[Commented On] D10791: revlog: move entry documentation alongside new related constants
baymax (Baymax, Your Personal Patch-care Companion)
phabricator at mercurial-scm.org
Mon Jun 7 09:19:15 UTC 2021
baymax added a comment.
baymax updated this revision to Diff 28472.
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REPOSITORY
rHG Mercurial
CHANGES SINCE LAST UPDATE
https://phab.mercurial-scm.org/D10791?vs=28450&id=28472
BRANCH
default
CHANGES SINCE LAST ACTION
https://phab.mercurial-scm.org/D10791/new/
REVISION DETAIL
https://phab.mercurial-scm.org/D10791
AFFECTED FILES
mercurial/revlog.py
mercurial/revlogutils/constants.py
CHANGE DETAILS
diff --git a/mercurial/revlogutils/constants.py b/mercurial/revlogutils/constants.py
--- a/mercurial/revlogutils/constants.py
+++ b/mercurial/revlogutils/constants.py
@@ -27,6 +27,81 @@
KIND_OTHER,
}
+### Index entry key
+#
+#
+# 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.
+ENTRY_DATA_OFFSET = 0
+
+# [1] compressed length:
+# The size, in bytes, of the chunk on disk
+ENTRY_DATA_COMPRESSED_LENGTH = 1
+
+# [2] uncompressed length:
+# The size, in bytes, of the full revision once reconstructed.
+ENTRY_DATA_UNCOMPRESSED_LENGTH = 2
+
+# [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.
+ENTRY_DELTA_BASE = 3
+
+# [4] link rev:
+# Changelog revision number of the changeset introducing this
+# revision.
+ENTRY_LINK_REV = 4
+
+# [5] parent 1 rev:
+# Revision number of the first parent
+ENTRY_PARENT_1 = 5
+
+# [6] parent 2 rev:
+# Revision number of the second parent
+ENTRY_PARENT_2 = 6
+
+# [7] node id:
+# The node id of the current revision
+ENTRY_NODE_ID = 7
+
+# [8] sidedata offset:
+# The byte index of the start of the revision's side-data chunk.
+ENTRY_SIDEDATA_OFFSET = 8
+
+# [9] sidedata chunk length:
+# The size, in bytes, of the revision's side-data chunk.
+ENTRY_SIDEDATA_COMPRESSED_LENGTH = 9
+
+# [10] data compression mode:
+# two bits that detail the way the data chunk is compressed on disk.
+# (see "COMP_MODE_*" constants for details). For revlog version 0 and
+# 1 this will always be COMP_MODE_INLINE.
+ENTRY_DATA_COMPRESSION_MODE = 10
+
+# [11] side-data compression mode:
+# two bits that detail the way the sidedata chunk is compressed on disk.
+# (see "COMP_MODE_*" constants for details)
+ENTRY_SIDEDATA_COMPRESSION_MODE = 11
+
### main revlog header
# We cannot rely on Struct.format is inconsistent for python <=3.6 versus above
diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -310,66 +310,8 @@
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.
-
- [10] data compression mode:
- two bits that detail the way the data chunk is compressed on disk.
- (see "COMP_MODE_*" constants for details). For revlog version 0 and
- 1 this will always be COMP_MODE_INLINE.
-
- [11] side-data compression mode:
- two bits that detail the way the sidedata chunk is compressed on disk.
- (see "COMP_MODE_*" constants for details)
+ See mercurial/revlogutils/contants.py for details about the content of an
+ index entry.
"""
_flagserrorclass = error.RevlogError
To: marmoute, indygreg, #hg-reviewers, Alphare
Cc: mercurial-patches
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