Re: [boost] [GSOC] Regarding the project Boost.DeVector

Subject: Re: [boost] [GSOC] Regarding the project Boost.DeVector
From: Satyam Shekhar (satyamshekhar_at_[hidden])
Date: 2009-03-27 15:02:41

Hi Thorsten,
I have been working on my proposal for the last few days and am almost
done. Some of the questions which came to my mind:

a. Why would deque need a reserve function?
Vector needs it because growing a vector is costly due to relocations,
and a reserve can reduce those relocations. A deque which is
*generally* (from the reading I did and the opinions on this list)
implemented as a list of blocks (whose addresses are stored in an
array) will not need the relocations because the blocks are all
scattered in memory. The only case where relocations would be required
is when the array storing the addresses grows and needs to be
relocated. Will this be frequent? Is this the case we are targeting
when we want to add the reserve function?

b. Why isn't the reserve function already there in a deque?
Assuming there is a valid case for this function, adding it shouldn't
be too difficult. Allocate a block(s) and add the address to the
top-level array.

c. Why would be want to specify the size of the chunks?
Again, as in a., relocation does not take place in a deque except the
top-level array, and changing the chunk size will not change the
frequency of relocations in that. Also, with blocks of unequal sizes,
providing constant time random access will be difficult.

Regarding the project proposal, I wished to know whether to put it on
the mailing list first, or submit it through the gsoc app.

Regards
Satyam