view hgext/remotefilelog/metadatastore.py @ 48973:e2f8ed37201c stable

rust-status: cap the number of concurrent threads to 16

During benchmarking it was determined that the use of more threads is very
advantageous... until we use more than 16. This is most likely due to some
resource contention (thrashing, etc.). Until we have time to figure out and
fix the underlying cause, let's just cap at 16 threads.

Differential Revision: https://phab.mercurial-scm.org/D12384

from __future__ import absolute_import

from mercurial.node import (
    hex,
    sha1nodeconstants,
)
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('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('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 != sha1nodeconstants.nullid and p1 not in known:
                    queue.append((copyfrom or curname, p1))
                if p2 != sha1nodeconstants.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(
            b"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(
            b"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(b"cannot add to a remote store")

    def getmissing(self, keys):
        return keys

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