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1 | package # hide from pause until we figure it all out |
2 | DBIx::Class::Storage::BlockRunner; |
3 | |
7f9a3f70 |
4 | use warnings; |
59d624cf |
5 | use strict; |
6 | |
cbd7f87a |
7 | use DBIx::Class::Exception; |
8 | use DBIx::Class::Carp; |
9 | use Context::Preserve 'preserve_context'; |
ddcc02d1 |
10 | use DBIx::Class::_Util qw( is_exception qsub dbic_internal_try ); |
cbd7f87a |
11 | use Scalar::Util qw(weaken blessed reftype); |
12 | use Try::Tiny; |
0020e364 |
13 | use Moo; |
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14 | use namespace::clean; |
15 | |
16 | =head1 NAME |
17 | |
18 | DBIx::Class::Storage::BlockRunner - Try running a block of code until success with a configurable retry logic |
19 | |
20 | =head1 DESCRIPTION |
21 | |
22 | =head1 METHODS |
23 | |
24 | =cut |
25 | |
26 | has storage => ( |
27 | is => 'ro', |
28 | required => 1, |
29 | ); |
30 | |
31 | has wrap_txn => ( |
32 | is => 'ro', |
33 | required => 1, |
34 | ); |
35 | |
36 | # true - retry, false - rethrow, or you can throw your own (not catching) |
37 | has retry_handler => ( |
38 | is => 'ro', |
39 | required => 1, |
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40 | isa => qsub q{ |
7d534e68 |
41 | (Scalar::Util::reftype($_[0])||'') eq 'CODE' |
9345b14c |
42 | or DBIx::Class::Exception->throw('retry_handler must be a CODE reference') |
7f9a3f70 |
43 | }, |
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44 | ); |
45 | |
46 | has retry_debug => ( |
47 | is => 'rw', |
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48 | # use a sub - to be evaluated on the spot lazily |
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49 | default => qsub '$ENV{DBIC_STORAGE_RETRY_DEBUG}', |
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50 | lazy => 1, |
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51 | ); |
52 | |
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53 | has max_attempts => ( |
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54 | is => 'ro', |
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55 | default => 20, |
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56 | ); |
57 | |
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58 | has failed_attempt_count => ( |
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59 | is => 'ro', |
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60 | init_arg => undef, # ensures one can't pass the value in |
61 | writer => '_set_failed_attempt_count', |
62 | default => 0, |
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63 | lazy => 1, |
7f9a3f70 |
64 | trigger => qsub q{ |
f9080e45 |
65 | $_[0]->throw_exception( sprintf ( |
7d534e68 |
66 | 'Reached max_attempts amount of %d, latest exception: %s', |
67 | $_[0]->max_attempts, $_[0]->last_exception |
68 | )) if $_[0]->max_attempts <= ($_[1]||0); |
7f9a3f70 |
69 | }, |
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70 | ); |
71 | |
72 | has exception_stack => ( |
73 | is => 'ro', |
74 | init_arg => undef, |
75 | clearer => '_reset_exception_stack', |
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76 | default => qsub q{ [] }, |
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77 | lazy => 1, |
78 | ); |
79 | |
80 | sub last_exception { shift->exception_stack->[-1] } |
81 | |
f9080e45 |
82 | sub throw_exception { shift->storage->throw_exception (@_) } |
83 | |
9345b14c |
84 | sub run { |
85 | my $self = shift; |
86 | |
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87 | $self->_reset_exception_stack; |
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88 | $self->_set_failed_attempt_count(0); |
89 | |
90 | my $cref = shift; |
91 | |
92 | $self->throw_exception('run() requires a coderef to execute as its first argument') |
93 | if ( reftype($cref)||'' ) ne 'CODE'; |
94 | |
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95 | my $storage = $self->storage; |
96 | |
7d534e68 |
97 | return $cref->( @_ ) if ( |
98 | $storage->{_in_do_block} |
99 | and |
100 | ! $self->wrap_txn |
101 | ); |
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102 | |
103 | local $storage->{_in_do_block} = 1 unless $storage->{_in_do_block}; |
104 | |
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105 | return $self->_run($cref, @_); |
9345b14c |
106 | } |
107 | |
108 | # this is the actual recursing worker |
109 | sub _run { |
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110 | # internal method - we know that both refs are strong-held by the |
111 | # calling scope of run(), hence safe to weaken everything |
112 | weaken( my $self = shift ); |
113 | weaken( my $cref = shift ); |
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114 | |
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115 | my $args = @_ ? \@_ : []; |
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116 | |
117 | # from this point on (defined $txn_init_depth) is an indicator for wrap_txn |
118 | # save a bit on method calls |
119 | my $txn_init_depth = $self->wrap_txn ? $self->storage->transaction_depth : undef; |
120 | my $txn_begin_ok; |
121 | |
122 | my $run_err = ''; |
123 | |
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124 | return preserve_context { |
ddcc02d1 |
125 | dbic_internal_try { |
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126 | if (defined $txn_init_depth) { |
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127 | $self->storage->txn_begin; |
9345b14c |
128 | $txn_begin_ok = 1; |
129 | } |
7d534e68 |
130 | $cref->( @$args ); |
9345b14c |
131 | } catch { |
132 | $run_err = $_; |
133 | (); # important, affects @_ below |
134 | }; |
135 | } replace => sub { |
136 | my @res = @_; |
137 | |
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138 | my $storage = $self->storage; |
9345b14c |
139 | |
729656c5 |
140 | if ( |
141 | defined $txn_init_depth |
142 | and |
143 | ! is_exception $run_err |
144 | and |
145 | defined( my $cur_depth = $storage->transaction_depth ) |
146 | ) { |
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147 | my $delta_txn = (1 + $txn_init_depth) - $cur_depth; |
148 | |
149 | if ($delta_txn) { |
150 | # a rollback in a top-level txn_do is valid-ish (seen in the wild and our own tests) |
151 | carp (sprintf |
152 | 'Unexpected reduction of transaction depth by %d after execution of ' |
153 | . '%s, skipping txn_commit()', |
154 | $delta_txn, |
7d534e68 |
155 | $cref, |
9345b14c |
156 | ) unless $delta_txn == 1 and $cur_depth == 0; |
157 | } |
158 | else { |
ddcc02d1 |
159 | dbic_internal_try { |
160 | $storage->txn_commit; |
161 | 1; |
162 | } |
163 | catch { |
164 | $run_err = $_; |
165 | }; |
9345b14c |
166 | } |
167 | } |
168 | |
169 | # something above threw an error (could be the begin, the code or the commit) |
841efcb3 |
170 | if ( is_exception $run_err ) { |
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171 | |
84efb6d7 |
172 | # Attempt a rollback if we did begin in the first place |
173 | # Will append rollback error if possible |
174 | $storage->__delicate_rollback( \$run_err ) |
175 | if $txn_begin_ok; |
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176 | |
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177 | push @{ $self->exception_stack }, $run_err; |
178 | |
179 | # this will throw if max_attempts is reached |
180 | $self->_set_failed_attempt_count($self->failed_attempt_count + 1); |
9345b14c |
181 | |
182 | # init depth of > 0 ( > 1 with AC) implies nesting - no retry attempt queries |
183 | $storage->throw_exception($run_err) if ( |
184 | ( |
185 | defined $txn_init_depth |
186 | and |
187 | # FIXME - we assume that $storage->{_dbh_autocommit} is there if |
188 | # txn_init_depth is there, but this is a DBI-ism |
189 | $txn_init_depth > ( $storage->{_dbh_autocommit} ? 0 : 1 ) |
7d534e68 |
190 | ) or ! $self->retry_handler->($self) |
9345b14c |
191 | ); |
192 | |
9345b14c |
193 | # we got that far - let's retry |
7d534e68 |
194 | carp( sprintf 'Retrying %s (attempt %d) after caught exception: %s', |
195 | $cref, |
196 | $self->failed_attempt_count + 1, |
9345b14c |
197 | $run_err, |
7d534e68 |
198 | ) if $self->retry_debug; |
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199 | |
200 | $storage->ensure_connected; |
201 | # if txn_depth is > 1 this means something was done to the |
4a0eed52 |
202 | # original $dbh, otherwise we would not get past the preceding if() |
9345b14c |
203 | $storage->throw_exception(sprintf |
204 | 'Unexpected transaction depth of %d on freshly connected handle', |
205 | $storage->transaction_depth, |
206 | ) if (defined $txn_init_depth and $storage->transaction_depth); |
207 | |
7d534e68 |
208 | return $self->_run($cref, @$args); |
9345b14c |
209 | } |
210 | |
211 | return wantarray ? @res : $res[0]; |
212 | }; |
213 | } |
214 | |
a2bd3796 |
215 | =head1 FURTHER QUESTIONS? |
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216 | |
a2bd3796 |
217 | Check the list of L<additional DBIC resources|DBIx::Class/GETTING HELP/SUPPORT>. |
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218 | |
a2bd3796 |
219 | =head1 COPYRIGHT AND LICENSE |
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220 | |
a2bd3796 |
221 | This module is free software L<copyright|DBIx::Class/COPYRIGHT AND LICENSE> |
222 | by the L<DBIx::Class (DBIC) authors|DBIx::Class/AUTHORS>. You can |
223 | redistribute it and/or modify it under the same terms as the |
224 | L<DBIx::Class library|DBIx::Class/COPYRIGHT AND LICENSE>. |
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225 | |
226 | =cut |
227 | |
228 | 1; |