Jian Zhang zz-jason

## 2017-03-22.md

      
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              Created
              March 22, 2017 10:13
            
              
                使用 gcc 的 __attribute__ 扩展来控制符号的可见性
              
          
    gcc 4.0 以上的版本中支持通过 __attribute__((visibility("default"))) 来显示符号，__attribute__((visibility("hidden"))) 来隐藏符号
参考：Visibility - GCC WiKi

  
## [C++]2017-03-22_2.md

      
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                / [C++]2017-03-22_2.md
            
            
              Last active
              March 22, 2017 14:52
            
          
    C++ source 文件中的 static 和 unamed namespace

在 C 中，使用 static 关键字来限制变量或者函数只能在当前文件中使用，在 C++ 中弱化了 static 的概念，取而代之的是 unamed namespace，就像下面这样：
namespace {
int sum(int a, int b) {
  return a + b;
}
}

  
## utf8_iterator.h
class Utf8Iterator
{
public:
    Utf8Iterator(const char* data, size_t size): mData(data), mSize(size), mPos(0) {}
    ~Utf8Iterator() {}

    bool HasNext() const
    {
        return mPos < mSize;
    }

## char_to_hex.h
std::string char_to_hex(unsigned char input)
{
    static const char* const dict = "0123456789ABCDEF";
    std::string result("0x");
    result.push_back(dict[input >> 4]);
    result.push_back(dict[input & 0x0F]);
    return result;
}

## sum-jit.cpp
#include <string>
#include <iostream>

#include "llvm/ExecutionEngine/JIT.h"

#include "llvm/ADT/OwningPtr.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/FileSystem.h"

## memory_manager.h
#include <assert.h>

class MemoryManager
{
public:
    MemoryManager();
    ~MemoryManager();
    char* Allocate(size_t bytes);
    char* AllocateAligned(size_t bytes);
    size_t GetTotal() const { return mTotal; }

## latency.txt
Latency Comparison Numbers
--------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

## pool_bench_test.go
package chunk

import (
	"container/list"
	"sync"
	"testing"
)

// implementation and benchmark of colPoolSlice.
type colPoolSlice struct {

## prompt.md

      
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                / prompt.md
            
            
              Last active
              January 4, 2023 05:30
            
              
                prompts
              
          
    bash

export PS1='\n\033[0;33m\u@10.150.180.208:\033[0;34m\w\033[0;32m$(__git_ps1 " (git:%s)") \033[0;39m\n$ '

mysql

export mysql_local = 'mysql --default-character-set=utf8 -h 127.0.0.1 -P 3306 -u root -D test --local-infile --prompt="MySQL(\\u@\\h:\\d) &gt; "'


## .vimrc
""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
" General
""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
" set how many lines of history VIM has to remember
set history=1000

" enable filetype plugins
" filetype plugin on
" filetype indent on
filetype on
	class Utf8Iterator
	{
	public:
	Utf8Iterator(const char* data, size_t size): mData(data), mSize(size), mPos(0) {}
	~Utf8Iterator() {}

	bool HasNext() const
	{
	return mPos < mSize;
	}
	std::string char_to_hex(unsigned char input)
	{
	static const char* const dict = "0123456789ABCDEF";
	std::string result("0x");
	result.push_back(dict[input >> 4]);
	result.push_back(dict[input & 0x0F]);
	return result;
	}
	#include <string>
	#include <iostream>

	#include "llvm/ExecutionEngine/JIT.h"

	#include "llvm/ADT/OwningPtr.h"
	#include "llvm/Bitcode/ReaderWriter.h"
	#include "llvm/IR/LLVMContext.h"
	#include "llvm/IR/Module.h"
	#include "llvm/Support/FileSystem.h"
	#include <assert.h>

	class MemoryManager
	{
	public:
	MemoryManager();
	~MemoryManager();
	char* Allocate(size_t bytes);
	char* AllocateAligned(size_t bytes);
	size_t GetTotal() const { return mTotal; }
	Latency Comparison Numbers
	--------------------------
	L1 cache reference 0.5 ns
	Branch mispredict 5 ns
	L2 cache reference 7 ns 14x L1 cache
	Mutex lock/unlock 25 ns
	Main memory reference 100 ns 20x L2 cache, 200x L1 cache
	Compress 1K bytes with Zippy 3,000 ns 3 us
	Send 1K bytes over 1 Gbps network 10,000 ns 10 us
	Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD
	package chunk

	import (
	"container/list"
	"sync"
	"testing"
	)

	// implementation and benchmark of colPoolSlice.
	type colPoolSlice struct {
	""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
	" General
	""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
	" set how many lines of history VIM has to remember
	set history=1000

	" enable filetype plugins
	" filetype plugin on
	" filetype indent on
	filetype on