Unlike the existing net package own pollster, runtime-integrated
network pollster on BSD variants, actually kqueue, requires a socket
that has beed passed to syscall.Listen previously for a stream
listener.
This CL separates pollDesc.Init (actually runtime_pollOpen) from newFD
to allow control of each state of sockets and adds init method to netFD
instead. Upcoming CLs will rearrange the call order of runtime-integrated
pollster and syscall functions like the following;
- For dialers that open active connections, runtime_pollOpen will be
called in between syscall.Bind and syscall.Connect.
- For stream listeners that open passive stream connections,
runtime_pollOpen will be called just after syscall.Listen.
- For datagram listeners that open datagram connections,
runtime_pollOpen will be called just after syscall.Bind.
This is in preparation for runtime-integrated network pollster for BSD
variants.
Update #5199
R=dvyukov, alex.brainman, minux.ma
CC=golang-dev
https://golang.org/cl/8608044
This means that in the common case (modern kernel), we only
make 1 system call to dup instead of two, and we also avoid
grabbing the syscall.ForkLock.
R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/12476043
