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Re: cURL Write Data Buffer size

From: doa379 <>
Date: Thu, 16 Mar 2017 20:18:02 +0000

> On 3/16/2017 3:16 PM, doa379 wrote:
>> I'm using the API to fetch data and am using the WRITEDATA,
>> WRITEFUNCTION options to handle it. Unfortunately I am finding that in
>> some instances where the data is too long it gets separated in more
>> than one call of the WRITEFUNCTION callback function. At this point
>> the application loses track of the data because I am using the API to
>> fetch other URLs as well. Is there any way to control the size of the
>> buffer so that all of the data can be handled in a single call of
>> An earlier approach that I tried was to have predefined slots for each
>> of the URLs (tracks of data). In which case each of the slots got
>> populated with data at leisure over multiple calls of the
>> WRITEFUNCTION. This works but there's some drawback in efficiency and
>> this implementation faces some other symptomatic inadequacies with the
>> cURL API.
>> I have now decided to use a single WRITEDATA buffer. But I wish to set
>> or increase its size so that WRITEFUNCTION need only be called a
>> single time for any given track of data or URL.
> No, there's no guarantee of how many times the write function will be
> called regardless of the data size. If you are doing multiple transfers
> in parallel using multi you'll need to account for that, in your case I
> suspect by using separate buffers.

That's a solution I got from you IIRC, to store the data into multiple
slots. Based on the getinmemory.c prototype. I am trying to look at this
problem again in order to tidy it up using a single buffer slot if possible.

Yes, I appreciate there is no control over how many times the
WRITEFUNCTION will be called. But I would like to parse the data
obtained through any given URL using a single pass of WRITEFUNCTION.
Well I suppose it's possible implementing a more elaborate parser by
using intermediate storage to reconstruct the structure of the data. I
am curious why are the data chunks sent to WRITEFUNCTION they size that
they are and if it was possible to adjust the size of these chunks.
Received on 2017-03-16