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1 | package DBIx::Class::Storage::TxnScopeGuard; |
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2 | |
3 | use strict; |
4 | use warnings; |
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5 | use Try::Tiny; |
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6 | use Scalar::Util qw/weaken blessed refaddr/; |
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7 | use DBIx::Class; |
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8 | use DBIx::Class::Exception; |
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9 | use DBIx::Class::Carp; |
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10 | use namespace::clean; |
11 | |
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12 | my ($guards_count, $compat_handler, $foreign_handler); |
13 | |
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14 | sub new { |
15 | my ($class, $storage) = @_; |
16 | |
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17 | my $guard = { |
18 | inactivated => 0, |
19 | storage => $storage, |
20 | }; |
21 | |
22 | # we are starting with an already set $@ - in order for things to work we need to |
23 | # be able to recognize it upon destruction - store its weakref |
24 | # recording it before doing the txn_begin stuff |
25 | if (defined $@ and $@ ne '') { |
26 | $guard->{existing_exception_ref} = (ref $@ ne '') ? $@ : \$@; |
27 | weaken $guard->{existing_exception_ref}; |
28 | } |
29 | |
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30 | $storage->txn_begin; |
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31 | |
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32 | $guard->{dbh} = $storage->_dbh; |
33 | weaken $guard->{dbh}; |
34 | |
35 | bless $guard, ref $class || $class; |
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36 | |
37 | # install a callback carefully |
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38 | if (DBIx::Class::_ENV_::INVISIBLE_DOLLAR_AT and !$guards_count) { |
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39 | |
40 | # if the thrown exception is a plain string, wrap it in our |
41 | # own exception class |
42 | # this is actually a pretty cool idea, may very well keep it |
43 | # after perl is fixed |
44 | $compat_handler ||= bless( |
45 | sub { |
46 | $@ = (blessed($_[0]) or ref($_[0])) |
47 | ? $_[0] |
48 | : bless ( { msg => $_[0] }, 'DBIx::Class::Exception') |
49 | ; |
50 | die; |
51 | }, |
52 | '__TxnScopeGuard__FIXUP__', |
53 | ); |
54 | |
55 | if ($foreign_handler = $SIG{__DIE__}) { |
56 | $SIG{__DIE__} = bless ( |
57 | sub { |
58 | # we trust the foreign handler to do whatever it wants, all we do is set $@ |
59 | eval { $compat_handler->(@_) }; |
60 | $foreign_handler->(@_); |
61 | }, |
62 | '__TxnScopeGuard__FIXUP__', |
63 | ); |
64 | } |
65 | else { |
66 | $SIG{__DIE__} = $compat_handler; |
67 | } |
68 | } |
69 | |
70 | $guards_count++; |
71 | |
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72 | $guard; |
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73 | } |
74 | |
75 | sub commit { |
76 | my $self = shift; |
77 | |
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78 | $self->{storage}->throw_exception("Refusing to execute multiple commits on scope guard $self") |
79 | if $self->{inactivated}; |
80 | |
81 | $self->{storage}->txn_commit; |
82 | $self->{inactivated} = 1; |
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83 | } |
84 | |
85 | sub DESTROY { |
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86 | my $self = shift; |
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87 | |
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88 | $guards_count--; |
89 | |
90 | # don't touch unless it's ours, and there are no more of us left |
91 | if ( |
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92 | DBIx::Class::_ENV_::INVISIBLE_DOLLAR_AT |
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93 | and |
94 | !$guards_count |
95 | ) { |
96 | |
97 | if (ref $SIG{__DIE__} eq '__TxnScopeGuard__FIXUP__') { |
98 | # restore what we saved |
99 | if ($foreign_handler) { |
100 | $SIG{__DIE__} = $foreign_handler; |
101 | } |
102 | else { |
103 | delete $SIG{__DIE__}; |
104 | } |
105 | } |
106 | |
107 | # make sure we do not leak the foreign one in case it exists |
108 | undef $foreign_handler; |
109 | } |
110 | |
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111 | return if $self->{inactivated}; |
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112 | |
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113 | # if our dbh is not ours anymore, the $dbh weakref will go undef |
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114 | $self->{storage}->_verify_pid unless DBIx::Class::_ENV_::BROKEN_FORK; |
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115 | return unless $self->{dbh}; |
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116 | |
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117 | my $exception = $@ if ( |
118 | defined $@ |
119 | and |
120 | $@ ne '' |
121 | and |
122 | ( |
123 | ! defined $self->{existing_exception_ref} |
124 | or |
125 | refaddr( ref $@ eq '' ? \$@ : $@ ) != refaddr($self->{existing_exception_ref}) |
126 | ) |
127 | ); |
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128 | |
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129 | { |
130 | local $@; |
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131 | |
132 | carp 'A DBIx::Class::Storage::TxnScopeGuard went out of scope without explicit commit or error. Rolling back.' |
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133 | unless defined $exception; |
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134 | |
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135 | my $rollback_exception; |
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136 | # do minimal connectivity check due to weird shit like |
137 | # https://rt.cpan.org/Public/Bug/Display.html?id=62370 |
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138 | try { $self->{storage}->_seems_connected && $self->{storage}->txn_rollback } |
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139 | catch { $rollback_exception = shift }; |
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140 | |
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141 | if ( $rollback_exception and ( |
142 | ! defined blessed $rollback_exception |
143 | or |
144 | ! $rollback_exception->isa('DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION') |
145 | ) ) { |
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146 | # append our text - THIS IS A TEMPORARY FIXUP! |
147 | # a real stackable exception object is in the works |
148 | if (ref $exception eq 'DBIx::Class::Exception') { |
149 | $exception->{msg} = "Transaction aborted: $exception->{msg} " |
150 | ."Rollback failed: ${rollback_exception}"; |
151 | } |
152 | elsif ($exception) { |
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153 | $exception = "Transaction aborted: ${exception} " |
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154 | ."Rollback failed: ${rollback_exception}"; |
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155 | } |
156 | else { |
157 | carp (join ' ', |
158 | "********************* ROLLBACK FAILED!!! ********************", |
159 | "\nA rollback operation failed after the guard went out of scope.", |
160 | 'This is potentially a disastrous situation, check your data for', |
161 | "consistency: $rollback_exception" |
162 | ); |
163 | } |
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164 | } |
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165 | } |
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166 | |
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167 | $@ = $exception unless DBIx::Class::_ENV_::INVISIBLE_DOLLAR_AT; |
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168 | } |
169 | |
170 | 1; |
171 | |
172 | __END__ |
173 | |
174 | =head1 NAME |
175 | |
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176 | DBIx::Class::Storage::TxnScopeGuard - Scope-based transaction handling |
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177 | |
178 | =head1 SYNOPSIS |
179 | |
180 | sub foo { |
181 | my ($self, $schema) = @_; |
182 | |
183 | my $guard = $schema->txn_scope_guard; |
184 | |
185 | # Multiple database operations here |
186 | |
187 | $guard->commit; |
188 | } |
189 | |
190 | =head1 DESCRIPTION |
191 | |
192 | An object that behaves much like L<Scope::Guard>, but hardcoded to do the |
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193 | right thing with transactions in DBIx::Class. |
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194 | |
195 | =head1 METHODS |
196 | |
197 | =head2 new |
198 | |
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199 | Creating an instance of this class will start a new transaction (by |
200 | implicitly calling L<DBIx::Class::Storage/txn_begin>. Expects a |
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201 | L<DBIx::Class::Storage> object as its only argument. |
202 | |
203 | =head2 commit |
204 | |
205 | Commit the transaction, and stop guarding the scope. If this method is not |
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206 | called and this object goes out of scope (e.g. an exception is thrown) then |
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207 | the transaction is rolled back, via L<DBIx::Class::Storage/txn_rollback> |
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208 | |
209 | =cut |
210 | |
211 | =head1 SEE ALSO |
212 | |
213 | L<DBIx::Class::Schema/txn_scope_guard>. |
214 | |
215 | =head1 AUTHOR |
216 | |
217 | Ash Berlin, 2008. |
218 | |
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219 | Inspired by L<Scope::Guard> by chocolateboy. |
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220 | |
221 | This module is free software. It may be used, redistributed and/or modified |
222 | under the same terms as Perl itself. |
223 | |
224 | =cut |