Option B avoids an extra copy of the data.  It should work with all versions
of protocol buffers.  Use it if profiling shows a lot of time spent in this
code, otherwise use whichever version you find easier to follow.

On Tue, Aug 17, 2010 at 8:51 AM, nirajshr <niraj...@gmail.com> wrote:

> I want to know which of the following implementation is better in
> terms of performance and usability. Option A is much easier and
> portable across different protobuf versions. Is it worth the trouble
> trying to go with Option B? In my tests, I could not find much of a
> performance gain by using Option B.
>
> Option A uses the protobuf compiler generated class to loop through
> each elements of a repeated doubles.
> On the other hand, Option B uses RepeatedField class to extract a
> pointer to the array of doubles.
>
>
> Option A:
>
> --------------------------------------------------------------------------------
> int size = bucket.bucketdouble(j).data_size();
> double* doubleVector = new double[size];
> for(int k=0; k<size; k++) {
>    doubleVector[k] = bucket.bucketdouble(j).data(k);
> }
> // Custom function that takes arrays of doubles
> add_double_vector(doubleVector, size);
> delete [] doubleVector;
>
>
> Option B:
>
> --------------------------------------------------------------------------------
> using namespace google::protobuf;
> DoubleData* doubledata_m = deal_pb.mutable_bucket(i)-
> >mutable_bucketdouble(j);
> RepeatedField< double >* doublearray_m = doubledata_m->mutable_data();
> // Custom function that takes arrays of doubles
> add_double_vector(doublearray_m->mutable_data(), doublearray_m-
> >size());
>
>
>
> My .proto file looks something like this:
>
> --------------------------------------------------------------------------------
> message DoubleData {
>    required string name = 1 [default = "noname"];
>    repeated double data = 2;
> }
>
> message Bucket {
>   repeated DoubleData bucketDouble = 2;
> }
>
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