postSpreadType
.replaceParameterTypes(leadingArgCount, postSpreadType.parameterCount(), argArrayType);
MethodHandle arrayInvoker = MethodHandles.invoker(preSpreadType);
MethodHandle makeSpreader = MethodHandles.insertArguments(Lazy.MH_asSpreader, 1, argArrayType, spreadArgCount);
return MethodHandles.filterArgument(arrayInvoker, 0, makeSpreader);
}
private static Class<?> impliedRestargType(MethodType restargType, int fromPos) {
if (restargType.isGeneric()) return Object[].class; // can be nothing else
int maxPos = restargType.parameterCount();
if (fromPos >= maxPos) return Object[].class; // reasonable default
Class<?> argType = restargType.parameterType(fromPos);
for (int i = fromPos+1; i < maxPos; i++) {
if (argType != restargType.parameterType(i))
throw newIllegalArgumentException("need homogeneous rest arguments", restargType);
}
if (argType == Object.class) return Object[].class;
return Array.newInstance(argType, 0).getClass();
}
public String toString() {
return "Invokers"+targetType;
}
static MemberName methodHandleInvokeLinkerMethod(String name,
MethodType mtype,
Object[] appendixResult) {
int which;
switch (name) {
case "invokeExact": which = MethodTypeForm.LF_EX_LINKER; break;
case "invoke": which = MethodTypeForm.LF_GEN_LINKER; break;
default: throw new InternalError("not invoker: "+name);
}
LambdaForm lform;
if (mtype.parameterSlotCount() <= MethodType.MAX_MH_ARITY - MH_LINKER_ARG_APPENDED) {
lform = invokeHandleForm(mtype, false, which);
appendixResult[0] = mtype;
} else {
lform = invokeHandleForm(mtype, true, which);
}
return lform.vmentry;
}
// argument count to account for trailing "appendix value" (typically the mtype)
private static final int MH_LINKER_ARG_APPENDED = 1;
/** Returns an adapter for invokeExact or generic invoke, as a MH or constant pool linker.
* If !customized, caller is responsible for supplying, during adapter execution,
* a copy of the exact mtype. This is because the adapter might be generalized to
* a basic type.
* @param mtype the caller's method type (either basic or full-custom)
* @param customized whether to use a trailing appendix argument (to carry the mtype)
* @param which bit-encoded 0x01 whether it is a CP adapter ("linker") or MHs.invoker value ("invoker");
* 0x02 whether it is for invokeExact or generic invoke
*/
private static LambdaForm invokeHandleForm(MethodType mtype, boolean customized, int which) {
boolean isCached;
if (!customized) {
mtype = mtype.basicType(); // normalize Z to I, String to Object, etc.
isCached = true;
} else {
isCached = false; // maybe cache if mtype == mtype.basicType()
}
boolean isLinker, isGeneric;
String debugName;
switch (which) {
case MethodTypeForm.LF_EX_LINKER: isLinker = true; isGeneric = false; debugName = "invokeExact_MT"; break;
case MethodTypeForm.LF_EX_INVOKER: isLinker = false; isGeneric = false; debugName = "exactInvoker"; break;
case MethodTypeForm.LF_GEN_LINKER: isLinker = true; isGeneric = true; debugName = "invoke_MT"; break;
case MethodTypeForm.LF_GEN_INVOKER: isLinker = false; isGeneric = true; debugName = "invoker"; break;
default: throw new InternalError();
}
LambdaForm lform;
if (isCached) {
lform = mtype.form().cachedLambdaForm(which);
if (lform != null) return lform;
}
// exactInvokerForm (Object,Object)Object
// link with java.lang.invoke.MethodHandle.invokeBasic(MethodHandle,Object,Object)Object/invokeSpecial
final int THIS_MH = 0;
final int CALL_MH = THIS_MH + (isLinker ? 0 : 1);
final int ARG_BASE = CALL_MH + 1;
final int OUTARG_LIMIT = ARG_BASE + mtype.parameterCount();
final int INARG_LIMIT = OUTARG_LIMIT + (isLinker && !customized ? 1 : 0);
int nameCursor = OUTARG_LIMIT;
final int MTYPE_ARG = customized ? -1 : nameCursor++; // might be last in-argument
final int CHECK_TYPE = nameCursor++;
final int LINKER_CALL = nameCursor++;
MethodType invokerFormType = mtype.invokerType();
if (isLinker) {
if (!customized)
invokerFormType = invokerFormType.appendParameterTypes(MemberName.class);
} else {
invokerFormType = invokerFormType.invokerType();
}
Name[] names = arguments(nameCursor - INARG_LIMIT, invokerFormType);
assert(names.length == nameCursor)
: Arrays.asList(mtype, customized, which, nameCursor, names.length);
if (MTYPE_ARG >= INARG_LIMIT) {
assert(names[MTYPE_ARG] == null);
BoundMethodHandle.SpeciesData speciesData = BoundMethodHandle.speciesData_L();
names[THIS_MH] = names[THIS_MH].withConstraint(speciesData);
NamedFunction getter = speciesData.getterFunction(0);
names[MTYPE_ARG] = new Name(getter, names[THIS_MH]);
// else if isLinker, then MTYPE is passed in from the caller (e.g., the JVM)
}
// Make the final call. If isGeneric, then prepend the result of type checking.
MethodType outCallType = mtype.basicType();
Object[] outArgs = Arrays.copyOfRange(names, CALL_MH, OUTARG_LIMIT, Object[].class);
Object mtypeArg = (customized ? mtype : names[MTYPE_ARG]);
if (!isGeneric) {
names[CHECK_TYPE] = new Name(NF_checkExactType, names[CALL_MH], mtypeArg);
// mh.invokeExact(a*):R => checkExactType(mh, TYPEOF(a*:R)); mh.invokeBasic(a*)
} else {
names[CHECK_TYPE] = new Name(NF_checkGenericType, names[CALL_MH], mtypeArg);
// mh.invokeGeneric(a*):R => checkGenericType(mh, TYPEOF(a*:R)).invokeBasic(a*)
outArgs[0] = names[CHECK_TYPE];
}
names[LINKER_CALL] = new Name(outCallType, outArgs);
lform = new LambdaForm(debugName, INARG_LIMIT, names);
if (isLinker)
lform.compileToBytecode(); // JVM needs a real methodOop
if (isCached)
lform = mtype.form().setCachedLambdaForm(which, lform);
return lform;
}
/*non-public*/ static
WrongMethodTypeException newWrongMethodTypeException(MethodType actual, MethodType expected) {
// FIXME: merge with JVM logic for throwing WMTE
return new WrongMethodTypeException("expected "+expected+" but found "+actual);
}
/** Static definition of MethodHandle.invokeExact checking code. */
/*non-public*/ static
@ForceInline
void checkExactType(Object mhObj, Object expectedObj) {
MethodHandle mh = (MethodHandle) mhObj;
MethodType expected = (MethodType) expectedObj;
MethodType actual = mh.type();
if (actual != expected)
throw newWrongMethodTypeException(expected, actual);
}
/** Static definition of MethodHandle.invokeGeneric checking code.
* Directly returns the type-adjusted MH to invoke, as follows:
* {@code (R)MH.invoke(a*) => MH.asType(TYPEOF(a*:R)).invokeBasic(a*)}
*/
/*non-public*/ static
@ForceInline
Object checkGenericType(Object mhObj, Object expectedObj) {
MethodHandle mh = (MethodHandle) mhObj;
MethodType expected = (MethodType) expectedObj;
return mh.asType(expected);
/* Maybe add more paths here. Possible optimizations:
* for (R)MH.invoke(a*),
* let MT0 = TYPEOF(a*:R), MT1 = MH.type
*
* if MT0==MT1 or MT1 can be safely called by MT0
* => MH.invokeBasic(a*)
* if MT1 can be safely called by MT0[R := Object]
* => MH.invokeBasic(a*) & checkcast(R)
* if MT1 can be safely called by MT0[* := Object]
* => checkcast(A)* & MH.invokeBasic(a*) & checkcast(R)
* if a big adapter BA can be pulled out of (MT0,MT1)
* => BA.invokeBasic(MT0,MH,a*)
* if a local adapter LA can cached on static CS0 = new GICS(MT0)
* => CS0.LA.invokeBasic(MH,a*)
* else
* => MH.asType(MT0).invokeBasic(A*)
*/
}
static MemberName linkToCallSiteMethod(MethodType mtype) {
LambdaForm lform = callSiteForm(mtype, false);
return lform.vmentry;
}
static MemberName linkToTargetMethod(MethodType mtype) {
LambdaForm lform = callSiteForm(mtype, true);
return lform.vmentry;
}
// skipCallSite is true if we are optimizing a ConstantCallSite
private static LambdaForm callSiteForm(MethodType mtype, boolean skipCallSite) {
mtype = mtype.basicType(); // normalize Z to I, String to Object, etc.
final int which = (skipCallSite ? MethodTypeForm.LF_MH_LINKER : MethodTypeForm.LF_CS_LINKER);
LambdaForm lform = mtype.form().cachedLambdaForm(which);
if (lform != null) return lform;
// exactInvokerForm (Object,Object)Object
// link with java.lang.invoke.MethodHandle.invokeBasic(MethodHandle,Object,Object)Object/invokeSpecial
final int ARG_BASE = 0;
final int OUTARG_LIMIT = ARG_BASE + mtype.parameterCount();
final int INARG_LIMIT = OUTARG_LIMIT + 1;
int nameCursor = OUTARG_LIMIT;
final int APPENDIX_ARG = nameCursor++; // the last in-argument
final int CSITE_ARG = skipCallSite ? -1 : APPENDIX_ARG;
final int CALL_MH = skipCallSite ? APPENDIX_ARG : nameCursor++; // result of getTarget
final int LINKER_CALL = nameCursor++;
MethodType invokerFormType = mtype.appendParameterTypes(skipCallSite ? MethodHandle.class : CallSite.class);
Name[] names = arguments(nameCursor - INARG_LIMIT, invokerFormType);
assert(names.length == nameCursor);
assert(names[APPENDIX_ARG] != null);
if (!skipCallSite)
names[CALL_MH] = new Name(NF_getCallSiteTarget, names[CSITE_ARG]);
// (site.)invokedynamic(a*):R => mh = site.getTarget(); mh.invokeBasic(a*)
final int PREPEND_MH = 0, PREPEND_COUNT = 1;
Object[] outArgs = Arrays.copyOfRange(names, ARG_BASE, OUTARG_LIMIT + PREPEND_COUNT, Object[].class);
// prepend MH argument:
System.arraycopy(outArgs, 0, outArgs, PREPEND_COUNT, outArgs.length - PREPEND_COUNT);
outArgs[PREPEND_MH] = names[CALL_MH];
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