X-Git-Url: https://git.p6c8.net/selfforum.git/blobdiff_plain/2427a7a4ff1fe48d61d649a0c1618f3528a95231..b9021e9738004ee35018d3ec16495b7dc1a287f0:/selfforum-cgi/shared/Lock.pm?ds=sidebyside

diff --git a/selfforum-cgi/shared/Lock.pm b/selfforum-cgi/shared/Lock.pm
index f3291c6..6dbef1a 100644
--- a/selfforum-cgi/shared/Lock.pm
+++ b/selfforum-cgi/shared/Lock.pm
@@ -4,841 +4,61 @@ package Lock;
 #                                                                              #
 # File:        shared/Lock.pm                                                  #
 #                                                                              #
-# Authors:     Andre Malo       <nd@o3media.de>, 2001-04-01                    #
+# Authors:     André Malo <nd@o3media.de>                                      #
 #                                                                              #
-# Description: file locking                                                    #
+# Description: Locking and Filehandle class                                    #
 #                                                                              #
 ################################################################################
 
 use strict;
-use Carp;
-use vars qw(
-  @EXPORT_OK
-  %EXPORT_TAGS
-  $Timeout
-  $violentTimeout
-  $masterTimeout
-  $iAmMaster
-);
-
-################################################################################
-#
-# Export
-#
-use base qw(Exporter);
-
-@EXPORT_OK   = qw(
-  lock_file
-  unlock_file
-  write_lock_file
-  write_unlock_file
-  violent_unlock_file
-  set_master_lock
-  release_file
-);
+use vars qw($module);
 
-%EXPORT_TAGS = (
-  READ  => [qw(
-    lock_file
-    unlock_file
-    violent_unlock_file
-  )],
-  WRITE => [qw(
-    write_lock_file
-    write_unlock_file
-    violent_unlock_file
-  )],
-  ALL   => [qw(
-    lock_file
-    unlock_file
-    write_lock_file
-    write_unlock_file
-    violent_unlock_file
-    set_master_lock
-    release_file
-  )]
-);
+use Fcntl;
 
 ################################################################################
 #
-# Windows section (no symlinks)
-#
-
-### sub w_lock_file ($;$) ######################################################
-#
-# set read lock (shared lock)
-# (for no-symlink-systems)
-#
-# Params: $filename - file to lock
-#         $timeout  - Lock Timeout (sec.)
-#
-# Return: Status Code (Bool)
-#
-sub w_lock_file ($;$) {
-  my $filename = shift;
-  my $timeout  = +shift || $Timeout;
-
-  if (-f &masterlockfile($filename)) {
-    for (0..$timeout) {
-
-      # try to increment the reference counter
-      #
-      &set_ref($filename,1,$timeout) and return 1;
-      sleep (1);
-    }
-   }
-
-  else {
-    # master lock is set
-    # or file has not been realeased yet
-    #
-    return;
-  }
-
-  # time out
-  # maybe the system is occupied
-  0;
-}
-
-### sub w_unlock_file ($;$) ####################################################
-#
-# remove read lock (shared lock)
-# (for no-symlink-systems)
-#
-# Params: $filename - locked file
-#         $timeout  - timeout (sec.)
-#
-# Return: Status Code (Bool)
-#
-sub w_unlock_file ($;$) {
-  my $filename = shift;
-  my $timeout  = shift || $Timeout;
-
-  if (-f &masterlockfile($filename)) {
-
-    # try do decrement the reference counter
-    #
-    &set_ref($filename,-1,$timeout) and return 1;
-  }
-
-  # time out
-  # maybe the system is occupied
-  # or file has not been released yet
-  #
-  return;
-}
-
-### sub w_write_lock_file ($;$) ################################################
-#
-# set write lock (exclusive lock)
-# (for no-symlink-systems)
-#
-# Params: $filename - file to lock
-#         $timeout  - timeout (sec.)
-#
-# Return: Status Code (Bool)
-#
-sub w_write_lock_file ($;$) {
-  my $filename=shift;
-  my $timeout= shift || $Timeout;
-
-  if (-f &masterlockfile($filename) or $iAmMaster) {
-
-    # announce the write lock
-    # and wait $timeout seconds for
-    # references == 0 (no shared locks set)
-    #
-    &simple_lock ($filename,$timeout) or return 0;
-    for (0..$timeout) {
-      # lock reference counter
-      # or fail
-      #
-      unless (&simple_lock (&reffile($filename),$timeout)) {
-        &simple_unlock($filename,$timeout);
-        return 0;
-      }
-
-      # ready if we have no shared locks
-      #
-      return 1 if (&get_ref ($filename) == 0);
-
-      # release reference counter
-      # shared locks get the chance to be removed
-      #
-      unless (&simple_unlock (&reffile($filename),$timeout)) {
-        &simple_unlock($filename,$timeout);
-        return 0;
-      }
-      sleep(1);
-    }
-
-    # write lock failed
-    # remove the announcement
-    #
-    &simple_unlock ($filename);}
-
-  else {
-    # master lock is set
-    # or file has not been released yet
-    #
-    return;}
-
-  # time out
-  # maybe the system is occupied
-  #
-  0;
-}
-
-### sub w_write_unlock_file ($;$) ##############################################
-#
-# remove write lock (exclusive lock)
-# (for no-symlink-systems)
-#
-# Params: $filename - locked file
-#         $timeout  - timeout (sec.)
-#
-# Return: Status Code (Bool)
-#
-sub w_write_unlock_file ($;$) {
-  my $filename = shift;
-  my $timeout  = shift || $Timeout;
-
-  if (-f &masterlockfile($filename) or $iAmMaster) {
-
-    # remove reference counter lock
-    #
-    &simple_unlock (&reffile($filename),$timeout) or return;
-
-    # remove the write lock announce
-    #
-    &simple_unlock ($filename,$timeout) or return;}
-
-  # done
-  1;
-}
-
-### sub w_violent_unlock_file ($) ##############################################
-#
-# remove any lock violent  (excl. master lock)
-# (for no-symlink-systems)
-#
-# Params: $filename - locked file
-#
-# Return: -none- (the success is not defined)
-#
-sub w_violent_unlock_file ($) {
-  my $filename = shift;
-
-  if (-f &masterlockfile($filename)) {
-
-    # find out last modification time
-    # and do nothing unless 'violent-timout' is over
-    #
-    my $reffile;
-    if (-f ($reffile = $filename) or -f ($reffile = &lockfile($filename))) {
-      my $time = (stat $reffile)[9];
-      return if ((time - $time) < $violentTimeout);}
-
-    write_lock_file ($filename,1);       # last try, to set an exclusive lock on $filename
-    unlink (&reffile($filename));        # reference counter = 0
-    simple_unlock (&reffile($filename)); # release reference counter file
-    simple_unlock ($filename);}          # release file
-
-  return;
-}
-
-### sub w_set_master_lock ($;$) ################################################
-#
-# set master lock
-# (for no-symlink-systems)
-#
-# Params: $filename - file to lock
-#         $timeout  - timeout (sec.)
-#
-# Return: Status Code (Bool)
-#
-sub w_set_master_lock ($;$) {
-  my $filename = shift;
-  my $timeout  = shift || $masterTimeout;
-
-  # set exclusive lock or fail
-  #
-  return unless (&write_lock_file ($filename,$timeout));
-
-  # set master lock
-  #
-  unlink &masterlockfile($filename) and return 1;
-
-  # no chance (occupied?, master lock set yet?)
-  return;
-}
-
-### sub w_release_file ($) #####################################################
-#
-# remove any locks (incl. master lock)
-# (for no-symlink-systems)
-#
-# Params: $filename - file to lock
-#         $timeout  - timeout (sec.)
-#
-# Return: Status Code (Bool)
-#
-sub w_release_file ($) {
-  my $filename=shift;
-
-  unlink (&reffile($filename));                              # reference counter = 0
-  return if (-f &reffile($filename));                      # really?
-  return unless (simple_unlock (&reffile($filename)));     # release reference counter
-  return unless (&simple_unlock ($filename));              # remove any write lock announce
-  return unless (&simple_unlock (&masterfile($filename))); # remove master lock
-
-  # done
-  1;
-}
-
-################################################################################
-#
-# *n*x section (symlinks possible)
-#
-
-### sub x_lock_file ($;$) ######################################################
-#
-# set read lock (shared lock)
-# (symlinks possible)
-#
-# Params: $filename - file to lock
-#         $timeout  - Lock Timeout (sec.)
-#
-# Return: Status Code (Bool)
-#
-sub x_lock_file ($;$) {
-  my $filename = shift;
-  my $timeout  = shift || $Timeout;
-
-  unless (-l &masterlockfile($filename)) {
-    for (0..$timeout) {
-
-      # try to increment the reference counter
-      #
-      &set_ref($filename,1,$timeout) and return 1;
-      sleep (1);
-    }
-  }
-
-  else {
-    # master lock is set
-    # or file has not been realeased yet
-    #
-    return;
-  }
-
-  # time out
-  # maybe the system is occupied
-  0;
-}
-
-### sub x_unlock_file ($;$) ####################################################
-#
-# remove read lock (shared lock)
-# (symlinks possible)
-#
-# Params: $filename - locked file
-#         $timeout  - timeout (sec.)
-#
-# Return: Status Code (Bool)
-#
-sub x_unlock_file ($;$) {
-  my $filename=shift;
-  my ($timeout)=(shift (@_) or $Timeout);
-
-  unless (-l &masterlockfile($filename)) {
-    # try do decrement the reference counter
-    #
-    &set_ref($filename,-1,$timeout) and return 1;}
-
-  # time out
-  # maybe the system is occupied
-  # or file has not been released yet
-  #
-  return;
-}
-
-### sub x_write_lock_file ($;$) ################################################
-#
-# set write lock (exclusive lock)
-# (symlinks possible)
-#
-# Params: $filename - file to lock
-#         $timeout  - timeout (sec.)
-#
-# Return: Status Code (Bool)
-#
-sub x_write_lock_file ($;$) {
-  my $filename = shift;
-  my $timeout  = shift || $Timeout;
-
-  unless (-l &masterlockfile($filename) and not $iAmMaster) {
-    # announce the write lock
-    # and wait $timeout seconds for
-    # references == 0 (no shared locks set)
-    #
-    &simple_lock ($filename,$timeout) or return 0;
-    for (0..$timeout) {
-
-      # lock reference counter
-      # or fail
-      #
-      unless (&simple_lock (&reffile($filename),$timeout)) {
-        &simple_unlock($filename,$timeout);
-        return 0;
-      }
-
-      # ready if we have no shared locks
-      #
-      return 1 if (&get_ref ($filename) == 0);
-
-      # release reference counter
-      # shared locks get the chance to be removed
-      #
-      unless (&simple_unlock (&reffile($filename),$timeout)) {
-        &simple_unlock($filename,$timeout);
-        return 0;
-      }
-      sleep(1);
-    }
-
-    # write lock failed
-    # remove the announcement
-    #
-    &simple_unlock ($filename);}
-
-  else {
-    # master lock is set
-    # or file has not been released yet
-    #
-    return;
-  }
-
-  # time out
-  # maybe the system is occupied
-  #
-  0;
-}
-
-### sub x_write_unlock_file ($;$) ##############################################
-#
-# remove write lock (exclusive lock)
-# (symlinks possible)
-#
-# Params: $filename - locked file
-#         $timeout  - timeout (sec.)
-#
-# Return: Status Code (Bool)
-#
-sub x_write_unlock_file ($;$) {
-  my $filename = shift;
-  my $timeout  = shift || $Timeout;
-
-  unless (-l &masterlockfile($filename) and not $iAmMaster) {
-    # remove reference counter lock
-    #
-    &simple_unlock (&reffile($filename),$timeout) or return;
-
-    # remove the write lock announce
-    #
-    &simple_unlock ($filename,$timeout) or return;
-  }
-
-  # done
-  1;
-}
-
-### sub x_violent_unlock_file ($) ##############################################
-#
-# remove any lock violent  (excl. master lock)
-# (symlinks possible)
-#
-# Params: $filename - locked file
-#
-# Return: -none- (the success is not defined)
-#
-sub x_violent_unlock_file ($) {
-  my $filename=shift;
-
-  unless (-l &masterlockfile($filename)) {
-
-    # find out last modification time
-    # and do nothing unless 'violent-timout' is over
-    #
-    my ($reffile,$time);
-
-    if (-f ($reffile = $filename)) {
-      $time = (stat $reffile)[9];}
-
-    elsif (-l ($reffile = &lockfile($filename))) {
-      $time = (lstat $reffile)[9];}
-
-    if ($reffile) {
-      return if ((time - $time) < $violentTimeout);}
-
-    write_lock_file ($filename,1);       # last try, to set an exclusive lock on $filename
-    unlink (&reffile($filename));        # reference counter = 0
-    simple_unlock (&reffile($filename)); # release reference counter file
-    simple_unlock ($filename);}          # release file
-}
-
-### sub x_set_master_lock ($;$) ################################################
-#
-# set master lock
-# (symlinks possible)
-#
-# Params: $filename - file to lock
-#         $timeout  - timeout (sec.)
-#
-# Return: Status Code (Bool)
-#
-sub x_set_master_lock ($;$) {
-  my $filename = shift;
-  my $timeout  = shift || $masterTimeout;
-
-  # set exclusive lock or fail
-  #
-  return unless (&write_lock_file ($filename,$timeout));
-
-  # set master lock
-  #
-  symlink $filename, &masterlockfile($filename) and return 1;
-
-  # no chance (occupied?, master lock set yet?)
-  return;
-}
-
-### sub x_release_file ($) #####################################################
-#
-# remove any locks (incl. master lock)
-# (symlinks possible)
-#
-# Params: $filename - file to lock
-#         $timeout  - timeout (sec.)
+# Version check
 #
-# Return: Status Code (Bool)
+# last modified:
+#    $Date$ (GMT)
+# by $Author$
 #
-sub x_release_file ($) {
-  my $filename=shift;
-
-  unlink (&reffile($filename));                            # reference counter = 0
-  return if (-f &reffile($filename));                      # really?
-  return unless (simple_unlock (&reffile($filename)));     # release reference counter
-  return unless (&simple_unlock ($filename));              # remove any write lock announce
-  return unless (&simple_unlock (&masterfile($filename))); # remove master lock
-
-  # done
-  1;
-}
+sub VERSION {(q$Revision$ =~ /([\d.]+)\s*$/)[0] or '0.0'}
 
 ################################################################################
 #
-# private subs
-#
-
-### sub ~file ($) ##############################################################
-#
-# create lock file names
-#
-sub reffile ($) {
-  "$_[0].lock.ref";
-}
-sub lockfile ($) {
-  "$_[0].lock";
-}
-sub masterlockfile ($) {
-  &lockfile(&masterfile($_[0]));
-}
-sub masterfile ($) {
-  confess unless defined $_[0];
-  "$_[0].master";
-}
-
-### sub w_simple_lock ($;$) ####################################################
-### sub w_simple_unlock ($) ####################################################
-#
-# simple file lock/unlock
-# (for no-symlink-systems: kill/create lockfile)
-#
-# Params: $filename  - file to lock
-#         [ $timeout - Lock time out (sec.) ]
+# load the specific module
 #
-# Return: Status Code (Bool)
-#
-sub w_simple_lock ($;$) {
-  my $filename = shift;
-  my $timeout  = shift || $Timeout;
-  my $lockfile = lockfile $filename;
-
-  for (0..$timeout) {
-    unlink $lockfile and return 1;
-    sleep(1);
-  }
-
-  # timeout
-  # occupied?
-  return;
-}
-
-sub w_simple_unlock ($) {
-  my $filename = shift;
-  my $lockfile = lockfile $filename;
-  local *LF;
-
-  if (open(LF, "> $lockfile")) {
-    return 1 if close (LF);
-  }
-
-  # not able to create lockfile, hmmm...
-  #
-  return;
-}
-
-### sub w_simple_lock ($;$) ####################################################
-### sub w_simple_unlock ($) ####################################################
-#
-# simple file lock/unlock
-# (symlinks possible: create/unlink symlink)
-#
-# Params: $filename  - file to lock
-#         [ $timeout - Lock time out (sec.) ]
-#
-# Return: Status Code (Bool)
-#
-sub x_simple_lock ($;$) {
-  my $filename = shift;
-  my $timeout  = shift || $Timeout;
-  my $lockfile = lockfile $filename;
-
-  for (0..$timeout) {
-    symlink $filename,$lockfile and return 1;
-    sleep(1);
-  }
-
-  # time out
-  # locking failed (occupied?)
-  #
-  return;
-}
-
-sub x_simple_unlock ($) {
-  my $filename=shift;
-
-  unlink (&lockfile($filename)) and return 1;
-
-  # not able to unlink symlink, hmmm...
-  #
-  return;
-}
-
-### sub w_set_ref ($$$) ########################################################
-#
-# add $_[1] to reference counter
-# (may be negative...)
-# (for no-symlink-systems)
-#
-# Params: $filename - file, reference counter belongs to
-#         $z        - value, added to reference counter
-#         $timeout  - lock time out
-#
-# Return: Status Code (Bool)
-#
-sub w_set_ref ($$$) {
-  my $filename = shift;
-  my $z        = shift;
-  my $timeout  = shift || $Timeout;
-  my $old;
-  my $reffile = reffile $filename;
-  local *REF;
-
-  # if write lock announced, only count down allowed
-  #
-  if ($z > 0) {
-    return unless(-f lockfile($filename));
-  }
-
-  # lock reference counter file
-  #
-  return unless(&simple_lock ($reffile,$timeout));
-
-  # load reference counter
-  #
-  unless (open REF,"<$reffile") {
-    $old=0;
-  }
-  else {
-    $old=<REF>;
-    chomp $old;
-    close REF or return;
-  }
-
-  # compute and write new ref. counter
-  #
-  $old += $z;
-  $old = 0 if ($old < 0);
-
-  # kill reference counter file
-  # if ref. counter == 0
-  #
-  if ($old == 0) {
-    unlink $reffile or return;
-  }
-  else {
-    open REF,">$reffile" or return;
-    print REF $old or return;
-    close REF or return;
-  }
-
-  # release ref. counter file
-  #
-  return unless(&simple_unlock($reffile));
-
-  # done
-  1;
-}
-
-### sub x_set_ref ($$$) ########################################################
-#
-# add $_[1] to reference counter
-# (may be negative...)
-# (symlinks possible)
-#
-# Params: $filename - file, reference counter belongs to
-#         $z        - value, added to reference counter
-#         $timeout  - lock time out
-#
-# Return: Status Code (Bool)
-#
-sub x_set_ref ($$$) {
-  my $filename = shift;
-  my $z        = shift;
-  my $timeout  = shift || $Timeout;
-  my $old;
-  my $reffile = reffile $filename;
-  local *REF;
-
-  # if write lock announced, only count down allowed
-  #
-  if ($z > 0) {
-    return if(-l &lockfile($filename));
-  }
-
-  # lock reference counter file
-  #
-  return unless(&simple_lock ($reffile,$timeout));
-
-  # load reference counter
-  #
-  unless (open REF,"<$reffile") {
-    $old=0;
-  }
-  else {
-    $old=<REF>;
-    chomp $old;
-    close REF or return;
-  }
-
-  # compute and write new ref. counter
-  #
-  $old += $z;
-  $old = 0 if ($old < 0);
-  if ($old == 0) {
-    unlink $reffile or return;
-  }
-  else {
-    open REF,">$reffile" or return;
-    print REF $old or return;
-    close REF or return;
-  }
-
-  # release ref. counter file
-  #
-  return unless(&simple_unlock($reffile));
-
-  # done
-  1;
-}
-
-### sub get_ref ($) ############################################################
-#
-# read out the reference counter
-# (system independant)
-# no locking here!
-#
-# Params: $filename - file, the ref. counter belongs to
-#
-# Return: reference counter
-#
-sub get_ref ($$) {
-  my $filename = shift;
-  my $reffile  = reffile $filename;
-  my $old;
-  local *REF;
-
-  unless (open REF,"< $reffile") {
-    $old = 0;
-  }
-  else {
-    $old=<REF>;
-    chomp $old;
-    close REF;
-  }
-
-  # return value
-  $old;
-}
+BEGIN {
+  local $SIG{__DIE__};
+
+  $module = 'Lock::'.(
+    eval {symlink('',''); 1}
+    ? 'Symlink'
+    : ( eval {O_EXCL}
+      ? 'Exclusive'
+      : 'Unlink'
+    )
+  );
+}
+use base (
+  $module,
+  'Lock::API'
+);
 
 ################################################################################
 #
-# initializing the module
+# export constants
 #
-BEGIN {
-  # global variables (time in seconds)
-  #
-  $Timeout        =  10; # normal timeout
-  $violentTimeout = 600; # violent timeout (10 minutes)
-  $masterTimeout  =  20; # master timeout
+use constant LH_SHARED => 0;
+use constant LH_EXCL   => 1;
+use constant LH_EXSH   => 2;
+use constant LH_MASTER => 3;
 
-  $iAmMaster = 0;        # default: I am nobody
-
-  # assign the aliases to the needed functions
-  # (perldoc -f symlink)
-
-  if ( eval {local $SIG{__DIE__}; symlink('',''); 1 } ) {
-    *lock_file           = \&x_lock_file;
-    *unlock_file         = \&x_unlock_file;
-    *write_lock_file     = \&x_write_lock_file;
-    *write_unlock_file   = \&x_write_unlock_file;
-    *violent_unlock_file = \&x_violent_unlock_file;
-    *set_master_lock     = \&x_set_master_lock;
-    *release_file        = \&x_release_file;
-
-    *simple_lock         = \&x_simple_lock;
-    *simple_unlock       = \&x_simple_unlock;
-    *set_ref             = \&x_set_ref;
-  }
-
-  else {
-    *lock_file           = \&w_lock_file;
-    *unlock_file         = \&w_unlock_file;
-    *write_lock_file     = \&w_write_lock_file;
-    *write_unlock_file   = \&w_write_unlock_file;
-    *violent_unlock_file = \&w_violent_unlock_file;
-    *set_master_lock     = \&w_set_master_lock;
-    *release_file        = \&w_release_file;
-
-    *simple_lock         = \&w_simple_lock;
-    *simple_unlock       = \&w_simple_unlock;
-    *set_ref             = \&w_set_ref;
-  }
-}
+use base 'Exporter';
+@Lock::EXPORT = qw(LH_SHARED LH_EXCL LH_EXSH LH_MASTER);
 
-# keeping require happy
+# keep require happy
 1;
 
 #