In S3 client both read and write metrics have three counters -- number
of requests made, number of bytes processed and request latency. In most
of the cases all three counters are updated at once -- upon response
arrival.
However, in case of chunked download source this way of accounting
metrics is misleading. In this code the request is made once, and then
the obtained bytes are consumed eventually as the data arrive.
Currently, each time a new portion of data is read from the socket the
number of read requests is incremented. That's wrong, the request is
made once, and this counter should also be incremented once, not for
every data buffer that arrived in response.
Same for read request latency -- it's "added" for every data buffer that
arrives, but it's a lenghy process, the _request_ latency should be
accounted once per responce. Maybe later we'll want to have "data
latency" metrics as well, but for what we have now it's request latency.
The number of read bytes is accounted properly, so not touched here.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Closesscylladb/scylladb#25770
9deea3655f