comparison mercurial/configitems.py @ 47387:75e1104f23a2

revlog: use dedicated code for reading sidedata

We are about to introduce a new, dedicated, file to store sidedata. Before doing so, we make sidedata reading go through different code as reading data chunk. This will simplify some of the complexity of the next changesets.

The reading is very simple right now and will need some improvement later to
reuse some of the caching strategy we use for the data file.

Differential Revision: https://phab.mercurial-scm.org/D10785

47386:0d0fb091c49f

# * track garbage data to evemtually allow rewriting -existing- sidedata.
# * Exchange-wise, we will also need to do something more efficient than
#   keeping references to the affected revlogs, especially memory-wise when
#   rewriting sidedata.
# * introduce a proper solution to reduce the number of filelog related files.
# * Improvement to consider
#   - avoid compression header in chunk using the default compression?
#   - forbid "inline" compression mode entirely?
#   - split the data offset and flag field (the 2 bytes save are mostly trouble)
#   - keep track of uncompressed -chunk- size (to preallocate memory better)

47387:75e1104f23a2

# * track garbage data to evemtually allow rewriting -existing- sidedata.
# * Exchange-wise, we will also need to do something more efficient than
#   keeping references to the affected revlogs, especially memory-wise when
#   rewriting sidedata.
# * introduce a proper solution to reduce the number of filelog related files.
# * use caching for reading sidedata (similar to what we do for data).
# * Improvement to consider
#   - avoid compression header in chunk using the default compression?
#   - forbid "inline" compression mode entirely?
#   - split the data offset and flag field (the 2 bytes save are mostly trouble)
#   - keep track of uncompressed -chunk- size (to preallocate memory better)