RFR: 8004518 & 8010122 : Default methods on Map

Akhil Arora akhil.arora at oracle.com
Fri Apr 12 12:50:38 PDT 2013


Hi Mike,

a few small things -

UnmodifiableMap.forEach
   is missing Objects.requireNonNull(action);

EmptyMap.replaceAll(BiFunction)
   should just return instead of throwing UnsupportedOpEx
   particularly since EmptyList.replaceAll also returns silently
   after checking if function is null to fulfil the NPE contract

Hashtable
   is missing a synchronized override of forEach

CheckedMap.typeCheck(BiFunction)
   is missing from the patch (won't compile without it)

On 04/11/2013 01:03 PM, Mike Duigou wrote:
> Another revision incorporating primarily documentation feedback.
>
> http://cr.openjdk.java.net/~mduigou/JDK-8010122/2/webrev/
>
> I've also included the java.util.Collections overrides for the default methods. All of these are performance enhancements--the semantics were already correct because the defaults use only public methods.
>
> This is likely, modulo formatting of the source examples, the version that will be pushed to TL on Friday unless somebody squawks.
>
> Moving the current compute, computeIfPresent, computeIfAbsent and merge defaults to ConcurrentMap and replacing the current Map defaults with versions that throw ConcurrentModificationException will likely be resolved in a future issue if the EG determines it to be important.
>
> Mike
>
>
> On Apr 10 2013, at 22:42 , Mike Duigou wrote:
>
>> I've posted an updated webrev with the review comments I have received.
>>
>> http://cr.openjdk.java.net/~mduigou/JDK-8010122/1/webrev/
>>
>> One important point to consider:
>>
>> - The current implementations of compute, computeIfPresent, computeIfAbsent, merge are implemented so that they can work correctly for ConcurrentMap instances. For non-concurrent implementations it might be better to fail and throw ConcurrentModification exception whenever concurrent modification is detected. For regular Map implementations the retry behaviour will only serve to mask errors.
>>
>> Thoughts?
>>
>> Mike
>>
>> On Apr 8 2013, at 11:07 , Mike Duigou wrote:
>>
>>> Hello all;
>>>
>>> This is a combined review for the new default methods on the java.util.Map interface being added for the JSR-335 lambda libraries. The reviews are being combined because they share a common unit test.
>>>
>>> http://cr.openjdk.java.net/~mduigou/JDK-8010122/0/webrev/
>>>
>>> 8004518: Add in-place operations to Map
>>> forEach()
>>> replaceAll()
>>>
>>> 8010122: Add atomic operations to Map
>>> getOrDefault()
>>> putIfAbsent()          *
>>> remove(K, V)
>>> replace(K, V)
>>> replace(K, V, V)
>>> compute()              *
>>> merge()                *
>>> computeIfAbsent()      *
>>> computeIfPresent()     *
>>>
>>> The * operations treat null values as being absent. (ie. the same as there being no mapping for the specified key).
>>>
>>> The default implementations provided in Map are overridden in HashMap for performance purposes, in Hashtable for atomicity and performance purposes and in Collections for atomicity.
>>>
>>> Mike
>>
>



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