mercurial/help/internals/censor.txt
author Georges Racinet <georges.racinet@octobus.net>
Tue, 21 May 2019 20:07:20 +0200
changeset 42357 5b795108dd17
parent 31280 1b699a208cee
permissions -rw-r--r--
rust-python3: useless python2 specific import This python27_sys import prevents building with python3, it had been previously removed in a5fa9140ce4c, but that has been since pruned Differential Revision: https://phab.mercurial-scm.org/D6415
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
31280
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
     1
The censor system allows retroactively removing content from
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
     2
files. Actually censoring a node requires using the censor extension,
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
     3
but the functionality for handling censored nodes is partially in core.
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
     4
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
     5
Censored nodes in a filelog have the flag ``REVIDX_ISCENSORED`` set,
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
     6
and the contents of the censored node are replaced with a censor
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
     7
tombstone. For historical reasons, the tombstone is packed in the
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
     8
filelog metadata field ``censored``. This allows censored nodes to be
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
     9
(mostly) safely transmitted through old formats like changegroup
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
    10
versions 1 and 2. When using changegroup formats older than 3, the
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
    11
receiver is required to re-add the ``REVIDX_ISCENSORED`` flag when
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
    12
storing the revision. This depends on the ``censored`` metadata key
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
    13
never being used for anything other than censoring revisions, which is
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
    14
true as of January 2017. Note that the revlog flag is the
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
    15
authoritative marker of a censored node: the tombstone should only be
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
    16
consulted when looking for a reason a node was censored or when revlog
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
    17
flags are unavailable as mentioned above.
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
    18
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
    19
The tombstone data is a free-form string. It's expected that users of
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
    20
censor will want to record the reason for censoring a node in the
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
    21
tombstone. Censored nodes must be able to fit in the size of the
1b699a208cee internals: add some brief documentation about censor
Augie Fackler <augie@google.com>
parents:
diff changeset
    22
content being censored.