1
* Write-once store of files identified by globally-unique names
2
(e.g. hashes or UUIDs).
4
Simplest option is to just dump them in a directory.
6
Optionally do delta-compression between similar/related files; or
7
build this on top of deltas.
9
* Tree manifests/inventories which say which files should be assembled at
10
particular points to build a tree. These too can be stored indexed
13
- Reconstruct a revision by pulling out the manifest and then all
16
- Manipulate working copy of inventory by add/mv/remove/commands.
20
- Calculate diffs between two file versions, just by getting them
23
- Retrieve deltas between any two revisions: requires looking for
24
changes to the structure of the tree, and then text changes for
27
- Deltas may be either stored or calculated on demand. They can be
28
put in the store just indexed by the from and to manifest id.
30
- Calculate diff between a previous revision and the working copy.
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* Commit and retrieve revisions
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- Revisions hold metadata (date, committer, comment, optional
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parents, merged patches), and a pointer to the inventory.
37
- Stored in a write-once store.
39
* Branch holds a linear history of revisions.
41
- This is mostly redundant; we could just remember the current base
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revision and walk backwards from there. But it still seems
43
possibly useful to hold; we can check that the two are always
46
(This suggests that we actually *could* do ``switch`` if we
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really wanted to, by replacing the revision history and head
48
revision. But I don't think it's a good idea.)
50
- Can add a new revision to the end.
52
- By indexing into this can translate between 0-based revision
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numbers and revision ids.
55
- By walking through and looking at revision dates can find
56
revisions in a particular date range.
58
* Calculations on branch histories:
60
- Find if one branch is a prefix of another.
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- Find the latest common ancestor of another.
64
* Three-way merge between revisions
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- Resolve shape of directory
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- Then resolve textual conflicts
70
* Pull/push changes when they perfectly match
72
- Possible when the destination is a prefix of the source
74
- Just move all revisions, manifests and texts across, and
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* Merge all changes from one branch into another
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* Signatures applied to revisions
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- There is a separable module for checking a signature: this is
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passed the claimed author, changeset, date. This needs to fetch
82
an appropriate key, decide if it is trusted to correspond to that
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author, is not revoked, etc.
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- If it is unknown, untrusted, revoked, etc, that is reported.
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Depending on a paranoia level it may cause the operation to
added
removed
doc/layers.txt
