ed2a9b8750
Fixes #16298 The adjusted buffer position calculation in buffer_position(), introduced in https://github.com/scylladb/scylladb/pull/15494 was in fact broken. It calculated (like previously) a "position" based on diff between underlying buffer size and ostream size() (i.e. avail), then adjusted this according to sector overhead rules. However, the underlying buffer size is in unadjusted terms, and the ostream is adjusted. The two cannot be compared as such, which means the "positions" we get here are borked. Luckily for us (sarcasm), the position calculation in replayer made a similar error, in that it adjusts up current position by one sector overhead to much, leading to us more or less getting the same, erroneous results in both ends. However, when/iff one needs to adjust the segment file format further, one might very quickly realize that this does not work well if, say, one needs to be able to safely read some extra bytes before first chunk in a segment. Conversely, trying to adjust this also exposes a latent potential error in the skip mechanism, manifesting here. Issue fixed by keeping track of the initial ostream capacity for segment buffer, and use this for position calculation, and in the case of replayer, move file pos adjustment from read_data() to subroutine (shared with skipping), that better takes data stream position vs. file position adjustment. In implementaion terms, we first inc the "data stream" pos (i.e. pos in data without overhead), then adjust for overhead. Also fix replayer::skip, so that we handle the buffer/pos relation correctly now. Added test for intial entry position, as well as data replay consistency for single entry_writer paths. Fixes #16301 The calculation on whether data may be added is based on position vs. size of incoming data. However, it did not take sector overhead into account, which lead us to writing past allowed segment end, which in turn also leads to metrics overflows. Closes scylladb/scylladb#16302 * github.com:scylladb/scylladb: commitlog: Fix allocation size check to take sector overhead into account. commitlog: Fix commitlog_segment::buffer_position() calculation and replay counterpart
119 KiB
119 KiB