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=head1 NAME |
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|
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AnyEvent::DBI - asynchronous DBI access |
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|
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=head1 SYNOPSIS |
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|
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use AnyEvent::DBI; |
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|
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=head1 DESCRIPTION |
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|
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This module is an L<AnyEvent> user, you need to make sure that you use and |
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run a supported event loop. |
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|
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This module implements asynchronous DBI access my forking or executing |
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separate "DBI-Server" processes and sending them requests. |
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|
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It means that you can run DBI requests in parallel to other tasks. |
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|
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=cut |
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|
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package AnyEvent::DBI; |
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|
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use strict; |
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no warnings; |
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|
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use Carp; |
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use Socket (); |
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use Scalar::Util (); |
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use Storable (); |
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|
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use DBI (); |
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|
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use AnyEvent (); |
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use AnyEvent::Util (); |
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|
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our $VERSION = '1.0'; |
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|
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# this is the forked server code |
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|
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our $DBH; |
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|
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sub req_open { |
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my (undef, $dbi, $user, $pass, %attr) = @{+shift}; |
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|
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$DBH = DBI->connect ($dbi, $user, $pass, \%attr); |
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|
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[1] |
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} |
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|
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sub serve { |
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my ($fh) = @_; |
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|
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no strict; |
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|
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eval { |
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my $rbuf; |
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|
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while () { |
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sysread $fh, $rbuf, 16384, length $rbuf |
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or last; |
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|
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while () { |
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my $len = unpack "L", $rbuf; |
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|
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# full request available? |
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last unless $len && $len + 4 <= length $rbuf; |
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|
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my $req = Storable::thaw substr $rbuf, 4; |
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substr $rbuf, 0, $len + 4, ""; # remove length + request |
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|
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my $wbuf = eval { pack "L/a*", Storable::freeze $req->[0]($req) }; |
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|
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$wbuf = pack "L/a*", Storable::freeze [undef, "$@"] |
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if $@; |
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|
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for (my $ofs = 0; $ofs < length $wbuf; ) { |
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$ofs += (syswrite $fh, substr $wbuf, $ofs |
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or die "unable to write results"); |
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} |
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} |
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} |
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}; |
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|
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warn $@;#d# |
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|
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kill 9, $$; # no other way on the broken windows platform |
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} |
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|
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=head2 METHODS |
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|
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=over 4 |
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|
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=item $dbh = new AnyEvent::DBI $database, $user, $pass, [key => value]... |
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|
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Returns a database handle for the given database. Each database handle |
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has an associated server process that executes statements in order. If |
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you want to run more than one statement in parallel, you need to create |
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additional database handles. |
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|
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The advantage of this approach is that transactions work as state is |
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preserved. |
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|
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Example: |
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|
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$dbh = new AnyEvent::DBI |
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"DBI:mysql:test;mysql_read_default_file=/root/.my.cnf", "", ""; |
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|
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Additional key-value pairs can be used to adjust behaviour: |
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|
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=over 4 |
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|
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=item on_error => $callback->($dbh, $filename, $line, $fatal) |
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|
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When an error occurs, then this callback will be invoked. On entry, C<$@> |
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is set to the error message. C<$filename> and C<$line> is where the |
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original request was submitted. |
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|
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If this callback returns and this was a fatal error (C<$fatal> is true) |
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then AnyEvent::DBI die's, otherwise it calls the original request callback |
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without any arguments. |
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|
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If omitted, then C<die> will be called on any fatal errors, others will be ignored. |
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|
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=back |
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|
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=cut |
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|
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# stupid Storable autoloading, total loss-loss situation |
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Storable::thaw Storable::freeze []; |
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|
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sub new { |
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my ($class, $dbi, $user, $pass, %arg) = @_; |
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|
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socketpair my $client, my $server, &Socket::AF_UNIX, &Socket::SOCK_STREAM, &Socket::PF_UNSPEC |
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or croak "unable to create dbi communicaiton pipe: $!"; |
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|
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my $self = bless \%arg, $class; |
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|
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$self->{fh} = $client; |
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|
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Scalar::Util::weaken (my $wself = $self); |
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|
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AnyEvent::Util::fh_nonblocking $client, 1; |
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|
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my $rbuf; |
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my @caller = (caller)[1,2]; # the "default" caller |
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|
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$self->{rw} = AnyEvent->io (fh => $client, poll => "r", cb => sub { |
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my $len = sysread $client, $rbuf, 65536, length $rbuf; |
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|
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if ($len > 0) { |
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|
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while () { |
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my $len = unpack "L", $rbuf; |
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|
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# full request available? |
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last unless $len && $len + 4 <= length $rbuf; |
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|
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my $res = Storable::thaw substr $rbuf, 4; |
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substr $rbuf, 0, $len + 4, ""; # remove length + request |
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|
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my $req = shift @{ $wself->{queue} }; |
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|
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if (defined $res->[0]) { |
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$req->[0](@$res); |
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} else { |
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my $cb = shift @$req; |
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$wself->_error ($res->[1], @$req); |
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$cb->[0](); |
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} |
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} |
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|
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} elsif (defined $len) { |
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$wself->_error ("unexpected eof", @caller, 1); |
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} else { |
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$wself->_error ("read error: $!", @caller, 1); |
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} |
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}); |
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|
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my $pid = fork; |
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|
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if ($pid) { |
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# parent |
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close $server; |
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|
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} elsif (defined $pid) { |
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# child |
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close $client; |
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@_ = $server; |
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goto &serve; |
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|
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} else { |
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croak "fork: $!"; |
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} |
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|
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$self->_req (sub { }, (caller)[1,2], 1, req_open => $dbi, $user, $pass); |
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|
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$self |
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} |
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|
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sub _error { |
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my ($self, $error, $filename, $line, $fatal) = @_; |
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|
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delete $self->{rw}; |
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delete $self->{ww}; |
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delete $self->{fh}; |
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$@ = $error; |
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|
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$self->{on_error}($self, $filename, $line, $fatal) |
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if $self->{on_error}; |
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die "$error at $filename, line $line\n" |
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if $fatal; |
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} |
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|
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sub _req { |
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warn "<req(@_>\n";#d# |
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my ($self, $cb, $filename, $line, $fatal) = splice @_, 0, 5, (); |
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|
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push @{ $self->{queue} }, [$cb, $filename, $line, $fatal]; |
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|
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$self->{wbuf} .= pack "L/a*", Storable::freeze \@_; |
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|
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unless ($self->{ww}) { |
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my $len = syswrite $self->{fh}, $self->{wbuf}; |
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substr $self->{wbuf}, 0, $len, ""; |
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|
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#TODO, ww_cb |
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# still any left? then install a write watcher |
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$self->{ww} = AnyEvent->io (fh => $self->{fh}, poll => "w", cb => $self->{ww_cb}) |
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if length $self->{wbuf}; |
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} |
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} |
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|
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=item $dbh->exec ("statement", @args, $cb->($rows, %extra)) |
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|
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Executes the given SQL statement with placeholders replaced by |
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C<@args>. The statement will be prepared and cached on the |
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server side, so using placeholders is compulsory. |
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|
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The callback will be called with the result of C<fetchall_arrayref> as |
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first argument and possibly a hash reference with additional information. |
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|
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=cut |
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|
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sub exec { |
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my $cb = pop; |
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splice @_, 1, 0, $cb, (caller)[1,2], 0, "exec"; |
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|
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goto &_req; |
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} |
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|
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=back |
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|
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=head1 SEE ALSO |
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|
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L<AnyEvent>, L<DBI>. |
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|
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=head1 AUTHOR |
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|
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Marc Lehmann <schmorp@schmorp.de> |
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http://home.schmorp.de/ |
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|
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=cut |
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|
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1 |
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