package core

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package core
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Interface to Linux-specific system calls.

sysinfo

module Sysinfo : sig ... end

Filesystem functions

val sendfile : (?pos:int -> ?len:int -> fd:Unix.file_descr -> Unix.file_descr -> int) Core_kernel.Or_error.t

sendfile ?pos ?len ~fd sock sends mmap-able data from file descriptor fd to socket sock using offset pos and length len. Returns the number of characters actually written.

NOTE: If the returned value is unequal to what was requested (= the initial size of the data by default), the system call may have been interrupted by a signal, the source file may have been truncated during operation, or a timeout may have occurred on the socket during sending. It is currently impossible to find out which of these events actually happened. Calling sendfile several times on the same descriptor that only partially accepted data due to a timeout will eventually lead to the Unix error EAGAIN.

Raises Unix_error on Unix-errors.

Non-portable TCP functionality

type tcp_bool_option =
  1. | TCP_CORK
    (*

    (Since Linux 2.2) If set, don’t send out partial frames. All queued partial frames are sent when the option is cleared again. This is useful for prepending headers before calling sendfile(2), or for throughput optimization. As currently implemented, there is a 200ms ceiling on the time for which output is corked by TCP_CORK. If this ceiling is reached, queued data is automatically transmitted.

    This option should not be used in code intended to be portable.

    *)
  2. | TCP_QUICKACK
    (*

    (Since Linux 2.4.4) Quick ack solves an unfortunate interaction between the delayed acks and the Nagle algorithm (TCP_NODELAY). On fast LANs, the Linux TCP stack quickly reaches a CWND (congestion window) of 1 (Linux interprets this as "1 unacknowledged packet", BSD/Windows and others consider it "1 unacknowledged segment of data").

    If Linux determines a connection to be bidirectional, it will delay sending acks, hoping to bundle them with other outgoing data. This can lead to serious connection stalls on, say, a TCP market data connection with one second heartbeats. TCP_QUICKACK can be used to prevent entering this delayed ack state.

    This option should not be used in code intended to be portable.

    *)
val tcp_bool_option_of_sexp : Ppx_sexp_conv_lib.Sexp.t -> tcp_bool_option
val sexp_of_tcp_bool_option : tcp_bool_option -> Ppx_sexp_conv_lib.Sexp.t
val bin_read_tcp_bool_option : tcp_bool_option Core_kernel.Bin_prot.Read.reader
val __bin_read_tcp_bool_option__ : (int -> tcp_bool_option) Core_kernel.Bin_prot.Read.reader
val bin_size_tcp_bool_option : tcp_bool_option Core_kernel.Bin_prot.Size.sizer
val bin_write_tcp_bool_option : tcp_bool_option Core_kernel.Bin_prot.Write.writer
val bin_shape_tcp_bool_option : Core_kernel.Bin_prot.Shape.t
val gettcpopt_bool : (Unix.file_descr -> tcp_bool_option -> bool) Core_kernel.Or_error.t

gettcpopt_bool sock opt Returns the current value of the boolean TCP socket option opt for socket sock.

val settcpopt_bool : (Unix.file_descr -> tcp_bool_option -> bool -> unit) Core_kernel.Or_error.t

settcpopt_bool sock opt v sets the current value of the boolean TCP socket option opt for socket sock to value v.

val send_nonblocking_no_sigpipe : (Unix.file_descr -> ?pos:int -> ?len:int -> Core_kernel.Bytes.t -> int option) Core_kernel.Or_error.t

send_nonblocking_no_sigpipe sock ?pos ?len buf tries to do a nonblocking send on socket sock given buffer buf, offset pos and length len. Prevents SIGPIPE, i.e., raises a Unix-error in that case immediately. Returns Some bytes_written or None if the operation would have blocked.

Raises Invalid_argument if the designated buffer range is invalid. Raises Unix_error on Unix-errors.

val send_no_sigpipe : (Unix.file_descr -> ?pos:int -> ?len:int -> Core_kernel.Bytes.t -> int) Core_kernel.Or_error.t

send_no_sigpipe sock ?pos ?len buf tries to do a blocking send on socket sock given buffer buf, offset pos and length len. Prevents SIGPIPE, i.e., raises a Unix-error in that case immediately. Returns the number of bytes written.

Raises Invalid_argument if the designated buffer range is invalid. Raises Unix_error on Unix-errors.

val sendmsg_nonblocking_no_sigpipe : (Unix.file_descr -> ?count:int -> string Core__.Core_unix.IOVec.t array -> int option) Core_kernel.Or_error.t

sendmsg_nonblocking_no_sigpipe sock ?count iovecs tries to do a nonblocking send on socket sock using count I/O-vectors iovecs. Prevents SIGPIPE, i.e., raises a Unix-error in that case immediately. Returns Some bytes_written or None if the operation would have blocked.

Raises Invalid_argument if the designated ranges are invalid. Raises Unix_error on Unix-errors.

Clock functions

module Clock : sig ... end

Eventfd functions

module Eventfd : sig ... end

Timerfd functions

module Timerfd : sig ... end

Parent death notifications

val pr_set_pdeathsig : (Signal.t -> unit) Core_kernel.Or_error.t

pr_set_pdeathsig s sets the signal s to be sent to the executing process when its parent dies. NOTE: the parent may have died before or while executing this system call. To make sure that you do not miss this event, you should call getppid to get the parent process id after this system call. If the parent has died, the returned parent PID will be 1, i.e., the init process will have adopted the child. You should then either send the signal to yourself using Unix.kill, or execute an appropriate handler.

val pr_get_pdeathsig : (unit -> Signal.t) Core_kernel.Or_error.t

pr_get_pdeathsig () gets the signal that will be sent to the currently executing process when its parent dies.

Task name

val pr_set_name_first16 : (string -> unit) Core_kernel.Or_error.t

pr_set_name_first16 name sets the name of the executing thread to name. Only the first 16 bytes in name will be used; the rest is ignored.

val pr_get_name : (unit -> string) Core_kernel.Or_error.t

pr_get_name () gets the name of the executing thread. The name is at most 16 bytes long.

Pathname resolution

val file_descr_realpath : (Unix.file_descr -> string) Core_kernel.Or_error.t

file_descr_realpath fd returns the canonicalized absolute pathname of the file associated with file descriptor fd.

Raises Unix_error on errors.

val out_channel_realpath : (Core_kernel.Out_channel.t -> string) Core_kernel.Or_error.t

out_channel_realpath oc returns the canonicalized absolute pathname of the file associated with output channel oc.

Raises Unix_error on errors.

val in_channel_realpath : (Core_kernel.In_channel.t -> string) Core_kernel.Or_error.t

in_channel_realpath ic returns the canonicalized absolute pathname of the file associated with input channel ic.

Raises Unix_error on errors.

Affinity

val sched_setaffinity : (?pid:Core_kernel.Pid.t -> cpuset:int list -> unit -> unit) Core_kernel.Or_error.t

Setting the CPU affinity causes a process to only run on the cores chosen. You can find out how many cores a system has in /proc/cpuinfo. This can be useful in two ways: first, it limits a process to a core so that it won't interfere with processes on other cores. Second, you save time by not moving the process back and forth between CPUs, which sometimes invalidates their cache. See man sched_setaffinity for details.

val sched_setaffinity_this_thread : (cpuset:int list -> unit) Core_kernel.Or_error.t
val cores : (unit -> int) Core_kernel.Or_error.t

cores () returns the number of cores on the machine. This may be different than the number of cores available to the calling process.

val get_terminal_size : (unit -> int * int) Core_kernel.Or_error.t

get_terminal_size () returns (rows, cols), the number of rows and columns of the terminal.

module Priority : sig ... end

Priority.t is what is usually referred to as the "nice" value of a process. It is also known as the "dynamic" priority. It is used with normal (as opposed to real-time) processes that have static priority zero. See Unix.Scheduler.set for setting the static priority.

val setpriority : (Priority.t -> unit) Core_kernel.Or_error.t

Set the calling thread's priority in the Linux scheduler

val getpriority : (unit -> Priority.t) Core_kernel.Or_error.t

Get the calling thread's priority in the Linux scheduler

val get_ipv4_address_for_interface : (string -> string) Core_kernel.Or_error.t

get_ipv4_address_for_interface "eth0" returns the IP address assigned to eth0, or throws an exception if no IP address is configured.

val bind_to_interface : (Unix.file_descr -> [ `Any | `Interface_name of string ] -> unit) Core_kernel.Or_error.t

bind_to_interface fd (`Interface_name "eth0") restricts packets from being received/sent on the given file descriptor fd on any interface other than "eth0". Use bind_to_interface fd `Any to allow traffic on any interface. The bindings are not cumulative; you may only select one interface, or `Any.

Not to be confused with a traditional BSD sockets API bind() call, this Linux-specific socket option (SO_BINDTODEVICE) is used for applications on multi-homed machines with specific security concerns. For similar functionality when using multicast, see Core_unix.mcast_set_ifname.

module Epoll : sig ... end

epoll(): a Linux I/O multiplexer of the same family as select() or poll(). Its main differences are support for Edge- or Level-triggered notifications (we're using Level-triggered to emulate "select") and much better scaling with the number of file descriptors.

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