view hgext/infinitepush/store.py @ 48295:bf11ff22a9af

dirstate-v2: freeze the on-disk format

It seems the format as reached a good balance. With a core of new capabilities
that motivated it initially and enough new feature and room for future
improvement to be a clear progress we can set a milestone for.

Having the format frozen will help the feature to get real life testing, outside
of the test suite.

The feature itself stay experimental but the config gains a new name to avoid
people enable non-frozen version by default.

If too many bugs are reported during the RC we might move the format back to
experimental and drop its support in future version (in favor of a new one)

Differential Revision: https://phab.mercurial-scm.org/D11709

# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

# based on bundleheads extension by Gregory Szorc <[e-mail]>

from __future__ import absolute_import

import abc
import os
import subprocess

from mercurial.node import hex
from mercurial.pycompat import open
from mercurial import pycompat
from mercurial.utils import (
    hashutil,
    procutil,
)


class BundleWriteException(Exception):
    pass


class BundleReadException(Exception):
    pass


class abstractbundlestore(object):  # pytype: disable=ignored-metaclass
    """Defines the interface for bundle stores.

    A bundle store is an entity that stores raw bundle data. It is a simple
    key-value store. However, the keys are chosen by the store. The keys can
    be any Python object understood by the corresponding bundle index (see
    ``abstractbundleindex`` below).
    """

    __metaclass__ = abc.ABCMeta

    @abc.abstractmethod
    def write(self, data):
        """Write bundle data to the store.

        This function receives the raw data to be written as a str.
        Throws BundleWriteException
        The key of the written data MUST be returned.
        """

    @abc.abstractmethod
    def read(self, key):
        """Obtain bundle data for a key.

        Returns None if the bundle isn't known.
        Throws BundleReadException
        The returned object should be a file object supporting read()
        and close().
        """


class filebundlestore(object):
    """bundle store in filesystem

    meant for storing bundles somewhere on disk and on network filesystems
    """

    def __init__(self, ui, repo):
        self.ui = ui
        self.repo = repo
        self.storepath = ui.configpath(b'scratchbranch', b'storepath')
        if not self.storepath:
            self.storepath = self.repo.vfs.join(
                b"scratchbranches", b"filebundlestore"
            )
        if not os.path.exists(self.storepath):
            os.makedirs(self.storepath)

    def _dirpath(self, hashvalue):
        """First two bytes of the hash are the name of the upper
        level directory, next two bytes are the name of the
        next level directory"""
        return os.path.join(self.storepath, hashvalue[0:2], hashvalue[2:4])

    def _filepath(self, filename):
        return os.path.join(self._dirpath(filename), filename)

    def write(self, data):
        filename = hex(hashutil.sha1(data).digest())
        dirpath = self._dirpath(filename)

        if not os.path.exists(dirpath):
            os.makedirs(dirpath)

        with open(self._filepath(filename), b'wb') as f:
            f.write(data)

        return filename

    def read(self, key):
        try:
            with open(self._filepath(key), b'rb') as f:
                return f.read()
        except IOError:
            return None


def format_placeholders_args(args, filename=None, handle=None):
    """Formats `args` with Infinitepush replacements.

    Hack to get `str.format()`-ed strings working in a BC way with
    bytes.
    """
    formatted_args = []
    for arg in args:
        if filename and arg == b'{filename}':
            formatted_args.append(filename)
        elif handle and arg == b'{handle}':
            formatted_args.append(handle)
        else:
            formatted_args.append(arg)
    return formatted_args


class externalbundlestore(abstractbundlestore):
    def __init__(self, put_binary, put_args, get_binary, get_args):
        """
        `put_binary` - path to binary file which uploads bundle to external
            storage and prints key to stdout
        `put_args` - format string with additional args to `put_binary`
                     {filename} replacement field can be used.
        `get_binary` - path to binary file which accepts filename and key
            (in that order), downloads bundle from store and saves it to file
        `get_args` - format string with additional args to `get_binary`.
                     {filename} and {handle} replacement field can be used.
        """

        self.put_args = put_args
        self.get_args = get_args
        self.put_binary = put_binary
        self.get_binary = get_binary

    def _call_binary(self, args):
        p = subprocess.Popen(
            pycompat.rapply(procutil.tonativestr, args),
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            close_fds=True,
        )
        stdout, stderr = p.communicate()
        returncode = p.returncode
        return returncode, stdout, stderr

    def write(self, data):
        # Won't work on windows because you can't open file second time without
        # closing it
        # TODO: rewrite without str.format() and replace NamedTemporaryFile()
        # with pycompat.namedtempfile()
        with pycompat.namedtempfile() as temp:
            temp.write(data)
            temp.flush()
            temp.seek(0)
            formatted_args = format_placeholders_args(
                self.put_args, filename=temp.name
            )
            returncode, stdout, stderr = self._call_binary(
                [self.put_binary] + formatted_args
            )

            if returncode != 0:
                raise BundleWriteException(
                    b'Failed to upload to external store: %s' % stderr
                )
            stdout_lines = stdout.splitlines()
            if len(stdout_lines) == 1:
                return stdout_lines[0]
            else:
                raise BundleWriteException(
                    b'Bad output from %s: %s' % (self.put_binary, stdout)
                )

    def read(self, handle):
        # Won't work on windows because you can't open file second time without
        # closing it
        with pycompat.namedtempfile() as temp:
            formatted_args = format_placeholders_args(
                self.get_args, filename=temp.name, handle=handle
            )
            returncode, stdout, stderr = self._call_binary(
                [self.get_binary] + formatted_args
            )

            if returncode != 0:
                raise BundleReadException(
                    b'Failed to download from external store: %s' % stderr
                )
            return temp.read()