1AnyEvent::Util(3)     User Contributed Perl Documentation    AnyEvent::Util(3)
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NAME

6       AnyEvent::Util - various utility functions.
7

SYNOPSIS

9          use AnyEvent::Util;
10

DESCRIPTION

12       This module implements various utility functions, mostly replacing
13       well-known functions by event-ised counterparts.
14
15       All functions documented without "AnyEvent::Util::" prefix are exported
16       by default.
17
18       ($r, $w) = portable_pipe
19           Calling "pipe" in Perl is portable - except it doesn't really work
20           on sucky windows platforms (at least not with most perls - cygwin's
21           perl notably works fine): On windows, you actually get two file
22           handles you cannot use select on.
23
24           This function gives you a pipe that actually works even on the
25           broken windows platform (by creating a pair of TCP sockets on
26           windows, so do not expect any speed from that) and using "pipe"
27           everywhere else.
28
29           See "portable_socketpair", below, for a bidirectional "pipe".
30
31           Returns the empty list on any errors.
32
33       ($fh1, $fh2) = portable_socketpair
34           Just like "portable_pipe", above, but returns a bidirectional pipe
35           (usually by calling "socketpair" to create a local loopback socket
36           pair, except on windows, where it again returns two interconnected
37           TCP sockets).
38
39           Returns the empty list on any errors.
40
41       fork_call { CODE } @args, $cb->(@res)
42           Executes the given code block asynchronously, by forking.
43           Everything the block returns will be transferred to the calling
44           process (by serialising and deserialising via Storable).
45
46           If there are any errors, then the $cb will be called without any
47           arguments. In that case, either $@ contains the exception (and $!
48           is irrelevant), or $! contains an error number. In all other cases,
49           $@ will be "undef"ined.
50
51           The code block must not ever call an event-polling function or use
52           event-based programming that might cause any callbacks registered
53           in the parent to run.
54
55           Win32 spoilers: Due to the endlessly sucky and broken native
56           windows perls (there is no way to cleanly exit a child process on
57           that platform that doesn't also kill the parent), you have to make
58           sure that your main program doesn't exit as long as any
59           "fork_calls" are still in progress, otherwise the program won't
60           exit. Also, on most windows platforms some memory will leak for
61           every invocation. We are open for improvements that don't require
62           XS hackery.
63
64           Note that forking can be expensive in large programs (RSS 200MB+).
65           On windows, it is abysmally slow, do not expect more than 5..20
66           forks/s on that sucky platform (note this uses perl's pseudo-
67           threads, so avoid those like the plague).
68
69           Example: poor man's async disk I/O (better use AnyEvent::IO
70           together with IO::AIO).
71
72              fork_call {
73                 open my $fh, "</etc/passwd"
74                    or die "passwd: $!";
75                 local $/;
76                 <$fh>
77              } sub {
78                 my ($passwd) = @_;
79                 ...
80              };
81
82       $AnyEvent::Util::MAX_FORKS [default: 10]
83           The maximum number of child processes that "fork_call" will fork in
84           parallel. Any additional requests will be queued until a slot
85           becomes free again.
86
87           The environment variable "PERL_ANYEVENT_MAX_FORKS" is used to
88           initialise this value.
89
90       fh_nonblocking $fh, $nonblocking
91           Sets the blocking state of the given filehandle (true ==
92           nonblocking, false == blocking). Uses fcntl on anything sensible
93           and ioctl FIONBIO on broken (i.e. windows) platforms.
94
95           Instead of using this function, you could use "AnyEvent::fh_block"
96           or "AnyEvent::fh_unblock".
97
98       $guard = guard { CODE }
99           This function creates a special object that, when destroyed, will
100           execute the code block.
101
102           This is often handy in continuation-passing style code to clean up
103           some resource regardless of where you break out of a process.
104
105           The Guard module will be used to implement this function, if it is
106           available. Otherwise a pure-perl implementation is used.
107
108           While the code is allowed to throw exceptions in unusual
109           conditions, it is not defined whether this exception will be
110           reported (at the moment, the Guard module and AnyEvent's pure-perl
111           implementation both try to report the error and continue).
112
113           You can call one method on the returned object:
114
115       $guard->cancel
116           This simply causes the code block not to be invoked: it "cancels"
117           the guard.
118
119       AnyEvent::Util::close_all_fds_except @fds
120           This rarely-used function simply closes all file descriptors (or
121           tries to) of the current process except the ones given as
122           arguments.
123
124           When you want to start a long-running background server, then it is
125           often beneficial to do this, as too many C-libraries are too stupid
126           to mark their internal fd's as close-on-exec.
127
128           The function expects to be called shortly before an "exec" call.
129
130           Example: close all fds except 0, 1, 2.
131
132              close_all_fds_except 0, 2, 1;
133
134       $cv = run_cmd $cmd, key => value...
135           Run a given external command, potentially redirecting file
136           descriptors and return a condition variable that gets sent the exit
137           status (like $?)  when the program exits and all redirected file
138           descriptors have been exhausted.
139
140           The $cmd is either a single string, which is then passed to a
141           shell, or an arrayref, which is passed to the "execvp" function
142           (the first array element is used both for the executable name and
143           argv[0]).
144
145           The key-value pairs can be:
146
147           ">" => $filename
148               Redirects program standard output into the specified filename,
149               similar to ">filename" in the shell.
150
151           ">" => \$data
152               Appends program standard output to the referenced scalar. The
153               condvar will not be signalled before EOF or an error is
154               signalled.
155
156               Specifying the same scalar in multiple ">" pairs is allowed,
157               e.g. to redirect both stdout and stderr into the same scalar:
158
159                   ">"  => \$output,
160                   "2>" => \$output,
161
162           ">" => $filehandle
163               Redirects program standard output to the given filehandle (or
164               actually its underlying file descriptor).
165
166           ">" => $callback->($data)
167               Calls the given callback each time standard output receives
168               some data, passing it the data received. On EOF or error, the
169               callback will be invoked once without any arguments.
170
171               The condvar will not be signalled before EOF or an error is
172               signalled.
173
174           "fd>" => $see_above
175               Like ">", but redirects the specified fd number instead.
176
177           "<" => $see_above
178               The same, but redirects the program's standard input instead.
179               The same forms as for ">" are allowed.
180
181               In the callback form, the callback is supposed to return data
182               to be written, or the empty list or "undef" or a zero-length
183               scalar to signal EOF.
184
185               Similarly, either the write data must be exhausted or an error
186               is to be signalled before the condvar is signalled, for both
187               string-reference and callback forms.
188
189           "fd<" => $see_above
190               Like "<", but redirects the specified file descriptor instead.
191
192           on_prepare => $cb
193               Specify a callback that is executed just before the command is
194               "exec"'ed, in the child process. Be careful not to use any
195               event handling or other services not available in the child.
196
197               This can be useful to set up the environment in special ways,
198               such as changing the priority of the command or manipulating
199               signal handlers (e.g.  setting "SIGINT" to "IGNORE").
200
201           close_all => $boolean
202               When "close_all" is enabled (default is disabled), then all
203               extra file descriptors will be closed, except the ones that
204               were redirected and 0, 1 and 2.
205
206               See "close_all_fds_except" for more details.
207
208           '$$' => \$pid
209               A reference to a scalar which will receive the PID of the
210               newly-created subprocess after "run_cmd" returns.
211
212               Note the the PID might already have been recycled and used by
213               an unrelated process at the time "run_cmd" returns, so it's not
214               useful to send signals, use as a unique key in data structures
215               and so on.
216
217           Example: run "rm -rf /", redirecting standard input, output and
218           error to /dev/null.
219
220              my $cv = run_cmd [qw(rm -rf /)],
221                 "<", "/dev/null",
222                 ">", "/dev/null",
223                 "2>", "/dev/null";
224              $cv->recv and die "d'oh! something survived!"
225
226           Example: run openssl and create a self-signed certificate and key,
227           storing them in $cert and $key. When finished, check the exit
228           status in the callback and print key and certificate.
229
230              my $cv = run_cmd [qw(openssl req
231                                -new -nodes -x509 -days 3650
232                                -newkey rsa:2048 -keyout /dev/fd/3
233                                -batch -subj /CN=AnyEvent
234                               )],
235                 "<", "/dev/null",
236                 ">" , \my $cert,
237                 "3>", \my $key,
238                 "2>", "/dev/null";
239
240              $cv->cb (sub {
241                 shift->recv and die "openssl failed";
242
243                 print "$key\n$cert\n";
244              });
245
246       AnyEvent::Util::punycode_encode $string
247           Punycode-encodes the given $string and returns its punycode form.
248           Note that uppercase letters are not casefolded - you have to do
249           that yourself.
250
251           Croaks when it cannot encode the string.
252
253       AnyEvent::Util::punycode_decode $string
254           Tries to punycode-decode the given $string and return its unicode
255           form. Again, uppercase letters are not casefoled, you have to do
256           that yourself.
257
258           Croaks when it cannot decode the string.
259
260       AnyEvent::Util::idn_nameprep $idn[, $display]
261           Implements the IDNA nameprep normalisation algorithm. Or actually
262           the UTS#46 algorithm. Or maybe something similar - reality is
263           complicated between IDNA2003, UTS#46 and IDNA2008. If $display is
264           true then the name is prepared for display, otherwise it is
265           prepared for lookup (default).
266
267           If you have no clue what this means, look at "idn_to_ascii"
268           instead.
269
270           This function is designed to avoid using a lot of resources - it
271           uses about 1MB of RAM (most of this due to Unicode::Normalize).
272           Also, names that are already "simple" will only be checked for
273           basic validity, without the overhead of full nameprep processing.
274
275       $domainname = AnyEvent::Util::idn_to_ascii $idn
276           Converts the given unicode string ($idn, international domain name,
277           e.g. 日本語。JP) to a pure-ASCII domain name (this is usually
278           called the "IDN ToAscii" transform). This transformation is
279           idempotent, which means you can call it just in case and it will do
280           the right thing.
281
282           Unlike some other "ToAscii" implementations, this one works on full
283           domain names and should never fail - if it cannot convert the name,
284           then it will return it unchanged.
285
286           This function is an amalgam of IDNA2003, UTS#46 and IDNA2008 - it
287           tries to be reasonably compatible to other implementations,
288           reasonably secure, as much as IDNs can be secure, and reasonably
289           efficient when confronted with IDNs that are already valid DNS
290           names.
291
292       $idn = AnyEvent::Util::idn_to_unicode $idn
293           Converts the given unicode string ($idn, international domain name,
294           e.g. 日本語。JP, www.deliantra.net, www.xn--l-0ga.de) to unicode
295           form (this is usually called the "IDN ToUnicode" transform). This
296           transformation is idempotent, which means you can call it just in
297           case and it will do the right thing.
298
299           Unlike some other "ToUnicode" implementations, this one works on
300           full domain names and should never fail - if it cannot convert the
301           name, then it will return it unchanged.
302
303           This function is an amalgam of IDNA2003, UTS#46 and IDNA2008 - it
304           tries to be reasonably compatible to other implementations,
305           reasonably secure, as much as IDNs can be secure, and reasonably
306           efficient when confronted with IDNs that are already valid DNS
307           names.
308
309           At the moment, this function simply calls "idn_nameprep $idn, 1",
310           returning its argument when that function fails.
311

AUTHOR

313        Marc Lehmann <schmorp@schmorp.de>
314        http://anyevent.schmorp.de
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318perl v5.34.0                      2021-07-22                 AnyEvent::Util(3)
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