X-Git-Url: https://git.p6c8.net/selfforum.git/blobdiff_plain/85946d0838c74882bd707bd1f5dbeeb7ea80944f..4efca15bb2136c3e226eb4e372776fad95a955c9:/selfforum-cgi/shared/Lock/API.pm

diff --git a/selfforum-cgi/shared/Lock/API.pm b/selfforum-cgi/shared/Lock/API.pm
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+package Lock::API;
+
+################################################################################
+#                                                                              #
+# File:        shared/Lock/API.pm                                              #
+#                                                                              #
+# Authors:     Andre Malo       <nd@o3media.de>, 2001-05-25                    #
+#                                                                              #
+# Description: system independent part of Locking and Filehandle class         #
+#              NOT FOR PUBLIC USE                                              #
+#                                                                              #
+################################################################################
+
+use strict;
+use vars qw(
+  $VERSION
+);
+
+use Carp;
+
+use base qw(
+  Lock::Handle
+  Lock::_simple
+);
+
+################################################################################
+#
+# Version check
+#
+$VERSION = do { my @r =(q$Revision$ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
+
+### sub lock ###################################################################
+#
+# set a lock on the file
+#
+# Params: $locktype - what kind of locking?
+#         $timeout  - (optional) Timeout
+#
+# Return: success (boolean)
+#
+sub lock {
+  my $self = shift;
+  my $locktype = shift;
+
+  return if $self -> masterlocked;
+
+  ###########################################
+  # shared lock
+  #
+  if ($locktype == $self -> LH_SHARED) {
+    return 1 if $self -> locked_shared;
+    return   if $self -> locked_exclusive;
+
+    my $timeout  = shift || $self -> timeout ('shared');
+
+    # try to increase the reference counter
+    #
+    if ($self -> add_ref($timeout)) {
+      $self -> set_static (locked_shared => 1);
+      return 1;
+    }
+  }
+
+
+  ###########################################
+  # exclusive lock
+  #
+  elsif ($locktype == $self -> LH_EXCL) {
+    return 1 if $self -> locked_exclusive;
+
+    my $timeout  = shift || $self -> timeout ('exclusive');
+
+    #####################
+    # transform exclusive shared lock into exclusive lock
+    #
+    if ($self -> locked_exsh) {
+      my $reflock = new Lock::Handle ($self -> reflock);
+
+      for (0..$timeout) {
+        if ($self -> set_excl_announce and $self -> _simple_lock ($reflock)) {
+          if ($self -> get_ref == 1) {
+            $self -> set_ref(0);
+            $self -> remove_exsh_announce;
+            $self -> set_static (locked_exsh      => 0);
+            $self -> set_static (locked_exclusive => 1);
+            return 1;
+          }
+
+          last unless ($self -> _simple_unlock ($reflock->filename));
+        }
+
+        sleep 1;
+      }
+      $self -> remove_excl_announce;
+    }
+
+    #####################
+    # set exclusive lock
+    #
+    else {
+      my $reflock = new Lock::Handle ($self -> reflock);
+
+      for (0..$timeout) {
+        if ($self -> set_excl_announce and $self -> _simple_lock ($reflock)) {
+          if ($self -> get_ref == 0) {
+            $self -> set_static (locked_exclusive => 1);
+            return 1;
+          }
+
+          last unless ($self -> _simple_unlock ($reflock->filename));
+        }
+
+        sleep 1;
+      }
+      $self -> remove_excl_announce;
+    }
+  }
+
+
+  ###########################################
+  # exclusive shared lock
+  #
+  elsif ($locktype == $self -> LH_EXSH) {
+    return 1 if $self -> locked_exsh;
+    return   if ($self -> locked_shared or $self -> locked_exclusive);
+
+    my $timeout  = shift || $self -> timeout ('shared');
+
+    # try to increase the reference counter
+    #
+    if ($self -> es_add_ref($timeout)) {
+      $self -> set_static (locked_exsh => 1);
+      return 1;
+    }
+  }
+
+
+  ###########################################
+  # master lock
+  #
+  elsif ($locktype == $self -> LH_MASTER) {
+    $self -> lock ($self->LH_EXCL, $self -> timeout('master'))   and
+    $self -> _simple_lock (new Lock::Handle ($self->masterlock)) and
+    return 1;
+  }
+
+  ###########################################
+  # unknown locking type
+  #
+  else {
+    croak "unknown locking type '$locktype'";
+  }
+
+  # timeout
+  #
+  $self -> unlock_violent;
+  return;
+}
+
+### sub unlock #################################################################
+#
+# remove shared or exclusive lock
+#
+# Params: $timeout - (optional) Timeout
+#
+# Return: success (boolean)
+#
+sub unlock {
+  my $self = shift;
+  my $timeout = shift || $self -> timeout ('shared');
+
+  return if $self -> masterlocked;
+
+  ###########################################
+  # shared lock
+  #
+  if ($self -> locked_shared) {
+    # try to decrease the reference counter
+    #
+    if ($self -> sub_ref($timeout)) {
+      $self -> set_static (locked_shared => 0);
+      return 1;
+    }
+  }
+
+
+  ###########################################
+  # exclusive lock
+  #
+  elsif ($self -> locked_exclusive) {
+    my $reflock = new Lock::Handle ($self -> reflock);
+
+    for (0..$timeout) {
+      if ($self -> _simple_unlock ($reflock->filename)) {
+        $self -> remove_excl_announce;
+        $self -> set_static (locked_exclusive => 0);
+        return 1;
+      }
+
+      sleep 1;
+    }
+  }
+
+
+  ###########################################
+  # exclusive shared lock
+  #
+  elsif ($self -> locked_exsh) {
+    # try to decrease the reference counter
+    #
+    if ($self -> es_sub_ref($timeout)) {
+      $self -> remove_exsh_announce;
+      $self -> set_static (locked_exsh => 0);
+      return 1;
+    }
+  }
+
+
+  ###########################################
+  # not locked
+  #
+  else {
+    return 1;
+  }
+
+  # unlocking failed
+  #
+  $self -> unlock_violent;
+  return;
+}
+
+### sub unlock_violent #########################################################
+#
+# remove any lock violently  (excludes master lock)
+#
+# Params: ~none~
+#
+# Return: -none- (the success is undefined)
+#
+sub unlock_violent {
+  my $self = shift;
+
+  unless ($self -> masterlocked) {
+
+    # find out last modification time
+    # and do nothing unless 'violent-timout' is over
+    #
+    my $time = $self -> _reftime;
+
+    if ($time) {
+      return if ((time - $time) < $self -> timeout('violent'));
+    }
+
+    $self -> set_ref (0);                        # reference counter = 0
+    $self -> _simple_unlock ($self -> reflock);  # release reference counter file
+    $self -> _simple_unlock ($self -> exshlock); # remove excl shared lock
+    $self -> _simple_unlock ($self -> lockfile); # release file
+  }
+
+  return;
+}
+
+### sub release ################################################################
+#
+# release a file
+#
+# Params: ~none~
+#
+# Return: ~none~
+#
+sub release {
+  my $self = shift;
+
+  $self -> set_ref (0);                           # reference counter = 0
+  $self -> _simple_unlock ($self -> reflock);     # release reference counter
+  $self -> _simple_unlock ($self -> lockfile);    # remove any write lock announce
+  $self -> _simple_unlock ($self -> exshlock);    # remove any excl shared lock
+  $self -> _simple_unlock ($self -> masterlock);  # remove master lock
+
+  return;
+}
+
+# keep 'require' happy
+1;
+
+#
+#
+### end of Lock::API ###########################################################
\ No newline at end of file