1// Licensed to the Apache Software Foundation (ASF) under one
2// or more contributor license agreements. See the NOTICE file
3// distributed with this work for additional information
4// regarding copyright ownership. The ASF licenses this file
5// to you under the Apache License, Version 2.0 (the
6// "License"); you may not use this file except in compliance
7// with the License. You may obtain a copy of the License at
8//
9// http://www.apache.org/licenses/LICENSE-2.0
10//
11// Unless required by applicable law or agreed to in writing,
12// software distributed under the License is distributed on an
13// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
14// KIND, either express or implied. See the License for the
15// specific language governing permissions and limitations
16// under the License.
17
18// Date 2014/09/25 17:50:21
19
20#ifndef BVAR_RECORDER_H
21#define BVAR_RECORDER_H
22
23#include <stdint.h> // int64_t uint64_t
24#include "butil/macros.h" // BAIDU_CASSERT
25#include "butil/logging.h" // LOG
26#include "bvar/detail/combiner.h" // detail::AgentCombiner
27#include "bvar/variable.h"
28#include "bvar/window.h"
29#include "bvar/detail/sampler.h"
30
31namespace bvar {
32
33struct Stat {
34 Stat() : sum(0), num(0) {};
35 Stat(int64_t sum2, int64_t num2) : sum(sum2), num(num2) {}
36 int64_t sum;
37 int64_t num;
38
39 int64_t get_average_int() const {
40 //num can be changed by sampling thread, use tmp_num
41 int64_t tmp_num = num;
42 if (tmp_num == 0) {
43 return 0;
44 }
45 return sum / (int64_t)tmp_num;
46 }
47 double get_average_double() const {
48 int64_t tmp_num = num;
49 if (tmp_num == 0) {
50 return 0.0;
51 }
52 return (double)sum / (double)tmp_num;
53 }
54 Stat operator-(const Stat& rhs) const {
55 return Stat(sum - rhs.sum, num - rhs.num);
56 }
57 void operator-=(const Stat& rhs) {
58 sum -= rhs.sum;
59 num -= rhs.num;
60 }
61 Stat operator+(const Stat& rhs) const {
62 return Stat(sum + rhs.sum, num + rhs.num);
63 }
64 void operator+=(const Stat& rhs) {
65 sum += rhs.sum;
66 num += rhs.num;
67 }
68};
69
70inline std::ostream& operator<<(std::ostream& os, const Stat& s) {
71 const int64_t v = s.get_average_int();
72 if (v != 0) {
73 return os << v;
74 } else {
75 return os << s.get_average_double();
76 }
77}
78
79// For calculating average of numbers.
80// Example:
81// IntRecorder latency;
82// latency << 1 << 3 << 5;
83// CHECK_EQ(3, latency.average());
84class IntRecorder : public Variable {
85public:
86 // Compressing format:
87 // | 20 bits (unsigned) | sign bit | 43 bits |
88 // num sum
89 const static size_t SUM_BIT_WIDTH=44;
90 const static uint64_t MAX_SUM_PER_THREAD = (1ul << SUM_BIT_WIDTH) - 1;
91 const static uint64_t MAX_NUM_PER_THREAD = (1ul << (64ul - SUM_BIT_WIDTH)) - 1;
92 BAIDU_CASSERT(SUM_BIT_WIDTH > 32 && SUM_BIT_WIDTH < 64,
93 SUM_BIT_WIDTH_must_be_between_33_and_63);
94
95 struct AddStat {
96 void operator()(Stat& s1, const Stat& s2) const { s1 += s2; }
97 };
98 struct MinusStat {
99 void operator()(Stat& s1, const Stat& s2) const { s1 -= s2; }
100 };
101
102 typedef Stat value_type;
103 typedef detail::ReducerSampler<IntRecorder, Stat,
104 AddStat, MinusStat> sampler_type;
105
106 typedef Stat SampleSet;
107
108 struct AddToStat {
109 void operator()(Stat& lhs, uint64_t rhs) const {
110 lhs.sum += _extend_sign_bit(_get_sum(rhs));
111 lhs.num += _get_num(rhs);
112 }
113 };
114
115 typedef detail::AgentCombiner<Stat, uint64_t, AddToStat> combiner_type;
116 typedef combiner_type::Agent agent_type;
117
118 IntRecorder() : _sampler(NULL) {}
119
120 explicit IntRecorder(const butil::StringPiece& name) : _sampler(NULL) {
121 expose(name);
122 }
123
124 IntRecorder(const butil::StringPiece& prefix, const butil::StringPiece& name)
125 : _sampler(NULL) {
126 expose_as(prefix, name);
127 }
128
129 ~IntRecorder() {
130 hide();
131 if (_sampler) {
132 _sampler->destroy();
133 _sampler = NULL;
134 }
135 }
136
137 // Note: The input type is acutally int. Use int64_t to check overflow.
138 IntRecorder& operator<<(int64_t/*note*/ sample);
139
140 int64_t average() const {
141 return _combiner.combine_agents().get_average_int();
142 }
143
144 double average(double) const {
145 return _combiner.combine_agents().get_average_double();
146 }
147
148 Stat get_value() const {
149 return _combiner.combine_agents();
150 }
151
152 Stat reset() {
153 return _combiner.reset_all_agents();
154 }
155
156 AddStat op() const { return AddStat(); }
157 MinusStat inv_op() const { return MinusStat(); }
158
159 void describe(std::ostream& os, bool /*quote_string*/) const override {
160 os << get_value();
161 }
162
163 bool valid() const { return _combiner.valid(); }
164
165 sampler_type* get_sampler() {
166 if (NULL == _sampler) {
167 _sampler = new sampler_type(this);
168 _sampler->schedule();
169 }
170 return _sampler;
171 }
172
173 // This name is useful for printing overflow log in operator<< since
174 // IntRecorder is often used as the source of data and not exposed.
175 void set_debug_name(const butil::StringPiece& name) {
176 _debug_name.assign(name.data(), name.size());
177 }
178
179private:
180 // TODO: The following numeric functions should be independent utils
181 static uint64_t _get_sum(const uint64_t n) {
182 return (n & MAX_SUM_PER_THREAD);
183 }
184
185 static uint64_t _get_num(const uint64_t n) {
186 return n >> SUM_BIT_WIDTH;
187 }
188
189 // Fill all the first (64 - SUM_BIT_WIDTH + 1) bits with 1 if the sign bit is 1
190 // to represent a complete 64-bit negative number
191 // Check out http://en.wikipedia.org/wiki/Signed_number_representations if
192 // you are confused
193 static int64_t _extend_sign_bit(const uint64_t sum) {
194 return (((1ul << (64ul - SUM_BIT_WIDTH + 1)) - 1)
195 * ((1ul << (SUM_BIT_WIDTH - 1) & sum)))
196 | (int64_t)sum;
197 }
198
199 // Convert complement into a |SUM_BIT_WIDTH|-bit unsigned integer
200 static uint64_t _get_complement(int64_t n) {
201 return n & (MAX_SUM_PER_THREAD);
202 }
203
204 static uint64_t _compress(const uint64_t num, const uint64_t sum) {
205 return (num << SUM_BIT_WIDTH)
206 // There is a redundant '1' in the front of sum which was
207 // combined with two negative number, so truncation has to be
208 // done here
209 | (sum & MAX_SUM_PER_THREAD)
210 ;
211 }
212
213 // Check whether the sum of the two integer overflows the range of signed
214 // integer with the width of SUM_BIT_WIDTH, which is
215 // [-2^(SUM_BIT_WIDTH -1), 2^(SUM_BIT_WIDTH -1) - 1) (eg. [-128, 127) for
216 // signed 8-bit integer)
217 static bool _will_overflow(const int64_t lhs, const int rhs) {
218 return
219 // Both integers are positive and the sum is larger than the largest
220 // number
221 ((lhs > 0) && (rhs > 0)
222 && (lhs + rhs > ((int64_t)MAX_SUM_PER_THREAD >> 1)))
223 // Or both integers are negative and the sum is less than the lowest
224 // number
225 || ((lhs < 0) && (rhs < 0)
226 && (lhs + rhs < (-((int64_t)MAX_SUM_PER_THREAD >> 1)) - 1))
227 // otherwise the sum cannot overflow iff lhs does not overflow
228 // because |sum| < |lhs|
229 ;
230 }
231
232private:
233 combiner_type _combiner;
234 sampler_type* _sampler;
235 std::string _debug_name;
236};
237
238inline IntRecorder& IntRecorder::operator<<(int64_t sample) {
239 if (BAIDU_UNLIKELY((int64_t)(int)sample != sample)) {
240 const char* reason = NULL;
241 if (sample > std::numeric_limits<int>::max()) {
242 reason = "overflows";
243 sample = std::numeric_limits<int>::max();
244 } else {
245 reason = "underflows";
246 sample = std::numeric_limits<int>::min();
247 }
248 // Truncate to be max or min of int. We're using 44 bits to store the
249 // sum thus following aggregations are not likely to be over/underflow.
250 if (!name().empty()) {
251 LOG(WARNING) << "Input=" << sample << " to `" << name()
252 << "\' " << reason;
253 } else if (!_debug_name.empty()) {
254 LOG(WARNING) << "Input=" << sample << " to `" << _debug_name
255 << "\' " << reason;
256 } else {
257 LOG(WARNING) << "Input=" << sample << " to IntRecorder("
258 << (void*)this << ") " << reason;
259 }
260 }
261 agent_type* agent = _combiner.get_or_create_tls_agent();
262 if (BAIDU_UNLIKELY(!agent)) {
263 LOG(FATAL) << "Fail to create agent";
264 return *this;
265 }
266 uint64_t n;
267 agent->element.load(&n);
268 const uint64_t complement = _get_complement(sample);
269 uint64_t num;
270 uint64_t sum;
271 do {
272 num = _get_num(n);
273 sum = _get_sum(n);
274 if (BAIDU_UNLIKELY((num + 1 > MAX_NUM_PER_THREAD) ||
275 _will_overflow(_extend_sign_bit(sum), sample))) {
276 // Although agent->element might have been cleared at this
277 // point, it is just OK because the very value is 0 in
278 // this case
279 agent->combiner->commit_and_clear(agent);
280 sum = 0;
281 num = 0;
282 n = 0;
283 }
284 } while (!agent->element.compare_exchange_weak(
285 n, _compress(num + 1, sum + complement)));
286 return *this;
287}
288
289} // namespace bvar
290
291#endif //BVAR_RECORDER_H
292