`read` 方法 - 同步非阻塞I/O模型

#include <unistd.h>

ssize_t read(int fd, void *buf, size_t count);

On files that support seeking, the read operation commences at the file offset, and the file offset is incremented by the number of bytes read. If the file offset is at or past the end of file, no bytes are read, and read() returns zero.

If count is zero, read() may detect the errors described below. In the absence of any errors, or if read() does not check for errors, a read() with a count of 0 returns zero and has no other effects.

read轮询方法对应read()系统调用。即用户线程需要在一定时间间隔内非阻塞地持续发起轮询请求来获知此I/O操作的当前状态。因此，轮询操作是由用户线程来负责的。

虽热用户线程不会被阻塞，但它需要不停地发起系统调用，直到数据可用为止。

它是较原始、性能较低的一种，不仅整体数据吞吐量较低，而且（相较于阻塞式系统调用）消耗了额外的CPU资源。

Reference

FEATURED TAGS

algorithm algorithmproblem architecturalpattern architecture aws c# cachesystem codis compile concurrentcontrol database dataformat datastructure debug design designpattern distributedsystem django docker domain engineering freebsd git golang grafana hackintosh hadoop hardware hexo http hugo ios iot java javaee javascript kafka kubernetes linux linuxcommand linuxio lock macos markdown microservices mysql nas network networkprogramming nginx node.js npm oop openwrt operatingsystem padavan performance programming prometheus protobuf python redis router security shell software testing spring sql systemdesign truenas ubuntu vmware vpn windows wmware wordpress xml zookeeper

【Linux】I/O 轮询技术 - read

`read` 方法 - 同步非阻塞I/O模型

Reference

FEATURED TAGS

FRIENDS

TOC

read 方法 - 同步非阻塞I/O模型

Reference

FEATURED TAGS

FRIENDS

`read` 方法 - 同步非阻塞I/O模型