nasacj

import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import javax.imageio.ImageIO;

public class ReadBufferedImageFromByte {

nasacj

Maven Dependency:

    <dependency>
      <groupId>com.jhlabs</groupId>
      <artifactId>filters</artifactId>
      <version>2.0.235</version>
    </dependency>

nasacj

Usage

You can make you C++ class derive from boost::noncopyable, which makes cannot be copied. The usage is very simple as following

#include <boost/core/noncopyable.hpp>

class your_class :
  private boost::noncopyable
{
  // ...
};

nasacj

/* int
 * inet_pton4(src, dst)
 *	like inet_aton() but without all the hexadecimal and shorthand.
 * return:
 *	1 if `src' is a valid dotted quad, else 0.
 * notice:
 *	does not touch `dst' unless it's returning 1.
 * author:
 *	Paul Vixie, 1996.
 */

nasacj

/* From openssh4.3p2 compat/inet_aton.c */
/*
 * Copyright (c) 1983, 1990, 1993
 *    The Regents of the University of California.  All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.

nasacj

#include <stdint.h>
#include <stdio.h>
#include <cassert>

static __inline int isdigit(char c)
{
  return c >= '0' && c <= '9';
}

int aton(const char* ip, int* inet_addr) {

nasacj

#include <stdio.h>
#include <unistd.h>

#define ONE_MB (1024 * 1024)

int main()
{
    printf("The number of processors configured is :%ld\n",
        sysconf(_SC_NPROCESSORS_CONF));
    printf("The number of processors currently online (available) is :%ld\n",

nasacj

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/hardirq.h>
#include <linux/preempt.h>
#include <linux/sched.h>
#include <linux/slab.h>

#define SIZE_OF_STAT 100000
#define BOUND_OF_LOOP 1000

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#include <cstdint>
#include <iostream>
//#include <linux/preempt.h>

__attribute__((always_inline)) uint64_t perf_counter(void)
{
  uint32_t lo, hi;
  // take time stamp counter, rdtscp does serialize by itself, and is much cheaper than using CPUID
  __asm__ __volatile__ (
      "rdtscp" : "=a"(lo), "=d"(hi)

nasacj

In my time at Headlands Technologies, I’ve gotten the opportunity to build some utilities that have improved the ergonomics of maintaining high-performance C++ codebases. This article will give a generic overview of one of those utilities, OutOfLine.

Let’s start with a motivating example. Suppose you have a system that opens a very large number of paths. Maybe they are files, maybe they are named UNIX sockets, maybe pipes. But for whatever reason, you open a lot of file descriptors at startup, then you do a lot of processing on those descriptors, and finally when you’re done you close the descriptors and unlink the paths.

An (abbreviated) initial design might look like this:

class UnlinkingFD {
  std::string path;
 public:
 int fd;