Golang implements epoll code

Golang is an open source, cross-platform programming language that is easy to learn and highly efficient. Its emergence provides better solutions for Web applications and distributed applications. In network programming, the widely used I/O multiplexing technology can effectively improve the performance of the program. Among them, epoll, as the most efficient I/O multiplexing mechanism under Linux, is very useful in high-concurrency server programming. important. This article will learn more about the use of epoll by implementing an epoll program based on golang.

epoll Introduction

epoll under the Linux kernel is an efficient I/O multiplexing mechanism that can monitor files corresponding to multiple file descriptors at the same time (including files, pipes and The read and write status of the network socket), when the file descriptor is ready, it is added to a linked list and returned to the application immediately, so that only one thread can handle multiple client requests at the same time without Poll all file descriptors like select and poll.

Epoll necessary data structures

To implement epoll in golang, you need to use the following data structures:

type epollFd int

// epollCtl is used for mod/add epollEventType of one target file descriptor.
// parameter 'operation' detail please refer to epoll_ctl(2)
type epollCtl struct {

op     int            //EPOLL_CTL_ADD、EPOLL_CTL_MOD、EPOLL_CTL_DEL
fd     int            //the target file descriptor
event  epollEventType //EPOLLIN，EPOLLOUT，EPOLLET

}

// epollEvent is the epoll event on a file descriptor.
type epollEvent struct {

events uint32
data   [8]byte // internal use only

}

// epollEventType is the epoll event type
type epollEventType uint32

const (

//EPOLLIN The associated file is available for read(2) operations.
EPOLLIN epollEventType = 0x001
//EPOLLOUT The associated file is available for write(2) operations.
EPOLLOUT epollEventType = 0x004
//EPOLLET Sets the Edge Triggered behavior for the associated file descriptor.
EPOLLET epollEventType = 1 << 31

)

epollFd: represents the epoll instance, represented by int type.

epollEvent: Represents the event of the file descriptor in epoll. The events flag is used to indicate the read and write events of the file descriptor (EPOLLIN, EPOLLOUT). Data is used to store the data of the file descriptor event.

epollCtl: used to control EPOLL_CTL_ADD, EPOLL_CTL_MOD, EPOLL_CTL_DEL operations. Among them, op represents the operation type, fd represents the file descriptor, event represents the operation to be performed, EPOOLIN and EPOLLOUT represent the read and write event types to be monitored, and EPOLLET represents the ET mode.

Golang implements epoll

To implement epoll in golang, you need to use the EpollCreate1, EpollCtl, EpollWait and other functions of the syscall library. For specific usage, please refer to the golang official documentation.

// NewEpoll will new a epoll instance
func NewEpoll() (epollFd, error) {

fd, err := syscall.EpollCreate1(syscall.EPOLL_CLOEXEC)
if err != nil {
    return -1, fmt.Errorf("epoll_create1 failed:%v", err)
}
return epollFd(fd), nil

}

// epollCtl is used for mod/add epollEventType of one target file descriptor.
// parameter 'operation' detail please refer to epoll_ctl(2)
func (efd epollFd) epollCtl(operation int, fd int, event *epollEvent) error {

err := syscall.EpollCtl(int(efd), operation, fd, *(*syscall.EpollEvent)(unsafe.Pointer(event)))
if err != nil {
    return fmt.Errorf("epoll_ctl error:%v", err)
}
return nil

}

// epollWait is used for blocking wait on multiple epoll event.
func (efd epollFd) epollWait(events []epollEvent, msec int) (int, error) {

nevents, err := syscall.EpollWait(int(efd), *(*[]syscall.EpollEvent)(unsafe.Pointer(&events)), msec)
if err != nil {
    return 0, fmt.Errorf("Epoll wait error:%v", err)
}
return nevents, nil

}

In the above code, we can see that NewEpoll creates an epoll instance, and epollCtl is used to modify the event. epollWait will wait for the event to occur and return. The blocking method is used here. Of course, the non-blocking method can also be used.

Conclusion

In this article we introduced the basic principles and usage of epoll in golang. Through this case, everyone can understand the usage and principle of epoll. In fact, golang's performance in system programming is very good. It can easily integrate system calls and also supports advanced primitives such as Unix domain sockets, making the program more efficient and easier to maintain.

The above is the detailed content of Golang implements epoll code. For more information, please follow other related articles on the PHP Chinese website!