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
|
/**
* Copyright (C) 2021-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* 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 Server Side 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/platform/basic.h"
#include "mongo/db/pipeline/change_stream_helpers.h"
#include "mongo/db/pipeline/change_stream_start_after_invalidate_info.h"
#include "mongo/db/pipeline/document_source_change_stream.h"
#include "mongo/db/pipeline/document_source_change_stream_check_invalidate.h"
#include "mongo/db/query/query_feature_flags_gen.h"
#include "mongo/util/assert_util.h"
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kCommand
namespace mongo {
using DSCS = DocumentSourceChangeStream;
REGISTER_INTERNAL_DOCUMENT_SOURCE(_internalChangeStreamCheckInvalidate,
LiteParsedDocumentSourceChangeStreamInternal::parse,
DocumentSourceChangeStreamCheckInvalidate::createFromBson,
true);
namespace {
// Returns true if the given 'operationType' should invalidate the change stream based on the
// namespace in 'pExpCtx'.
bool isInvalidatingCommand(const boost::intrusive_ptr<ExpressionContext>& pExpCtx,
StringData operationType) {
if (pExpCtx->isSingleNamespaceAggregation()) {
return operationType == DSCS::kDropCollectionOpType ||
operationType == DSCS::kRenameCollectionOpType ||
operationType == DSCS::kDropDatabaseOpType;
} else if (!pExpCtx->isClusterAggregation()) {
return operationType == DSCS::kDropDatabaseOpType;
} else {
return false;
}
};
} // namespace
boost::intrusive_ptr<DocumentSourceChangeStreamCheckInvalidate>
DocumentSourceChangeStreamCheckInvalidate::create(
const boost::intrusive_ptr<ExpressionContext>& expCtx,
const DocumentSourceChangeStreamSpec& spec) {
// If resuming from an "invalidate" using "startAfter", pass along the resume token data to
// DSCSCheckInvalidate to signify that another invalidate should not be generated.
auto resumeToken = change_stream::resolveResumeTokenFromSpec(expCtx, spec);
return new DocumentSourceChangeStreamCheckInvalidate(
expCtx, boost::make_optional(resumeToken.fromInvalidate, std::move(resumeToken)));
}
boost::intrusive_ptr<DocumentSourceChangeStreamCheckInvalidate>
DocumentSourceChangeStreamCheckInvalidate::createFromBson(
BSONElement spec, const boost::intrusive_ptr<ExpressionContext>& expCtx) {
uassert(5467602,
str::stream() << "the '" << kStageName << "' object spec must be an object",
spec.type() == Object);
auto parsed = DocumentSourceChangeStreamCheckInvalidateSpec::parse(
IDLParserContext("DocumentSourceChangeStreamCheckInvalidateSpec"), spec.embeddedObject());
return new DocumentSourceChangeStreamCheckInvalidate(
expCtx,
parsed.getStartAfterInvalidate() ? parsed.getStartAfterInvalidate()->getData()
: boost::optional<ResumeTokenData>());
}
DocumentSource::GetNextResult DocumentSourceChangeStreamCheckInvalidate::doGetNext() {
// To declare a change stream as invalidated, this stage first emits an invalidate event and
// then throws a 'ChangeStreamInvalidated' exception on the next call to this method.
if (_queuedInvalidate) {
const auto res = DocumentSource::GetNextResult(std::move(_queuedInvalidate.value()));
_queuedInvalidate.reset();
return res;
}
if (_queuedException) {
uasserted(static_cast<ChangeStreamInvalidationInfo>(*_queuedException),
"Change stream invalidated");
}
auto nextInput = pSource->getNext();
if (!nextInput.isAdvanced())
return nextInput;
auto doc = nextInput.getDocument();
const auto& kOperationTypeField = DSCS::kOperationTypeField;
DSCS::checkValueType(doc[kOperationTypeField], kOperationTypeField, BSONType::String);
auto operationType = doc[kOperationTypeField].getString();
// If this command should invalidate the stream, generate an invalidate entry and queue it up
// to be returned after the notification of this command. The new entry will have a nearly
// identical resume token to the notification for the command, except with an extra flag
// indicating that the token is from an invalidate. This flag is necessary to disambiguate
// the two tokens, and thus preserve a total ordering on the stream.
if (isInvalidatingCommand(pExpCtx, operationType)) {
// Regardless of whether we generate an invalidation event or, in the case of startAfter,
// swallow it, we should clear the _startAfterInvalidate field once this block completes.
ON_BLOCK_EXIT([this] { _startAfterInvalidate.reset(); });
// Extract the resume token from the invalidating command and set the 'fromInvalidate' bit.
auto resumeTokenData = ResumeToken::parse(doc[DSCS::kIdField].getDocument()).getData();
resumeTokenData.fromInvalidate = ResumeTokenData::FromInvalidate::kFromInvalidate;
// If a client receives an invalidate and wants to start a new stream after the invalidate,
// they can use the 'startAfter' option. In this case, '_startAfterInvalidate' will be set
// to the resume token with which the client restarted the stream. We must be sure to avoid
// re-invalidating the new stream, and so we will swallow the first invalidate we see on
// each shard. The one exception is the invalidate which matches the 'startAfter' resume
// token. We must re-generate this invalidate, since DSEnsureResumeTokenPresent needs to see
// (and will take care of swallowing) the event which exactly matches the client's token.
if (_startAfterInvalidate && resumeTokenData != _startAfterInvalidate) {
return nextInput;
}
auto resumeTokenDoc = ResumeToken(resumeTokenData).toDocument();
// Note: if 'showExpandedEvents' is false, 'wallTime' will be missing in the input document.
MutableDocument result(Document{{DSCS::kIdField, resumeTokenDoc},
{DSCS::kOperationTypeField, DSCS::kInvalidateOpType},
{DSCS::kClusterTimeField, doc[DSCS::kClusterTimeField]},
{DSCS::kWallTimeField, doc[DSCS::kWallTimeField]}});
result.copyMetaDataFrom(doc);
// We set the resume token as the document's sort key in both the sharded and non-sharded
// cases, since we will later rely upon it to generate a correct postBatchResumeToken. We
// must therefore update the sort key to match the new resume token that we generated above.
const bool isSingleElementKey = true;
result.metadata().setSortKey(Value{resumeTokenDoc}, isSingleElementKey);
// If we are here and '_startAfterInvalidate' is present, then the current event matches the
// resume token. We throw the event up to DSCSEnsureResumeTokenPresent, to ensure that it is
// always delivered regardless of any intervening $match stages.
uassert(ChangeStreamStartAfterInvalidateInfo(result.freeze().toBsonWithMetaData()),
"Change stream 'startAfter' invalidate event",
!_startAfterInvalidate);
// Otherwise, we are in a normal invalidation scenario. Queue up an invalidation event to be
// returned on the following call to getNext, and an invalidation exception to be thrown on
// the call after that.
_queuedInvalidate = result.freeze();
_queuedException = ChangeStreamInvalidationInfo(
_queuedInvalidate->metadata().getSortKey().getDocument().toBson());
}
// Regardless of whether the first document we see is an invalidating command, we only skip the
// first invalidate for streams with the 'startAfter' option, so we should not skip any
// invalidates that come after the first one.
_startAfterInvalidate.reset();
return nextInput;
}
Value DocumentSourceChangeStreamCheckInvalidate::serialize(SerializationOptions opts) const {
BSONObjBuilder builder;
if (opts.verbosity) {
BSONObjBuilder sub(builder.subobjStart(DocumentSourceChangeStream::kStageName));
sub.append("stage"_sd, kStageName);
sub.done();
} else {
BSONObjBuilder sub(builder.subobjStart(kStageName));
if (_startAfterInvalidate) {
if (opts.replacementForLiteralArgs) {
sub.append(
DocumentSourceChangeStreamCheckInvalidateSpec::kStartAfterInvalidateFieldName,
*opts.replacementForLiteralArgs);
} else {
DocumentSourceChangeStreamCheckInvalidateSpec spec;
spec.setStartAfterInvalidate(ResumeToken(*_startAfterInvalidate));
spec.serialize(&sub);
}
}
sub.done();
}
return Value(builder.obj());
}
} // namespace mongo
|
