动机
在用 elixir 写 rpc server/client 时, 需要对传入 gen_tcp 的参数做一些考量. 如, 部分参数应该允许用户修改, 比如 sndbuf recbuf, 让用户根据使用场景调节, 部分参数应该屏蔽, 减少使用理解成本. 故, 深挖了一下 gen_tcp 的 option
代码版本
erlang: OTP-21.0.9
options
Available options for tcp:connect
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Available options for tcp:connect
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
connect_options() ->
[tos, tclass, priority, reuseaddr, keepalive, linger, sndbuf, recbuf, nodelay,
header, active, packet, packet_size, buffer, mode, deliver, line_delimiter,
exit_on_close, high_watermark, low_watermark, high_msgq_watermark,
low_msgq_watermark, send_timeout, send_timeout_close, delay_send, raw,
show_econnreset, bind_to_device].
tos
type of service 下图来自 tcp ip 详解 卷 1
tclass
IPV6_TCLASS{tclass, Integer}Sets IPV6_TCLASS IP level options on platforms where this is implemented. The behavior and allowed range varies between different systems. The option is ignored on platforms where it is not implemented. Use with caution. 不知道具体含义, 忽略
priority
SO_PRIORITY
SO_PRIORITY
Set the protocol-defined priority for all packets to be sent
on this socket. Linux uses this value to order the networking
queues: packets with a higher priority may be processed first
depending on the selected device queueing discipline. Setting
a priority outside the range 0 to 6 requires the CAP_NET_ADMIN
capability.
reuseaddr
SO_REUSEPORT
SO_REUSEPORT (since Linux 3.9)
Permits multiple AF_INET or AF_INET6 sockets to be bound to an
identical socket address. This option must be set on each
socket (including the first socket) prior to calling bind(2)
on the socket. To prevent port hijacking, all of the pro‐
cesses binding to the same address must have the same effec‐
tive UID. This option can be employed with both TCP and UDP
sockets.
For TCP sockets, this option allows accept(2) load distribu‐
tion in a multi-threaded server to be improved by using a dis‐
tinct listener socket for each thread. This provides improved
load distribution as compared to traditional techniques such
using a single accept(2)ing thread that distributes connec‐
tions, or having multiple threads that compete to accept(2)
from the same socket.
For UDP sockets, the use of this option can provide better
distribution of incoming datagrams to multiple processes (or
threads) as compared to the traditional technique of having
multiple processes compete to receive datagrams on the same
socket.
keepalive
[SO_KEEPALIVE][6]
Enable sending of keep-alive messages on connection-oriented
sockets. Expects an integer boolean flag.