Hi Mandy,
On 2018-08-17 19:07, mandy chung wrote:
On 8/17/18 7:38 AM, Peter Levart wrote:
On 08/17/2018 04:32 PM, Claes Redestad wrote:
Hi Peter,
On 2018-08-17 16:04, Peter Levart wrote:
Hi Claes,
Nice trick.
+1
thanks!
You made MethodType(s) and WeakEntry(s) holding them equal,
respecting the equals()/hashCode() contract. When WeakEntry looses
the referent it is left equal to itself only, which is enough for
expunging it from map.
Good summary. Do you think we need a few comments to spell out these
intricacies?
Yes, perhaps just pointers from the two equals() methods to each
other, explaining that they are actually one method which is split
into two unrelated classes.
It'd be worth to document this as javadoc of these two equals methods
(that's probably what you are thinking).
While this could be an @implNote in the javadoc, I think as this is an
internal implementation detail with a private type (WeakEntry) (that
doesn't leak) we are better off just adding this as a code comment on
MethodType#equals:
diff -r a34087e2b440
src/java.base/share/classes/java/lang/invoke/MethodType.java
--- a/src/java.base/share/classes/java/lang/invoke/MethodType.java Mon
Aug 20 12:30:38 2018 +0200
+++ b/src/java.base/share/classes/java/lang/invoke/MethodType.java Mon
Aug 20 12:46:20 2018 +0200
@@ -786,6 +786,9 @@
* @param x object to compare
* @see Object#equals(Object)
*/
+ // This implementation may also return true if x is a WeakEntry
containing
+ // a method type that is equal to this. This is an internal
implementation
+ // detail to allow for faster method type lookups.
@Override
public boolean equals(Object x) {
if (this == x) {
@@ -1350,6 +1353,12 @@
hashcode = key.hashCode();
}
+ /**
+ * This implementation returns true both if {@code obj} is
another
+ * {@code WeakEntry} whose referent is equals to this
referent, but also
+ * if {@code obj} is equals to the referent directly. This
allows
+ * lookups to be made without wrapping in a {@code WeakEntry}.
+ */
@Override
public boolean equals(Object obj) {
Object mine = get();
/Claes
