.\" Automatically generated by Pod::Man 2.28 (Pod::Simple 3.28)
.\"
.\" Standard preamble:
.\" ========================================================================
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Vb \" Begin verbatim text
.ft CW
.nf
.ne \\$1
..
.de Ve \" End verbatim text
.ft R
.fi
..
.\" Set up some character translations and predefined strings.  \*(-- will
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
.\" double quote, and \*(R" will give a right double quote.  \*(C+ will
.\" give a nicer C++.  Capital omega is used to do unbreakable dashes and
.\" therefore won't be available.  \*(C` and \*(C' expand to `' in nroff,
.\" nothing in troff, for use with C<>.
.tr \(*W-
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
.ie n \{\
.    ds -- \(*W-
.    ds PI pi
.    if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
.    if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\"  diablo 12 pitch
.    ds L" ""
.    ds R" ""
.    ds C` ""
.    ds C' ""
'br\}
.el\{\
.    ds -- \|\(em\|
.    ds PI \(*p
.    ds L" ``
.    ds R" ''
.    ds C`
.    ds C'
'br\}
.\"
.\" Escape single quotes in literal strings from groff's Unicode transform.
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\"
.\" If the F register is turned on, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
.\" entries marked with X<> in POD.  Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.\"
.\" Avoid warning from groff about undefined register 'F'.
.de IX
..
.nr rF 0
.if \n(.g .if rF .nr rF 1
.if (\n(rF:(\n(.g==0)) \{
.    if \nF \{
.        de IX
.        tm Index:\\$1\t\\n%\t"\\$2"
..
.        if !\nF==2 \{
.            nr % 0
.            nr F 2
.        \}
.    \}
.\}
.rr rF
.\"
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
.\" Fear.  Run.  Save yourself.  No user-serviceable parts.
.    \" fudge factors for nroff and troff
.if n \{\
.    ds #H 0
.    ds #V .8m
.    ds #F .3m
.    ds #[ \f1
.    ds #] \fP
.\}
.if t \{\
.    ds #H ((1u-(\\\\n(.fu%2u))*.13m)
.    ds #V .6m
.    ds #F 0
.    ds #[ \&
.    ds #] \&
.\}
.    \" simple accents for nroff and troff
.if n \{\
.    ds ' \&
.    ds ` \&
.    ds ^ \&
.    ds , \&
.    ds ~ ~
.    ds /
.\}
.if t \{\
.    ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
.    ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
.    ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
.    ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
.    ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
.    ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
.\}
.    \" troff and (daisy-wheel) nroff accents
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
.ds ae a\h'-(\w'a'u*4/10)'e
.ds Ae A\h'-(\w'A'u*4/10)'E
.    \" corrections for vroff
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
.    \" for low resolution devices (crt and lpr)
.if \n(.H>23 .if \n(.V>19 \
\{\
.    ds : e
.    ds 8 ss
.    ds o a
.    ds d- d\h'-1'\(ga
.    ds D- D\h'-1'\(hy
.    ds th \o'bp'
.    ds Th \o'LP'
.    ds ae ae
.    ds Ae AE
.\}
.rm #[ #] #H #V #F C
.\" ========================================================================
.\"
.IX Title "Lucy::Store::Lock 3pm"
.TH Lucy::Store::Lock 3pm "2015-03-06" "perl v5.20.2" "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"
Lucy::Store::Lock \- Abstract class representing an interprocess mutex lock.
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 7
\&    my $lock = $lock_factory\->make_lock(
\&        name    => \*(Aqwrite\*(Aq,
\&        timeout => 5000,
\&    );
\&    $lock\->obtain or die "can\*(Aqt get lock for " . $lock\->get_name;
\&    do_stuff();
\&    $lock\->release;
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The Lock class produces an interprocess mutex lock.  The default subclass
uses dot-lock files, but alternative implementations are possible.
.PP
Each lock must have a name which is unique per resource to be locked.  Each
lock also has a \*(L"host\*(R" id which should be unique per machine; it is used to
help clear away stale locks.
.SH "CONSTRUCTORS"
.IX Header "CONSTRUCTORS"
.SS "new( \fI[labeled params]\fP )"
.IX Subsection "new( [labeled params] )"
.Vb 7
\&    my $lock = Lucy::Store::Lock\->new(
\&        name     => \*(Aqcommit\*(Aq,     # required
\&        folder   => $folder,      # required
\&        host     => $hostname,    # required
\&        timeout  => 5000,         # default: 0
\&        interval => 1000,         # default: 100
\&    );
.Ve
.PP
Abstract constructor.
.IP "\(bu" 4
\&\fBfolder\fR \- A Folder.
.IP "\(bu" 4
\&\fBname\fR \- String identifying the resource to be locked, which must
consist solely of characters matching [\-_.A\-Za\-z0\-9].
.IP "\(bu" 4
\&\fBhost\fR \- A unique per-machine identifier.
.IP "\(bu" 4
\&\fBtimeout\fR \- Time in milliseconds to keep retrying before abandoning
the attempt to \fIobtain()\fR a lock.
.IP "\(bu" 4
\&\fBinterval\fR \- Time in milliseconds between retries.
.SH "ABSTRACT METHODS"
.IX Header "ABSTRACT METHODS"
.SS "\fIrequest()\fP"
.IX Subsection "request()"
Make one attempt to acquire the lock.
.PP
The semantics of \fIrequest()\fR differ depending on whether \fIshared()\fR returns
true.  If the Lock is \fIshared()\fR, then \fIrequest()\fR should not fail if
another lock is held against the resource identified by
\&\f(CW\*(C`name\*(C'\fR (though it might fail for other reasons).  If it is
not \fIshared()\fR \*(-- i.e. it's an exclusive (write) lock \*(-- then other locks
should cause \fIrequest()\fR to fail.
.PP
Returns: true on success, false on failure (sets Lucy\->error).
.SS "\fIrelease()\fP"
.IX Subsection "release()"
Release the lock.
.SS "\fIis_locked()\fP"
.IX Subsection "is_locked()"
Indicate whether the resource identified by this lock's name is
currently locked.
.PP
Returns: true if the resource is locked, false otherwise.
.SS "\fIclear_stale()\fP"
.IX Subsection "clear_stale()"
Release all locks that meet the following three conditions: the lock
name matches, the host id matches, and the process id that the lock
was created under no longer identifies an active process.
.SH "METHODS"
.IX Header "METHODS"
.SS "\fIobtain()\fP"
.IX Subsection "obtain()"
Call \fIrequest()\fR once per \f(CW\*(C`interval\*(C'\fR until \fIrequest()\fR returns
success or the \f(CW\*(C`timeout\*(C'\fR has been reached.
.PP
Returns: true on success, false on failure (sets Lucy\->error).
.SH "INHERITANCE"
.IX Header "INHERITANCE"
Lucy::Store::Lock isa Lucy::Object::Obj.