On 07/27/2013 12:00 PM, Kinkie wrote:
>> > 1a. Reserve total buffer capacity. Ensure exclusive buffer ownership.
>> >
>> > 1b. Reserve buffer space. Ensure exclusive buffer ownership.
>> >
>> > 2. Reserve N space bytes for the caller to append to. No guarantees
>> > regarding buffer ownership are provided.
> I like Amos's suggestion more (two methods for the append-friendly
> optimization, and one for accessing the internals).
There should be no need for two methods for append-friendly optimization
because append only cares about the space size, not total size. This is
method #2 in the above list.
Methods #1a and #1b ensure exclusive ownership. They do not return a
pointer. They must not contain that append-friendly optimization!
AFAICT, Amos explanation of what I was getting at is correct. His email
did not discuss the optimization trick which is one more reason why we
want rawSpace(), but I think we both suggest the same set of three methods:
// 1a.
void reserveCapacity(size_type minCap) {
cow(minCap);
}
// 1b.
void reserveSpace(size_type minSpace) {
// check that the sum below does not exceed size_type
Must(size() <= size_type's limit - minSpace);
reserveCapacity(size() + minSpace);
}
// 2.
char *rawSpace(size_type minSpace) {
... your optimization goes here ...
return pointer to space;
}
Needless to say, it is critical to document these correctly and clearly
so that we do not have to come back to this discussion again.
HTH,
Alex.
