The Linux Programming Interface

63ALTERNATIVE I/O MODELS

This chapter discusses three alternatives to the conventional file I/O model that we have employed in most programs shown in this book:

• I/O multiplexing (the select() and poll() system calls);

• signal-driven I/O; and

• the Linux-specific epoll API.

63.1 Overview

Most of the programs that we have presented so far in this book employ an I/O model under which a process performs I/O on just one file descriptor at a time, and each I/O system call blocks until the data is transferred. For example, when reading from a pipe, a read() call normally blocks if no data is currently present in the pipe, and a write() call blocks if there is insufficient space in the pipe to hold the data to be written. Similar behavior occurs when ...