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package main

import (
	"fmt"
)

type Person struct{
	Name string
}

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package main

import (
	"bytes"
	"io"
	"io/ioutil"
	"log"
	"strings"
)

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// Copyright 2015 The Cockroach Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,

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package grpc

import (
	"math"
	"time"

	"github.com/davecgh/go-spew/spew"
	"github.com/facebookgo/stack"
	"github.com/grpc-ecosystem/go-grpc-middleware"
	grpclogrus "github.com/grpc-ecosystem/go-grpc-middleware/logging/logrus"

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## 系统执行一条SQL，到底慢在哪里？

如何跟踪一个分布式事务的所有行为？使用 [opentracing](http://opentracing.io/)！ opentracing 是一个标准的分布式 tracing 的协议。支持 Go, JavaScript, Java, Python, Ruby, PHP, Objective-C, C++, C# 等等许多的语言（暂时没看到 rust 的库）。

[一些基本的概念](https://github.com/opentracing/specification/blob/master/specification.md#the-opentracing-data-model)：一个 Trace 是由许多 Span 构成的一个有向无环图。Span 之间的边的关系叫做 Reference。

Span 里面的信息包括：操作的名字，开始时间和结束时间，可以附带多个 key:value 构成的 Tags(key必须是string，value可以是 string, bool 或者数字)，还可以附带 Logs 信息(不一定所有的实现都支持)，也是 key:value形式。

下面例子是一个 Trace，里面有8个 Span：

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-- Spawn a command in the background, optionally redirecting stderr and stdout
--
-- requiring this file returns a function(cmd_line, stdout_redirect, stderr_redirect)
--
-- `cmd_line` is the command with possible arguments
-- optional `stdout_redirect` is io.stdout, io.stderr, or a filename.  default/nil is io.stdout
-- optional `stderr_redirect` is io.stdout, io.stderr, or a filename.  default/nil is io.stderr
--
-- Example:
--     luajit -e 'require("spawn")("cat /etc/network/interfaces", "foo1", io.stdout)'

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func EqualWithDuration(t *testing.T, expected, actual interface{}, delta time.Duration) bool {
	a := reflect.ValueOf(actual)
	e := reflect.ValueOf(expected)

	for i := 0; i < a.NumField(); i++ {
		if a.Field(i).Type() == reflect.TypeOf(time.Time{}) {
			assert.WithinDuration(t, e.Field(i).Interface().(time.Time), a.Field(i).Interface().(time.Time), delta)
		} else {
			assert.Equal(t, e.Field(i).Interface(), a.Field(i).Interface())
		}

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package mail

import "time"

type From []Mailbox

type Sender Mailbox

type ReplyTo []Address

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SET @tables = NULL;
SELECT GROUP_CONCAT(table_schema, '.', table_name)
  INTO @tables
  FROM information_schema.tables 
 WHERE table_schema = 'ippart';
SET @tables = CONCAT('DROP TABLE ', @tables);
PREPARE stmt FROM @tables;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

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```
$ shopt -q login_shell && echo 'Login shell' || echo 'Not login shell'
```