NAME¶
"IO::Async::OS" - operating system abstractions for
"IO::Async"
DESCRIPTION¶
This module acts as a class to provide a number of utility methods whose exact
behaviour may depend on the type of OS it is running on. It is provided as a
class so that specific kinds of operating system can override methods in it.
As well as these support functions it also provides a number of constants, all
with names beginning "HAVE_" which describe various features that
may or may not be available on the OS or perl build. Most of these are either
hard-coded per OS, or detected at runtime.
The following constants may be overridden by environment variables.
- •
- HAVE_POSIX_FORK
True if the "fork()" call has full POSIX semantics (full process
separation). This is true on most OSes but false on MSWin32.
This may be overridden to be false by setting the environment variable
"IO_ASYNC_NO_FORK".
- •
- HAVE_THREADS
True if "ithreads" are available, meaning that the
"threads" module can be used. This depends on whether perl was
built with threading support.
This may be overridable to be false by setting the environment variable
"IO_ASYNC_NO_THREADS".
$family = IO::Async::OS->getfamilybyname( $name )¶
Return a protocol family value based on the given name. If $name looks like a
number it will be returned as-is. The string values "inet",
"inet6" and "unix" will be converted to the appropriate
"AF_*" constant.
$socktype = IO::Async::OS->getsocktypebyname( $name )¶
Return a socket type value based on the given name. If $name looks like a number
it will be returned as-is. The string values "stream",
"dgram" and "raw" will be converted to the appropriate
"SOCK_*" constant.
( $S1, $S2 ) = IO::Async::OS->socketpair( $family, $socktype, $proto )¶
An abstraction of the
socketpair(2) syscall, where any argument may be missing
(or given as "undef").
If $family is not provided, a suitable value will be provided by the OS (likely
"AF_UNIX" on POSIX-based platforms). If $socktype is not provided,
then "SOCK_STREAM" will be used.
Additionally, this method supports building connected "SOCK_STREAM" or
"SOCK_DGRAM" pairs in the "AF_INET" family even if the
underlying platform's
socketpair(2) does not, by connecting two normal sockets
together.
$family and $socktype may also be given symbolically as defined by
"getfamilybyname" and "getsocktypebyname".
( $rd, $wr ) = IO::Async::OS->pipepair¶
An abstraction of the
pipe(2) syscall, which returns the two new handles.
( $rdA, $wrA, $rdB, $wrB ) = IO::Async::OS->pipequad¶
This method is intended for creating two pairs of filehandles that are linked
together, suitable for passing as the STDIN/STDOUT pair to a child process.
After this function returns, $rdA and $wrA will be a linked pair, as will $rdB
and $wrB.
On platforms that support
socketpair(2), this implementation will be preferred,
in which case $rdA and $wrB will actually be the same filehandle, as will $rdB
and $wrA. This saves a file descriptor in the parent process.
When creating a "IO::Async::Stream" or subclass of it, the
"read_handle" and "write_handle" parameters should always
be used.
my ( $childRd, $myWr, $myRd, $childWr ) = IO::Async::OS->pipequad;
IO::Async::OS->open_child(
stdin => $childRd,
stdout => $childWr,
...
);
my $str = IO::Async::Stream->new(
read_handle => $myRd,
write_handle => $myWr,
...
);
IO::Async::OS->add( $str );
$signum = IO::Async::OS->signame2num( $signame )¶
This utility method converts a signal name (such as "TERM") into its
system- specific signal number. This may be useful to pass to
"POSIX::SigSet" or use in other places which use numbers instead of
symbolic names.
Given an ARRAY or HASH reference value containing an addrinfo, returns a family,
socktype and protocol argument suitable for a "socket" call and an
address suitable for "connect" or "bind".
If given an ARRAY it should be in the following form:
[ $family, $socktype, $protocol, $addr ]
If given a HASH it should contain the following keys:
family socktype protocol addr
Each field in the result will be initialised to 0 (or empty string for the
address) if not defined in the $ai value.
The family type may also be given as a symbolic string as defined by
"getfamilybyname".
The socktype may also be given as a symbolic string; "stream",
"dgram" or "raw"; this will be converted to the
appropriate "SOCK_*" constant.
Note that the "addr" field, if provided, must be a packed socket
address, such as returned by "pack_sockaddr_in" or
"pack_sockaddr_un".
If the HASH form is used, rather than passing a packed socket address in the
"addr" field, certain other hash keys may be used instead for
convenience on certain named families.
- family => 'inet'
- Will pack an IP address and port number from keys called "ip"
and "port". If "ip" is missing it will be set to
"0.0.0.0". If "port" is missing it will be set to
0.
- family => 'inet6'
- Will pack an IP address and port number from keys called "ip"
and "port". If "ip" is missing it will be set to
"::". If "port" is missing it will be set to 0.
Optionally will also include values from "scopeid" and
"flowinfo" keys if provided.
This will only work if a "pack_sockaddr_in6" function can be found
in "Socket"
- family => 'unix'
- Will pack a UNIX socket path from a key called "path".
LOOP IMPLEMENTATION METHODS¶
The following methods are provided on "IO::Async::OS" because they are
likely to require OS-specific implementations, but are used by IO::Async::Loop
to implement its functionality. It can use the HASH reference
"$loop->{os}" to store other data it requires.
IO::Async::OS->loop_watch_signal( $loop, $signal, $code )¶
IO::Async::OS->loop_unwatch_signal( $loop, $signal )¶
Used to implement the "watch_signal" / "unwatch_signal" Loop
pair.
@fds = IO::Async::OS->potentially_open_fds¶
Returns a list of filedescriptors which might need closing. By default this will
return "0 .. _SC_OPEN_MAX". OS-specific subclasses may have a better
guess.
AUTHOR¶
Paul Evans <leonerd@leonerd.org.uk>