RT# 78547 Library for SQL savepoints

1 files changed, 160 insertions, 0 deletions

diff --git a/FS/FS/Misc/Savepoint.pm b/FS/FS/Misc/Savepoint.pm
new file mode 100644
index 0000000..b15b36d
--- /dev/null
+++ b/FS/FS/Misc/Savepoint.pm
@@ -0,0 +1,160 @@
+package FS::Misc::Savepoint;
+
+use strict;
+use warnings;
+
+use Exporter;
+use vars qw( @ISA @EXPORT @EXPORT_OK );
+@ISA = qw( Exporter );
+@EXPORT = qw( savepoint_create savepoint_release savepoint_rollback );
+
+use FS::UID qw( dbh );
+use Carp qw( croak );
+
+=head1 NAME
+
+FS::Misc::Savepoint - Provides methods for SQL Savepoints
+
+=head1 SYNOPSIS
+
+  use FS::Misc::Savepoint;
+  
+  # Only valid within a transaction
+  local $FS::UID::AutoCommit = 0;
+  
+  savepoint_create( 'savepoint_label' );
+  
+  my $error_msg = do_some_things();
+  
+  if ( $error_msg ) {
+    savepoint_rollback_and_release( 'savepoint_label' );
+  } else {
+    savepoint_release( 'savepoint_label' );
+  }
+
+
+=head1 DESCRIPTION
+
+Provides methods for SQL Savepoints
+
+Using a savepoint allows for a partial roll-back of SQL statements without
+forcing a rollback of the entire enclosing transaction.
+
+=head1 METHODS
+
+=over 4
+
+=item savepoint_create LABEL
+
+=item savepoint_create { label => LABEL, dbh => DBH }
+
+Executes SQL to create a savepoint named LABEL.
+
+Savepoints cannot work while AutoCommit is enabled.
+
+Savepoint labels must be valid sql identifiers.  If your choice of label
+would not make a valid column name, it probably will not make a valid label.
+
+Savepint labels must be unique within the transaction.
+
+=cut
+
+sub savepoint_create {
+  my %param = _parse_params( @_ );
+
+  $param{dbh}->do("SAVEPOINT $param{label}")
+    or die $param{dbh}->errstr;
+}
+
+=item savepoint_release LABEL
+
+=item savepoint_release { label => LABEL, dbh => DBH }
+
+Release the savepoint - preserves the SQL statements issued since the
+savepoint was created, but does not commit the transaction.
+
+The savepoint label is freed for future use.
+
+=cut
+
+sub savepoint_release {
+  my %param = _parse_params( @_ );
+
+  $param{dbh}->do("RELEASE SAVEPOINT $param{label}")
+    or die $param{dbh}->errstr;
+}
+
+=item savepoint_rollback LABEL
+
+=item savepoint_rollback { label => LABEL, dbh => DBH }
+
+Roll back the savepoint - forgets all SQL statements issues since the
+savepoint was created, but does not commit or roll back the transaction.
+
+The savepoint still exists.  Additional statements may be executed,
+and savepoint_rollback called again.
+
+=cut
+
+sub savepoint_rollback {
+  my %param = _parse_params( @_ );
+
+  $param{dbh}->do("ROLLBACK TO SAVEPOINT $param{label}")
+    or die $param{dbh}->errstr;
+}
+
+=item savepoint_rollback_and_release LABEL
+
+=item savepoint_rollback_and_release { label => LABEL, dbh => DBH }
+
+Rollback and release the savepoint
+
+=cut
+
+sub savepoint_rollback_and_release {
+  savepoint_rollback( @_ );
+  savepoint_release( @_ );
+}
+
+=back
+
+=head1 METHODS - Internal
+
+=over 4
+
+=item _parse_params
+
+Create %params from function input
+
+Basic savepoint label validation
+
+Complain when trying to use savepoints without disabling AutoCommit
+
+=cut
+
+sub _parse_params {
+  my %param = ref $_[0] ? %{ $_[0] } : ( label => $_[0] );
+  $param{dbh} ||= dbh;
+
+  # Savepoints may be any valid SQL identifier up to 64 characters
+  $param{label} =~ /^\w+$/
+    or croak sprintf(
+      'Invalid savepont label(%s) - use only numbers, letters, _',
+      $param{label}
+    );
+
+  croak sprintf( 'Savepoint(%s) failed - AutoCommit=1', $param{label} )
+    if $FS::UID::AutoCommit;
+
+  %param;
+}
+
+=back
+
+=head1 BUGS
+
+=head1 SEE ALSO
+
+=cut
+
+1;
\ No newline at end of file