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9345b14c |
1 | package # hide from pause until we figure it all out |
2 | DBIx::Class::Storage::BlockRunner; |
3 | |
7f9a3f70 |
4 | use warnings; |
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5 | use strict; |
6 | |
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7 | # DO NOT edit away without talking to riba first, he will just put it back |
8 | # BEGIN pre-Moo2 import block |
9 | BEGIN { |
10 | my $initial_fatal_bits = (${^WARNING_BITS}||'') & $warnings::DeadBits{all}; |
11 | local $ENV{PERL_STRICTURES_EXTRA} = 0; |
12 | require Moo; Moo->import; |
13 | ${^WARNING_BITS} &= ( $initial_fatal_bits | ~ $warnings::DeadBits{all} ); |
14 | } |
15 | # END pre-Moo2 import block |
16 | |
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17 | use DBIx::Class::Exception; |
18 | use DBIx::Class::Carp; |
19 | use Context::Preserve 'preserve_context'; |
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20 | use DBIx::Class::_Util qw(is_exception qsub); |
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21 | use Scalar::Util qw(weaken blessed reftype); |
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22 | use Try::Tiny; |
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23 | |
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24 | use namespace::clean; |
25 | |
26 | =head1 NAME |
27 | |
28 | DBIx::Class::Storage::BlockRunner - Try running a block of code until success with a configurable retry logic |
29 | |
30 | =head1 DESCRIPTION |
31 | |
32 | =head1 METHODS |
33 | |
34 | =cut |
35 | |
36 | has storage => ( |
37 | is => 'ro', |
38 | required => 1, |
39 | ); |
40 | |
41 | has wrap_txn => ( |
42 | is => 'ro', |
43 | required => 1, |
44 | ); |
45 | |
46 | # true - retry, false - rethrow, or you can throw your own (not catching) |
47 | has retry_handler => ( |
48 | is => 'ro', |
49 | required => 1, |
7f9a3f70 |
50 | isa => qsub q{ |
7d534e68 |
51 | (Scalar::Util::reftype($_[0])||'') eq 'CODE' |
9345b14c |
52 | or DBIx::Class::Exception->throw('retry_handler must be a CODE reference') |
7f9a3f70 |
53 | }, |
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54 | ); |
55 | |
56 | has retry_debug => ( |
57 | is => 'rw', |
7d534e68 |
58 | # use a sub - to be evaluated on the spot lazily |
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59 | default => qsub '$ENV{DBIC_STORAGE_RETRY_DEBUG}', |
7d534e68 |
60 | lazy => 1, |
9345b14c |
61 | ); |
62 | |
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63 | has max_attempts => ( |
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64 | is => 'ro', |
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65 | default => 20, |
9345b14c |
66 | ); |
67 | |
7d534e68 |
68 | has failed_attempt_count => ( |
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69 | is => 'ro', |
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70 | init_arg => undef, # ensures one can't pass the value in |
71 | writer => '_set_failed_attempt_count', |
72 | default => 0, |
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73 | lazy => 1, |
7f9a3f70 |
74 | trigger => qsub q{ |
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75 | $_[0]->throw_exception( sprintf ( |
7d534e68 |
76 | 'Reached max_attempts amount of %d, latest exception: %s', |
77 | $_[0]->max_attempts, $_[0]->last_exception |
78 | )) if $_[0]->max_attempts <= ($_[1]||0); |
7f9a3f70 |
79 | }, |
9345b14c |
80 | ); |
81 | |
82 | has exception_stack => ( |
83 | is => 'ro', |
84 | init_arg => undef, |
85 | clearer => '_reset_exception_stack', |
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86 | default => qsub q{ [] }, |
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87 | lazy => 1, |
88 | ); |
89 | |
90 | sub last_exception { shift->exception_stack->[-1] } |
91 | |
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92 | sub throw_exception { shift->storage->throw_exception (@_) } |
93 | |
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94 | sub run { |
95 | my $self = shift; |
96 | |
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97 | $self->_reset_exception_stack; |
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98 | $self->_set_failed_attempt_count(0); |
99 | |
100 | my $cref = shift; |
101 | |
102 | $self->throw_exception('run() requires a coderef to execute as its first argument') |
103 | if ( reftype($cref)||'' ) ne 'CODE'; |
104 | |
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105 | my $storage = $self->storage; |
106 | |
7d534e68 |
107 | return $cref->( @_ ) if ( |
108 | $storage->{_in_do_block} |
109 | and |
110 | ! $self->wrap_txn |
111 | ); |
9345b14c |
112 | |
113 | local $storage->{_in_do_block} = 1 unless $storage->{_in_do_block}; |
114 | |
7d534e68 |
115 | return $self->_run($cref, @_); |
9345b14c |
116 | } |
117 | |
118 | # this is the actual recursing worker |
119 | sub _run { |
7d534e68 |
120 | # internal method - we know that both refs are strong-held by the |
121 | # calling scope of run(), hence safe to weaken everything |
122 | weaken( my $self = shift ); |
123 | weaken( my $cref = shift ); |
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124 | |
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125 | my $args = @_ ? \@_ : []; |
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126 | |
127 | # from this point on (defined $txn_init_depth) is an indicator for wrap_txn |
128 | # save a bit on method calls |
129 | my $txn_init_depth = $self->wrap_txn ? $self->storage->transaction_depth : undef; |
130 | my $txn_begin_ok; |
131 | |
132 | my $run_err = ''; |
133 | |
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134 | return preserve_context { |
135 | try { |
136 | if (defined $txn_init_depth) { |
7d534e68 |
137 | $self->storage->txn_begin; |
9345b14c |
138 | $txn_begin_ok = 1; |
139 | } |
7d534e68 |
140 | $cref->( @$args ); |
9345b14c |
141 | } catch { |
142 | $run_err = $_; |
143 | (); # important, affects @_ below |
144 | }; |
145 | } replace => sub { |
146 | my @res = @_; |
147 | |
7d534e68 |
148 | my $storage = $self->storage; |
9345b14c |
149 | my $cur_depth = $storage->transaction_depth; |
150 | |
9bea2000 |
151 | if (defined $txn_init_depth and ! is_exception $run_err) { |
9345b14c |
152 | my $delta_txn = (1 + $txn_init_depth) - $cur_depth; |
153 | |
154 | if ($delta_txn) { |
155 | # a rollback in a top-level txn_do is valid-ish (seen in the wild and our own tests) |
156 | carp (sprintf |
157 | 'Unexpected reduction of transaction depth by %d after execution of ' |
158 | . '%s, skipping txn_commit()', |
159 | $delta_txn, |
7d534e68 |
160 | $cref, |
9345b14c |
161 | ) unless $delta_txn == 1 and $cur_depth == 0; |
162 | } |
163 | else { |
164 | $run_err = eval { $storage->txn_commit; 1 } ? '' : $@; |
165 | } |
166 | } |
167 | |
168 | # something above threw an error (could be the begin, the code or the commit) |
841efcb3 |
169 | if ( is_exception $run_err ) { |
9345b14c |
170 | |
171 | # attempt a rollback if we did begin in the first place |
172 | if ($txn_begin_ok) { |
173 | # some DBDs go crazy if there is nothing to roll back on, perform a soft-check |
174 | my $rollback_exception = $storage->_seems_connected |
175 | ? (! eval { $storage->txn_rollback; 1 }) ? $@ : '' |
176 | : 'lost connection to storage' |
177 | ; |
178 | |
179 | if ( $rollback_exception and ( |
180 | ! defined blessed $rollback_exception |
181 | or |
182 | ! $rollback_exception->isa('DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION') |
183 | ) ) { |
184 | $run_err = "Transaction aborted: $run_err. Rollback failed: $rollback_exception"; |
185 | } |
186 | } |
187 | |
7d534e68 |
188 | push @{ $self->exception_stack }, $run_err; |
189 | |
190 | # this will throw if max_attempts is reached |
191 | $self->_set_failed_attempt_count($self->failed_attempt_count + 1); |
9345b14c |
192 | |
193 | # init depth of > 0 ( > 1 with AC) implies nesting - no retry attempt queries |
194 | $storage->throw_exception($run_err) if ( |
195 | ( |
196 | defined $txn_init_depth |
197 | and |
198 | # FIXME - we assume that $storage->{_dbh_autocommit} is there if |
199 | # txn_init_depth is there, but this is a DBI-ism |
200 | $txn_init_depth > ( $storage->{_dbh_autocommit} ? 0 : 1 ) |
7d534e68 |
201 | ) or ! $self->retry_handler->($self) |
9345b14c |
202 | ); |
203 | |
9345b14c |
204 | # we got that far - let's retry |
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205 | carp( sprintf 'Retrying %s (attempt %d) after caught exception: %s', |
206 | $cref, |
207 | $self->failed_attempt_count + 1, |
9345b14c |
208 | $run_err, |
7d534e68 |
209 | ) if $self->retry_debug; |
9345b14c |
210 | |
211 | $storage->ensure_connected; |
212 | # if txn_depth is > 1 this means something was done to the |
4a0eed52 |
213 | # original $dbh, otherwise we would not get past the preceding if() |
9345b14c |
214 | $storage->throw_exception(sprintf |
215 | 'Unexpected transaction depth of %d on freshly connected handle', |
216 | $storage->transaction_depth, |
217 | ) if (defined $txn_init_depth and $storage->transaction_depth); |
218 | |
7d534e68 |
219 | return $self->_run($cref, @$args); |
9345b14c |
220 | } |
221 | |
222 | return wantarray ? @res : $res[0]; |
223 | }; |
224 | } |
225 | |
0c11ad0e |
226 | =head1 AUTHOR AND CONTRIBUTORS |
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227 | |
0c11ad0e |
228 | See L<AUTHOR|DBIx::Class/AUTHOR> and L<CONTRIBUTORS|DBIx::Class/CONTRIBUTORS> in DBIx::Class |
9345b14c |
229 | |
230 | =head1 LICENSE |
231 | |
232 | You may distribute this code under the same terms as Perl itself. |
233 | |
234 | =cut |
235 | |
236 | 1; |