view hgext/infinitepush/indexapi.py @ 45095:8e04607023e5

procutil: ensure that procutil.std{out,err}.write() writes all bytes

Python 3 offers different kind of streams and it’s not guaranteed for all of
them that calling write() writes all bytes.

When Python is started in unbuffered mode, sys.std{out,err}.buffer are
instances of io.FileIO, whose write() can write less bytes for
platform-specific reasons (e.g. Linux has a 0x7ffff000 bytes maximum and could
write less if interrupted by a signal; when writing to Windows consoles, it’s
limited to 32767 bytes to avoid the "not enough space" error). This can lead to
silent loss of data, both when using sys.std{out,err}.buffer (which may in fact
not be a buffered stream) and when using the text streams sys.std{out,err}
(I’ve created a CPython bug report for that:
https://bugs.python.org/issue41221).

Python may fix the problem at some point. For now, we implement our own wrapper
for procutil.std{out,err} that calls the raw stream’s write() method until all
bytes have been written. We don’t use sys.std{out,err} for larger writes, so I
think it’s not worth the effort to patch them.

# Infinite push
#
# Copyright 2016 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


class indexapi(object):
    """Class that manages access to infinitepush index.

    This class is a context manager and all write operations (like
    deletebookmarks, addbookmark etc) should use `with` statement:

      with index:
          index.deletebookmarks(...)
          ...
    """

    def __init__(self):
        """Initializes the metadata store connection."""

    def close(self):
        """Cleans up the metadata store connection."""

    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        pass

    def addbundle(self, bundleid, nodesctx):
        """Takes a bundleid and a list of node contexts for each node
        in that bundle and records that."""
        raise NotImplementedError()

    def addbookmark(self, bookmark, node):
        """Takes a bookmark name and hash, and records mapping in the metadata
        store."""
        raise NotImplementedError()

    def addmanybookmarks(self, bookmarks):
        """Takes a dict with mapping from bookmark to hash and records mapping
        in the metadata store."""
        raise NotImplementedError()

    def deletebookmarks(self, patterns):
        """Accepts list of bookmarks and deletes them.
        """
        raise NotImplementedError()

    def getbundle(self, node):
        """Returns the bundleid for the bundle that contains the given node."""
        raise NotImplementedError()

    def getnode(self, bookmark):
        """Returns the node for the given bookmark. None if it doesn't exist."""
        raise NotImplementedError()

    def getbookmarks(self, query):
        """Returns bookmarks that match the query"""
        raise NotImplementedError()

    def saveoptionaljsonmetadata(self, node, jsonmetadata):
        """Saves optional metadata for a given node"""
        raise NotImplementedError()


class indexexception(Exception):
    pass