erlang

How to format a number with padding in Erlang

耗尽温柔 提交于 2019-12-17 16:32:29
问题 I need to pad the output of an integer to a given length. For example, with a length of 4 digits, the output of the integer 4 is "0004" instead of "4". How can I do this in Erlang? 回答1: adding a bit of explanation to Zed's answer: Erlang Format specification is: ~F.P.PadModC. "~4..0B~n" translates to: ~F. = ~4. (Field width of 4) P. = . (no Precision specified) Pad = 0 (Pad with zeroes) Mod = (no control sequence Modifier specified) C = B (Control sequence B = integer in default base 10) and

What is the best way to learn Erlang?

社会主义新天地 提交于 2019-12-17 14:57:32
问题 Locked . This question and its answers are locked because the question is off-topic but has historical significance. It is not currently accepting new answers or interactions. Other than specific projects (although those are welcome as well)... What tools, books, articles, and other resources should I have at my desk to help me learn Erlang? Also, are there mobile runtimes for Erlang? Please point me in the right direction. Note: yes, I have visited Erlang and Wikipedia, but I'd like to hear

rabbitmq安装

本小妞迷上赌 提交于 2019-12-17 11:45:43
windows环境下的安装 (1)下载并安装 Eralng 准备好otp_win64_20.2.exe (以管理员身份运行安装) (2)下载并安装rabbitmq 配套软件中已提供rabbitmq-server-3.7.4.exe。双击安装,注意不要安装在包含中文和 空格的目录下!安装后window服务中就存在rabbitMQ了,并且是启动状态。 (3)安装管理界面(插件) 进入rabbitMQ安装目录的sbin目录,输入命令 rabbitmq‐plugins enable rabbitmq_management (4)重新启动服务 (5)打开浏览器,地址栏输入http://127.0.0.1:15672 ,即可看到管理界面的登陆页 输入用户名和密码,都为guest 进入主界 docker环境下的安装 (1) 下载 docker pull rabbitmq:management (2)创建容器,rabbitmq需要有映射以下端口: 5671 5672 4369 15671 15672 25672 15672 (if management plugin is enabled) 15671 management监听端口 5672, 5671 (AMQP 0-9-1 without and with TLS) 4369 (epmd) epmd 代表 Erlang 端口映射守护进程

Docker搭建RabbitMQ集群

a 夏天 提交于 2019-12-17 07:16:21
Docker搭建RabbitMQ集群 Docker安装 见 官网 RabbitMQ镜像下载及配置 见 此博文 集群搭建 首先,我们需要启动运行RabbitMQ docker run -d --hostname my-rabbit -p 5671:5671 -p 5672:5672 -p 15671:15671 -p 15672:15672 -p 25672:25672 -p 4369:4369 -v $PWD/rabbitmq-data:/var/rabbitmq/lib --name my_rabbitmq rabbitmq:latest 参数说明: ​ -d:后台进程运行 ​ --hostname:主机名称 ​ -p:端口映射 ​ 15672:http访问端口 ​ 5672:AMQP访问端口 ​ -v:文件映射 ​ --name:容器名称 启动多个RabbitMQ docker run -d --hostname my-rabbit -p 5671:5671 -p 5672:5672 -p 15671:15671 -p 15672:15672 -p 25672:25672 -p 4369:4369 -v $PWD/rabbitmq-data:/var/rabbitmq/lib --name my_rabbitmq1 rabbitmq:latest docker run -d -

Erlang Processes vs Java Threads

旧时模样 提交于 2019-12-17 07:10:03
问题 I am reading "Elixir in Action" book by Saša Jurić, and in the first chapter it says: Erlang processes are completely isolated from each other. They share no memory, and a crash of one process doesn’t cause a crash of other processes. Isn't that true for Java threads as well? I mean when Java thread crashes, it too does not crash other threads - especially, if we are looking at request-processing threads (lets exclude the main thread from this disucussion) 回答1: Repeat after me: "These are

Speed comparison with Project Euler: C vs Python vs Erlang vs Haskell

和自甴很熟 提交于 2019-12-17 02:51:43
问题 I have taken Problem #12 from Project Euler as a programming exercise and to compare my (surely not optimal) implementations in C, Python, Erlang and Haskell. In order to get some higher execution times, I search for the first triangle number with more than 1000 divisors instead of 500 as stated in the original problem. The result is the following: C: lorenzo@enzo:~/erlang$ gcc -lm -o euler12.bin euler12.c lorenzo@enzo:~/erlang$ time ./euler12.bin 842161320 real 0m11.074s user 0m11.070s sys

认识RabbitMQ

纵饮孤独 提交于 2019-12-16 23:23:08
1.RabbitMQ 介绍 1.1应用场景 MQ全称Message Queue,即消息队列,Rabbit Mq使用erlang语言开发,基于AMQP(Advanced Message Queue 高级消息队列协议)协议实现的消息队列,是一种应用程序之间的通信的方法,消息队列在分布式系统开发中应用非常广泛。 其官网地址:http://www.rabbitmq.com a、任务异步处理: 将不需要同步处理的并且耗时长的操作由消息队列通知消息接收方进行异步处理。提高应用 程序的相应时间。 b、应用程序解耦合 mq相当于一个中介,生成方通过mq于消费方进行交互,作为两者中间的一个媒介,将应用程序进行解耦合。 c、市场上还有的消息队列 ActiveMQ,RabbitMQ,ZeroMQ,Kafka,MetaMq,RocketMq,redis. 2、RabbitMQ工作原理 2.1、RabbitMQ工作原理 下图是RabbitMQ的基本结构: 组成部分说明如下: Broker:消息队列服务进程,此进程包含两个部分Exchange(交换机)和Queue(队列)。 Exchange:消费队列交换机,按一定的规则将消息由路由转发到某个队列,对消息进行过滤转发。 Queue:消息队列,存储消息的队列,消息到达队列后并转发给特定的消费方。 Producer:消息生产方,即生产方客户端

windows环境安装RabbitMQ

安稳与你 提交于 2019-12-16 20:34:00
第一步:下载并安装erlang 原因:RabbitMQ服务端代码是使用并发式语言Erlang编写的,安装Rabbit MQ的前提是安装Erlang。 下载地址: http://www.erlang.org/downloads 配置环境变量 变量名:ERLANG_HOME 变量值就是刚才erlang的安装地址,点击确定。 然后双击系统变量path 点击“新建”,将%ERLANG_HOME%\bin加入到path中。 最后windows键+R键,输入cmd,再输入erl,看到版本号就说明erlang安装成功了。 第二步:下载并安装RabbitMQ 下载地址: http://www.rabbitmq.com/download.html 双击下载后的.exe文件,安装过程与erlang的安装过程相同。 RabbitMQ安装好后接下来安装RabbitMQ-Plugins。打开命令行cd,输入RabbitMQ的sbin目录。 我的目录是:D:\Program Files\RabbitMQ Server\rabbitmq_server-3.7.3\sbin 然后在后面输入rabbitmq-plugins enable rabbitmq_management命令进行安装 打开命令行命令行,进入RabbitMQ的安装目录: sbin ,输入 rabbitmqctl status , 如果出现以下的图

update multiple record in erlang

你说的曾经没有我的故事 提交于 2019-12-16 18:07:08
问题 I have a table person with this record -record(person, {id, firstname, lastname, phone}). I want to update the phone of all records of this table Itry with test()-> Newphone ="216", Update=#person{phone=Newphone} , Fun = fun() -> List = mnesia:match_object(Update), lists:foreach(fun(X) -> mnesia:write_object(X) end, List) end, mnesia:transaction(Fun). The table person contains 12 alen dumas 97888888 15 franco mocci 55522225 13 ali othmani 44444449 I want that this table became like this : 12

RabbitMq 安装

青春壹個敷衍的年華 提交于 2019-12-15 03:49:10
系统:centos7 (阿里云服务器) 安装Erlang 确定好你要安装的rabbitmq版本之后,去 这里 看一下与之对应的erlang版本, 否则启动会失败(很重要) 下载最新版本的erlang: // 下载安装包 wget https://packages.erlang-solutions.com/erlang-solutions-1.0-1.noarch.rpm // 升级按转包 rpm -Uvh erlang-solutions-1.0-1.noarch.rpm // 安装 sudo yum install erlang // 查看版本 erl -verison // 产看安装路径 whereis erlang 安装RabbitMq 下载(我以目前最新版本为例): wget https://github.com/rabbitmq/rabbitmq-server/releases/download/v3.8.1/rabbitmq-server-3.8.1-1.el8.noarch.rpm // 安装 yum install rabbitmq-server-3.8.1-1.el8.noarch.rpm // 启动 rabbitmq-server start & // 查看rabbitmq的状态 rabbitmqctl status //