from __future__ import print_function
from __future__ import absolute_import
from .mesh import (MeshSocket, MeshConnection)
from .utils import (inherit_doc, getUTC, sanitize_packet, log_entry)
from .base import (Message, flags, to_base_58, from_base_58, MsgPackable,
BaseConnection)
try:
from .cbase import protocol as Protocol
except:
from .base import Protocol
from logging import (DEBUG, INFO)
from typing import (cast, Any, Dict, Iterator, NamedTuple, Tuple, Union)
default_protocol = Protocol('sync', "Plaintext") # SSL")
[docs]class SyncSocket(MeshSocket):
"""This class is used to sync dictionaries between programs. It extends
:py:class:`py2p.mesh.MeshSocket`
.. inheritance-diagram:: py2p.sync.SyncSocket
Because of this inheritance, this can also be used as an alert network
This also implements and optional leasing system by default. This leasing
system means that if node A sets a key, node B cannot overwrite the value
at that key for an hour.
This may be turned off by adding ``leasing=False`` to the constructor.
Added Events:
.. raw:: html
<div id="SyncSocket.Event 'update'"></div>
.. py:function:: Event 'update'(conn, key, data, new_meta)
This event is triggered when a key is updated in your synchronized
dictionary. ``new_meta`` will be an object containing metadata of this
change, including the time of change, and who initiated the change.
:param py2p.sync.SyncSocket conn: A reference to this abstract socket
:param bytes key: The key which has a new value
:param new_data: The new value at that key
:param py2p.sync.metatuple new_meta: Metadata on the key changer
.. raw:: html
<div id="SyncSocket.Event 'delete'"></div>
.. py:function:: Event 'delete'(conn, key)
This event is triggered when a key is deleted from your synchronized
dictionary.
:param py2p.sync.SyncSocket conn: A reference to this abstract socket
:param bytes key: The key which has a new value
"""
__slots__ = ('__leasing', 'data', 'metadata')
@log_entry('py2p.sync.SyncSocket.__init__', DEBUG)
@inherit_doc(MeshSocket.__init__)
def __init__(
self, #type: Any
addr, #type: str
port, #type: int
prot=default_protocol, #type: Protocol
out_addr=None, #type: Union[None, Tuple[str, int]]
debug_level=0, #type: int
leasing=True #type: bool
): #type: (...) -> None
"""Initialize a chord socket"""
protocol_used = Protocol(prot[0] + str(int(leasing)), prot[1])
self.__leasing = leasing #type: bool
super(SyncSocket, self).__init__(addr, port, protocol_used, out_addr,
debug_level)
self.data = cast(Dict[bytes, MsgPackable],
{}) #type: Dict[bytes, MsgPackable]
self.metadata = {} #type: Dict[bytes, metatuple]
self.register_handler(self.__handle_store)
def __check_lease(self, key, new_data, new_meta):
#type: (SyncSocket, bytes, MsgPackable, metatuple) -> bool
meta = self.metadata.get(key, None)
return ((meta is None) or (meta.owner == new_meta.owner) or
(meta.timestamp < getUTC() - 3600) or
(meta.timestamp == new_meta.timestamp and
meta.owner > new_meta.owner) or
(meta.timestamp < new_meta.timestamp and not self.__leasing))
def __store(self, key, new_data, new_meta, error=True):
#type: (SyncSocket, bytes, MsgPackable, metatuple, bool) -> None
"""Private API method for storing data. You have permission to store
something if:
- The network is not enforcing leases, or
- There is no value at that key, or
- The lease on that key has lapsed (not been set in the last hour), or
- You are the owner of that key
Args:
key: The key you wish to store data at
new_data: The data you wish to store in said key
new_meta: The metadata associated with this storage
error: A boolean which says whether to raise a
:py:class:`KeyError` if you can't store there
Raises:
KeyError: If someone else has a lease at this value, and ``error``
is ``True``
"""
if self.__check_lease(key, new_data, new_meta):
if new_data == b'':
del self.data[key]
del self.metadata[key]
self.emit('delete', self, key)
else:
self.metadata[key] = new_meta
self.data[key] = new_data
self.emit('delete', self, key, new_data, new_meta)
elif error:
raise KeyError("You don't have permission to change this yet")
@inherit_doc(MeshSocket._send_peers)
[docs] def _send_peers(self, handler):
#type: (SyncSocket, BaseConnection) -> None
super(SyncSocket, self)._send_peers(handler)
for key in self:
meta = self.metadata[key]
handler.send(flags.whisper, flags.store, key, self[key],
meta.owner, to_base_58(meta.timestamp))
def __handle_store(self, msg, handler):
#type: (SyncSocket, Message, BaseConnection) -> Union[bool, None]
"""This callback is used to deal with data storage signals. Its two
primary jobs are:
- store data in a given key
- delete data in a given key
Args:
msg: A :py:class:`~py2p.base.Message`
handler: A :py:class:`~py2p.mesh.MeshConnection`
Returns:
Either ``True`` or ``None``
"""
packets = msg.packets
if packets[0] == flags.store:
meta = metatuple(msg.sender, msg.time)
if len(packets) == 5:
if self.data.get(packets[1]):
return None
meta = metatuple(packets[3], from_base_58(packets[4]))
self.__store(packets[1], packets[2], meta, error=False)
return True
[docs] def __setitem__(self, key, data):
#type: (SyncSocket, bytes, MsgPackable) -> None
"""Updates the value at a given key.
Args:
key: The key that you wish to update. Must be a :py:class:`str`
or :py:class:`bytes`-like object
value: The value you wish to put at this key.
Raises:
KeyError: If you do not have the lease for this slot. Lease is
given automatically for one hour if the slot is open.
TypeError: If your key is not :py:class:`bytes` -like OR if your
value is not serializable. This means your value must
be one of the following:
- :py:class:`bool`
- :py:class:`float`
- :py:class:`int` (if ``2**64 > x > -2**63``)
- :py:class:`str`
- :py:class:`bytes`
- :py:class:`unicode`
- :py:class:`tuple`
- :py:class:`list`
- :py:class:`dict` (if all keys are :py:class:`unicode`)
"""
new_meta = metatuple(self.id, getUTC())
key = sanitize_packet(key)
self.__store(key, data, new_meta)
self.send(key, data, type=flags.store)
@inherit_doc(__setitem__)
[docs] def set(self, key, data):
#type: (SyncSocket, bytes, MsgPackable) -> None
self.__setitem__(key, data)
[docs] def update(self, update_dict):
#type: (SyncSocket, Dict[bytes, MsgPackable]) -> None
"""Equivalent to :py:meth:`dict.update`
This calls :py:meth:`.SyncSocket.__setitem__` for each key/value
pair in the given dictionary.
Args:
update_dict: A :py:class:`dict`-like object to extract key/value
pairs from. Key and value be a :py:class:`str`
or :py:class:`bytes`-like object
Raises:
KeyError: If you do not have the lease for this slot. Lease is
given automatically for one hour if the slot is open.
"""
for key, value in update_dict.items():
self.__setitem__(key, value)
[docs] def __getitem__(self, key):
#type: (SyncSocket, bytes) -> MsgPackable
"""Looks up the value at a given key.
Args:
key: The key that you wish to check. Must be a :py:class:`str` or
:py:class:`bytes`-like object
Returns:
The value at said key
Raises:
KeyError: If there is no value assigned at that key
"""
key = sanitize_packet(key)
return self.data[key]
[docs] def get(self, key, ifError=None):
#type: (SyncSocket, bytes, Any) -> MsgPackable
"""Retrieves the value at a given key.
Args:
key: The key that you wish to check. Must be a :py:class:`str`
or :py:class:`bytes`-like object
ifError: The value you wish to return on exception (default:
``None``)
Returns:
The value at said key, or the value at ifError if there's an
:py:class:`Exception`
"""
key = sanitize_packet(key)
return self.data.get(key, ifError)
def __len__(self):
#type: (SyncSocket) -> int
return len(self.data)
def __delitem__(self, key):
#type: (SyncSocket, bytes) -> None
self[key] = b''
[docs] def keys(self):
#type: (SyncSocket) -> Iterator[bytes]
"""
Returns:
an iterator of the underlying :py:class:`dict` s keys
"""
return iter(self.data)
@inherit_doc(keys)
[docs] def __iter__(self):
#type: (SyncSocket) -> Iterator[bytes]
return self.keys()
[docs] def values(self):
#type: (SyncSocket) -> Iterator[MsgPackable]
"""
Returns:
an iterator of the underlying :py:class:`dict` s values
"""
return (self[key] for key in self.keys())
[docs] def items(self):
#type: (SyncSocket) -> Iterator[Tuple[bytes, MsgPackable]]
"""
Returns:
an iterator of the underlying :py:class:`dict` s items
"""
return ((key, self[key]) for key in self.keys())
[docs] def pop(self, key, *args):
#type: (SyncSocket, bytes, *Any) -> MsgPackable
"""Returns a value, with the side effect of deleting that association
Args:
Key: The key you wish to look up. Must be a :py:class:`str`
or :py:class:`bytes`-like object
ifError: The value you wish to return on Exception
(default: raise an Exception)
Returns:
The value of the supplied key, or ``ifError``
Raises:
KeyError: If the key does not have an associated value
"""
if len(args):
ret = self.get(key, args[0])
if ret != args[0]:
del self[key]
else:
ret = self[key]
del self[key]
return ret
[docs] def popitem(self):
#type: (SyncSocket) -> Tuple[bytes, MsgPackable]
"""Returns an association, with the side effect of deleting that
association
Returns:
An arbitrary association
"""
key = next(self.keys())
return (key, self.pop(key))
[docs] def copy(self):
#type: (SyncSocket) -> Dict[bytes, MsgPackable]
"""Returns a :py:class:`dict` copy of this synchronized hash table"""
return self.data.copy()