# streamclone.py - producing and consuming streaming repository data

#

# Copyright 2015 Gregory Szorc <gregory.szorc@gmail.com>

#

# 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 time

from .i18n import _

from . import (

    branchmap,

    error,

    store,

    util,

)

def canperformstreamclone(repo, remote, heads, streamrequested=None):

    """Whether it is possible to perform a streaming clone as part of pull.

    Returns a tuple of (supported, requirements). ``supported`` is True if

    streaming clone is supported and False otherwise. ``requirements`` is

    a set of repo requirements from the remote, or ``None`` if stream clone

    isn't supported.

    """

    # Streaming clone only works on empty repositories.

    if len(repo):

        return False, None

    # Streaming clone only works if all data is being requested.

    if heads:

        return False, None

    # If we don't have a preference, let the server decide for us. This

    # likely only comes into play in LANs.

    if streamrequested is None:

        # The server can advertise whether to prefer streaming clone.

        streamrequested = remote.capable('stream-preferred')

    if not streamrequested:

        return False, None

    # In order for stream clone to work, the client has to support all the

    # requirements advertised by the server.

    #

    # The server advertises its requirements via the "stream" and "streamreqs"

    # capability. "stream" (a value-less capability) is advertised if and only

    # if the only requirement is "revlogv1." Else, the "streamreqs" capability

    # is advertised and contains a comma-delimited list of requirements.

    requirements = set()

    if remote.capable('stream'):

        requirements.add('revlogv1')

    else:

        streamreqs = remote.capable('streamreqs')

        # This is weird and shouldn't happen with modern servers.

        if not streamreqs:

            return False, None

        streamreqs = set(streamreqs.split(','))

        # Server requires something we don't support. Bail.

        if streamreqs - repo.supportedformats:

            return False, None

        requirements = streamreqs

    return True, requirements

def maybeperformstreamclone(pullop):

    repo = pullop.repo

    remote = pullop.remote

    r = canperformstreamclone(repo, remote, pullop.heads,

                              streamrequested=pullop.streamclonerequested)

    supported, requirements = r

    if not supported:

        return

    # Save remote branchmap. We will use it later to speed up branchcache

    # creation.

    rbranchmap = None

    if remote.capable('branchmap'):

        rbranchmap = remote.branchmap()

    fp = remote.stream_out()

    l = fp.readline()

    try:

        resp = int(l)

    except ValueError:

        raise error.ResponseError(

            _('unexpected response from remote server:'), l)

    if resp == 1:

        raise util.Abort(_('operation forbidden by server'))

    elif resp == 2:

        raise util.Abort(_('locking the remote repository failed'))

    elif resp != 0:

        raise util.Abort(_('the server sent an unknown error code'))

def allowservergeneration(ui):

    """Whether streaming clones are allowed from the server."""

    return ui.configbool('server', 'uncompressed', True, untrusted=True)

# This is it's own function so extensions can override it.

def _walkstreamfiles(repo):

    return repo.store.walk()

def generatev1(repo):

    """Emit content for version 1 of a streaming clone.

    This is a generator of raw chunks that constitute a streaming clone.

    The stream begins with a line of 2 space-delimited integers containing the

    number of entries and total bytes size.

    Next, are N entries for each file being transferred. Each file entry starts

    as a line with the file name and integer size delimited by a null byte.

    The raw file data follows. Following the raw file data is the next file

    entry, or EOF.

    When used on the wire protocol, an additional line indicating protocol

    success will be prepended to the stream. This function is not responsible

    for adding it.

    This function will obtain a repository lock to ensure a consistent view of

    the store is captured. It therefore may raise LockError.

    """

    entries = []

    total_bytes = 0

    # Get consistent snapshot of repo, lock during scan.

    lock = repo.lock()

    try:

        repo.ui.debug('scanning\n')

        for name, ename, size in _walkstreamfiles(repo):

            if size:

                entries.append((name, size))

                total_bytes += size

    finally:

            lock.release()

    repo.ui.debug('%d files, %d bytes to transfer\n' %

                  (len(entries), total_bytes))

    yield '%d %d\n' % (len(entries), total_bytes)

    svfs = repo.svfs

    oldaudit = svfs.mustaudit

    debugflag = repo.ui.debugflag

    svfs.mustaudit = False

    try:

        for name, size in entries:

            if debugflag:

                repo.ui.debug('sending %s (%d bytes)\n' % (name, size))

            # partially encode name over the wire for backwards compat

            yield '%s\0%d\n' % (store.encodedir(name), size)

            if size <= 65536:

                fp = svfs(name)

                try:

                    data = fp.read(size)

                finally:

                    fp.close()

                yield data

            else:

                for chunk in util.filechunkiter(svfs(name), limit=size):

                    yield chunk

    finally:

        svfs.mustaudit = oldaudit

def consumev1(repo, fp):

    """Apply the contents from version 1 of a streaming clone file handle.

    This takes the output from "streamout" and applies it to the specified

    repository.

    Like "streamout," the status line added by the wire protocol is not handled

    by this function.

    """

    lock = repo.lock()

    try:

        repo.ui.status(_('streaming all changes\n'))

        l = fp.readline()

        try:

            total_files, total_bytes = map(int, l.split(' ', 1))

        except (ValueError, TypeError):

            raise error.ResponseError(

                _('unexpected response from remote server:'), l)

        repo.ui.status(_('%d files to transfer, %s of data\n') %

                       (total_files, util.bytecount(total_bytes)))

        handled_bytes = 0

        repo.ui.progress(_('clone'), 0, total=total_bytes)

        start = time.time()

        tr = repo.transaction(_('clone'))

        try:

            for i in xrange(total_files):

                # XXX doesn't support '\n' or '\r' in filenames

                l = fp.readline()

                try:

                    name, size = l.split('\0', 1)

                    size = int(size)

                except (ValueError, TypeError):

                    raise error.ResponseError(

                        _('unexpected response from remote server:'), l)

                if repo.ui.debugflag:

                    repo.ui.debug('adding %s (%s)\n' %

                                  (name, util.bytecount(size)))

                # for backwards compat, name was partially encoded

                ofp = repo.svfs(store.decodedir(name), 'w')

                for chunk in util.filechunkiter(fp, limit=size):

                    handled_bytes += len(chunk)

                    repo.ui.progress(_('clone'), handled_bytes,

                                     total=total_bytes)

                    ofp.write(chunk)

                ofp.close()

            tr.close()

        finally:

            tr.release()

        # Writing straight to files circumvented the inmemory caches

        repo.invalidate()

        elapsed = time.time() - start

        if elapsed <= 0:

            elapsed = 0.001

        repo.ui.progress(_('clone'), None)

        repo.ui.status(_('transferred %s in %.1f seconds (%s/sec)\n') %

                       (util.bytecount(total_bytes), elapsed,

                        util.bytecount(total_bytes / elapsed)))

    finally:

        lock.release()