[pacman-dev] [PATCH] Order downloads by descending max_size

[Charlie Sale]

On Wed, Aug 11, 2021 at 11:59 PM Charlie Sale <softwaresale01 at gmail.com> wrote:
>
> When downloading in parallel, sort by package size so that the larger
> packages are queued first to fully leverage parallelism.
> Addresses FS#70172
>
> Signed-off-by: Charlie Sale <softwaresale01 at gmail.com>
> ---
>  lib/libalpm/dload.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
>
> diff --git a/lib/libalpm/dload.c b/lib/libalpm/dload.c
> index ca6be7b6..58d2122f 100644
> --- a/lib/libalpm/dload.c
> +++ b/lib/libalpm/dload.c
> @@ -825,6 +825,19 @@ cleanup:
>         return ret;
>  }
>
> +/*
> + * Use to sort payloads by max size in decending order (largest -> smallest)
> + */
> +static int compare_dload_payload_sizes(const void *left_ptr, const void *right_ptr)
> +{
> +       struct dload_payload *left, *right;
> +
> +       left = (struct dload_payload *) left_ptr;
> +       right = (struct dload_payload *) right_ptr;
> +
> +       return right->max_size - left->max_size;
> +}
> +
>  /* Returns -1 if an error happened for a required file
>   * Returns 0 if a payload was actually downloaded
>   * Returns 1 if no files were downloaded and all errors were non-fatal
> @@ -838,6 +851,10 @@ static int curl_download_internal(alpm_handle_t *handle,
>         int max_streams = handle->parallel_downloads;
>         int updated = 0; /* was a file actually updated */
>         CURLM *curlm = handle->curlm;
> +       size_t payloads_size = alpm_list_count(payloads);
> +
> +       /* Sort payloads by package size */
> +       payloads = alpm_list_msort(payloads, payloads_size, &compare_dload_payload_sizes);
>
>         while(active_downloads_num > 0 || payloads) {
>                 CURLMcode mc;
> --
> 2.32.0
>

I'll also add that this is my first contribution to pacman. Please
inform me of anything I did incorrectly regarding the patch process.
Thank you in advance for your patience :)

Cheers!
~Charlie