summaryrefslogtreecommitdiff
path: root/src/mongo/util/fail_point.cpp
blob: 81da6d94723c2d600de546a12b5790bb6d9f4490 (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
/**
 *    Copyright (C) 2018-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.
 */

#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kControl

#include "mongo/util/fail_point.h"

#include "mongo/bson/util/bson_extract.h"
#include "mongo/platform/random.h"
#include "mongo/stdx/memory.h"
#include "mongo/stdx/thread.h"
#include "mongo/util/fail_point_service.h"
#include "mongo/util/log.h"
#include "mongo/util/str.h"
#include "mongo/util/time_support.h"

namespace mongo {
namespace {

/**
 * Type representing the per-thread PRNG used by fail-points.
 */
class FailPointPRNG {
public:
    FailPointPRNG() : _prng(std::unique_ptr<SecureRandom>(SecureRandom::create())->nextInt64()) {}

    void resetSeed(int32_t seed) {
        _prng = PseudoRandom(seed);
    }

    int32_t nextPositiveInt32() {
        return _prng.nextInt32() & ~(1 << 31);
    }

    static FailPointPRNG* current() {
        if (!_failPointPrng)
            _failPointPrng = stdx::make_unique<FailPointPRNG>();
        return _failPointPrng.get();
    }

private:
    PseudoRandom _prng;
    static thread_local std::unique_ptr<FailPointPRNG> _failPointPrng;
};

thread_local std::unique_ptr<FailPointPRNG> FailPointPRNG::_failPointPrng;

}  // namespace

void FailPoint::setThreadPRNGSeed(int32_t seed) {
    FailPointPRNG::current()->resetSeed(seed);
}

FailPoint::FailPoint() = default;

void FailPoint::shouldFailCloseBlock() {
    _fpInfo.subtractAndFetch(1);
}

void FailPoint::setMode(Mode mode, ValType val, const BSONObj& extra) {
    /**
     * Outline:
     *
     * 1. Deactivates fail point to enter write-only mode
     * 2. Waits for all current readers of the fail point to finish
     * 3. Sets the new mode.
     */

    stdx::lock_guard<stdx::mutex> scoped(_modMutex);

    // Step 1
    disableFailPoint();

    // Step 2
    while (_fpInfo.load() != 0) {
        sleepmillis(50);
    }

    _mode = mode;
    _timesOrPeriod.store(val);

    _data = extra.copy();

    if (_mode != off) {
        enableFailPoint();
    }
}

const BSONObj& FailPoint::getData() const {
    return _data;
}

void FailPoint::enableFailPoint() {
    _fpInfo.fetchAndBitOr(ACTIVE_BIT);
}

void FailPoint::disableFailPoint() {
    _fpInfo.fetchAndBitAnd(~ACTIVE_BIT);
}

FailPoint::RetCode FailPoint::slowShouldFailOpenBlock(
    stdx::function<bool(const BSONObj&)> cb) noexcept {
    ValType localFpInfo = _fpInfo.addAndFetch(1);

    if ((localFpInfo & ACTIVE_BIT) == 0) {
        return slowOff;
    }

    if (cb && !cb(getData())) {
        return userIgnored;
    }

    switch (_mode) {
        case alwaysOn:
            return slowOn;
        case random: {
            const int maxActivationValue = _timesOrPeriod.load();
            if (FailPointPRNG::current()->nextPositiveInt32() < maxActivationValue)
                return slowOn;

            return slowOff;
        }
        case nTimes: {
            if (_timesOrPeriod.subtractAndFetch(1) <= 0)
                disableFailPoint();

            return slowOn;
        }
        case skip: {
            // Ensure that once the skip counter reaches within some delta from 0 we don't continue
            // decrementing it unboundedly because at some point it will roll over and become
            // positive again
            if (_timesOrPeriod.load() <= 0 || _timesOrPeriod.subtractAndFetch(1) < 0)
                return slowOn;

            return slowOff;
        }
        default:
            error() << "FailPoint Mode not supported: " << static_cast<int>(_mode);
            fassertFailed(16444);
    }
}

StatusWith<std::tuple<FailPoint::Mode, FailPoint::ValType, BSONObj>> FailPoint::parseBSON(
    const BSONObj& obj) {
    Mode mode = FailPoint::alwaysOn;
    ValType val = 0;
    const BSONElement modeElem(obj["mode"]);
    if (modeElem.eoo()) {
        return {ErrorCodes::IllegalOperation, "When setting a failpoint, you must supply a 'mode'"};
    } else if (modeElem.type() == String) {
        const std::string modeStr(modeElem.valuestr());

        if (modeStr == "off") {
            mode = FailPoint::off;
        } else if (modeStr == "alwaysOn") {
            mode = FailPoint::alwaysOn;
        } else {
            return {ErrorCodes::BadValue, str::stream() << "unknown mode: " << modeStr};
        }
    } else if (modeElem.type() == Object) {
        const BSONObj modeObj(modeElem.Obj());

        if (modeObj.hasField("times")) {
            mode = FailPoint::nTimes;

            long long longVal;
            auto status = bsonExtractIntegerField(modeObj, "times", &longVal);
            if (!status.isOK()) {
                return status;
            }

            if (longVal < 0) {
                return {ErrorCodes::BadValue, "'times' option to 'mode' must be positive"};
            }

            if (longVal > std::numeric_limits<int>::max()) {
                return {ErrorCodes::BadValue, "'times' option to 'mode' is too large"};
            }
            val = static_cast<int>(longVal);
        } else if (modeObj.hasField("skip")) {
            mode = FailPoint::skip;

            long long longVal;
            auto status = bsonExtractIntegerField(modeObj, "skip", &longVal);
            if (!status.isOK()) {
                return status;
            }

            if (longVal < 0) {
                return {ErrorCodes::BadValue, "'skip' option to 'mode' must be positive"};
            }

            if (longVal > std::numeric_limits<int>::max()) {
                return {ErrorCodes::BadValue, "'skip' option to 'mode' is too large"};
            }
            val = static_cast<int>(longVal);
        } else if (modeObj.hasField("activationProbability")) {
            mode = FailPoint::random;

            if (!modeObj["activationProbability"].isNumber()) {
                return {ErrorCodes::TypeMismatch,
                        "the 'activationProbability' option to 'mode' must be a double between 0 "
                        "and 1"};
            }

            const double activationProbability = modeObj["activationProbability"].numberDouble();
            if (activationProbability < 0 || activationProbability > 1) {
                return {ErrorCodes::BadValue,
                        str::stream() << "activationProbability must be between 0.0 and 1.0; found "
                                      << activationProbability};
            }
            val = static_cast<int32_t>(std::numeric_limits<int32_t>::max() * activationProbability);
        } else {
            return {
                ErrorCodes::BadValue,
                "'mode' must be one of 'off', 'alwaysOn', 'times', and 'activationProbability'"};
        }
    } else {
        return {ErrorCodes::TypeMismatch, "'mode' must be a string or JSON object"};
    }

    BSONObj data;
    if (obj.hasField("data")) {
        if (!obj["data"].isABSONObj()) {
            return {ErrorCodes::TypeMismatch, "the 'data' option must be a JSON object"};
        }
        data = obj["data"].Obj().getOwned();
    }

    return std::make_tuple(mode, val, data);
}

BSONObj FailPoint::toBSON() const {
    BSONObjBuilder builder;

    stdx::lock_guard<stdx::mutex> scoped(_modMutex);
    builder.append("mode", _mode);
    builder.append("data", _data);

    return builder.obj();
}
}