Why does ACE_Message_Queue not provide the methods to dequeue multiple blocks

[smithAchang]

ACE_Message_Block has the capability to form a block chain.

ACE_Message_Queue provides the methods to enqueue multiple blocks. e.g. enqueue_head or enqueue_tail.

But It does not provide the methods to dequeue multiple blocks :(

for the enqueue & dequeue api's symmetry and embodying the design principle of ACE_Message_Block

I suggest ACE_Message_Queue implement the apis to dequeue multiple blocks.

I think the enhanced apis will reduce the overhead of lock in some case with bach operation mode.

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e.g.
dequeue_head_n(ACE_Message_Block *& first_item, size_t max_n, ACE_Time_Value * timeout = 0)
dequeue_tail_n(ACE_Message_Block *& dequeued, size_t max_n , ACE_Time_Value * timeout = 0)