Mercurial > hgsubversion
view notes/metadata.txt @ 1450:3c4fbf59e503
svnmeta: do not add instance references to the class object
This is part of a bigger plan to prevent a fd leak by making sure the sqlite
connection object is garbage collected.
Usually this is not a very serious issue but the testing framework will run
all tests in a single process by default. The fd leak will make tests fail
on systems with a low RLIMIT_NOFILE.
Previously, when we are adding new properties to the SVNMeta class, we bind
the current instance in the closure, which essentially prevents any SVNMeta
instances from being garbage collected (and its state like revmap). This
patch changed "self" from the closure one to the lambda argument to address
the issue.
| author | Jun Wu <quark@fb.com> |
|---|---|
| date | Fri, 27 May 2016 01:42:55 +0100 |
| parents | ba801f44d240 |
| children |
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Branches -------- In order to handle branches that are not immediate children of /branches/, the following information must be stored in the revmap: revision path Where path is the actual relative path of the branch in svn. An example, with the previous format for clarification: New | Old 3 <hash> trunk | 3 <hash> 4 <hash> branches/foo | 4 <hash> foo Tags ---- Note that if a tag is committed to, we can handle that case by making a branch and then marking it as deleted. The revmap line would look something like this: 10 <hash> tags/the_tag And the commit would be done on the hg branch 'modified-tag/the_tag'. Note that if this was 'tags/releases/1.0.0', then the branch would be 'modified-tag/releases/1.0.0'. Detecting Closing of Branches ----------------------------- Subversion users typically remove branches when done with them. This means that if a commit performs a delete operation on the '' path inside a branch, we can be sure that the branch no longer exists. The branch should then be marked as inactive. Closing Branches ---------------- As of this writing, Mercurial marks branches as inactive by merging them so they have no active heads. In order to mark a branch as closed, the active head on the branch will be used as the first parent of the new changeset, and the second changeset will be either the active head on the hg branch 'closed-branches' or be the nullrev. The commit to mark the branch as inactive will happen on the 'closed-branches' branch in Mercurial. Recovery -------- hgsubversion stores several pieces of essential metadata in .hg/svn/. In order to rebuild this data, the key 'convert_revision' should be stored in the extra dictionary of the converted revision. The key should contain data in the format: 'svn:<uuid>/abs/path@<rev>' where <uuid> is the repo UUID, /abs/path is the absolute path to the location the edits were made in Subversion (that is, if it was a trunk commit on /foo/trunk, then /foo/trunk is what gets stored here, even though the project root does not equal the repo root), and <rev> is the revision number of the change in Subversion. This key (and its contents) have been chosen to be compatible with the convert extension so that repos originally converted to hg using convert can be maintained using hgsubversion if desired. Tags (tag_info) can be reconstructed by listing the tags directory and then running log on each tag to determine its parent changeset. The last revision converted (last_rev) can be converted simply by using the highest revision number encountered while rebuilding the revision map. The legacy tag_locations file does not need to be replaced - it will be obsoleted as part of the long-term branch refactor. The url will have to be provided by the user. The uuid can be re-requested from the repository. branch_info can be rebuilt during the rebuild of the revision map by recording the revisions of all active heads of server-side branches. branch_info contains a map from branch: (parent_branch, parent_branch_rev, branch_created_rev)