view hgext/remotefilelog/metadatastore.py @ 42050:03f6480bfdda

unshelve: disable unshelve during merge (issue5123)

As stated in the issue5123, unshelve can destroy the second parent of
the context when tried to unshelve with an uncommitted merge. This
patch makes unshelve to abort when called with an uncommitted merge.

See how shelve.mergefiles works. Commit structure looks like this:
```
... -> pctx -> tmpwctx -> shelvectx
                  /
                 /
        second
        merge parent

pctx = parent before merging working context(first merge parent)
tmpwctx = commited working directory after merge(with two parents)
shelvectx = shelved context
```
shelve.mergefiles first updates to pctx then it reverts shelvectx to pctx with:

```
cmdutil.revert(ui, repo, shelvectx, repo.dirstate.parents(),
                       *pathtofiles(repo, files),
                       **{'no_backup': True})
```

Reverting tmpwctx files that were merged from second parent to pctx makes them
added because they are not in pctx.

Changing this revert operation is crucial to restore parents after unshelve.
This is a complicated issue as this is not fixing a regression. Thus, for the
time being, unshelve during an uncommitted merge can be aborted.

(Details taken from http://mercurial.808500.n3.nabble.com/PATCH-V3-shelve-restore-parents-after-unshelve-issue5123-tt4036858.html#a4037408)

Differential Revision: https://phab.mercurial-scm.org/D6169

from __future__ import absolute_import

from mercurial.node import hex, nullid
from . import (
    basestore,
    shallowutil,
)

class unionmetadatastore(basestore.baseunionstore):
    def __init__(self, *args, **kwargs):
        super(unionmetadatastore, self).__init__(*args, **kwargs)

        self.stores = args
        self.writestore = kwargs.get(r'writestore')

        # If allowincomplete==True then the union store can return partial
        # ancestor lists, otherwise it will throw a KeyError if a full
        # history can't be found.
        self.allowincomplete = kwargs.get(r'allowincomplete', False)

    def getancestors(self, name, node, known=None):
        """Returns as many ancestors as we're aware of.

        return value: {
           node: (p1, p2, linknode, copyfrom),
           ...
        }
        """
        if known is None:
            known = set()
        if node in known:
            return []

        ancestors = {}
        def traverse(curname, curnode):
            # TODO: this algorithm has the potential to traverse parts of
            # history twice. Ex: with A->B->C->F and A->B->D->F, both D and C
            # may be queued as missing, then B and A are traversed for both.
            queue = [(curname, curnode)]
            missing = []
            seen = set()
            while queue:
                name, node = queue.pop()
                if (name, node) in seen:
                    continue
                seen.add((name, node))
                value = ancestors.get(node)
                if not value:
                    missing.append((name, node))
                    continue
                p1, p2, linknode, copyfrom = value
                if p1 != nullid and p1 not in known:
                    queue.append((copyfrom or curname, p1))
                if p2 != nullid and p2 not in known:
                    queue.append((curname, p2))
            return missing

        missing = [(name, node)]
        while missing:
            curname, curnode = missing.pop()
            try:
                ancestors.update(self._getpartialancestors(curname, curnode,
                                                           known=known))
                newmissing = traverse(curname, curnode)
                missing.extend(newmissing)
            except KeyError:
                # If we allow incomplete histories, don't throw.
                if not self.allowincomplete:
                    raise
                # If the requested name+node doesn't exist, always throw.
                if (curname, curnode) == (name, node):
                    raise

        # TODO: ancestors should probably be (name, node) -> (value)
        return ancestors

    @basestore.baseunionstore.retriable
    def _getpartialancestors(self, name, node, known=None):
        for store in self.stores:
            try:
                return store.getancestors(name, node, known=known)
            except KeyError:
                pass

        raise KeyError((name, hex(node)))

    @basestore.baseunionstore.retriable
    def getnodeinfo(self, name, node):
        for store in self.stores:
            try:
                return store.getnodeinfo(name, node)
            except KeyError:
                pass

        raise KeyError((name, hex(node)))

    def add(self, name, node, data):
        raise RuntimeError("cannot add content only to remotefilelog "
                           "contentstore")

    def getmissing(self, keys):
        missing = keys
        for store in self.stores:
            if missing:
                missing = store.getmissing(missing)
        return missing

    def markledger(self, ledger, options=None):
        for store in self.stores:
            store.markledger(ledger, options)

    def getmetrics(self):
        metrics = [s.getmetrics() for s in self.stores]
        return shallowutil.sumdicts(*metrics)

class remotefilelogmetadatastore(basestore.basestore):
    def getancestors(self, name, node, known=None):
        """Returns as many ancestors as we're aware of.

        return value: {
           node: (p1, p2, linknode, copyfrom),
           ...
        }
        """
        data = self._getdata(name, node)
        ancestors = shallowutil.ancestormap(data)
        return ancestors

    def getnodeinfo(self, name, node):
        return self.getancestors(name, node)[node]

    def add(self, name, node, parents, linknode):
        raise RuntimeError("cannot add metadata only to remotefilelog "
                           "metadatastore")

class remotemetadatastore(object):
    def __init__(self, ui, fileservice, shared):
        self._fileservice = fileservice
        self._shared = shared

    def getancestors(self, name, node, known=None):
        self._fileservice.prefetch([(name, hex(node))], force=True,
                                   fetchdata=False, fetchhistory=True)
        return self._shared.getancestors(name, node, known=known)

    def getnodeinfo(self, name, node):
        return self.getancestors(name, node)[node]

    def add(self, name, node, data):
        raise RuntimeError("cannot add to a remote store")

    def getmissing(self, keys):
        return keys

    def markledger(self, ledger, options=None):
        pass