Commit | Line | Data |
9345b14c |
1 | package # hide from pause until we figure it all out |
2 | DBIx::Class::Storage::BlockRunner; |
3 | |
59d624cf |
4 | use strict; |
5 | |
9345b14c |
6 | use DBIx::Class::Exception; |
7 | use DBIx::Class::Carp; |
8 | use Context::Preserve 'preserve_context'; |
841efcb3 |
9 | use DBIx::Class::_Util 'is_exception'; |
7d534e68 |
10 | use Scalar::Util qw(weaken blessed reftype); |
9345b14c |
11 | use Try::Tiny; |
59d624cf |
12 | |
13 | # DO NOT edit away without talking to riba first, he will just put it back |
14 | BEGIN { |
15 | local $ENV{PERL_STRICTURES_EXTRA} = 0; |
16 | require Moo; Moo->import; |
17 | require Sub::Quote; Sub::Quote->import('quote_sub'); |
18 | } |
7d534e68 |
19 | use warnings NONFATAL => 'all'; |
9345b14c |
20 | use namespace::clean; |
21 | |
22 | =head1 NAME |
23 | |
24 | DBIx::Class::Storage::BlockRunner - Try running a block of code until success with a configurable retry logic |
25 | |
26 | =head1 DESCRIPTION |
27 | |
28 | =head1 METHODS |
29 | |
30 | =cut |
31 | |
32 | has storage => ( |
33 | is => 'ro', |
34 | required => 1, |
35 | ); |
36 | |
37 | has wrap_txn => ( |
38 | is => 'ro', |
39 | required => 1, |
40 | ); |
41 | |
42 | # true - retry, false - rethrow, or you can throw your own (not catching) |
43 | has retry_handler => ( |
44 | is => 'ro', |
45 | required => 1, |
7d534e68 |
46 | isa => quote_sub( q{ |
47 | (Scalar::Util::reftype($_[0])||'') eq 'CODE' |
9345b14c |
48 | or DBIx::Class::Exception->throw('retry_handler must be a CODE reference') |
7d534e68 |
49 | }), |
9345b14c |
50 | ); |
51 | |
52 | has retry_debug => ( |
53 | is => 'rw', |
7d534e68 |
54 | # use a sub - to be evaluated on the spot lazily |
9345b14c |
55 | default => quote_sub( '$ENV{DBIC_STORAGE_RETRY_DEBUG}' ), |
7d534e68 |
56 | lazy => 1, |
9345b14c |
57 | ); |
58 | |
7d534e68 |
59 | has max_attempts => ( |
9345b14c |
60 | is => 'ro', |
7d534e68 |
61 | default => 20, |
9345b14c |
62 | ); |
63 | |
7d534e68 |
64 | has failed_attempt_count => ( |
9345b14c |
65 | is => 'ro', |
7d534e68 |
66 | init_arg => undef, # ensures one can't pass the value in |
67 | writer => '_set_failed_attempt_count', |
68 | default => 0, |
9345b14c |
69 | lazy => 1, |
70 | trigger => quote_sub(q{ |
f9080e45 |
71 | $_[0]->throw_exception( sprintf ( |
7d534e68 |
72 | 'Reached max_attempts amount of %d, latest exception: %s', |
73 | $_[0]->max_attempts, $_[0]->last_exception |
74 | )) if $_[0]->max_attempts <= ($_[1]||0); |
9345b14c |
75 | }), |
76 | ); |
77 | |
78 | has exception_stack => ( |
79 | is => 'ro', |
80 | init_arg => undef, |
81 | clearer => '_reset_exception_stack', |
82 | default => quote_sub(q{ [] }), |
83 | lazy => 1, |
84 | ); |
85 | |
86 | sub last_exception { shift->exception_stack->[-1] } |
87 | |
f9080e45 |
88 | sub throw_exception { shift->storage->throw_exception (@_) } |
89 | |
9345b14c |
90 | sub run { |
91 | my $self = shift; |
92 | |
9345b14c |
93 | $self->_reset_exception_stack; |
7d534e68 |
94 | $self->_set_failed_attempt_count(0); |
95 | |
96 | my $cref = shift; |
97 | |
98 | $self->throw_exception('run() requires a coderef to execute as its first argument') |
99 | if ( reftype($cref)||'' ) ne 'CODE'; |
100 | |
9345b14c |
101 | my $storage = $self->storage; |
102 | |
7d534e68 |
103 | return $cref->( @_ ) if ( |
104 | $storage->{_in_do_block} |
105 | and |
106 | ! $self->wrap_txn |
107 | ); |
9345b14c |
108 | |
109 | local $storage->{_in_do_block} = 1 unless $storage->{_in_do_block}; |
110 | |
7d534e68 |
111 | return $self->_run($cref, @_); |
9345b14c |
112 | } |
113 | |
114 | # this is the actual recursing worker |
115 | sub _run { |
7d534e68 |
116 | # internal method - we know that both refs are strong-held by the |
117 | # calling scope of run(), hence safe to weaken everything |
118 | weaken( my $self = shift ); |
119 | weaken( my $cref = shift ); |
9345b14c |
120 | |
7d534e68 |
121 | my $args = @_ ? \@_ : []; |
9345b14c |
122 | |
123 | # from this point on (defined $txn_init_depth) is an indicator for wrap_txn |
124 | # save a bit on method calls |
125 | my $txn_init_depth = $self->wrap_txn ? $self->storage->transaction_depth : undef; |
126 | my $txn_begin_ok; |
127 | |
128 | my $run_err = ''; |
129 | |
9345b14c |
130 | return preserve_context { |
131 | try { |
132 | if (defined $txn_init_depth) { |
7d534e68 |
133 | $self->storage->txn_begin; |
9345b14c |
134 | $txn_begin_ok = 1; |
135 | } |
7d534e68 |
136 | $cref->( @$args ); |
9345b14c |
137 | } catch { |
138 | $run_err = $_; |
139 | (); # important, affects @_ below |
140 | }; |
141 | } replace => sub { |
142 | my @res = @_; |
143 | |
7d534e68 |
144 | my $storage = $self->storage; |
9345b14c |
145 | my $cur_depth = $storage->transaction_depth; |
146 | |
147 | if (defined $txn_init_depth and $run_err eq '') { |
148 | my $delta_txn = (1 + $txn_init_depth) - $cur_depth; |
149 | |
150 | if ($delta_txn) { |
151 | # a rollback in a top-level txn_do is valid-ish (seen in the wild and our own tests) |
152 | carp (sprintf |
153 | 'Unexpected reduction of transaction depth by %d after execution of ' |
154 | . '%s, skipping txn_commit()', |
155 | $delta_txn, |
7d534e68 |
156 | $cref, |
9345b14c |
157 | ) unless $delta_txn == 1 and $cur_depth == 0; |
158 | } |
159 | else { |
160 | $run_err = eval { $storage->txn_commit; 1 } ? '' : $@; |
161 | } |
162 | } |
163 | |
164 | # something above threw an error (could be the begin, the code or the commit) |
841efcb3 |
165 | if ( is_exception $run_err ) { |
9345b14c |
166 | |
167 | # attempt a rollback if we did begin in the first place |
168 | if ($txn_begin_ok) { |
169 | # some DBDs go crazy if there is nothing to roll back on, perform a soft-check |
170 | my $rollback_exception = $storage->_seems_connected |
171 | ? (! eval { $storage->txn_rollback; 1 }) ? $@ : '' |
172 | : 'lost connection to storage' |
173 | ; |
174 | |
175 | if ( $rollback_exception and ( |
176 | ! defined blessed $rollback_exception |
177 | or |
178 | ! $rollback_exception->isa('DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION') |
179 | ) ) { |
180 | $run_err = "Transaction aborted: $run_err. Rollback failed: $rollback_exception"; |
181 | } |
182 | } |
183 | |
7d534e68 |
184 | push @{ $self->exception_stack }, $run_err; |
185 | |
186 | # this will throw if max_attempts is reached |
187 | $self->_set_failed_attempt_count($self->failed_attempt_count + 1); |
9345b14c |
188 | |
189 | # init depth of > 0 ( > 1 with AC) implies nesting - no retry attempt queries |
190 | $storage->throw_exception($run_err) if ( |
191 | ( |
192 | defined $txn_init_depth |
193 | and |
194 | # FIXME - we assume that $storage->{_dbh_autocommit} is there if |
195 | # txn_init_depth is there, but this is a DBI-ism |
196 | $txn_init_depth > ( $storage->{_dbh_autocommit} ? 0 : 1 ) |
7d534e68 |
197 | ) or ! $self->retry_handler->($self) |
9345b14c |
198 | ); |
199 | |
9345b14c |
200 | # we got that far - let's retry |
7d534e68 |
201 | carp( sprintf 'Retrying %s (attempt %d) after caught exception: %s', |
202 | $cref, |
203 | $self->failed_attempt_count + 1, |
9345b14c |
204 | $run_err, |
7d534e68 |
205 | ) if $self->retry_debug; |
9345b14c |
206 | |
207 | $storage->ensure_connected; |
208 | # if txn_depth is > 1 this means something was done to the |
4a0eed52 |
209 | # original $dbh, otherwise we would not get past the preceding if() |
9345b14c |
210 | $storage->throw_exception(sprintf |
211 | 'Unexpected transaction depth of %d on freshly connected handle', |
212 | $storage->transaction_depth, |
213 | ) if (defined $txn_init_depth and $storage->transaction_depth); |
214 | |
7d534e68 |
215 | return $self->_run($cref, @$args); |
9345b14c |
216 | } |
217 | |
218 | return wantarray ? @res : $res[0]; |
219 | }; |
220 | } |
221 | |
0c11ad0e |
222 | =head1 AUTHOR AND CONTRIBUTORS |
9345b14c |
223 | |
0c11ad0e |
224 | See L<AUTHOR|DBIx::Class/AUTHOR> and L<CONTRIBUTORS|DBIx::Class/CONTRIBUTORS> in DBIx::Class |
9345b14c |
225 | |
226 | =head1 LICENSE |
227 | |
228 | You may distribute this code under the same terms as Perl itself. |
229 | |
230 | =cut |
231 | |
232 | 1; |