apr::pool.3

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

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.IX Title "mod_perl-2.0.2::docs::api::APR::Pool 3"
.TH mod_perl-2.0.2::docs::api::APR::Pool 3 "2005-10-21" "perl v5.10.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
APR::Pool \- Perl API for APR pools
.SH "Synopsis"
.IX Header "Synopsis"
.Vb 1
\&  use APR::Pool ();
\&  
\&  my $sp = $r\->pool\->new;
\&  my $sp2 = APR::Pool\->new;
\&  
\&  # $sp3 is a subpool of $sp,
\&  # which in turn is a subpool of $r\->pool
\&  $sp3 = $sp\->new;
\&  print \*(Aq$r\->pool is an ancestor of $sp3\*(Aq
\&      if $r\->pool\->is_ancestor($sp3);
\&  # but sp2 is not a sub\-pool of $r\->pool
\&  print \*(Aq$r\->pool is not an ancestor of $sp2\*(Aq
\&      unless $r\->pool\->is_ancestor($sp2);
\&  
\&  # $sp4 and $sp are the same pool (though you can\*(Aqt
\&  # compare the handle as variables)
\&  my $sp4 = $sp3\->parent_get;
\&  
\&
\&  # register a dummy cleanup function
\&  # that just prints the passed args
\&  $sp\->cleanup_register(sub { print @{ $_[0] || [] } }, [1..3]);
\&  
\&  # tag the pool
\&  $sp\->tag("My very best pool");
\&  
\&  # clear the pool
\&  $sp\->clear();
\&  
\&  # destroy sub pool
\&  $sp2\->destroy;
.Ve
.SH "Description"
.IX Header "Description"
\&\f(CW\*(C`APR::Pool\*(C'\fR provides an access to \s-1APR\s0 pools, which are used for an
easy memory management.
.PP
Different pools have different life scopes and therefore one doesn't
need to free allocated memory explicitly, but instead it's done when
the pool's life is getting to an end. For example a request pool is
created at the beginning of a request and destroyed at the end of it,
and all the memory allocated during the request processing using the
request pool is freed at once at the end of the request.
.PP
Most of the time you will just pass various pool objects to the
methods that require them. And you must understand the scoping of the
pools, since if you pass a long lived server pool to a method that
needs the memory only for a short scoped request, you are going to
leak memory. A request pool should be used in such a case. And vice
versa, if you need to allocate some memory for a scope longer than a
single request, then a request pool is inappropriate, since when the
request will be over, the memory will be freed and bad things may
happen.
.PP
If you need to create a new pool, you can always do that via the
\&\f(CW\*(C`new()\*(C'\fR method.
.SH "API"
.IX Header "API"
\&\f(CW\*(C`APR::Pool\*(C'\fR provides the following functions and/or methods:
.ie n .Sh """cleanup_register"""
.el .Sh "\f(CWcleanup_register\fP"
.IX Subsection "cleanup_register"
Register cleanup callback to run
.PP
.Vb 2
\&  $pool\->cleanup_register($callback);
\&  $pool\->cleanup_register($callback, $arg);
.Ve
.ie n .IP "obj: $pool\fR ( \f(CW""APR::Pool object"" )" 4
.el .IP "obj: \f(CW$pool\fR ( \f(CWAPR::Pool object\fR )" 4
.IX Item "obj: $pool ( APR::Pool object )"
The pool object to register the cleanup callback for
.ie n .IP "arg1: $callback ( \s-1CODE\s0 ref or sub name )" 4
.el .IP "arg1: \f(CW$callback\fR ( \s-1CODE\s0 ref or sub name )" 4
.IX Item "arg1: $callback ( CODE ref or sub name )"
a cleanup callback \s-1CODE\s0 reference or just a name of the subroutine
(fully qualified unless defined in the current package).
.ie n .IP "opt arg2: $arg ( \s-1SCALAR\s0 )" 4
.el .IP "opt arg2: \f(CW$arg\fR ( \s-1SCALAR\s0 )" 4
.IX Item "opt arg2: $arg ( SCALAR )"
If this optional argument is passed, the \f(CW$callback\fR function will
receive it as the first and only argument when executed.
.Sp
To pass more than one argument, use an \s-1ARRAY\s0 or a \s-1HASH\s0 reference
.IP "ret: no return value" 4
.IX Item "ret: no return value"
.PD 0
.IP "excpt:" 4
.IX Item "excpt:"
.PD
if the registered callback fails, it happens when the pool is
destroyed. The destruction is performed by Apache and it ignores any
failures. Even if it didn't ignore the failures, most of the time the
pool is destroyed when a request or connection handlers are long gone.
However the error \fBis\fR logged to \fIerror_log\fR, so if you monitor that
file you will spot if there are any problems with it.
.IP "since: 2.0.00" 4
.IX Item "since: 2.0.00"
.PP