hgext/infinitepush/store.py

# 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 hashlib
import os
import subprocess
import tempfile

NamedTemporaryFile = tempfile.NamedTemporaryFile

class BundleWriteException(Exception):
    pass

class BundleReadException(Exception):
    pass

class abstractbundlestore(object):
    """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('scratchbranch', 'storepath')
        if not self.storepath:
            self.storepath = self.repo.vfs.join("scratchbranches",
                                                "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 = hashlib.sha1(data).hexdigest()
        dirpath = self._dirpath(filename)

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

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

        return filename

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

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(
            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
        with NamedTemporaryFile() as temp:
            temp.write(data)
            temp.flush()
            temp.seek(0)
            formatted_args = [arg.format(filename=temp.name)
                              for arg in self.put_args]
            returncode, stdout, stderr = self._call_binary(
                [self.put_binary] + formatted_args)

            if returncode != 0:
                raise BundleWriteException(
                    'Failed to upload to external store: %s' % stderr)
            stdout_lines = stdout.splitlines()
            if len(stdout_lines) == 1:
                return stdout_lines[0]
            else:
                raise BundleWriteException(
                    '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 NamedTemporaryFile() as temp:
            formatted_args = [arg.format(filename=temp.name, handle=handle)
                              for arg in self.get_args]
            returncode, stdout, stderr = self._call_binary(
                [self.get_binary] + formatted_args)

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