Difference between WriterLoanExample and ZeroCopyExample

[duchengyao]

I noticed two particularly similar examples WriterLoanExample and ZeroCopyExample, The difference is that one uses take and the other uses take_next_sample().

Does it means take_next_sample() copy data, but take() wont' copy data?

[MiguelCompany]

Does it means take_next_sample() copy data, but take() wont' copy data?

Correct, but incomplete.

take_next_sample will always copy data.
take will not copy data when called with empty data_values and sample_infos.

Check here and here for more information.

[duchengyao]

Thanks.
What happens if data_values or sample_infos is not empty, I didn't find the relevant instructions from the above two links.

Regards,

[MiguelCompany]

Literally copied from here:

If the input max_len == 0, then the data_values and sample_infos collections will be filled with elements that are loaned by the DataReader. On output, owns will be false, len will be set to the number of values returned, and max_len will be set to a value verifying max_len >= len. The use of this variant allows for zero-copy access to the data and the application will need to return the loan to the DataReader using the return_loan operation.

If input max_len > 0 and the input owns == true, then the read operation will copy the Data values and SampleInfo values into the elements already inside the collections. On output, owns will be true, len will be set to the number of values copied, and max_len will remain unchanged. The use of this variant forces a copy but the application can control where the copy is placed and the application will not need to return the loan.

[duchengyao]

Thanks for your help ^_^