ceph/src/test/common/test_bloom_filter.cc

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Copyright (C) 2013 Inktank <info@inktank.com>
   7  *
   8  * LGPL2.1 (see COPYING-LGPL2.1) or later
   9  */
  10
  11 #include <iostream>
  12 #include <gtest/gtest.h>
  13
  14 #include "include/stringify.h"
  15 #include "common/bloom_filter.hpp"
  16
  17 TEST(BloomFilter, Basic) {
  18   bloom_filter bf(10, .1, 1);
  19   bf.insert("foo");
  20   bf.insert("bar");
  21
  22   ASSERT_TRUE(bf.contains("foo"));
  23   ASSERT_TRUE(bf.contains("bar"));
  24
  25   ASSERT_EQ(2U, bf.element_count());
  26 }
  27
  28 TEST(BloomFilter, Empty) {
  29   bloom_filter bf;
  30   for (int i=0; i<100; ++i) {
  31     ASSERT_FALSE(bf.contains(i));
  32     ASSERT_FALSE(bf.contains(stringify(i)));
  33   }
  34 }
  35
  36 TEST(BloomFilter, Sweep) {
  37   std::cout.setf(std::ios_base::fixed, std::ios_base::floatfield);
  38   std::cout.precision(5);
  39   std::cout << "# max\tfpp\tactual\tsize\tB/insert" << std::endl;
  40   for (int ex = 3; ex < 12; ex += 2) {
  41     for (float fpp = .001; fpp < .5; fpp *= 4.0) {
  42       int max = 2 << ex;
  43       bloom_filter bf(max, fpp, 1);
  44       bf.insert("foo");
  45       bf.insert("bar");
  46
  47       ASSERT_TRUE(bf.contains("foo"));
  48       ASSERT_TRUE(bf.contains("bar"));
  49
  50       for (int n = 0; n < max; n++)
  51         bf.insert("ok" + stringify(n));
  52
  53       int test = max * 100;
  54       int hit = 0;
  55       for (int n = 0; n < test; n++)
  56         if (bf.contains("asdf" + stringify(n)))
  57           hit++;
  58
  59       ASSERT_TRUE(bf.contains("foo"));
  60       ASSERT_TRUE(bf.contains("bar"));
  61
  62       double actual = (double)hit / (double)test;
  63
  64       bufferlist bl;
  65       ::encode(bf, bl);
  66
  67       double byte_per_insert = (double)bl.length() / (double)max;
  68
  69       std::cout << max << "\t" << fpp << "\t" << actual << "\t" << bl.length() << "\t" << byte_per_insert << std::endl;
  70       ASSERT_TRUE(actual < fpp * 10);
  71
  72     }
  73   }
  74 }
  75
  76 TEST(BloomFilter, SweepInt) {
  77   std::cout.setf(std::ios_base::fixed, std::ios_base::floatfield);
  78   std::cout.precision(5);
  79   std::cout << "# max\tfpp\tactual\tsize\tB/insert\tdensity\tapprox_element_count" << std::endl;
  80   for (int ex = 3; ex < 12; ex += 2) {
  81     for (float fpp = .001; fpp < .5; fpp *= 4.0) {
  82       int max = 2 << ex;
  83       bloom_filter bf(max, fpp, 1);
  84       bf.insert("foo");
  85       bf.insert("bar");
  86
  87       ASSERT_TRUE(123);
  88       ASSERT_TRUE(456);
  89
  90       for (int n = 0; n < max; n++)
  91         bf.insert(n);
  92
  93       int test = max * 100;
  94       int hit = 0;
  95       for (int n = 0; n < test; n++)
  96         if (bf.contains(100000 + n))
  97           hit++;
  98
  99       ASSERT_TRUE(123);
 100       ASSERT_TRUE(456);
 101
 102       double actual = (double)hit / (double)test;
 103
 104       bufferlist bl;
 105       ::encode(bf, bl);
 106
 107       double byte_per_insert = (double)bl.length() / (double)max;
 108
 109       std::cout << max << "\t" << fpp << "\t" << actual << "\t" << bl.length() << "\t" << byte_per_insert
 110                 << "\t" << bf.density() << "\t" << bf.approx_unique_element_count() << std::endl;
 111       ASSERT_TRUE(actual < fpp * 10);
 112       ASSERT_TRUE(actual > fpp / 10);
 113       ASSERT_TRUE(bf.density() > 0.40);
 114       ASSERT_TRUE(bf.density() < 0.60);
 115     }
 116   }
 117 }
 118
 119
 120 TEST(BloomFilter, CompressibleSweep) {
 121   std::cout.setf(std::ios_base::fixed, std::ios_base::floatfield);
 122   std::cout.precision(5);
 123   std::cout << "# max\tins\test ins\tafter\ttgtfpp\tactual\tsize\tb/elem\n";
 124   float fpp = .01;
 125   int max = 1024;
 126   for (int div = 1; div < 10; div++) {
 127     compressible_bloom_filter bf(max, fpp, 1);
 128     int t = max/div;
 129     for (int n = 0; n < t; n++)
 130       bf.insert(n);
 131
 132     unsigned est = bf.approx_unique_element_count();
 133     if (div > 1)
 134       bf.compress(1.0 / div);
 135
 136     for (int n = 0; n < t; n++)
 137       ASSERT_TRUE(bf.contains(n));
 138
 139     int test = max * 100;
 140     int hit = 0;
 141     for (int n = 0; n < test; n++)
 142       if (bf.contains(100000 + n))
 143         hit++;
 144
 145     double actual = (double)hit / (double)test;
 146
 147     bufferlist bl;
 148     ::encode(bf, bl);
 149
 150     double byte_per_insert = (double)bl.length() / (double)max;
 151     unsigned est_after = bf.approx_unique_element_count();
 152     std::cout << max
 153               << "\t" << t
 154               << "\t" << est
 155               << "\t" << est_after
 156               << "\t" << fpp
 157               << "\t" << actual
 158               << "\t" << bl.length() << "\t" << byte_per_insert
 159               << std::endl;
 160
 161     ASSERT_TRUE(actual < fpp * 2.0);
 162     ASSERT_TRUE(actual > fpp / 2.0);
 163     ASSERT_TRUE(est_after < est * 2);
 164     ASSERT_TRUE(est_after > est / 2);
 165   }
 166 }
 167
 168
 169
 170 TEST(BloomFilter, BinSweep) {
 171   std::cout.setf(std::ios_base::fixed, std::ios_base::floatfield);
 172   std::cout.precision(5);
 173   int total_max = 16384;
 174   float total_fpp = .01;
 175   std::cout << "total_inserts " << total_max << " target-fpp " << total_fpp << std::endl;
 176   for (int bins = 1; bins < 16; ++bins) {
 177     int max = total_max / bins;
 178     float fpp = total_fpp / bins;//pow(total_fpp, bins);
 179
 180     std::vector<bloom_filter*> ls;
 181     bufferlist bl;
 182     for (int i=0; i<bins; i++) {
 183       ls.push_back(new bloom_filter(max, fpp, i));
 184       for (int j=0; j<max; j++) {
 185         ls.back()->insert(10000 * (i+1) + j);
 186       }
 187       ::encode(*ls.front(), bl);
 188     }
 189
 190     int hit = 0;
 191     int test = max * 100;
 192     for (int i=0; i<test; ++i) {
 193       for (std::vector<bloom_filter*>::iterator j = ls.begin(); j != ls.end(); ++j) {
 194         if ((*j)->contains(i * 732)) {  // note: sequential i does not work here; the intenral int hash is weak!!
 195           hit++;
 196           break;
 197         }
 198       }
 199     }
 200
 201     double actual = (double)hit / (double)test;
 202     std::cout << "bins " << bins << " bin-max " << max << " bin-fpp " << fpp
 203               << " actual-fpp " << actual
 204               << " total-size " << bl.length() << std::endl;
 205   }
 206 }
 207
 208 // disable these tests; doing dual insertions in consecutive filters
 209 // appears to be equivalent to doing a single insertion in a bloom
 210 // filter that is twice as big.
 211 #if 0
 212
 213 // test the fpp over a sequence of bloom filters, each with unique
 214 // items inserted into it.
 215 //
 216 // we expect:  actual_fpp = num_filters * per_filter_fpp
 217 TEST(BloomFilter, Sequence) {
 218
 219   int max = 1024;
 220   double fpp = .01;
 221   for (int seq = 2; seq <= 128; seq *= 2) {
 222     std::vector<bloom_filter*> ls;
 223     for (int i=0; i<seq; i++) {
 224       ls.push_back(new bloom_filter(max*2, fpp, i));
 225       for (int j=0; j<max; j++) {
 226         ls.back()->insert("ok" + stringify(j) + "_" + stringify(i));
 227         if (ls.size() > 1)
 228           ls[ls.size() - 2]->insert("ok" + stringify(j) + "_" + stringify(i));
 229       }
 230     }
 231
 232     int hit = 0;
 233     int test = max * 100;
 234     for (int i=0; i<test; ++i) {
 235       for (std::vector<bloom_filter*>::iterator j = ls.begin(); j != ls.end(); ++j) {
 236         if ((*j)->contains("bad" + stringify(i))) {
 237           hit++;
 238           break;
 239         }
 240       }
 241     }
 242
 243     double actual = (double)hit / (double)test;
 244     std::cout << "seq " << seq << " max " << max << " fpp " << fpp << " actual " << actual << std::endl;
 245   }
 246 }
 247
 248 // test the ffp over a sequence of bloom filters, where actual values
 249 // are always inserted into a consecutive pair of filters.  in order
 250 // to have a false positive, we need to falsely match two consecutive
 251 // filters.
 252 //
 253 // we expect:  actual_fpp = num_filters * per_filter_fpp^2
 254 TEST(BloomFilter, SequenceDouble) {
 255   int max = 1024;
 256   double fpp = .01;
 257   for (int seq = 2; seq <= 128; seq *= 2) {
 258     std::vector<bloom_filter*> ls;
 259     for (int i=0; i<seq; i++) {
 260       ls.push_back(new bloom_filter(max*2, fpp, i));
 261       for (int j=0; j<max; j++) {
 262         ls.back()->insert("ok" + stringify(j) + "_" + stringify(i));
 263         if (ls.size() > 1)
 264           ls[ls.size() - 2]->insert("ok" + stringify(j) + "_" + stringify(i));
 265       }
 266     }
 267
 268     int hit = 0;
 269     int test = max * 100;
 270     int run = 0;
 271     for (int i=0; i<test; ++i) {
 272       for (std::vector<bloom_filter*>::iterator j = ls.begin(); j != ls.end(); ++j) {
 273         if ((*j)->contains("bad" + stringify(i))) {
 274           run++;
 275           if (run >= 2) {
 276             hit++;
 277             break;
 278           }
 279         } else {
 280           run = 0;
 281         }
 282       }
 283     }
 284
 285     double actual = (double)hit / (double)test;
 286     std::cout << "seq " << seq << " max " << max << " fpp " << fpp << " actual " << actual
 287               << " expected " << (fpp*fpp*(double)seq) << std::endl;
 288   }
 289 }
 290
 291 #endif
 292
 293 TEST(BloomFilter, Assignement) {
 294   bloom_filter bf1(10, .1, 1), bf2;
 295
 296   bf1.insert("foo");
 297   bf2 = bf1;
 298   bf1.insert("bar");
 299
 300   ASSERT_TRUE(bf2.contains("foo"));
 301   ASSERT_FALSE(bf2.contains("bar"));
 302
 303   ASSERT_EQ(2U, bf1.element_count());
 304   ASSERT_EQ(1U, bf2.element_count());
 305 }