Conversion of eval => try (part 1)

[dbsrgits/DBIx-Class.git] / lib / DBIx / Class / Storage.pm

diff --git a/lib/DBIx/Class/Storage.pm b/lib/DBIx/Class/Storage.pm
index 941dc07..08ea155 100644 (file)
--- a/lib/DBIx/Class/Storage.pm
+++ b/lib/DBIx/Class/Storage.pm
@@ -4,9 +4,10 @@ use strict;
 use warnings;
 
 use base qw/DBIx::Class/;
+use mro 'c3';
 
-use Scalar::Util qw/weaken/;
-use Carp::Clan qw/^DBIx::Class/;
+use DBIx::Class::Exception;
+use Scalar::Util();
 use IO::File;
 use DBIx::Class::Storage::TxnScopeGuard;
 
@@ -82,7 +83,7 @@ storage object, such as during L<DBIx::Class::Schema/clone>.
 sub set_schema {
   my ($self, $schema) = @_;
   $self->schema($schema);
-  weaken($self->{schema}) if ref $self->{schema};
+  Scalar::Util::weaken($self->{schema}) if ref $self->{schema};
 }
 
 =head2 connected
@@ -119,8 +120,12 @@ Throws an exception - croaks.
 sub throw_exception {
   my $self = shift;
 
-  $self->schema->throw_exception(@_) if $self->schema;
-  croak @_;
+  if ($self->schema) {
+    $self->schema->throw_exception(@_);
+  }
+  else {
+    DBIx::Class::Exception->throw(@_);
+  }
 }
 
 =head2 txn_do
@@ -153,23 +158,28 @@ For example,
   };
 
   my $rs;
-  eval {
+  try {
     $rs = $schema->txn_do($coderef);
-  };
-
-  if ($@) {                                  # Transaction failed
+  } catch {
+    # Transaction failed
     die "something terrible has happened!"   #
       if ($@ =~ /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.
 
-Unlike L</DBIx::Class::Storage/dbh_do>, the coderef will I<not> be
-automatically retried on error.
+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
 
@@ -186,7 +196,7 @@ sub txn_do {
   my $wantarray = wantarray; # Need to save this since the context
                              # inside the eval{} block is independent
                              # of the context that called txn_do()
-  eval {
+  try {
 
     # Need to differentiate between scalar/list context to allow for
     # returning a list in scalar context to get the size of the list
@@ -201,16 +211,12 @@ sub txn_do {
       $coderef->(@args);
     }
     $self->txn_commit;
-  };
-
-  if ($@) {
+  } catch {
     my $error = $@;
 
-    eval {
+    try {
       $self->txn_rollback;
-    };
-
-    if ($@) {
+    } catch {
       my $rollback_error = $@;
       my $exception_class = "DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION";
       $self->throw_exception($error)  # propagate nested rollback
@@ -219,9 +225,8 @@ sub txn_do {
       $self->throw_exception(
         "Transaction aborted: $error. Rollback failed: ${rollback_error}"
       );
-    } else {
-      $self->throw_exception($error); # txn failed but rollback succeeded
     }
+    $self->throw_exception($error); # txn failed but rollback succeeded
   }
 
   return $wantarray ? @return_values : $return_value;
@@ -242,6 +247,9 @@ sub txn_begin { die "Virtual method!" }
 
 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!" }
@@ -339,7 +347,7 @@ shell environment.
 =head2 debugfh
 
 Set or retrieve the filehandle used for trace/debug output.  This should be
-an IO::Handle compatible ojbect (only the C<print> method is used.  Initially
+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.