--- a/mercurial/revlog.py Mon May 03 23:45:05 2021 +0200
+++ b/mercurial/revlog.py Mon May 03 16:52:38 2021 +0200
@@ -284,6 +284,58 @@
file handle, a filename, and an expected position. It should check whether
the current position in the file handle is valid, and log/warn/fail (by
raising).
+
+
+ Internal details
+ ----------------
+
+ A large part of the revlog logic deals with revisions' "index entries", tuple
+ objects that contains the same "items" whatever the revlog version.
+ Different versions will have different ways of storing these items (sometimes
+ not having them at all), but the tuple will always be the same. New fields
+ are usually added at the end to avoid breaking existing code that relies
+ on the existing order. The field are defined as follows:
+
+ [0] offset:
+ The byte index of the start of revision data chunk.
+ That value is shifted up by 16 bits. use "offset = field >> 16" to
+ retrieve it.
+
+ flags:
+ A flag field that carries special information or changes the behavior
+ of the revision. (see `REVIDX_*` constants for details)
+ The flag field only occupies the first 16 bits of this field,
+ use "flags = field & 0xFFFF" to retrieve the value.
+
+ [1] compressed length:
+ The size, in bytes, of the chunk on disk
+
+ [2] uncompressed length:
+ The size, in bytes, of the full revision once reconstructed.
+
+ [3] base rev:
+ Either the base of the revision delta chain (without general
+ delta), or the base of the delta (stored in the data chunk)
+ with general delta.
+
+ [4] link rev:
+ Changelog revision number of the changeset introducing this
+ revision.
+
+ [5] parent 1 rev:
+ Revision number of the first parent
+
+ [6] parent 2 rev:
+ Revision number of the second parent
+
+ [7] node id:
+ The node id of the current revision
+
+ [8] sidedata offset:
+ The byte index of the start of the revision's side-data chunk.
+
+ [9] sidedata chunk length:
+ The size, in bytes, of the revision's side-data chunk.
"""
_flagserrorclass = error.RevlogError