On Mon, 2 Nov 2020 11:22:07 GMT, Jorn Vernee <jver...@openjdk.org> wrote:
>> Hi, >> >> This patch adds an asExact() combinator to VarHandle, that will return a new >> VarHandle that performs exact type checks, similar to >> MethodHandle::invokeExact, to help developers catch inexact VarHandle usage, >> which can lead to performance degradation. >> >> This is implemented using a boolean flag in VarForm. If the flag is set, the >> exact type of the invocation is checked against the exact type in the >> VarForm. If there is a mismatch, a WrongMethodTypeException is thrown. >> >> Other than that, there is also an asGeneric() combinator added that does the >> inverse operation (thanks to Rémi for the suggestion). I've also added The >> `@Hidden` annotation to the VarHandleGuards methods, as well as a >> type-checking helper method called from the generic invocation lambda form, >> so that the stack trace we get points at the location where the VarHandle is >> being used. >> >> Thanks, >> Jorn >> >> CSR link: https://bugs.openjdk.java.net/browse/JDK-8255375 > > Jorn Vernee has updated the pull request incrementally with one additional > commit since the last revision: > > s/an arity/and arity src/java.base/share/classes/java/lang/invoke/VarHandle.java line 1600: > 1598: * If this VarHandle already has invoke-exact behavior this > VarHandle is returned. > 1599: * @apiNote > 1600: * Invoke-exact behavior guarantees that that upon invocation of an > access mode method minor typo "that that" src/java.base/share/classes/java/lang/invoke/VarHandle.java line 1603: > 1601: * the types and arity of the arguments must match the {@link > #accessModeType(AccessMode) access mode type}, > 1602: * otherwise a {@link WrongMethodTypeException} is thrown. > 1603: * While not strictly necessary, the pedantic part to me likes to see assertions like this in the spec: "Invoking `hasInvokeExactBehavior` on the returned VarHandle is guaranteed to return true." And conversely, for withInvokeBehavior. ------------- PR: https://git.openjdk.java.net/jdk/pull/843
