view hgext/lfs/blobstore.py @ 35280:8e72f9152c4d

lfs: introduce a user level cache for lfs files

This is the same mechanism in place for largefiles, and solves several problems
working with multiple local repositories.  The existing largefiles method is
reused in place, because I suspect that there are other functions that can be
shared.  If we wait a bit to identify more before `hg cp lfutil.py ...`, the
history will be easier to trace.

The push between repo14 and repo15 in test-lfs.t arguably shouldn't be uploading
any files with a local push.  Maybe we can revisit that when `hg push` without
'lfs.url' can upload files to the push destination.  Then it would be consistent
for blobs in a local push to be linked to the local destination's cache.

The cache property is added to run-tests.py, the same as the largefiles
property, so that test generated files don't pollute the real location.  Having
files available locally broke a couple existing lfs-test-server tests, so the
cache is cleared in a few places to force file download.

# blobstore.py - local and remote (speaking Git-LFS protocol) blob storages
#
# Copyright 2017 Facebook, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import json
import os
import re

from mercurial.i18n import _

from mercurial import (
    error,
    url as urlmod,
    util,
    vfs as vfsmod,
)

from ..largefiles import lfutil

# 64 bytes for SHA256
_lfsre = re.compile(r'\A[a-f0-9]{64}\Z')

class lfsvfs(vfsmod.vfs):
    def join(self, path):
        """split the path at first two characters, like: XX/XXXXX..."""
        if not _lfsre.match(path):
            raise error.ProgrammingError('unexpected lfs path: %s' % path)
        return super(lfsvfs, self).join(path[0:2], path[2:])

class filewithprogress(object):
    """a file-like object that supports __len__ and read.

    Useful to provide progress information for how many bytes are read.
    """

    def __init__(self, fp, callback):
        self._fp = fp
        self._callback = callback # func(readsize)
        fp.seek(0, os.SEEK_END)
        self._len = fp.tell()
        fp.seek(0)

    def __len__(self):
        return self._len

    def read(self, size):
        if self._fp is None:
            return b''
        data = self._fp.read(size)
        if data:
            if self._callback:
                self._callback(len(data))
        else:
            self._fp.close()
            self._fp = None
        return data

class local(object):
    """Local blobstore for large file contents.

    This blobstore is used both as a cache and as a staging area for large blobs
    to be uploaded to the remote blobstore.
    """

    def __init__(self, repo):
        fullpath = repo.svfs.join('lfs/objects')
        self.vfs = lfsvfs(fullpath)
        usercache = lfutil._usercachedir(repo.ui, 'lfs')
        self.cachevfs = lfsvfs(usercache)

    def write(self, oid, data):
        """Write blob to local blobstore."""
        with self.vfs(oid, 'wb', atomictemp=True) as fp:
            fp.write(data)

        # XXX: should we verify the content of the cache, and hardlink back to
        # the local store on success, but truncate, write and link on failure?
        if not self.cachevfs.exists(oid):
            lfutil.link(self.vfs.join(oid), self.cachevfs.join(oid))

    def read(self, oid):
        """Read blob from local blobstore."""
        if not self.vfs.exists(oid):
            lfutil.link(self.cachevfs.join(oid), self.vfs.join(oid))
        return self.vfs.read(oid)

    def has(self, oid):
        """Returns True if the local blobstore contains the requested blob,
        False otherwise."""
        return self.cachevfs.exists(oid) or self.vfs.exists(oid)

class _gitlfsremote(object):

    def __init__(self, repo, url):
        ui = repo.ui
        self.ui = ui
        baseurl, authinfo = url.authinfo()
        self.baseurl = baseurl.rstrip('/')
        self.urlopener = urlmod.opener(ui, authinfo)
        self.retry = ui.configint('lfs', 'retry')

    def writebatch(self, pointers, fromstore):
        """Batch upload from local to remote blobstore."""
        self._batch(pointers, fromstore, 'upload')

    def readbatch(self, pointers, tostore):
        """Batch download from remote to local blostore."""
        self._batch(pointers, tostore, 'download')

    def _batchrequest(self, pointers, action):
        """Get metadata about objects pointed by pointers for given action

        Return decoded JSON object like {'objects': [{'oid': '', 'size': 1}]}
        See https://github.com/git-lfs/git-lfs/blob/master/docs/api/batch.md
        """
        objects = [{'oid': p.oid(), 'size': p.size()} for p in pointers]
        requestdata = json.dumps({
            'objects': objects,
            'operation': action,
        })
        batchreq = util.urlreq.request('%s/objects/batch' % self.baseurl,
                                       data=requestdata)
        batchreq.add_header('Accept', 'application/vnd.git-lfs+json')
        batchreq.add_header('Content-Type', 'application/vnd.git-lfs+json')
        try:
            rawjson = self.urlopener.open(batchreq).read()
        except util.urlerr.httperror as ex:
            raise LfsRemoteError(_('LFS HTTP error: %s (action=%s)')
                                 % (ex, action))
        try:
            response = json.loads(rawjson)
        except ValueError:
            raise LfsRemoteError(_('LFS server returns invalid JSON: %s')
                                 % rawjson)
        return response

    def _checkforservererror(self, pointers, responses):
        """Scans errors from objects

        Returns LfsRemoteError if any objects has an error"""
        for response in responses:
            error = response.get('error')
            if error:
                ptrmap = {p.oid(): p for p in pointers}
                p = ptrmap.get(response['oid'], None)
                if error['code'] == 404 and p:
                    filename = getattr(p, 'filename', 'unknown')
                    raise LfsRemoteError(
                        _(('LFS server error. Remote object '
                          'for file %s not found: %r')) % (filename, response))
                raise LfsRemoteError(_('LFS server error: %r') % response)

    def _extractobjects(self, response, pointers, action):
        """extract objects from response of the batch API

        response: parsed JSON object returned by batch API
        return response['objects'] filtered by action
        raise if any object has an error
        """
        # Scan errors from objects - fail early
        objects = response.get('objects', [])
        self._checkforservererror(pointers, objects)

        # Filter objects with given action. Practically, this skips uploading
        # objects which exist in the server.
        filteredobjects = [o for o in objects if action in o.get('actions', [])]
        # But for downloading, we want all objects. Therefore missing objects
        # should be considered an error.
        if action == 'download':
            if len(filteredobjects) < len(objects):
                missing = [o.get('oid', '?')
                           for o in objects
                           if action not in o.get('actions', [])]
                raise LfsRemoteError(
                    _('LFS server claims required objects do not exist:\n%s')
                    % '\n'.join(missing))

        return filteredobjects

    def _basictransfer(self, obj, action, localstore, progress=None):
        """Download or upload a single object using basic transfer protocol

        obj: dict, an object description returned by batch API
        action: string, one of ['upload', 'download']
        localstore: blobstore.local

        See https://github.com/git-lfs/git-lfs/blob/master/docs/api/\
        basic-transfers.md
        """
        oid = str(obj['oid'])

        href = str(obj['actions'][action].get('href'))
        headers = obj['actions'][action].get('header', {}).items()

        request = util.urlreq.request(href)
        if action == 'upload':
            # If uploading blobs, read data from local blobstore.
            request.data = filewithprogress(localstore.vfs(oid), progress)
            request.get_method = lambda: 'PUT'

        for k, v in headers:
            request.add_header(k, v)

        response = b''
        try:
            req = self.urlopener.open(request)
            while True:
                data = req.read(1048576)
                if not data:
                    break
                if action == 'download' and progress:
                    progress(len(data))
                response += data
        except util.urlerr.httperror as ex:
            raise LfsRemoteError(_('HTTP error: %s (oid=%s, action=%s)')
                                 % (ex, oid, action))

        if action == 'download':
            # If downloading blobs, store downloaded data to local blobstore
            localstore.write(oid, response)

    def _batch(self, pointers, localstore, action):
        if action not in ['upload', 'download']:
            raise error.ProgrammingError('invalid Git-LFS action: %s' % action)

        response = self._batchrequest(pointers, action)
        prunningsize = [0]
        objects = self._extractobjects(response, pointers, action)
        total = sum(x.get('size', 0) for x in objects)
        topic = {'upload': _('lfs uploading'),
                 'download': _('lfs downloading')}[action]
        if self.ui.verbose and len(objects) > 1:
            self.ui.write(_('lfs: need to transfer %d objects (%s)\n')
                          % (len(objects), util.bytecount(total)))
        self.ui.progress(topic, 0, total=total)
        def progress(size):
            # advance progress bar by "size" bytes
            prunningsize[0] += size
            self.ui.progress(topic, prunningsize[0], total=total)
        for obj in sorted(objects, key=lambda o: o.get('oid')):
            objsize = obj.get('size', 0)
            if self.ui.verbose:
                if action == 'download':
                    msg = _('lfs: downloading %s (%s)\n')
                elif action == 'upload':
                    msg = _('lfs: uploading %s (%s)\n')
                self.ui.write(msg % (obj.get('oid'), util.bytecount(objsize)))
            origrunningsize = prunningsize[0]
            retry = self.retry
            while True:
                prunningsize[0] = origrunningsize
                try:
                    self._basictransfer(obj, action, localstore,
                                        progress=progress)
                    break
                except Exception as ex:
                    if retry > 0:
                        if self.ui.verbose:
                            self.ui.write(
                                _('lfs: failed: %r (remaining retry %d)\n')
                                % (ex, retry))
                        retry -= 1
                        continue
                    raise

        self.ui.progress(topic, pos=None, total=total)

    def __del__(self):
        # copied from mercurial/httppeer.py
        urlopener = getattr(self, 'urlopener', None)
        if urlopener:
            for h in urlopener.handlers:
                h.close()
                getattr(h, "close_all", lambda : None)()

class _dummyremote(object):
    """Dummy store storing blobs to temp directory."""

    def __init__(self, repo, url):
        fullpath = repo.vfs.join('lfs', url.path)
        self.vfs = lfsvfs(fullpath)

    def writebatch(self, pointers, fromstore):
        for p in pointers:
            content = fromstore.read(p.oid())
            with self.vfs(p.oid(), 'wb', atomictemp=True) as fp:
                fp.write(content)

    def readbatch(self, pointers, tostore):
        for p in pointers:
            content = self.vfs.read(p.oid())
            tostore.write(p.oid(), content)

class _nullremote(object):
    """Null store storing blobs to /dev/null."""

    def __init__(self, repo, url):
        pass

    def writebatch(self, pointers, fromstore):
        pass

    def readbatch(self, pointers, tostore):
        pass

class _promptremote(object):
    """Prompt user to set lfs.url when accessed."""

    def __init__(self, repo, url):
        pass

    def writebatch(self, pointers, fromstore, ui=None):
        self._prompt()

    def readbatch(self, pointers, tostore, ui=None):
        self._prompt()

    def _prompt(self):
        raise error.Abort(_('lfs.url needs to be configured'))

_storemap = {
    'https': _gitlfsremote,
    'http': _gitlfsremote,
    'file': _dummyremote,
    'null': _nullremote,
    None: _promptremote,
}

def remote(repo):
    """remotestore factory. return a store in _storemap depending on config"""
    defaulturl = ''

    # convert deprecated configs to the new url. TODO: remove this if other
    # places are migrated to the new url config.
    # deprecated config: lfs.remotestore
    deprecatedstore = repo.ui.config('lfs', 'remotestore')
    if deprecatedstore == 'dummy':
        # deprecated config: lfs.remotepath
        defaulturl = 'file://' + repo.ui.config('lfs', 'remotepath')
    elif deprecatedstore == 'git-lfs':
        # deprecated config: lfs.remoteurl
        defaulturl = repo.ui.config('lfs', 'remoteurl')
    elif deprecatedstore == 'null':
        defaulturl = 'null://'

    url = util.url(repo.ui.config('lfs', 'url', defaulturl))
    scheme = url.scheme
    if scheme not in _storemap:
        raise error.Abort(_('lfs: unknown url scheme: %s') % scheme)
    return _storemap[scheme](repo, url)

class LfsRemoteError(error.RevlogError):
    pass