Programming VIP

preface Purpose of this Code: as a door lock, raspberry pie has an id that uniquely identifies the door lock. In order to enable raspberry pie and app to communicate effectively with each other, tcp sockets are used. In order to easily identify the content of communication, the codes of the three are utf-8 java Server theory Write the s ...

Asynchronous notification When using sleep wake and POLL mechanisms, sleep is required. When waiting for an event to occur, the difference between them is that the latter can specify the duration of sleep. What if APP doesn't want to sleep? There are similar methods: when the driver has data, it actively notifies the APP, and the APP executes ...

I checked the problem for a week. I was a little nervous and panicked. I was ignorant before I determined the cause of the problem. 1. It is found that there is mysql connection timeout (Communications link failure, The last packet sent successfully to the server was 0 milliseconds ago. Caused by: java.net.ConnectException: Connection timed ou ...

Learning record of PSR-[0-4] code specification in php 1. What is PSR? PSR is a set of code writing specifications used to constrain code style. In the past, when there was no standard, everyone wrote code according to their own habits, but everyone's style was different, and your code was very uncomfortable in the eyes of others. And it will ...

1. Prepare table information 2.MySQL advanced statement 2.1 alias Field alias, table alias Syntax: SELECT "table alias" "Field 1" [AS] "field alias" FROM "table name" [AS] "table alias"; Example: select A.age 'Age' from REGION A order by Age asc; 2.2 sub query: join table Insert ...

Zero revision record Serial numberRevised contentRevision time1newly added20210423 I. summary This article introduces CentOS 7 6 use ceph deploy to install the version of ceph nautilus. This paper mainly deploys ceph based on the production environment, especially the redundant configuration at the network level. II. Environmental informatio ...

JVM fatal error log (hs_err_pid.log) analysis CrashAnalysis Function introduction This is a jvm crash analysis tool, which mainly analyzes the causes of jvm crash and common solutions. Mode of use java -jar CrashAnalysis-1.0-SNAPSHOT.jar ${hs_err_pid.log} ${hs_err_pid.log} is the log generated after the jvm crash. effect After the analys ...

1. What is TD agent TD agent is a log collector, which provides rich plug-ins to adapt to different data sources, output destinations and so on In use, we can collect information from different sources to different places through simple configuration, and first send it to fluent D, and then fluent D forwards the information to different place ...

1, Linux system basic instructions and text editor 1. Basic instructions of Linux system 1.1 shutdown and restart (1) Shutdown: 1.shutdown -h //Turn it off immediately 2.shutdown -h 5 // Shutdown in 5 minutes 3.shutdow -h 20:25 //Shut down at 8:25 p.m 4.poweroff // Turn it of ...

HTTP learning notes HTTP Fundamentals Common request methods of HTTP protocol methodDescriptionGETRequest the specified page information and return the response contentPOSTSubmit data to the specified resources for processing requests (such as submitting forms or uploading files), and the data is included in the request body. POST requests ...