> On 25 Sep 2015, at 17:19, Peter Levart <peter.lev...@gmail.com> wrote: > > Hi Paul, > > Thanks for looking into this. >
Apologies for the late reply. > On 09/25/2015 04:07 PM, Paul Sandoz wrote: >> Hi, >> >> This looks like a partial dup of >> https://bugs.openjdk.java.net/browse/JDK-8076596 > > Ah, sorry, I wasn't aware this has already been registered in JIRA. I have > linked the two issues together as DUPs. > Thanks. >> >> The changes look ok, but I am concerned post initialization there may be >> code paths taken that require the system class loader to be used but instead >> the boot stream class loader is used instead. Is that a legitimate concern? > > It is legitimate, but I have inspected usages and: > > - In java.lang.invoke.BoundMethodHandle.Factory#makeCbmhCtor, null is passed > explicitly and this method is used only from > java.lang.invoke.BoundMethodHandle.Factory#makeCtors which is used from > java.lang.invoke.BoundMethodHandle.SpeciesData#initForBootstrap and > java.lang.invoke.BoundMethodHandle.SpeciesData#SpeciesData(java.lang.String, > java.lang.Class<? extends java.lang.invoke.BoundMethodHandle>). These usages > only deal with erased MH types (Object, long, int, double, float). > > - In java.lang.invoke.MemberName#getMethodType, the result of > MemberName.getClassLoader() is passed to the method. This is the class loader > of the member's declaring class. Any types referenced from the member > declaration should be resolvable from this class loader. A member declared by > a bootstrap class (MemberName.getClassLoader() returns null) can only > reference types resolvable from bootstrap loader. > > - In java.lang.invoke.MemberName#getFieldType, the result of > MemberName.getClassLoader() is passed to the method. Similar applies as above. > > - In java.lang.invoke.MethodHandleNatives#fixMethodType(Class<?> callerClass, > Object type), the callerClass.getClassLoader() is passed to the method. This > is invoked from: > java.lang.invoke.MethodHandleNatives#linkMethodImpl( > Class<?> callerClass, int refKind, > Class<?> defc, String name, Object type, > Object[] appendixResult) > which is called from java.lang.invoke.MethodHandleNatives#linkMethod(same > args) > > I suppose this is an upcall from VM to link a call to the > @PolymorphicSignature method and callerClass is the class in which the > invocation bytecodes are executed. Am I right? Yes. And before that there is an upcall to MethodHandleNatives.findMethodHandleType, see SystemDictionary::find_method_handle_invoker in src/share/vm/classfile/systemDictionary.cpp. AFAICT the “type” argument passed to the linkMethod should always be of MethodType: static MemberName linkMethod(Class<?> callerClass, int refKind, Class<?> defc, String name, Object type, Object[] appendixResult) { if (!TRACE_METHOD_LINKAGE) return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult); return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult); } static MemberName linkMethodImpl(Class<?> callerClass, int refKind, Class<?> defc, String name, Object type, Object[] appendixResult) { try { if (defc == MethodHandle.class && refKind == REF_invokeVirtual) { return Invokers.methodHandleInvokeLinkerMethod(name, fixMethodType(callerClass, type), appendixResult); } } catch (Throwable ex) { if (ex instanceof LinkageError) throw (LinkageError) ex; else throw new LinkageError(ex.getMessage(), ex); } throw new LinkageError("no such method "+defc.getName()+"."+name+type); } private static MethodType fixMethodType(Class<?> callerClass, Object type) { if (type instanceof MethodType) return (MethodType) type; else return MethodType.fromMethodDescriptorString((String)type, callerClass.getClassLoader()); } Thus it seems fixMethodType is not necessary. I think this is confirmed when looking at up calls to linkMethodHandleConstant and linkCallSite. > The reasoning is as follows: if callerClass.getClassLoader() is sufficient > for resolving types that appear at the call site in a non-bootstrap > callerClass, then bootstrap classloader should be sufficient to resolve types > that appear at the call site in a bootstrap callerClass. Does anybody have > any other opinion? > > - sun.invoke.util.BytecodeDescriptor#parseMethod(java.lang.String, > java.lang.ClassLoader) is only used from the newly introduced > java.lang.invoke.MethodType#fromDescriptor > Ok, i think you have things covered, thanks, Paul.
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