fixed AbstractAdapter::internalDecrementItems

[marc-mabe]

• was calling decrementItem instead of internalDecrementItem
• triggered events for bulk decrement as well as for every items

Noted by benchmarks of #35

Before:

ZendBench\Cache\MemoryStorageAdapterBench
    Method Name                    Iterations   Average Time      Ops/second 
    ----------------------------- ------------ ----------------- -------------
    decrementMissingItemsSingle : [       100] [0.0008270716667] [1,209.08507]
    decrementMissingItemsBulk   : [       100] [0.0009380531311] [1,066.03770]
    decrementExistingItemsSingle: [       100] [0.0008216524124] [1,217.05965]
    decrementExistingItemsBulk  : [       100] [0.0009412384033] [1,062.43009]

After:

ZendBench\Cache\MemoryStorageAdapterBench
    Method Name                    Iterations   Average Time      Ops/second 
    ----------------------------- ------------ ----------------- -------------
    decrementMissingItemsSingle : [       100] [0.0008160185814] [1,225.46229]
    decrementMissingItemsBulk   : [       100] [0.0001660728455] [6,021.45400]
    decrementExistingItemsSingle: [       100] [0.0008193802834] [1,220.43454]
    decrementExistingItemsBulk  : [       100] [0.0001683640480] [5,939.51032]

PS: tests are passing but I need to write a new test catching this

[marc-mabe]

Test is added by #38

[Maks3w]

I prefer if tests are added in this PR. #38 is too long

[marc-mabe]

@Maks3w

I prefer if tests are added in this PR. #38 is too long

-> If I merge #38 into this one it gets more long.

Does I understand you correctly that you prefer to only move the one failing test into this PR?

I would more prefer to ignore this PR and see #38 as only one thing that adds missing tests to AbstractAdapter as is where one test fails. Afterwards this PR comes up to fix this bug.
-> Nearly all the tests in #38 are written in a very similar way including testGetMetadatas[Fail], testSetItems[Fail], testAddItems[Fail|Exists], testReplaceItems[Fail|Missing], testRemoveItems[Fail], testIncrementItems[Fail], testDecrementItems[Fail], testTouchItems[Fail]. It would be strange to move testIncrementItems into another PR.

[marc-mabe]

@Maks3w ping