Hands-On High Performance with Go

Channel internals

Channels are invoked using the make() Golang built-in, where an hchan struct is created. The hchan struct contains a count of the data in the queue, the size of the queue, an array pointer for the buffer, send and receive indices and waiters, and a mutex lock. The following code block illustrates this:

type hchan struct {    qcount   uint           // total data in the queue    dataqsiz uint           // size of the circular queue    buf      unsafe.Pointer // points to an array of dataqsiz elements    elemsize uint16    closed   uint32    elemtype *_type // element type    sendx    uint   // send index    recvx    uint   // receive index    recvq    waitq  // list of recv waiters    sendq    waitq  // list of send waiters    // lock protects all fields in hchan, as well as several // fields in sudogs ...