piker/piker/data/_sharedmem.py

462 lines
13 KiB
Python

# piker: trading gear for hackers
# Copyright (C) 2018-present Tyler Goodlet (in stewardship of piker0)
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Affero General Public License for more details.
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
"""
NumPy compatible shared memory buffers for real-time FSP.
"""
from dataclasses import dataclass, asdict
from sys import byteorder
from typing import List, Tuple, Optional
from multiprocessing.shared_memory import SharedMemory, _USE_POSIX
from multiprocessing import resource_tracker as mantracker
if _USE_POSIX:
from _posixshmem import shm_unlink
import tractor
import numpy as np
from ..log import get_logger
from ._source import base_ohlc_dtype, base_iohlc_dtype
log = get_logger(__name__)
# Tell the "resource tracker" thing to fuck off.
class ManTracker(mantracker.ResourceTracker):
def register(self, name, rtype):
pass
def unregister(self, name, rtype):
pass
def ensure_running(self):
pass
# "know your land and know your prey"
# https://www.dailymotion.com/video/x6ozzco
mantracker._resource_tracker = ManTracker()
mantracker.register = mantracker._resource_tracker.register
mantracker.ensure_running = mantracker._resource_tracker.ensure_running
ensure_running = mantracker._resource_tracker.ensure_running
mantracker.unregister = mantracker._resource_tracker.unregister
mantracker.getfd = mantracker._resource_tracker.getfd
class SharedInt:
"""Wrapper around a single entry shared memory array which
holds an ``int`` value used as an index counter.
"""
def __init__(
self,
shm: SharedMemory,
) -> None:
self._shm = shm
@property
def value(self) -> int:
return int.from_bytes(self._shm.buf, byteorder)
@value.setter
def value(self, value) -> None:
self._shm.buf[:] = value.to_bytes(self._shm.size, byteorder)
def destroy(self) -> None:
if _USE_POSIX:
# We manually unlink to bypass all the "resource tracker"
# nonsense meant for non-SC systems.
shm_unlink(self._shm.name)
@dataclass
class _Token:
"""Internal represenation of a shared memory "token"
which can be used to key a system wide post shm entry.
"""
shm_name: str # this servers as a "key" value
shm_first_index_name: str
shm_last_index_name: str
dtype_descr: List[Tuple[str]]
def __post_init__(self):
# np.array requires a list for dtype
self.dtype_descr = np.dtype(
list(self.dtype_descr)).descr
def as_msg(self):
return asdict(self)
@classmethod
def from_msg(self, msg: dict) -> '_Token':
return msg if isinstance(msg, _Token) else _Token(**msg)
# TODO: this api?
# _known_tokens = tractor.ActorVar('_shm_tokens', {})
# _known_tokens = tractor.ContextStack('_known_tokens', )
# _known_tokens = trio.RunVar('shms', {})
# process-local store of keys to tokens
_known_tokens = {}
def get_shm_token(key: str) -> _Token:
"""Convenience func to check if a token
for the provided key is known by this process.
"""
return _known_tokens.get(key)
def _make_token(
key: str,
dtype: Optional[np.dtype] = None,
) -> _Token:
"""Create a serializable token that can be used
to access a shared array.
"""
dtype = base_iohlc_dtype if dtype is None else dtype
return _Token(
key,
key + "_first",
key + "_last",
np.dtype(dtype).descr
)
class ShmArray:
"""A shared memory ``numpy`` (compatible) array API.
An underlying shared memory buffer is allocated based on
a user specified ``numpy.ndarray``. This fixed size array
can be read and written to by pushing data both onto the "front"
or "back" of a set index range. The indexes for the "first" and
"last" index are themselves stored in shared memory (accessed via
``SharedInt`` interfaces) values such that multiple processes can
interact with the same array using a synchronized-index.
"""
def __init__(
self,
shmarr: np.ndarray,
first: SharedInt,
last: SharedInt,
shm: SharedMemory,
# readonly: bool = True,
) -> None:
self._array = shmarr
# indexes for first and last indices corresponding
# to fille data
self._first = first
self._last = last
self._len = len(shmarr)
self._shm = shm
# pushing data does not write the index (aka primary key)
self._write_fields = list(shmarr.dtype.fields.keys())[1:]
# TODO: ringbuf api?
@property
def _token(self) -> _Token:
return _Token(
self._shm.name,
self._first._shm.name,
self._last._shm.name,
self._array.dtype.descr,
)
@property
def token(self) -> dict:
"""Shared memory token that can be serialized and used by
another process to attach to this array.
"""
return self._token.as_msg()
@property
def index(self) -> int:
return self._last.value % self._len
@property
def array(self) -> np.ndarray:
return self._array[self._first.value:self._last.value]
def last(
self,
length: int = 1,
) -> np.ndarray:
return self.array[-length:]
def push(
self,
data: np.ndarray,
prepend: bool = False,
) -> int:
"""Ring buffer like "push" to append data
into the buffer and return updated "last" index.
"""
length = len(data)
if prepend:
index = self._first.value - length
else:
index = self._last.value
end = index + length
fields = self._write_fields
try:
self._array[fields][index:end] = data[fields][:]
if prepend:
self._first.value = index
else:
self._last.value = end
return end
except ValueError as err:
# shoudl raise if diff detected
self.diff_err_fields(data)
raise err
def diff_err_fields(
self,
data: np.ndarray,
) -> None:
# reraise with any field discrepancy
our_fields, their_fields = (
set(self._array.dtype.fields),
set(data.dtype.fields),
)
only_in_ours = our_fields - their_fields
only_in_theirs = their_fields - our_fields
if only_in_ours:
raise TypeError(
f"Input array is missing field(s): {only_in_ours}"
)
elif only_in_theirs:
raise TypeError(
f"Input array has unknown field(s): {only_in_theirs}"
)
def prepend(
self,
data: np.ndarray,
) -> int:
end = self.push(data, prepend=True)
assert end
def close(self) -> None:
self._first._shm.close()
self._last._shm.close()
self._shm.close()
def destroy(self) -> None:
if _USE_POSIX:
# We manually unlink to bypass all the "resource tracker"
# nonsense meant for non-SC systems.
shm_unlink(self._shm.name)
self._first.destroy()
self._last.destroy()
def flush(self) -> None:
# TODO: flush to storage backend like markestore?
...
# how much is probably dependent on lifestyle
_secs_in_day = int(60 * 60 * 12)
_default_size = 2 * _secs_in_day
def open_shm_array(
key: Optional[str] = None,
size: int = _default_size,
dtype: Optional[np.dtype] = None,
readonly: bool = False,
) -> ShmArray:
"""Open a memory shared ``numpy`` using the standard library.
This call unlinks (aka permanently destroys) the buffer on teardown
and thus should be used from the parent-most accessor (process).
"""
# create new shared mem segment for which we
# have write permission
a = np.zeros(size, dtype=dtype)
a['index'] = np.arange(len(a))
shm = SharedMemory(
name=key,
create=True,
size=a.nbytes
)
array = np.ndarray(a.shape, dtype=a.dtype, buffer=shm.buf)
array[:] = a[:]
array.setflags(write=int(not readonly))
token = _make_token(
key=key,
dtype=dtype
)
# create single entry arrays for storing an first and last indices
first = SharedInt(
shm=SharedMemory(
name=token.shm_first_index_name,
create=True,
size=4, # std int
)
)
last = SharedInt(
shm=SharedMemory(
name=token.shm_last_index_name,
create=True,
size=4, # std int
)
)
last.value = first.value = int(_secs_in_day)
shmarr = ShmArray(
array,
first,
last,
shm,
)
assert shmarr._token == token
_known_tokens[key] = shmarr.token
# "unlink" created shm on process teardown by
# pushing teardown calls onto actor context stack
tractor._actor._lifetime_stack.callback(shmarr.close)
tractor._actor._lifetime_stack.callback(shmarr.destroy)
return shmarr
def attach_shm_array(
token: Tuple[str, str, Tuple[str, str]],
size: int = _default_size,
readonly: bool = True,
) -> ShmArray:
"""Attach to an existing shared memory array previously
created by another process using ``open_shared_array``.
No new shared mem is allocated but wrapper types for read/write
access are constructed.
"""
token = _Token.from_msg(token)
key = token.shm_name
if key in _known_tokens:
assert _known_tokens[key] == token, "WTF"
# attach to array buffer and view as per dtype
shm = SharedMemory(name=key)
shmarr = np.ndarray(
(size,),
dtype=token.dtype_descr,
buffer=shm.buf
)
shmarr.setflags(write=int(not readonly))
first = SharedInt(
shm=SharedMemory(
name=token.shm_first_index_name,
create=False,
size=4, # std int
),
)
last = SharedInt(
shm=SharedMemory(
name=token.shm_last_index_name,
create=False,
size=4, # std int
),
)
# make sure we can read
first.value
sha = ShmArray(
shmarr,
first,
last,
shm,
)
# read test
sha.array
# Stash key -> token knowledge for future queries
# via `maybe_opepn_shm_array()` but only after we know
# we can attach.
if key not in _known_tokens:
_known_tokens[key] = token
# "close" attached shm on process teardown
tractor._actor._lifetime_stack.callback(sha.close)
return sha
def maybe_open_shm_array(
key: str,
dtype: Optional[np.dtype] = None,
**kwargs,
) -> Tuple[ShmArray, bool]:
"""Attempt to attach to a shared memory block using a "key" lookup
to registered blocks in the users overall "system" registryt
(presumes you don't have the block's explicit token).
This function is meant to solve the problem of discovering whether
a shared array token has been allocated or discovered by the actor
running in **this** process. Systems where multiple actors may seek
to access a common block can use this function to attempt to acquire
a token as discovered by the actors who have previously stored
a "key" -> ``_Token`` map in an actor local (aka python global)
variable.
If you know the explicit ``_Token`` for your memory segment instead
use ``attach_shm_array``.
"""
try:
# see if we already know this key
token = _known_tokens[key]
return attach_shm_array(token=token, **kwargs), False
except KeyError:
log.warning(f"Could not find {key} in shms cache")
if dtype:
token = _make_token(key, dtype)
try:
return attach_shm_array(token=token, **kwargs), False
except FileNotFoundError:
log.warning(f"Could not attach to shm with token {token}")
# This actor does not know about memory
# associated with the provided "key".
# Attempt to open a block and expect
# to fail if a block has been allocated
# on the OS by someone else.
return open_shm_array(key=key, dtype=dtype, **kwargs), True