X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FStorage.pm;h=edfef850866823dcb37f38fc6fd71b3c2f33528d;hb=3b80fa31b60050d4c8df91457ba6fd51b579a7a6;hp=6a519794a40c368ff9623dcd7e27a70c2450c5cf;hpb=a62cf8d4bbd7df7082e0fab3d52a45afeeb64293;p=dbsrgits%2FDBIx-Class.git

diff --git a/lib/DBIx/Class/Storage.pm b/lib/DBIx/Class/Storage.pm
index 6a51979..edfef85 100644
--- a/lib/DBIx/Class/Storage.pm
+++ b/lib/DBIx/Class/Storage.pm
@@ -3,37 +3,548 @@ package DBIx::Class::Storage;
 use strict;
 use warnings;
 
-sub new { die "Virtual method!" }
-sub debug { die "Virtual method!" }
-sub debugcb { die "Virtual method!" }
-sub debugfh { die "Virtual method!" }
-sub disconnect { die "Virtual method!" }
+use base qw/DBIx::Class/;
+use mro 'c3';
+
+use DBIx::Class::Exception;
+use Scalar::Util 'weaken';
+use DBIx::Class::Storage::TxnScopeGuard;
+use Try::Tiny;
+use namespace::clean;
+
+__PACKAGE__->mk_group_accessors('simple' => qw/debug schema/);
+__PACKAGE__->mk_group_accessors('inherited' => 'cursor_class');
+
+__PACKAGE__->cursor_class('DBIx::Class::Cursor');
+
+sub cursor { shift->cursor_class(@_); }
+
+package # Hide from PAUSE
+    DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION;
+
+use overload '"' => sub {
+  'DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION'
+};
+
+sub new {
+  my $class = shift;
+  my $self = {};
+  return bless $self, $class;
+}
+
+package DBIx::Class::Storage;
+
+=head1 NAME
+
+DBIx::Class::Storage - Generic Storage Handler
+
+=head1 DESCRIPTION
+
+A base implementation of common Storage methods.  For specific
+information about L<DBI>-based storage, see L<DBIx::Class::Storage::DBI>.
+
+=head1 METHODS
+
+=head2 new
+
+Arguments: $schema
+
+Instantiates the Storage object.
+
+=cut
+
+sub new {
+  my ($self, $schema) = @_;
+
+  $self = ref $self if ref $self;
+
+  my $new = {};
+  bless $new, $self;
+
+  $new->set_schema($schema);
+  $new->debug(1)
+    if $ENV{DBIX_CLASS_STORAGE_DBI_DEBUG} || $ENV{DBIC_TRACE};
+
+  $new;
+}
+
+=head2 set_schema
+
+Used to reset the schema class or object which owns this
+storage object, such as during L<DBIx::Class::Schema/clone>.
+
+=cut
+
+sub set_schema {
+  my ($self, $schema) = @_;
+  $self->schema($schema);
+  weaken $self->{schema} if ref $self->{schema};
+}
+
+=head2 connected
+
+Returns true if we have an open storage connection, false
+if it is not (yet) open.
+
+=cut
+
 sub connected { die "Virtual method!" }
+
+=head2 disconnect
+
+Closes any open storage connection unconditionally.
+
+=cut
+
+sub disconnect { die "Virtual method!" }
+
+=head2 ensure_connected
+
+Initiate a connection to the storage if one isn't already open.
+
+=cut
+
 sub ensure_connected { die "Virtual method!" }
-sub sql_maker { die "Virtual method!" }
+
+=head2 throw_exception
+
+Throws an exception - croaks.
+
+=cut
+
+sub throw_exception {
+  my $self = shift;
+
+  if (ref $self and $self->schema) {
+    $self->schema->throw_exception(@_);
+  }
+  else {
+    DBIx::Class::Exception->throw(@_);
+  }
+}
+
+=head2 txn_do
+
+=over 4
+
+=item Arguments: C<$coderef>, @coderef_args?
+
+=item Return Value: The return value of $coderef
+
+=back
+
+Executes C<$coderef> with (optional) arguments C<@coderef_args> atomically,
+returning its result (if any). If an exception is caught, a rollback is issued
+and the exception is rethrown. If the rollback fails, (i.e. throws an
+exception) an exception is thrown that includes a "Rollback failed" message.
+
+For example,
+
+  my $author_rs = $schema->resultset('Author')->find(1);
+  my @titles = qw/Night Day It/;
+
+  my $coderef = sub {
+    # If any one of these fails, the entire transaction fails
+    $author_rs->create_related('books', {
+      title => $_
+    }) foreach (@titles);
+
+    return $author->books;
+  };
+
+  my $rs;
+  try {
+    $rs = $schema->txn_do($coderef);
+  } catch {
+    my $error = shift;
+    # Transaction failed
+    die "something terrible has happened!"   #
+      if ($error =~ /Rollback failed/);          # Rollback failed
+
+    deal_with_failed_transaction();
+  };
+
+In a nested transaction (calling txn_do() from within a txn_do() coderef) only
+the outermost transaction will issue a L</txn_commit>, and txn_do() can be
+called in void, scalar and list context and it will behave as expected.
+
+Please note that all of the code in your coderef, including non-DBIx::Class
+code, is part of a transaction.  This transaction may fail out halfway, or
+it may get partially double-executed (in the case that our DB connection
+failed halfway through the transaction, in which case we reconnect and
+restart the txn).  Therefore it is best that any side-effects in your coderef
+are idempotent (that is, can be re-executed multiple times and get the
+same result), and that you check up on your side-effects in the case of
+transaction failure.
+
+=cut
+
+sub txn_do {
+  my $self = shift;
+  my $coderef = shift;
+
+  ref $coderef eq 'CODE' or $self->throw_exception
+    ('$coderef must be a CODE reference');
+
+  my (@return_values, $return_value);
+
+  $self->txn_begin; # If this throws an exception, no rollback is needed
+
+  my $wantarray = wantarray; # Need to save this since the context
+                             # inside the try{} block is independent
+                             # of the context that called txn_do()
+  my $args = \@_;
+
+  try {
+
+    # Need to differentiate between scalar/list context to allow for
+    # returning a list in scalar context to get the size of the list
+    if ($wantarray) {
+      # list context
+      @return_values = $coderef->(@$args);
+    } elsif (defined $wantarray) {
+      # scalar context
+      $return_value = $coderef->(@$args);
+    } else {
+      # void context
+      $coderef->(@$args);
+    }
+    $self->txn_commit;
+  }
+  catch {
+    my $error = shift;
+
+    try {
+      $self->txn_rollback;
+    } catch {
+      my $exception_class = "DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION";
+      $self->throw_exception($error)  # propagate nested rollback
+        if $_ =~ /$exception_class/;
+
+      $self->throw_exception(
+        "Transaction aborted: $error. Rollback failed: $_"
+      );
+    }
+    $self->throw_exception($error); # txn failed but rollback succeeded
+  };
+
+  return wantarray ? @return_values : $return_value;
+}
+
+=head2 txn_begin
+
+Starts a transaction.
+
+See the preferred L</txn_do> method, which allows for
+an entire code block to be executed transactionally.
+
+=cut
+
 sub txn_begin { die "Virtual method!" }
+
+=head2 txn_commit
+
+Issues a commit of the current transaction.
+
+It does I<not> perform an actual storage commit unless there's a DBIx::Class
+transaction currently in effect (i.e. you called L</txn_begin>).
+
+=cut
+
 sub txn_commit { die "Virtual method!" }
+
+=head2 txn_rollback
+
+Issues a rollback of the current transaction. A nested rollback will
+throw a L<DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION> exception,
+which allows the rollback to propagate to the outermost transaction.
+
+=cut
+
 sub txn_rollback { die "Virtual method!" }
+
+=head2 svp_begin
+
+Arguments: $savepoint_name?
+
+Created a new savepoint using the name provided as argument. If no name
+is provided, a random name will be used.
+
+=cut
+
+sub svp_begin { die "Virtual method!" }
+
+=head2 svp_release
+
+Arguments: $savepoint_name?
+
+Release the savepoint provided as argument. If none is provided,
+release the savepoint created most recently. This will implicitly
+release all savepoints created after the one explicitly released as well.
+
+=cut
+
+sub svp_release { die "Virtual method!" }
+
+=head2 svp_rollback
+
+Arguments: $savepoint_name?
+
+Rollback to the savepoint provided as argument. If none is provided,
+rollback to the savepoint created most recently. This will implicitly
+release all savepoints created after the savepoint we rollback to.
+
+=cut
+
+sub svp_rollback { die "Virtual method!" }
+
+=for comment
+
+=head2 txn_scope_guard
+
+An alternative way of transaction handling based on
+L<DBIx::Class::Storage::TxnScopeGuard>:
+
+ my $txn_guard = $storage->txn_scope_guard;
+
+ $row->col1("val1");
+ $row->update;
+
+ $txn_guard->commit;
+
+If an exception occurs, or the guard object otherwise leaves the scope
+before C<< $txn_guard->commit >> is called, the transaction will be rolled
+back by an explicit L</txn_rollback> call. In essence this is akin to
+using a L</txn_begin>/L</txn_commit> pair, without having to worry
+about calling L</txn_rollback> at the right places. Note that since there
+is no defined code closure, there will be no retries and other magic upon
+database disconnection. If you need such functionality see L</txn_do>.
+
+=cut
+
+sub txn_scope_guard {
+  return DBIx::Class::Storage::TxnScopeGuard->new($_[0]);
+}
+
+=head2 sql_maker
+
+Returns a C<sql_maker> object - normally an object of class
+C<DBIx::Class::SQLMaker>.
+
+=cut
+
+sub sql_maker { die "Virtual method!" }
+
+=head2 debug
+
+Causes trace information to be emitted on the L</debugobj> object.
+(or C<STDERR> if L</debugobj> has not specifically been set).
+
+This is the equivalent to setting L</DBIC_TRACE> in your
+shell environment.
+
+=head2 debugfh
+
+Set or retrieve the filehandle used for trace/debug output.  This should be
+an IO::Handle compatible object (only the C<print> method is used.  Initially
+set to be STDERR - although see information on the
+L<DBIC_TRACE> environment variable.
+
+=cut
+
+sub debugfh {
+    my $self = shift;
+
+    if ($self->debugobj->can('debugfh')) {
+        return $self->debugobj->debugfh(@_);
+    }
+}
+
+=head2 debugobj
+
+Sets or retrieves the object used for metric collection. Defaults to an instance
+of L<DBIx::Class::Storage::Statistics> that is compatible with the original
+method of using a coderef as a callback.  See the aforementioned Statistics
+class for more information.
+
+=cut
+
+sub debugobj {
+  my $self = shift;
+
+  if (@_) {
+    return $self->{debugobj} = $_[0];
+  }
+
+  $self->{debugobj} ||= do {
+    if (my $profile = $ENV{DBIC_TRACE_PROFILE}) {
+      require DBIx::Class::Storage::Debug::PrettyPrint;
+      if ($profile =~ /^\.?\//) {
+        require Config::Any;
+
+        my $cfg = try {
+          Config::Any->load_files({ files => [$profile], use_ext => 1 });
+        } catch {
+          # sanitize the error message a bit
+          $_ =~ s/at \s+ .+ Storage\.pm \s line \s \d+ $//x;
+          $self->throw_exception("Failure processing \$ENV{DBIC_TRACE_PROFILE}: $_");
+        };
+
+        DBIx::Class::Storage::Debug::PrettyPrint->new(values %{$cfg->[0]});
+      }
+      else {
+        DBIx::Class::Storage::Debug::PrettyPrint->new({ profile => $profile });
+      }
+    }
+    else {
+      require DBIx::Class::Storage::Statistics;
+      DBIx::Class::Storage::Statistics->new
+    }
+  };
+}
+
+=head2 debugcb
+
+Sets a callback to be executed each time a statement is run; takes a sub
+reference.  Callback is executed as $sub->($op, $info) where $op is
+SELECT/INSERT/UPDATE/DELETE and $info is what would normally be printed.
+
+See L</debugobj> for a better way.
+
+=cut
+
+sub debugcb {
+    my $self = shift;
+
+    if ($self->debugobj->can('callback')) {
+        return $self->debugobj->callback(@_);
+    }
+}
+
+=head2 cursor_class
+
+The cursor class for this Storage object.
+
+=cut
+
+=head2 deploy
+
+Deploy the tables to storage (CREATE TABLE and friends in a SQL-based
+Storage class). This would normally be called through
+L<DBIx::Class::Schema/deploy>.
+
+=cut
+
+sub deploy { die "Virtual method!" }
+
+=head2 connect_info
+
+The arguments of C<connect_info> are always a single array reference,
+and are Storage-handler specific.
+
+This is normally accessed via L<DBIx::Class::Schema/connection>, which
+encapsulates its argument list in an arrayref before calling
+C<connect_info> here.
+
+=cut
+
+sub connect_info { die "Virtual method!" }
+
+=head2 select
+
+Handle a select statement.
+
+=cut
+
+sub select { die "Virtual method!" }
+
+=head2 insert
+
+Handle an insert statement.
+
+=cut
+
 sub insert { die "Virtual method!" }
+
+=head2 update
+
+Handle an update statement.
+
+=cut
+
 sub update { die "Virtual method!" }
+
+=head2 delete
+
+Handle a delete statement.
+
+=cut
+
 sub delete { die "Virtual method!" }
-sub select { die "Virtual method!" }
+
+=head2 select_single
+
+Performs a select, fetch and return of data - handles a single row
+only.
+
+=cut
+
 sub select_single { die "Virtual method!" }
+
+=head2 columns_info_for
+
+Returns metadata for the given source's columns.  This
+is *deprecated*, and will be removed before 1.0.  You should
+be specifying the metadata yourself if you need it.
+
+=cut
+
 sub columns_info_for { die "Virtual method!" }
 
+=head1 ENVIRONMENT VARIABLES
 
+=head2 DBIC_TRACE
 
+If C<DBIC_TRACE> is set then trace information
+is produced (as when the L</debug> method is set).
 
-package DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION;
+If the value is of the form C<1=/path/name> then the trace output is
+written to the file C</path/name>.
 
-use overload '"' => sub {
-  'DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION'
-};
+This environment variable is checked when the storage object is first
+created (when you call connect on your schema).  So, run-time changes
+to this environment variable will not take effect unless you also
+re-connect on your schema.
 
-sub new {
-  my $class = shift;
+=head2 DBIC_TRACE_PROFILE
 
-  return bless {}, $class;
-}
+If C<DBIC_TRACE_PROFILE> is set, L<DBIx::Class::Storage::PrettyPrint>
+will be used to format the output from C<DBIC_TRACE>.  The value it
+is set to is the C<profile> that it will be used.  If the value is a
+filename the file is read with L<Config::Any> and the results are
+used as the configuration for tracing.  See L<SQL::Abstract::Tree/new>
+for what that structure should look like.
+
+
+=head2 DBIX_CLASS_STORAGE_DBI_DEBUG
+
+Old name for DBIC_TRACE
+
+=head1 SEE ALSO
+
+L<DBIx::Class::Storage::DBI> - reference storage implementation using
+SQL::Abstract and DBI.
+
+=head1 AUTHORS
+
+Matt S. Trout <mst@shadowcatsystems.co.uk>
+
+Andy Grundman <andy@hybridized.org>
+
+=head1 LICENSE
+
+You may distribute this code under the same terms as Perl itself.
+
+=cut
 
 1;