Commit | Line | Data |
f0276afb |
1 | package DBM::Deep::Engine::Sector::Reference; |
2 | |
3 | use 5.006_000; |
4 | |
5 | use strict; |
6 | use warnings FATAL => 'all'; |
7 | |
8 | use base qw( DBM::Deep::Engine::Sector::Data ); |
9 | |
5ae752e2 |
10 | my $STALE_SIZE = 2; |
11 | |
12 | # Please refer to the pack() documentation for further information |
13 | my %StP = ( |
14 | 1 => 'C', # Unsigned char value (no order needed as it's just one byte) |
15 | 2 => 'n', # Unsigned short in "network" (big-endian) order |
16 | 4 => 'N', # Unsigned long in "network" (big-endian) order |
17 | 8 => 'Q', # Usigned quad (no order specified, presumably machine-dependent) |
18 | ); |
19 | |
f0276afb |
20 | sub _init { |
21 | my $self = shift; |
22 | |
23 | my $e = $self->engine; |
24 | |
25 | unless ( $self->offset ) { |
26 | my $classname = Scalar::Util::blessed( delete $self->{data} ); |
27 | my $leftover = $self->size - $self->base_size - 3 * $e->byte_size; |
28 | |
29 | my $class_offset = 0; |
30 | if ( defined $classname ) { |
31 | my $class_sector = DBM::Deep::Engine::Sector::Scalar->new({ |
32 | engine => $e, |
33 | data => $classname, |
34 | }); |
35 | $class_offset = $class_sector->offset; |
36 | } |
37 | |
38 | $self->{offset} = $e->_request_data_sector( $self->size ); |
39 | $e->storage->print_at( $self->offset, $self->type ); # Sector type |
40 | # Skip staleness counter |
41 | $e->storage->print_at( $self->offset + $self->base_size, |
42 | pack( $StP{$e->byte_size}, 0 ), # Index/BList loc |
43 | pack( $StP{$e->byte_size}, $class_offset ), # Classname loc |
44 | pack( $StP{$e->byte_size}, 1 ), # Initial refcount |
45 | chr(0) x $leftover, # Zero-fill the rest |
46 | ); |
47 | } |
48 | else { |
49 | $self->{type} = $e->storage->read_at( $self->offset, 1 ); |
50 | } |
51 | |
52 | $self->{staleness} = unpack( |
53 | $StP{$STALE_SIZE}, |
54 | $e->storage->read_at( $self->offset + $e->SIG_SIZE, $STALE_SIZE ), |
55 | ); |
56 | |
57 | return; |
58 | } |
59 | |
60 | sub staleness { $_[0]{staleness} } |
61 | |
62 | sub get_data_location_for { |
63 | my $self = shift; |
64 | my ($args) = @_; |
65 | |
66 | # Assume that the head is not allowed unless otherwise specified. |
67 | $args->{allow_head} = 0 unless exists $args->{allow_head}; |
68 | |
69 | # Assume we don't create a new blist location unless otherwise specified. |
70 | $args->{create} = 0 unless exists $args->{create}; |
71 | |
72 | my $blist = $self->get_bucket_list({ |
73 | key_md5 => $args->{key_md5}, |
74 | key => $args->{key}, |
75 | create => $args->{create}, |
76 | }); |
77 | return unless $blist && $blist->{found}; |
78 | |
79 | # At this point, $blist knows where the md5 is. What it -doesn't- know yet |
80 | # is whether or not this transaction has this key. That's part of the next |
81 | # function call. |
82 | my $location = $blist->get_data_location_for({ |
83 | allow_head => $args->{allow_head}, |
84 | }) or return; |
85 | |
86 | return $location; |
87 | } |
88 | |
89 | sub get_data_for { |
90 | my $self = shift; |
91 | my ($args) = @_; |
92 | |
93 | my $location = $self->get_data_location_for( $args ) |
94 | or return; |
95 | |
96 | return $self->engine->_load_sector( $location ); |
97 | } |
98 | |
99 | sub write_data { |
100 | my $self = shift; |
101 | my ($args) = @_; |
102 | |
103 | my $blist = $self->get_bucket_list({ |
104 | key_md5 => $args->{key_md5}, |
105 | key => $args->{key}, |
106 | create => 1, |
107 | }) or DBM::Deep->_throw_error( "How did write_data fail (no blist)?!" ); |
108 | |
109 | # Handle any transactional bookkeeping. |
110 | if ( $self->engine->trans_id ) { |
111 | if ( ! $blist->has_md5 ) { |
112 | $blist->mark_deleted({ |
113 | trans_id => 0, |
114 | }); |
115 | } |
116 | } |
117 | else { |
118 | my @trans_ids = $self->engine->get_running_txn_ids; |
119 | if ( $blist->has_md5 ) { |
120 | if ( @trans_ids ) { |
121 | my $old_value = $blist->get_data_for; |
122 | foreach my $other_trans_id ( @trans_ids ) { |
123 | next if $blist->get_data_location_for({ |
124 | trans_id => $other_trans_id, |
125 | allow_head => 0, |
126 | }); |
127 | $blist->write_md5({ |
128 | trans_id => $other_trans_id, |
129 | key => $args->{key}, |
130 | key_md5 => $args->{key_md5}, |
131 | value => $old_value->clone, |
132 | }); |
133 | } |
134 | } |
135 | } |
136 | else { |
137 | if ( @trans_ids ) { |
138 | foreach my $other_trans_id ( @trans_ids ) { |
139 | #XXX This doesn't seem to possible to ever happen . . . |
140 | next if $blist->get_data_location_for({ trans_id => $other_trans_id, allow_head => 0 }); |
141 | $blist->mark_deleted({ |
142 | trans_id => $other_trans_id, |
143 | }); |
144 | } |
145 | } |
146 | } |
147 | } |
148 | |
149 | #XXX Is this safe to do transactionally? |
150 | # Free the place we're about to write to. |
151 | if ( $blist->get_data_location_for({ allow_head => 0 }) ) { |
152 | $blist->get_data_for({ allow_head => 0 })->free; |
153 | } |
154 | |
155 | $blist->write_md5({ |
156 | key => $args->{key}, |
157 | key_md5 => $args->{key_md5}, |
158 | value => $args->{value}, |
159 | }); |
160 | } |
161 | |
162 | sub delete_key { |
163 | my $self = shift; |
164 | my ($args) = @_; |
165 | |
166 | # XXX What should happen if this fails? |
167 | my $blist = $self->get_bucket_list({ |
168 | key_md5 => $args->{key_md5}, |
169 | }) or DBM::Deep->_throw_error( "How did delete_key fail (no blist)?!" ); |
170 | |
171 | # Save the location so that we can free the data |
172 | my $location = $blist->get_data_location_for({ |
173 | allow_head => 0, |
174 | }); |
175 | my $old_value = $location && $self->engine->_load_sector( $location ); |
176 | |
177 | my @trans_ids = $self->engine->get_running_txn_ids; |
178 | |
179 | # If we're the HEAD and there are running txns, then we need to clone this value to the other |
180 | # transactions to preserve Isolation. |
181 | if ( $self->engine->trans_id == 0 ) { |
182 | if ( @trans_ids ) { |
183 | foreach my $other_trans_id ( @trans_ids ) { |
184 | next if $blist->get_data_location_for({ trans_id => $other_trans_id, allow_head => 0 }); |
185 | $blist->write_md5({ |
186 | trans_id => $other_trans_id, |
187 | key => $args->{key}, |
188 | key_md5 => $args->{key_md5}, |
189 | value => $old_value->clone, |
190 | }); |
191 | } |
192 | } |
193 | } |
194 | |
195 | my $data; |
196 | if ( @trans_ids ) { |
197 | $blist->mark_deleted( $args ); |
198 | |
199 | if ( $old_value ) { |
200 | $data = $old_value->data({ export => 1 }); |
201 | $old_value->free; |
202 | } |
203 | } |
204 | else { |
205 | $data = $blist->delete_md5( $args ); |
206 | } |
207 | |
208 | return $data; |
209 | } |
210 | |
211 | sub get_blist_loc { |
212 | my $self = shift; |
213 | |
214 | my $e = $self->engine; |
215 | my $blist_loc = $e->storage->read_at( $self->offset + $self->base_size, $e->byte_size ); |
216 | return unpack( $StP{$e->byte_size}, $blist_loc ); |
217 | } |
218 | |
219 | sub get_bucket_list { |
220 | my $self = shift; |
221 | my ($args) = @_; |
222 | $args ||= {}; |
223 | |
224 | # XXX Add in check here for recycling? |
225 | |
226 | my $engine = $self->engine; |
227 | |
228 | my $blist_loc = $self->get_blist_loc; |
229 | |
230 | # There's no index or blist yet |
231 | unless ( $blist_loc ) { |
232 | return unless $args->{create}; |
233 | |
234 | my $blist = DBM::Deep::Engine::Sector::BucketList->new({ |
235 | engine => $engine, |
236 | key_md5 => $args->{key_md5}, |
237 | }); |
238 | |
239 | $engine->storage->print_at( $self->offset + $self->base_size, |
240 | pack( $StP{$engine->byte_size}, $blist->offset ), |
241 | ); |
242 | |
243 | return $blist; |
244 | } |
245 | |
246 | my $sector = $engine->_load_sector( $blist_loc ) |
247 | or DBM::Deep->_throw_error( "Cannot read sector at $blist_loc in get_bucket_list()" ); |
248 | my $i = 0; |
249 | my $last_sector = undef; |
250 | while ( $sector->isa( 'DBM::Deep::Engine::Sector::Index' ) ) { |
251 | $blist_loc = $sector->get_entry( ord( substr( $args->{key_md5}, $i++, 1 ) ) ); |
252 | $last_sector = $sector; |
253 | if ( $blist_loc ) { |
254 | $sector = $engine->_load_sector( $blist_loc ) |
255 | or DBM::Deep->_throw_error( "Cannot read sector at $blist_loc in get_bucket_list()" ); |
256 | } |
257 | else { |
258 | $sector = undef; |
259 | last; |
260 | } |
261 | } |
262 | |
263 | # This means we went through the Index sector(s) and found an empty slot |
264 | unless ( $sector ) { |
265 | return unless $args->{create}; |
266 | |
267 | DBM::Deep->_throw_error( "No last_sector when attempting to build a new entry" ) |
268 | unless $last_sector; |
269 | |
270 | my $blist = DBM::Deep::Engine::Sector::BucketList->new({ |
271 | engine => $engine, |
272 | key_md5 => $args->{key_md5}, |
273 | }); |
274 | |
275 | $last_sector->set_entry( ord( substr( $args->{key_md5}, $i - 1, 1 ) ) => $blist->offset ); |
276 | |
277 | return $blist; |
278 | } |
279 | |
280 | $sector->find_md5( $args->{key_md5} ); |
281 | |
282 | # See whether or not we need to reindex the bucketlist |
283 | # Yes, the double-braces are there for a reason. if() doesn't create a redo-able block, |
284 | # so we have to create a bare block within the if() for redo-purposes. Patch and idea |
285 | # submitted by sprout@cpan.org. -RobK, 2008-01-09 |
286 | if ( !$sector->has_md5 && $args->{create} && $sector->{idx} == -1 ) {{ |
287 | my $redo; |
288 | |
289 | my $new_index = DBM::Deep::Engine::Sector::Index->new({ |
290 | engine => $engine, |
291 | }); |
292 | |
293 | my %blist_cache; |
294 | #XXX q.v. the comments for this function. |
295 | foreach my $entry ( $sector->chopped_up ) { |
296 | my ($spot, $md5) = @{$entry}; |
297 | my $idx = ord( substr( $md5, $i, 1 ) ); |
298 | |
299 | # XXX This is inefficient |
300 | my $blist = $blist_cache{$idx} |
301 | ||= DBM::Deep::Engine::Sector::BucketList->new({ |
302 | engine => $engine, |
303 | }); |
304 | |
305 | $new_index->set_entry( $idx => $blist->offset ); |
306 | |
307 | my $new_spot = $blist->write_at_next_open( $md5 ); |
308 | $engine->reindex_entry( $spot => $new_spot ); |
309 | } |
310 | |
311 | # Handle the new item separately. |
312 | { |
313 | my $idx = ord( substr( $args->{key_md5}, $i, 1 ) ); |
314 | |
315 | # If all the previous blist's items have been thrown into one |
316 | # blist and the new item belongs in there too, we need |
317 | # another index. |
318 | if ( keys %blist_cache == 1 and each %blist_cache == $idx ) { |
319 | ++$i, ++$redo; |
320 | } else { |
321 | my $blist = $blist_cache{$idx} |
322 | ||= DBM::Deep::Engine::Sector::BucketList->new({ |
323 | engine => $engine, |
324 | }); |
325 | |
326 | $new_index->set_entry( $idx => $blist->offset ); |
327 | |
328 | #XXX THIS IS HACKY! |
329 | $blist->find_md5( $args->{key_md5} ); |
330 | $blist->write_md5({ |
331 | key => $args->{key}, |
332 | key_md5 => $args->{key_md5}, |
333 | value => DBM::Deep::Engine::Sector::Null->new({ |
334 | engine => $engine, |
335 | data => undef, |
336 | }), |
337 | }); |
338 | } |
339 | # my $blist = $blist_cache{$idx} |
340 | # ||= DBM::Deep::Engine::Sector::BucketList->new({ |
341 | # engine => $engine, |
342 | # }); |
343 | # |
344 | # $new_index->set_entry( $idx => $blist->offset ); |
345 | # |
346 | # #XXX THIS IS HACKY! |
347 | # $blist->find_md5( $args->{key_md5} ); |
348 | # $blist->write_md5({ |
349 | # key => $args->{key}, |
350 | # key_md5 => $args->{key_md5}, |
351 | # value => DBM::Deep::Engine::Sector::Null->new({ |
352 | # engine => $engine, |
353 | # data => undef, |
354 | # }), |
355 | # }); |
356 | } |
357 | |
358 | if ( $last_sector ) { |
359 | $last_sector->set_entry( |
360 | ord( substr( $args->{key_md5}, $i - 1, 1 ) ), |
361 | $new_index->offset, |
362 | ); |
363 | } else { |
364 | $engine->storage->print_at( $self->offset + $self->base_size, |
365 | pack( $StP{$engine->byte_size}, $new_index->offset ), |
366 | ); |
367 | } |
368 | |
369 | $sector->clear; |
370 | $sector->free; |
371 | |
372 | if ( $redo ) { |
373 | (undef, $sector) = %blist_cache; |
374 | $last_sector = $new_index; |
375 | redo; |
376 | } |
377 | |
378 | $sector = $blist_cache{ ord( substr( $args->{key_md5}, $i, 1 ) ) }; |
379 | $sector->find_md5( $args->{key_md5} ); |
380 | }} |
381 | |
382 | return $sector; |
383 | } |
384 | |
385 | sub get_class_offset { |
386 | my $self = shift; |
387 | |
388 | my $e = $self->engine; |
389 | return unpack( |
390 | $StP{$e->byte_size}, |
391 | $e->storage->read_at( |
392 | $self->offset + $self->base_size + 1 * $e->byte_size, $e->byte_size, |
393 | ), |
394 | ); |
395 | } |
396 | |
397 | sub get_classname { |
398 | my $self = shift; |
399 | |
400 | my $class_offset = $self->get_class_offset; |
401 | |
402 | return unless $class_offset; |
403 | |
404 | return $self->engine->_load_sector( $class_offset )->data; |
405 | } |
406 | |
407 | sub data { |
408 | my $self = shift; |
409 | my ($args) = @_; |
410 | $args ||= {}; |
411 | |
412 | my $obj; |
413 | unless ( $obj = $self->engine->cache->{ $self->offset } ) { |
414 | $obj = DBM::Deep->new({ |
415 | type => $self->type, |
416 | base_offset => $self->offset, |
417 | staleness => $self->staleness, |
418 | storage => $self->engine->storage, |
419 | engine => $self->engine, |
420 | }); |
421 | |
422 | if ( $self->engine->storage->{autobless} ) { |
423 | my $classname = $self->get_classname; |
424 | if ( defined $classname ) { |
425 | bless $obj, $classname; |
426 | } |
427 | } |
428 | |
429 | $self->engine->cache->{$self->offset} = $obj; |
430 | } |
431 | |
432 | # We're not exporting, so just return. |
433 | unless ( $args->{export} ) { |
434 | return $obj; |
435 | } |
436 | |
437 | # We shouldn't export if this is still referred to. |
438 | if ( $self->get_refcount > 1 ) { |
439 | return $obj; |
440 | } |
441 | |
442 | return $obj->export; |
443 | } |
444 | |
445 | sub free { |
446 | my $self = shift; |
447 | |
448 | # We're not ready to be removed yet. |
449 | if ( $self->decrement_refcount > 0 ) { |
450 | return; |
451 | } |
452 | |
453 | # Rebless the object into DBM::Deep::Null. |
454 | eval { %{ $self->engine->cache->{ $self->offset } } = (); }; |
455 | eval { @{ $self->engine->cache->{ $self->offset } } = (); }; |
456 | bless $self->engine->cache->{ $self->offset }, 'DBM::Deep::Null'; |
457 | delete $self->engine->cache->{ $self->offset }; |
458 | |
459 | my $blist_loc = $self->get_blist_loc; |
460 | $self->engine->_load_sector( $blist_loc )->free if $blist_loc; |
461 | |
462 | my $class_loc = $self->get_class_offset; |
463 | $self->engine->_load_sector( $class_loc )->free if $class_loc; |
464 | |
465 | $self->SUPER::free(); |
466 | } |
467 | |
468 | sub increment_refcount { |
469 | my $self = shift; |
470 | |
471 | my $refcount = $self->get_refcount; |
472 | |
473 | $refcount++; |
474 | |
475 | $self->write_refcount( $refcount ); |
476 | |
477 | return $refcount; |
478 | } |
479 | |
480 | sub decrement_refcount { |
481 | my $self = shift; |
482 | |
483 | my $refcount = $self->get_refcount; |
484 | |
485 | $refcount--; |
486 | |
487 | $self->write_refcount( $refcount ); |
488 | |
489 | return $refcount; |
490 | } |
491 | |
492 | sub get_refcount { |
493 | my $self = shift; |
494 | |
495 | my $e = $self->engine; |
496 | return unpack( |
497 | $StP{$e->byte_size}, |
498 | $e->storage->read_at( |
499 | $self->offset + $self->base_size + 2 * $e->byte_size, $e->byte_size, |
500 | ), |
501 | ); |
502 | } |
503 | |
504 | sub write_refcount { |
505 | my $self = shift; |
506 | my ($num) = @_; |
507 | |
508 | my $e = $self->engine; |
509 | $e->storage->print_at( |
510 | $self->offset + $self->base_size + 2 * $e->byte_size, |
511 | pack( $StP{$e->byte_size}, $num ), |
512 | ); |
513 | } |
514 | |
515 | 1; |
516 | __END__ |