X-Git-Url: https://git.p6c8.net/selfforum.git/blobdiff_plain/42e7ab8a13679442f2cd7524ab7fa38bb2166951..f91793544f0d5c7f978e5cf6214d9882d7c4db7c:/selfforum-cgi/shared/Lock.pm diff --git a/selfforum-cgi/shared/Lock.pm b/selfforum-cgi/shared/Lock.pm index 3f01861..6dbef1a 100644 --- a/selfforum-cgi/shared/Lock.pm +++ b/selfforum-cgi/shared/Lock.pm @@ -4,855 +4,61 @@ package Lock; # # # File: shared/Lock.pm # # # -# Authors: Andre Malo , 2001-04-01 # +# Authors: André Malo # # # -# Description: file locking # +# Description: Locking and Filehandle class # # # ################################################################################ use strict; -use vars qw( - @EXPORT_OK - %EXPORT_TAGS - %LOCKED - $Timeout - $violentTimeout - $masterTimeout - $iAmMaster -); +use vars qw($module); -use Carp; use Fcntl; ################################################################################ # -# 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 -); - -%EXPORT_TAGS = ( - READ => [qw( - lock_file - unlock_file - violent_unlock_file - )], - WRITE => [qw( - write_lock_file - write_unlock_file - violent_unlock_file - )], - ALL => \@EXPORT_OK -); - -### sub ~file ($) ############################################################## -# -# create lock file names -# -sub reffile ($) { - return $_[0].'.lock.ref'; -} -sub lockfile ($) { - return $_[0].'.lock'; -} -sub masterfile ($) { - return $_[0].'.master'; -} -sub masterlockfile ($) { - return lockfile(masterfile $_[0]); -} - -################################################################################ -# -# Windows section (no symlinks) -# - -### sub w_lock_file ($;$) ###################################################### -# -# 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 || $Timeout; - - unless ($LOCKED{$filename}) { - if (-f masterlockfile($filename)) { - for (1..$timeout) { - - # try to increment the reference counter - # - if (set_ref($filename,1,$timeout)) { - $LOCKED{$filename}=1; - return 1; - } - sleep (1); - } - } - else { - # master lock is set or file has not been released 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 || $Timeout; - - if ($LOCKED{$filename}) { - if ($LOCKED{$filename} == 3) { - return unless write_unlock_file($filename, $timeout); - $LOCKED{$filename} = 1; - } - if ($LOCKED{$filename} == 1) { - if (-f masterlockfile($filename)) { - - # try do decrement the reference counter - # - if (set_ref($filename,-1,$timeout)) { - delete $LOCKED{$filename}; - return 1; - } - } - } - } - - # time out - 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; - my $rest = ($LOCKED{$filename} and $LOCKED{$filename} == 1) ? 1 : 0; - - if (-f masterlockfile($filename) or $iAmMaster) { - - # announce the write lock - # and wait $timeout seconds for - # references == 0 (no shared locks set) - # - simple_lock ($filename,$timeout) or return 0; - for (1..$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 - # - if (get_ref ($filename) == $rest) { - $LOCKED{$filename} = 2 | ($rest ? 1 : 0); - return 1; - }; - - # release reference counter - # shared locks get the chance to be removed - # - unless (simple_unlock (reffile($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 - 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 - delete $LOCKED{$filename}; - 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]; - (time - $time) >= $violentTimeout or return; - } - - write_lock_file ($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 - delete $LOCKED{$filename}; - - 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.) +# Version check # -# Return: Status Code (Bool) +# last modified: +# $Date$ (GMT) +# by $Author$ # -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 - delete $LOCKED{$filename}; - - # done - 1; -} +sub VERSION {(q$Revision$ =~ /([\d.]+)\s*$/)[0] or '0.0'} ################################################################################ # -# *n*x section (symlinks possible) -# - -### sub x_lock_file ($;$) ###################################################### -# -# 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 || $Timeout; - - unless ($LOCKED{$filename}) { - unless (-l masterlockfile($filename)) { - for (1..$timeout) { - - # try to increment the reference counter - # - if (set_ref($filename,1,$timeout)) { - $LOCKED{$filename} = 1; - return 1; - } - sleep (1); - } - } - - else { - # master lock is set or file has not been realeased yet - return; - } - } - - # time out - 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 $Timeout); - - if ($LOCKED{$filename}) { - if ($LOCKED{$filename} == 3) { - return unless write_unlock_file($filename, $timeout); - $LOCKED{$filename} = 1; - } - if ($LOCKED{$filename} == 1) { - unless (-l masterlockfile($filename)) { - # try to decrement the reference counter - # - set_ref($filename,-1,$timeout) and do { - delete $LOCKED{$filename}; - return 1; - } - } - - # time out - 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; - my $rest = ($LOCKED{$filename} and $LOCKED{$filename} == 1) ? 1 : 0; - - 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,$timeout) or return 0; - for (1..$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 - # - if (get_ref ($filename) == $rest) { - $LOCKED{$filename} = 2 | ($rest ? 1 : 0); - return 1; - }; - - # release reference counter - # shared locks get the chance to be removed - # - unless (simple_unlock (&reffile($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 - delete $LOCKED{$filename}; - 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 - delete $LOCKED{$filename}; -} - -### 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 -# $timeout - timeout (sec.) -# -# Return: Status Code (Bool) -# -sub x_release_file ($) { - 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 - delete $LOCKED{$filename}; - - # done - 1; -} - -### sub w_simple_lock ($;$) #################################################### -### sub w_simple_unlock ($) #################################################### -# -# simple file lock/unlock -# (for no-symlink-systems: kill/create lockfile) -# -# Params: $filename - file to lock -# [ $timeout - Lock time out (sec.) ] -# -# Return: Status Code (Bool) -# -sub w_simple_lock ($;$) { - my $filename = shift; - my $timeout = shift || $Timeout; - my $lockfile = lockfile $filename; - - for (1..$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 (sysopen(LF, $lockfile, O_WRONLY|O_CREAT|O_TRUNC)) { - return 1 if close (LF); - } - - # not able to create lockfile, hmmm... - # - return; -} - -### sub x_simple_lock ($;$) #################################################### -### sub x_simple_unlock ($) #################################################### -# -# 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 $filename; - - for (1..$timeout) { - symlink $filename,$lockfile and return 1; - sleep(1); - } - - # time out - 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 $reffile = reffile $filename; - local *REF; - - # if write lock announced, only count down allowed - # - ($z < 0 or -f lockfile ($filename)) or return; - - # lock reference counter file - # - simple_lock ($reffile,$timeout) or return; - - # load reference counter - # - my $old = get_ref ($filename); - - # 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 { - local $\="\n"; - sysopen (REF, $reffile, O_WRONLY | O_TRUNC | O_CREAT) or return; - print REF $old or do { - close REF; - return - }; - close REF or return; - } - - # release ref. counter file - # - simple_unlock($reffile) or return; - - # done - 1; -} - -### sub x_set_ref ($$$) ######################################################## -# -# add $_[1] to reference counter -# (may be negative...) -# (symlinks possible) -# -# Params: $filename - file, reference counter belongs to -# $z - value, added to reference counter -# $timeout - lock time out +# load the specific module # -# Return: Status Code (Bool) -# -sub x_set_ref ($$$) { - my $filename = shift; - my $z = shift; - my $timeout = shift || $Timeout; - 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 - # - my $old = get_ref ($filename); - - # compute and write new ref. counter - # - $old += $z; - $old = 0 if ($old < 0); - - if ($old == 0) { - unlink $reffile or return; - } - else { - local $\="\n"; - sysopen (REF, $reffile, O_WRONLY | O_TRUNC | O_CREAT) or return; - print REF $old or do { - close REF; - return - }; - close REF or return; - } - - # release ref. counter file - # - simple_unlock($reffile) or return; - - # 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; - - if (sysopen (REF, $reffile, O_RDONLY)) { - local $/="\n"; - read REF, $old, -s $reffile; - close REF; - chomp $old; - } - - # return value - $old or 0; -} +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 - - $iAmMaster = 0; # default: I am nobody +use constant LH_SHARED => 0; +use constant LH_EXCL => 1; +use constant LH_EXSH => 2; +use constant LH_MASTER => 3; - %LOCKED = (); - - # 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; #