summaryrefslogtreecommitdiff
path: root/src/mongo/db/ops/update.cpp
blob: 2dbea65d03e9c247fceeb69f07fe45fd2bceaf8e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
//@file update.cpp

/**
 *    Copyright (C) 2008 10gen Inc.
 *
 *    This program is free software: you can redistribute it and/or  modify
 *    it under the terms of the GNU Affero General Public License, version 3,
 *    as published by the Free Software Foundation.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the GNU Affero General Public License in all respects for
 *    all of the code used other than as permitted herein. If you modify file(s)
 *    with this exception, you may extend this exception to your version of the
 *    file(s), but you are not obligated to do so. If you do not wish to do so,
 *    delete this exception statement from your version. If you delete this
 *    exception statement from all source files in the program, then also delete
 *    it in the license file.
 */

#include "mongo/pch.h"

#include "mongo/db/ops/update.h"

#include <cstring>  // for memcpy

#include "mongo/bson/mutable/damage_vector.h"
#include "mongo/bson/mutable/document.h"
#include "mongo/client/dbclientinterface.h"
#include "mongo/db/clientcursor.h"
#include "mongo/db/index_set.h"
#include "mongo/db/namespace_details.h"
#include "mongo/db/ops/update_driver.h"
#include "mongo/db/pagefault.h"
#include "mongo/db/pdfile.h"
#include "mongo/db/query_optimizer.h"
#include "mongo/db/query_runner.h"
#include "mongo/db/queryutil.h"
#include "mongo/db/storage/record.h"
#include "mongo/db/repl/oplog.h"
#include "mongo/platform/unordered_set.h"

namespace mongo {

    namespace {

        // TODO: Make this a function on NamespaceString, or make it cleaner.
        inline void validateUpdate( const char* ns , const BSONObj& updateobj, const BSONObj& patternOrig ) {
            uassert( 10155 , "cannot update reserved $ collection", strchr(ns, '$') == 0 );
            if ( strstr(ns, ".system.") ) {
                /* dm: it's very important that system.indexes is never updated as IndexDetails
                   has pointers into it */
                uassert( 10156,
                         str::stream() << "cannot update system collection: "
                         << ns << " q: " << patternOrig << " u: " << updateobj,
                         legalClientSystemNS( ns , true ) );
            }
        }

        /**
         * return a BSONObj with the _id field of the doc passed in. If no _id and multi, error.
         */
        BSONObj makeOplogEntryQuery(const BSONObj doc, bool multi) {
            BSONObjBuilder idPattern;
            BSONElement id;
            // NOTE: If the matching object lacks an id, we'll log
            // with the original pattern.  This isn't replay-safe.
            // It might make sense to suppress the log instead
            // if there's no id.
            if ( doc.getObjectID( id ) ) {
                idPattern.append( id );
                return idPattern.obj();
            }
            else {
                uassert( 10157, "multi-update requires all modified objects to have an _id" , ! multi );
                return doc;
            }
        }

    } // namespace

    UpdateResult update(const UpdateRequest& request, OpDebug* opDebug) {

        // Should the modifiers validate their embedded docs via okForStorage
        // Only user updates should be checked. Any system or replication stuff should pass through.
        // Config db docs shouldn't get checked for valid field names since the shard key can have
        // a dot (".") in it.
        bool shouldValidate = !(request.isFromReplication() ||
                                request.getNamespaceString().isConfigDB());

        // TODO: Consider some sort of unification between the UpdateDriver, ModifierInterface
        // and UpdateRequest structures.
        UpdateDriver::Options opts;
        opts.multi = request.isMulti();
        opts.upsert = request.isUpsert();
        opts.logOp = request.shouldUpdateOpLog();
        opts.modOptions = ModifierInterface::Options( request.isFromReplication(), shouldValidate );
        UpdateDriver driver( opts );

        Status status = driver.parse( request.getUpdates() );
        if ( !status.isOK() ) {
            uasserted( 16840, status.reason() );
        }

        return update(request, opDebug, &driver);
    }

    UpdateResult update(const UpdateRequest& request, OpDebug* opDebug, UpdateDriver* driver) {

        const NamespaceString& nsString = request.getNamespaceString();

        validateUpdate( nsString.ns().c_str(), request.getUpdates(), request.getQuery() );

        NamespaceDetails* nsDetails = nsdetails( nsString.ns() );
        NamespaceDetailsTransient* nsDetailsTransient =
            &NamespaceDetailsTransient::get( nsString.ns().c_str() );

        // TODO: This seems a bit circuitious.
        opDebug->updateobj = request.getUpdates();

        driver->refreshIndexKeys( nsDetailsTransient->indexKeys() );

        shared_ptr<Cursor> cursor = getOptimizedCursor(
            nsString.ns(), request.getQuery(), BSONObj(), request.getQueryPlanSelectionPolicy() );

        // If the update was marked with '$isolated' (a.k.a '$atomic'), we are not allowed to
        // yield while evaluating the update loop below.
        //
        // TODO: Old code checks this repeatedly within the update loop. Is that necessary? It seems
        // that once atomic should be always atomic.
        const bool isolated =
            cursor->ok() &&
            cursor->matcher() &&
            cursor->matcher()->docMatcher().atomic();

        // The 'cursor' the optimizer gave us may contain query plans that generate duplicate
        // diskloc's. We set up here the mechanims that will prevent us from processing those
        // twice if we see them. We also set up a 'ClientCursor' so that we can support
        // yielding.
        //
        // TODO: Is it valid to call this on a non-ok cursor?
        const bool dedupHere = cursor->autoDedup();

        //
        // We'll start assuming we have one or more documents for this update. (Othwerwise,
        // we'll fallback to upserting.)
        //

        // We record that this will not be an upsert, in case a mod doesn't want to be applied
        // when in strict update mode.
        driver->setContext( ModifierInterface::ExecInfo::UPDATE_CONTEXT );

        // Let's fetch each of them and pipe them through the update expression, making sure to
        // keep track of the necessary stats. Recall that we'll be pulling documents out of
        // cursors and some of them do not deduplicate the entries they generate. We have
        // deduping logic in here, too -- for now.
        unordered_set<DiskLoc, DiskLoc::Hasher> seenLocs;
        int numMatched = 0;
        opDebug->nscanned = 0;

        Client& client = cc();

        mutablebson::Document doc;

        // If we are going to be yielding, we will need a ClientCursor scoped to this loop. We
        // only loop as long as the underlying cursor is OK.
        for ( auto_ptr<ClientCursor> clientCursor; cursor->ok(); ) {

            // If we haven't constructed a ClientCursor, and if the client allows us to throw
            // page faults, and if we are referring to a location that is likely not in
            // physical memory, then throw a PageFaultException. The entire operation will be
            // restarted.
            if ( clientCursor.get() == NULL &&
                 client.allowedToThrowPageFaultException() &&
                 !cursor->currLoc().isNull() &&
                 !cursor->currLoc().rec()->likelyInPhysicalMemory() ) {
                // We should never throw a PFE if we have already updated items.
                dassert((numMatched == 0) || (numMatched == opDebug->nupdateNoops));
                throw PageFaultException( cursor->currLoc().rec() );
            }

            if ( !isolated && opDebug->nscanned != 0 ) {

                // We are permitted to yield. To do so we need a ClientCursor, so create one
                // now if we have not yet done so.
                if ( !clientCursor.get() )
                    clientCursor.reset(
                        new ClientCursor( QueryOption_NoCursorTimeout, cursor, nsString.ns() ) );

                // Ask the client cursor to yield. We get two bits of state back: whether or not
                // we yielded, and whether or not we correctly recovered from yielding.
                bool yielded = false;
                const bool recovered = clientCursor->yieldSometimes(
                    ClientCursor::WillNeed, &yielded );

                if ( !recovered ) {
                    // If we failed to recover from the yield, then the ClientCursor is already
                    // gone. Release it so we don't destroy it a second time.
                    clientCursor.release();
                    break;
                }

                if ( !cursor->ok() ) {
                    // If the cursor died while we were yielded, just get out of the update loop.
                    break;
                }

                if ( yielded ) {
                    // We yielded and recovered OK, and our cursor is still good. Details about
                    // our namespace may have changed while we were yielded, so we re-acquire
                    // them here. If we can't do so, escape the update loop. Otherwise, refresh
                    // the driver so that it knows about what is currently indexed.
                    nsDetails = nsdetails( nsString.ns() );
                    if ( !nsDetails )
                        break;
                    nsDetailsTransient = &NamespaceDetailsTransient::get( nsString.ns().c_str() );

                    // TODO: This copies the index keys, but it may not need to do so.
                    driver->refreshIndexKeys( nsDetailsTransient->indexKeys() );
                }

            }

            // Let's fetch the next candidate object for this update.
            Record* record = cursor->_current();
            DiskLoc loc = cursor->currLoc();
            const BSONObj oldObj = loc.obj();

            // We count how many documents we scanned even though we may skip those that are
            // deemed duplicated. The final 'numUpdated' and 'nscanned' numbers may differ for
            // that reason.
            opDebug->nscanned++;

            // Skips this document if it:
            // a) doesn't match the query portion of the update
            // b) was deemed duplicate by the underlying cursor machinery
            //
            // Now, if we are going to update the document,
            // c) we don't want to do so while the cursor is at it, as that may invalidate
            // the cursor. So, we advance to next document, before issuing the update.
            MatchDetails matchDetails;
            matchDetails.requestElemMatchKey();
            if ( !cursor->currentMatches( &matchDetails ) ) {
                // a)
                cursor->advance();
                continue;
            }
            else if ( cursor->getsetdup( loc ) && dedupHere ) {
                // b)
                cursor->advance();
                continue;
            }
            else if (!driver->isDocReplacement() && request.isMulti()) {
                // c)
                cursor->advance();
                if ( dedupHere ) {
                    if ( seenLocs.count( loc ) ) {
                        continue;
                    }
                }

                // There are certain kind of cursors that hold multiple pointers to data
                // underneath. $or cursors is one example. In a $or cursor, it may be the case
                // that when we did the last advance(), we finished consuming documents from
                // one of $or child and started consuming the next one. In that case, it is
                // possible that the last document of the previous child is the same as the
                // first document of the next (see SERVER-5198 and jstests/orp.js).
                //
                // So we advance the cursor here until we see a new diskloc.
                //
                // Note that we won't be yielding, and we may not do so for a while if we find
                // a particularly duplicated sequence of loc's. That is highly unlikely,
                // though.  (See SERVER-5725, if curious, but "stage" based $or will make that
                // ticket moot).
                while( cursor->ok() && loc == cursor->currLoc() ) {
                    cursor->advance();
                }
            }

            // For some (unfortunate) historical reasons, not all cursors would be valid after
            // a write simply because we advanced them to a document not affected by the write.
            // To protect in those cases, not only we engaged in the advance() logic above, but
            // we also tell the cursor we're about to write a document that we've just seen.
            // prepareToTouchEarlierIterate() requires calling later
            // recoverFromTouchingEarlierIterate(), so we make a note here to do so.
            bool touchPreviousDoc = request.isMulti() && cursor->ok();
            if ( touchPreviousDoc ) {
                if ( clientCursor.get() )
                    clientCursor->setDoingDeletes( true );
                cursor->prepareToTouchEarlierIterate();
            }

            // Found a matching document
            numMatched++;

            // Ask the driver to apply the mods. It may be that the driver can apply those "in
            // place", that is, some values of the old document just get adjusted without any
            // change to the binary layout on the bson layer. It may be that a whole new
            // document is needed to accomodate the new bson layout of the resulting document.
            doc.reset( oldObj, mutablebson::Document::kInPlaceEnabled );
            BSONObj logObj;

            // If there was a matched field, obtain it.
            string matchedField;
            if (matchDetails.hasElemMatchKey())
                matchedField = matchDetails.elemMatchKey();

            Status status = driver->update( matchedField, &doc, &logObj );
            if ( !status.isOK() ) {
                uasserted( 16837, status.reason() );
            }

            // If the driver applied the mods in place, we can ask the mutable for what
            // changed. We call those changes "damages". :) We use the damages to inform the
            // journal what was changed, and then apply them to the original document
            // ourselves. If, however, the driver applied the mods out of place, we ask it to
            // generate a new, modified document for us. In that case, the file manager will
            // take care of the journaling details for us.
            //
            // This code flow is admittedly odd. But, right now, journaling is baked in the file
            // manager. And if we aren't using the file manager, we have to do jounaling
            // ourselves.
            bool objectWasChanged = false;
            BSONObj newObj;
            const char* source = NULL;
            mutablebson::DamageVector damages;
            bool inPlace = doc.getInPlaceUpdates(&damages, &source);
            if ( inPlace && !damages.empty() && !driver->modsAffectIndices() ) {
                nsDetails->paddingFits();

                // All updates were in place. Apply them via durability and writing pointer.
                mutablebson::DamageVector::const_iterator where = damages.begin();
                const mutablebson::DamageVector::const_iterator end = damages.end();
                for( ; where != end; ++where ) {
                    const char* sourcePtr = source + where->sourceOffset;
                    void* targetPtr = getDur().writingPtr(
                        const_cast<char*>(oldObj.objdata()) + where->targetOffset,
                        where->size);
                    std::memcpy(targetPtr, sourcePtr, where->size);
                }
                newObj = oldObj;
                opDebug->fastmod = true;

                objectWasChanged = true;
            }
            else {

                // The updates were not in place. Apply them through the file manager.
                newObj = doc.getObject();
                DiskLoc newLoc = theDataFileMgr.updateRecord(nsString.ns().c_str(),
                                                             nsDetails,
                                                             nsDetailsTransient,
                                                             record,
                                                             loc,
                                                             newObj.objdata(),
                                                             newObj.objsize(),
                                                             *opDebug);

                // If we've moved this object to a new location, make sure we don't apply
                // that update again if our traversal picks the objecta again.
                //
                // We also take note that the diskloc if the updates are affecting indices.
                // Chances are that we're traversing one of them and they may be multi key and
                // therefore duplicate disklocs.
                if ( newLoc != loc || driver->modsAffectIndices()  ) {
                    seenLocs.insert( newLoc );
                }

                objectWasChanged = true;
            }

            // Log Obj
            if ( request.shouldUpdateOpLog() ) {
                if ( driver->isDocReplacement() || !logObj.isEmpty() ) {
                    BSONObj idQuery = driver->makeOplogEntryQuery(newObj, request.isMulti());
                    logOp("u", nsString.ns().c_str(), logObj , &idQuery,
                          NULL, request.isFromMigration(), &newObj);
                }
            }

            // If it was noop since the document didn't change, record that.
            if (!objectWasChanged)
                opDebug->nupdateNoops++;

            if (!request.isMulti()) {
                break;
            }

            // If we used the cursor mechanism that prepares an earlier seen document for a
            // write we need to tell such mechanisms that the write is over.
            if ( touchPreviousDoc ) {
                cursor->recoverFromTouchingEarlierIterate();
            }

            getDur().commitIfNeeded();

        }

        // TODO: Can this be simplified?
        if ((numMatched > 0) || (numMatched == 0 && !request.isUpsert()) ) {
            opDebug->nupdated = numMatched;
            return UpdateResult( numMatched > 0 /* updated existing object(s) */,
                                 !driver->isDocReplacement() /* $mod or obj replacement */,
                                 numMatched /* # of docments update, even no-ops */,
                                 BSONObj() );
        }

        //
        // We haven't found any existing document so an insert is done
        // (upsert is true).
        //
        opDebug->upsert = true;

        // Since this is an insert (no docs found and upsert:true), we will be logging it
        // as an insert in the oplog. We don't need the driver's help to build the
        // oplog record, then. We also set the context of the update driver to the INSERT_CONTEXT.
        // Some mods may only work in that context (e.g. $setOnInsert).
        driver->setLogOp( false );
        driver->setContext( ModifierInterface::ExecInfo::INSERT_CONTEXT );

        BSONObj baseObj;

        // Reset the document we will be writing to
        doc.reset( baseObj, mutablebson::Document::kInPlaceDisabled );
        if ( request.getQuery().hasElement("_id") ) {
            uassertStatusOK(doc.root().appendElement(request.getQuery().getField("_id")));
        }


        // If this is a $mod base update, we need to generate a document by examining the
        // query and the mods. Otherwise, we can use the object replacement sent by the user
        // update command that was parsed by the driver before.
        // In the following block we handle the query part, and then do the regular mods after.
        if ( *request.getUpdates().firstElementFieldName() == '$' ) {
            uassertStatusOK(UpdateDriver::createFromQuery(request.getQuery(), doc));
            opDebug->fastmodinsert = true;
        }

        // Apply the update modifications and then log the update as an insert manually.
        Status status = driver->update( StringData(), &doc, NULL /* no oplog record */);
        if ( !status.isOK() ) {
            uasserted( 16836, status.reason() );
        }

        BSONObj newObj = doc.getObject();
        theDataFileMgr.insertWithObjMod( nsString.ns().c_str(), newObj, false, request.isGod() );
        if ( request.shouldUpdateOpLog() ) {
            logOp( "i", nsString.ns().c_str(), newObj,
                   NULL, NULL, request.isFromMigration(), &newObj );
        }

        opDebug->nupdated = 1;
        return UpdateResult( false /* updated a non existing document */,
                             !driver->isDocReplacement() /* $mod or obj replacement? */,
                             1 /* count of updated documents */,
                             newObj /* object that was upserted */ );
    }

    BSONObj applyUpdateOperators( const BSONObj& from, const BSONObj& operators ) {
        UpdateDriver::Options opts;
        opts.multi = false;
        opts.upsert = false;
        UpdateDriver driver( opts );
        Status status = driver.parse( operators );
        if ( !status.isOK() ) {
            uasserted( 16838, status.reason() );
        }

        mutablebson::Document doc( from, mutablebson::Document::kInPlaceDisabled );
        status = driver.update( StringData(), &doc, NULL /* not oplogging */ );
        if ( !status.isOK() ) {
            uasserted( 16839, status.reason() );
        }

        return doc.getObject();
    }

}  // namespace mongo