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View absl_flat_hash_map_latency.txt
// Abseil absl::flat_hash_map
// Analysis of the critical path for perfectly predicted load hit.
// https://godbolt.org/z/P_ksaa
//
// x86_64
// Instruction latencies have been entirely ignored.
# rdi = desired key
mov rax, qword ptr [rip + kHashSeed] # [a00] rax = per-process seed (with entropy)
add rax, rdi # [a01] rax = hash so far
@Nexuapex
Nexuapex / bit_cast.h
Created Apr 1, 2018
Minimal-dependencies implementation of bit_cast.
View bit_cast.h
#include <string.h>
#if defined(__has_attribute)
#if __has_attribute(always_inline)
#define ALWAYS_INLINE __attribute__((always_inline))
#endif
#endif
#if defined(_MSC_VER)
// To reduce debug build overhead:
@Nexuapex
Nexuapex / resource_table.cc
Created Apr 26, 2016
Sketch of a few ways to store 8 or 16 elements indexed by a packed byte array.
View resource_table.cc
#include <xmmintrin.h>
#include <stdint.h>
struct ResourceTable8
{
uint64_t type_bits_;
uintptr_t elements_[8];
inline uint64_t mask_for_type(uint8_t type)
{
@Nexuapex
Nexuapex / env.cmd
Created Mar 6, 2015
A Python script that injects environment variables into the calling cmd.exe shell.
View env.cmd
@echo off
rem = """
rem This is a hybrid batch and Python script. The batch (right here) invokes
rem the Python script and treats its standard output as a list of environment
rem variables to set in the current environment.
rem The -x argument causes the Python interpreter to ignore the first line.
rem The -S argument disables the implicit 'site' package import (speed go fast).
FOR /F "tokens=1,2 delims==" %%v IN ('python -x -S "%~f0" %*') DO SET %%v=%%w
GOTO :eof
"""
@Nexuapex
Nexuapex / workerpool.py
Created Jan 8, 2015
Simple Python MPMC queue and thread pool.
View workerpool.py
from __future__ import absolute_import
import sys
import threading
import collections
class WorkerPool(object):
"""A thread pool that processes items from an unbounded work queue, for
simple multi-producer, multi-consumer processes.
@Nexuapex
Nexuapex / Microsoft C++.sublime-build
Created Nov 17, 2014
A simple Sublime Text 3 build system for Visual Studio 2013's C/C++ compiler.
View Microsoft C++.sublime-build
{
"shell_cmd": "\"%VS120COMNTOOLS%\\..\\..\\VC\\vcvarsall.bat\" amd64 && cl /nologo \"$file\"",
"file_regex": "^(.*?)\\(([0-9+])(?:,([0-9+]))?\\)\\s+:\\s+(.*)$",
"working_dir": "${file_path}",
"selector": "source.c, source.c++"
}
View simultaneous_initiation.py
import socket
create_socket = lambda: socket.socket(socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_TCP)
target_port = 49400 # Any port in the ephemeral port range that no process on your machine is using.
port = 0
# Create and bind sockets, working our way through the ephemeral port space, until we get close to our target.
while not (target_port - 5 < port < target_port):
sock = create_socket()
sock.bind(('127.0.0.1', 0))
@Nexuapex
Nexuapex / plaintive_function.cc
Last active Aug 29, 2015
An attempt to reinvent `std::function' that ended up being about things I don't like about C++.
View plaintive_function.cc
// Because it was possible to implement std::move and std::forward<T> as library
// functions, so that's what happened. Now this header is everywhere. This is
// 2,800 lines of kitchen sink for me.
#include <utility>
// C++ has half-decent pattern matching, but only on types. If only some of this
// energy could be thrown at language constructs like `switch'.
//
// Oh, right, and this relies on partial specialization, which only works on
// classes. So you get these pointless classes that contain a single typedef.
@Nexuapex
Nexuapex / inlined.h
Last active Aug 29, 2015
I would get behind this if I could just static_assert(size <= Size) in the placement operator new. Close but no cigar.
View inlined.h
#ifndef INLINED_OBJECT_H
#define INLINED_OBJECT_H
#include <string.h>
template <typename T, size_t Size>
class inlined
{
public:
inlined();
@Nexuapex
Nexuapex / msvcrt_heap_exc.cc
Last active Dec 24, 2015
There's this handy flag on Win32 heap objects called HEAP_GENERATE_EXCEPTIONS, which causes the heap manager to raise a structured exception instead of returning null on a failed allocation. But the C runtime creates its heap behind the scenes and doesn't allow you access to it, and you can't add this flag after creation anyway. Unless you are t…
View msvcrt_heap_exc.cc
#include <malloc.h>
#include <windows.h>
static HANDLE FindCrtHeap()
{
// Pick a block that we know is in the CRT heap.
//
_HEAPINFO crtEntry = {};
if (_HEAPOK != _heapwalk(&crtEntry))
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