RFR: 8004518 & 8010122 : Default methods on Map

[Mike Duigou]

On Apr 14 2013, at 11:35 , Peter Levart wrote:

> 
> On 04/14/2013 07:54 PM, Peter Levart wrote:
>> Hi Mike,
>> 
>> Just a nit: The order of boolean sub-expressions in Map.replace(key, oldValue, newValue):
>> 
>>  740         if (!containsKey(key) || !Objects.equals(get(key), oldValue))
>> 
>> ...would be more optimal if reversed (like in Map.remove(key, value)).
>> 
>> Regards, Peter
> 
> I think the most optimal is actually this:
> 
> default boolean remove((Object key, Object value) {
>     Object curValue = get(key);
>     if (curValue == null && (value != null || !containsKey(key)) ||
>         curValue != value && !curValue.equals(value)) {
>         return false;
>     }
>     remove(key);
>     return true;
> }
> 
> ...and the same for replace(key, oldValue, newValue)...

In the current patch I've used:

    default boolean remove(Object key, Object value) {
        Object curValue = get(key);
        if (!Objects.equals(curValue, value) ||
            (curValue == null && !containsKey(key))) {
            return false;
        }
        remove(key);
        return true;
    }

and similar for replace(K,V,V)

I rearranged it mostly so that calling containsKey is a last resort.

Mike

> 
> Regards, Peter
> 
>> 
>> On 04/13/2013 12:02 AM, Mike Duigou wrote:
>>> I have updated the webrev with these changes and a few more.
>>> 
>>> merge() required an update to it's specification to correctly account for null values.
>>> 
>>> http://cr.openjdk.java.net/~mduigou/JDK-8010122/5/webrev/
>>> 
>>> This version is currently undergoing final pre-integration testing. Unless additional problems are found or the testing fails this version will be integrated.
>>> 
>>> Mike
>>> 
>>> On Apr 12 2013, at 12:53 , Mike Duigou wrote:
>>> 
>>>> Thanks for the corrections. I have incorporated all of these into the integration version of the patch.
>>>> 
>>>> On Apr 12 2013, at 12:50 , Akhil Arora wrote:
>>>> 
>>>>> Hi Mike,
>>>>> 
>>>>> a few small things -
>>>>> 
>>>>> UnmodifiableMap.forEach
>>>>> is missing Objects.requireNonNull(action);
>>>> Added.
>>>> 
>>>>> 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
>>>> I agree. 
>>>> 
>>>>> Hashtable
>>>>> is missing a synchronized override of forEach
>>>> added.
>>>> 
>>>>> CheckedMap.typeCheck(BiFunction)
>>>>> is missing from the patch (won't compile without it)
>>>> Apparently I forgot a qrefresh before generating the webrev. I had this in my local copy as it's necessary.
>>>> 
>>>>> 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
>> 
>