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Michal Charemza michalc

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@michalc
michalc / table_csv_view.py
Created March 7, 2019 09:19
Django + gevent + psycopg2 download whole PostgreSQL table as CSV
import csv
import logging
import gevent
from psycopg2 import (
connect,
sql,
)
from django.conf import (
@michalc
michalc / getaddrinfo_via_libc.py
Last active December 2, 2018 19:51
Own implementation of getaddrinfo by calling libc directly from Python + ctypes, supporting IPv4 and IPv6 (experimental)
from ctypes import (
byref,
c_char_p, c_uint32, c_uint16, c_ubyte,
CDLL,
POINTER,
pointer,
Structure, Union,
sizeof,
)
import platform
@michalc
michalc / path_lock_local_read_write_ancestor.py
Last active November 25, 2018 09:14
Path lock using a read/write/ancestor lock on each ancestor path
import asyncio
import contextlib
import weakref
from fifolock import FifoLock
class ReadAncestor(asyncio.Future):
@staticmethod
def is_compatible(holds):
return not holds[Write]
@michalc
michalc / path_lock_local_read_write.py
Last active November 25, 2018 09:15
Path lock using a read/write lock on each ancestor path
import asyncio
import contextlib
import weakref
from fifolock import FifoLock
class Read(asyncio.Future):
@staticmethod
def is_compatible(holds):
return not holds[Write]
@michalc
michalc / path_lock_global_read_write.py
Last active November 25, 2018 09:17
Path lock using a global read/write lock
import asyncio
import contextlib
from fifolock import FifoLock
class Read(asyncio.Future):
@staticmethod
def is_compatible(holds):
return not holds[Write]
@michalc
michalc / path_lock_global_exclusive.py
Last active November 22, 2018 19:23
Path lock using a global exclusive lock
import asyncio
import contextlib
class PathLock():
def __init__(self):
self.lock = asyncio.Lock()
@contextlib.asynccontextmanager
async def __call__(self, read, write):
@michalc
michalc / asyncio_read_write_lock.py
Last active January 3, 2022 09:46
Python asyncio read-write lock, using a generic first-in-first-out lock
import asyncio
import collections
import contextlib
class Read(asyncio.Future):
@staticmethod
def is_compatible(holds):
return not holds[Write]
class Write(asyncio.Future):
@michalc
michalc / aws_sig_v4_headers_aiohttp_s3_put.py
Created October 28, 2018 10:37
PUTting an object to S3 using aiohttp and aws_sig_v4_headers
import asyncio
import os
import aiohttp
from aws_sig_v4_headers import aws_sig_v4_headers
async def main():
method = 'PUT'
host = 's3-eu-west-1.amazonaws.com'
@michalc
michalc / aws_sig_v4_headers.py
Created October 23, 2018 05:33
Function that calculates AWS signature version 4 headers
import datetime
import hashlib
import hmac
import urllib.parse
def aws_sig_v4_headers(access_key_id, secret_access_key, pre_auth_headers,
service, region, host, method, path, query, payload):
algorithm = 'AWS4-HMAC-SHA256'
@michalc
michalc / normalise_environment.py
Last active October 8, 2023 07:05
Structured data in environment variables: nested dictionaries and lists
def normalise_environment(key_values):
''' Converts denormalised dict of (string -> string) pairs, where the first string
is treated as a path into a nested list/dictionary structure
{
"FOO__1__BAR": "setting-1",
"FOO__1__BAZ": "setting-2",
"FOO__2__FOO": "setting-3",
"FOO__2__BAR": "setting-4",
"FIZZ": "setting-5",