/[wait]/cvs-head/lib/WAIT/Table.pm

This is repository of my old source code which isn't updated any more. Go to git.rot13.org for current projects!

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-branches/CPAN/lib/WAIT/Table.pm
revision 13 by ulpfr,
Fri Apr 28 15:42:44 2000 UTC
+cvs-head/lib/WAIT/Table.pm
revision 85 by ulpfr,
Fri May  3 16:16:10 2002 UTC
 Line 4
  # Author          : Ulrich Pfeifer
  # Created On      : Thu Aug  8 13:05:10 1996
  # Last Modified By: Ulrich Pfeifer
- # Last Modified On: Sun May 30 20:42:30 1999
+ # Last Modified On: Sat Apr 27 17:20:31 2002
  # Language        : CPerl
- # Update Count    : 56
+ # Update Count    : 172
  # Status          : Unknown, Use with caution!
  #
  # Copyright (c) 1996-1997, Ulrich Pfeifer
 Line 32 
 require WAIT::Parse::Base;
  use strict;
  use Carp;
  # use autouse Carp => qw( croak($) );
- use DB_File;
+ use BerkeleyDB;
  use Fcntl;
+ use LockFile::Simple ();
  my $USE_RECNO = 0;
-Line 158 
 sub new {
+Line 159 
 sub new {
    }
    $self->{file}     = $parm{file}     or croak "No file specified";
-   if (-d  $self->{file}){
+   if (-e  $self->{file}){
-     warn "Warning: Directory '$self->{file}' already exists\n";
+     warn "Warning: file '$self->{file}' already exists\n";
-   } elsif (!mkdir($self->{file}, 0775)) {
-     croak "Could not 'mkdir $self->{file}': $!\n";
    }
    $self->{djk}      = $parm{djk}      if defined $parm{djk};
    $self->{layout}   = $parm{layout} || new WAIT::Parse::Base;
    $self->{access}   = $parm{access} if defined $parm{access};
 Line 171 
 sub new {
    $self->{indexes}  = {};
    bless $self, $type;
+   # Checking for readers is not necessary, but let's go with the
+   # generic method.
+   $self->getlock(O_RDWR|O_CREAT); # dies when failing
    # Call create_index() and create_index() for compatibility
    for (@{$self->{keyset}||[]}) {
      #carp "Specification of indexes at table create time is deprecated";
-Line 188 
 sub new {
+Line 193 
 sub new {
      }
      $self->create_inverted_index(attribute => $att, pipeline  => \@spec, @opt);
    }
    $self;
    # end of backwarn compatibility stuff
  }
-Line 215 
 sub create_index {
+Line 221 
 sub create_index {
    my $name = join '-', @_;
    $self->{indexes}->{$name} =
-     new WAIT::Index file => $self->{file}.'/'.$name, attr => $_;
+     new WAIT::Index file => $self->{file}, name => $name, attr => $_;
  }
  =head2 Creating an inverted index
-Line 315 
 Must be called via C<WAIT::Database::dro
+Line 321 
 Must be called via C<WAIT::Database::dro
  sub drop {
    my $self = shift;
+   unless ($self->{write_lock}){
+     warn "Cannot drop table without write lock. Nothing done";
+     return;
+   }
    if ((caller)[0] eq 'WAIT::Database') { # database knows about this
      $self->close;               # just make sure
      my $file = $self->{file};
      for (values %{$self->{indexes}}) {
        $_->drop;
      }
-     unlink "$file/records";
+     rmdir "$file.read" or warn "Could not rmdir '$file/read'";
-     ! (!-e $file or rmdir $file);
+     unlink "$file";
    } else {
      croak ref($self)."::drop called directly";
    }
-Line 363 
 sub open {
+Line 377 
 sub open {
      }
      require WAIT::InvertedIndex;
    }
+   $self->getlock($self->{mode});
+   my $dbmode = ($self->{mode} & O_CREAT) ? DB_CREATE : 0;
    unless (defined $self->{dbh}) {
      if ($USE_RECNO) {
-       $self->{dbh} = tie(@{$self->{db}}, 'DB_File', $file,
+       tie(%{$self->{db}}, 'BerkeleyDB::Recno',
-                          $self->{mode}, 0664, $DB_RECNO);
+           -Filename => $self->{file},
+           -Subname  => 'records',
+           -Flags    => $dbmode);
      } else {
        $self->{dbh} =
-         tie(%{$self->{db}}, 'DB_File', $file,
+         tie(%{$self->{db}}, 'BerkeleyDB::Btree',
-                          $self->{mode}, 0664, $DB_BTREE);
+             -Filename => $self->{file},
+             -Subname  => 'records',
+             -Mode     => 0664,
+             -Flags    => $dbmode);
      }
    }
    $self;
  }
-Line 432 
 sub insert {
+Line 457 
 sub insert {
    my $tuple = join($;, map($parm{$_} || '', @{$self->{attr}}));
    my $key;
    my @deleted = keys %{$self->{deleted}};
+   my $gotkey = 0;
    if (@deleted) {
      $key = pop @deleted;
      delete $self->{deleted}->{$key};
+     # Sanity check
+     if ($key && $key>0) {
+       $gotkey=1;
    } else {
+       warn(sprintf("WAIT database inconsistency during insert ".
+                    "key[%s]: Please rebuild index\n",
+                    $key
+                   ));
+     }
+   }
+   unless ($gotkey) {
      $key = $self->{nextk}++;
    }
    if ($USE_RECNO) {
-Line 450 
 sub insert {
+Line 486 
 sub insert {
        if ($key == $self->{nextk}-1) {
          $self->{nextk}--;
        } else {
+         # warn "setting key[$key] deleted during insert";
          $self->{deleted}->{$key}=1;
        }
        my $idx;
-Line 504 
 sub delete_by_key {
+Line 541 
 sub delete_by_key {
    my $self  = shift;
    my $key   = shift;
+   unless ($key) {
+     Carp::cluck "Warning: delete_by_key called without key. Looks like a bug in WAIT?";
+     return;
+   }
    return $self->{deleted}->{$key} if defined $self->{deleted}->{$key};
    my %tuple = $self->fetch($key);
    for (values %{$self->{indexes}}) {
-Line 520 
 sub delete_by_key {
+Line 562 
 sub delete_by_key {
        }
      }
    }
+   # warn "setting key[$key] deleted during delete_by_key";
    ++$self->{deleted}->{$key};
  }
  sub delete {
    my $self  = shift;
    my $tkey = $self->have(@_);
+   # warn "tkey[$tkey]\@_[@_]";
    defined $tkey && $self->delete_by_key($tkey, @_);
  }
  sub unpack {
-   my $self = shift;
+   my($self, $tuple) = @_;
-   my $tuple = shift;
+   unless (defined $tuple){
+     # require Carp; # unfortunately gives us "bizarre copy...." :-(((((
+     warn("Debug: somebody called unpack without argument tuple!");
+     return;
+   }
    my $att;
    my @result;
-Line 544 
 sub unpack {
+Line 592 
 sub unpack {
    @result;
  }
+ sub set {
+   my ($self, $iattr, $value) = @_;
+   unless ($self->{write_lock}){
+     warn "Cannot set iattr[$iattr] without write lock. Nothing done";
+     return;
+   }
+   # in the rare case that they haven't written a single record yet, we
+   # make sure, the inverted inherits our $self->{mode}:
+   defined $self->{db} or $self->open;
+   for my $att (keys %{$self->{inverted}}) {
+     if ($] > 5.003) {         # avoid bug in perl up to 5.003_05
+       my $idx;
+       for $idx (@{$self->{inverted}->{$att}}) {
+         $idx->set($iattr, $value);
+       }
+     } else {
+       map $_->set($iattr, $value), @{$self->{inverted}->{$att}};
+     }
+   }
+;
+ }
  sub close {
    my $self = shift;
    if (exists $self->{'access'}) {
      eval {$self->{'access'}->close}; # dont bother if not opened
    }
-   for (values %{$self->{indexes}}) {
+   if ($WAIT::Index::VERSION) {
-     $_->close();
+     for (values %{$self->{indexes}}) {
+       $_->close();
+     }
    }
-   if (defined $self->{inverted}) {
+   if (defined $self->{inverted} && $WAIT::InvertedIndex::VERSION) {
+     # require WAIT::InvertedIndex; Uli: we can avoid closing indexes:
+     # if WAIT::InvertedIndex has not been loaded, they cannot have
+     # been altered so far
      my $att;
      for $att (keys %{$self->{inverted}}) {
        if ($] > 5.003) {         # avoid bug in perl up to 5.003_05
-Line 577 
 sub close {
+Line 656 
 sub close {
      delete $self->{db};
    }
+   $self->unlock;
 ;
  }
+ # Locking
+ #
+ # We allow multiple readers to coexists.  But write access excludes
+ # all read access and vice versa.  In practice read access on tables
+ # open for writing will mostly work ;-)
+ # If a "write" lock is requested, an existing "read" lock will be
+ # released.  If a "read" lock ist requested, an existing "write" lock
+ # will be released.  Requiring a lock already hold has no effect.
+ sub getlock {
+   my ($self, $mode) = @_;
+   # autoclean cleans on DESTROY, stale sends SIGZERO to the owner
+   #
+   my $lockmgr = LockFile::Simple->make(-autoclean => 1, -stale => 1);
+   my $file    = $self->{file};
+   my $lockdir = $self->{file} . '.read';
+   unless (-d $lockdir) {
+     mkdir $lockdir, 0755 or die "Could not mkdir $lockdir: $!";
+   }
+   if ($mode & O_RDWR) {         # Get a write lock.  Release it again
+                                 # and die if there is any valid
+                                 # readers.
+     # Have a write lock already
+     return $self if $self->{write_lock};
+     if ($self->{read_lock}) {   # We are a becoming a writer now. So
+                                 # we release the read lock to avoid
+                                 # blocking ourselves.
+       $self->{read_lock}->release;
+       delete $self->{read_lock};
+     }
+     # Get the preliminary write lock
+     $self->{write_lock} = $lockmgr->lock($self->{file} . '.write')
+       or die "Can't lock '$self->{file}.write'";
+     # If we actually want to write we must check if there are any
+     # readers.  The write lock is confirmed if wen cannot find any
+     # valid readers.
+     local *DIR;
+     opendir DIR, $lockdir or
+       die "Could not opendir '$lockdir': $!";
+     for my $lockfile (grep { -f "$lockdir/$_" } readdir DIR) {
+       # Check if the locks are still valid.  Since we are protected by
+       # a write lock, we could use a plain file.  But we want to use
+       # the stale testing from LockFile::Simple.
+       if (my $lck = $lockmgr->trylock("$lockdir/$lockfile")) {
+         warn "Removing stale lockfile '$lockdir/$lockfile'";
+         $lck->release;
+       } else {                  # Found an active reader, rats!
+         $self->{write_lock}->release;
+         die "Cannot write table '$file' while it's in use";
+       }
+     }
+     closedir DIR;
+   } else {
+     # Have a read lock already
+     return $self if $self->{read_lock};
+     # Get the preliminary write lock to protect the directory
+     # operations.
+     my $write_lock = $lockmgr->lock($self->{file} . '.read/write')
+       or die "Can't lock '$self->{file}.read/write'";
+     # Find a new read slot.  Maybe the plain file would be better?
+     my $id = time;
+     while (-f "$lockdir/$id.lock") { # here assume ".lock" format!
+       $id++;
+     }
+     $self->{read_lock} = $lockmgr->lock("$lockdir/$id")
+       or die "Can't lock '$lockdir/$id'";
+     # We are a reader now. So we release the write lock
+     $write_lock->release;
+   }
+   return $self;
+ }
+ sub unlock {
+   my $self = shift;
+   # Either we have a read or a write lock (or we close the table already)
+   # unless ($self->{read_lock} || $self->{write_lock}) {
+   #   warn "WAIT::Table::unlock: Table aparently hold's no lock"
+   # }
+   if ($self->{write_lock}) {
+     $self->{write_lock}->release();
+     delete $self->{write_lock};
+   }
+   if ($self->{read_lock}) {
+     $self->{read_lock}->release();
+     delete $self->{read_lock};
+   }
+ }
  sub DESTROY {
    my $self = shift;
-   warn "Table handle destroyed without closing it first"
+   if ($self->{write_lock} || $self->{read_lock}) {
-     if $self->{db} and $self->{mode}&O_RDWR;
+     warn "Table handle destroyed without closing it first";
+     $self->unlock;
+   }
  }
  sub open_scan {
-Line 642 
 sub intervall {
+Line 829 
 sub intervall {
  }
  sub search {
-   my $self = shift;
+   my $self  = shift;
-   my $attr = shift;
+   my ($query, $attr, $cont, $raw);
-   my $cont = shift;
+   if (ref $_[0]) {
-   my $raw  = shift;
+     $query = shift;
+     $attr = $query->{attr};
+     $cont = $query->{cont};
+     $raw  = $query->{raw};
+   } else {
+     require Carp;
+     Carp::cluck("Using three argument search interface is deprecated, use hashref interface instead");
+     $attr = shift;
+     $cont = shift;
+     $raw  = shift;
+     $query = {
+               attr => $attr,
+               cont => $cont,
+               raw  => $raw,
+              };
+   }
    my %result;
    defined $self->{db} or $self->open; # require layout
-Line 655 
 sub search {
+Line 859 
 sub search {
        my $name = $_->name;
        if (exists $raw->{$name} and @{$raw->{$name}}) {
          my $scale = 1/scalar(@{$raw->{$name}});
-         my %r = $_->search_raw(@{$raw->{$name}});
+         my %r = $_->search_raw($query, @{$raw->{$name}});
          my ($key, $val);
          while (($key, $val) = each %r) {
            if (exists $result{$key}) {
-Line 669 
 sub search {
+Line 873 
 sub search {
    }
    if (defined $cont and $cont ne '') {
      for (@{$self->{inverted}->{$attr}}) {
-       my %r = $_->search($cont);
+       my %r = $_->search($query, $cont);
        my ($key, $val);
        while (($key, $val) = each %r) {
          if (exists $result{$key}) {

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