comparison tests/test-help.t @ 40047:8e398628a3f2

repository: define and use revision flag constants

Revlogs have a per-revision 2 byte field holding integer flags that
define how revision data should be interpreted. For historical reasons,
these integer values are sent verbatim on the wire protocol as part of
changegroup data.

From a semantic standpoint, the flags that go out over the wire are
different from the flags stored internally by revlogs. Failure to
establish this semantic distinction creates unwanted strong coupling
between revlog's internals and the wire protocol.

This commit establishes new constants on the repository module that
define the revision flags used by the wire protocol (and by some
internal storage APIs, sadly). The changegroups internals documentation
has been updated to document them explicitly. Various references
throughout the repo now use the repository constants instead of the
revlog constants. This is done to make it clear that we're operating
on generic revision data and this isn't tied to revlogs.

Differential Revision: https://phab.mercurial-scm.org/D4860

40046:50700a025953

      the changelog data, root/flat manifest data, treemanifest data, and
      filelogs.
  
      There are 3 versions of changegroups: "1", "2", and "3". From a high-
      level, versions "1" and "2" are almost exactly the same, with the only
      difference being an additional item in the *delta header*.  Version "3"
      adds support for revlog flags in the *delta header* and optionally
      exchanging treemanifests (enabled by setting an option on the
      "changegroup" part in the bundle2).
  
      Changegroups when not exchanging treemanifests consist of 3 logical
      segments:

      changegroup.
  
      In version 2 and up, the delta base node is encoded in the entry in the
      changegroup. This allows the delta to be expressed against any parent,
      which can result in smaller deltas and more efficient encoding of data.
  
      Changeset Segment
      =================
  
      The *changeset segment* consists of a single *delta group* holding

  filelogs.
  </p>
  <p>
  There are 3 versions of changegroups: &quot;1&quot;, &quot;2&quot;, and &quot;3&quot;. From a
  high-level, versions &quot;1&quot; and &quot;2&quot; are almost exactly the same, with the
  only difference being an additional item in the *delta header*.  Version
  &quot;3&quot; adds support for revlog flags in the *delta header* and optionally
  exchanging treemanifests (enabled by setting an option on the
  &quot;changegroup&quot; part in the bundle2).
  </p>
  <p>
  Changegroups when not exchanging treemanifests consist of 3 logical

  </p>
  <p>
  In version 2 and up, the delta base node is encoded in the entry in the
  changegroup. This allows the delta to be expressed against any parent,
  which can result in smaller deltas and more efficient encoding of data.
  </p>
  <h2>Changeset Segment</h2>
  <p>
  The *changeset segment* consists of a single *delta group* holding
  changelog data. The *empty chunk* at the end of the *delta group* denotes

40047:8e398628a3f2

      the changelog data, root/flat manifest data, treemanifest data, and
      filelogs.
  
      There are 3 versions of changegroups: "1", "2", and "3". From a high-
      level, versions "1" and "2" are almost exactly the same, with the only
      difference being an additional item in the *delta header*. Version "3"
      adds support for storage flags in the *delta header* and optionally
      exchanging treemanifests (enabled by setting an option on the
      "changegroup" part in the bundle2).
  
      Changegroups when not exchanging treemanifests consist of 3 logical
      segments:

      changegroup.
  
      In version 2 and up, the delta base node is encoded in the entry in the
      changegroup. This allows the delta to be expressed against any parent,
      which can result in smaller deltas and more efficient encoding of data.
  
      The *flags* field holds bitwise flags affecting the processing of revision
      data. The following flags are defined:
  
      32768
         Censored revision. The revision's fulltext has been replaced by censor
         metadata. May only occur on file revisions.
  
      16384
         Ellipsis revision. Revision hash does not match data (likely due to
         rewritten parents).
  
      8192
         Externally stored. The revision fulltext contains "key:value" "\n"
         delimited metadata defining an object stored elsewhere. Used by the LFS
         extension.
  
      For historical reasons, the integer values are identical to revlog version
      1 per-revision storage flags and correspond to bits being set in this
      2-byte field. Bits were allocated starting from the most-significant bit,
      hence the reverse ordering and allocation of these flags.
  
      Changeset Segment
      =================
  
      The *changeset segment* consists of a single *delta group* holding

  filelogs.
  </p>
  <p>
  There are 3 versions of changegroups: &quot;1&quot;, &quot;2&quot;, and &quot;3&quot;. From a
  high-level, versions &quot;1&quot; and &quot;2&quot; are almost exactly the same, with the
  only difference being an additional item in the *delta header*. Version
  &quot;3&quot; adds support for storage flags in the *delta header* and optionally
  exchanging treemanifests (enabled by setting an option on the
  &quot;changegroup&quot; part in the bundle2).
  </p>
  <p>
  Changegroups when not exchanging treemanifests consist of 3 logical

  </p>
  <p>
  In version 2 and up, the delta base node is encoded in the entry in the
  changegroup. This allows the delta to be expressed against any parent,
  which can result in smaller deltas and more efficient encoding of data.
  </p>
  <p>
  The *flags* field holds bitwise flags affecting the processing of revision
  data. The following flags are defined:
  </p>
  <dl>
   <dt>32768
   <dd>Censored revision. The revision's fulltext has been replaced by censor metadata. May only occur on file revisions.
   <dt>16384
   <dd>Ellipsis revision. Revision hash does not match data (likely due to rewritten parents).
   <dt>8192
   <dd>Externally stored. The revision fulltext contains &quot;key:value&quot; &quot;\n&quot; delimited metadata defining an object stored elsewhere. Used by the LFS extension.
  </dl>
  <p>
  For historical reasons, the integer values are identical to revlog version 1
  per-revision storage flags and correspond to bits being set in this 2-byte
  field. Bits were allocated starting from the most-significant bit, hence the
  reverse ordering and allocation of these flags.
  </p>
  <h2>Changeset Segment</h2>
  <p>
  The *changeset segment* consists of a single *delta group* holding
  changelog data. The *empty chunk* at the end of the *delta group* denotes