src/CacheDigest.cc

   1 /*
   2  * Copyright (C) 1996-2021 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 /* DEBUG: section 70    Cache Digest */
  10
  11 #include "squid.h"
  12 #include "md5.h"
  13 #include "StatCounters.h"
  14 #include "Store.h"
  15 #include "store_key_md5.h"
  16
  17 #if USE_CACHE_DIGESTS
  18
  19 #include "CacheDigest.h"
  20 #include "util.h"
  21
  22 /* local types */
  23
  24 typedef struct {
  25     int bit_count;      /* total number of bits */
  26     int bit_on_count;       /* #bits turned on */
  27     int bseq_len_sum;       /* sum of all bit seq length */
  28     int bseq_count;     /* number of bit seqs */
  29 } CacheDigestStats;
  30
  31 /* local functions */
  32 static void cacheDigestHashKey(const CacheDigest * cd, const cache_key * key);
  33
  34 /* static array used by cacheDigestHashKey for optimization purposes */
  35 static uint32_t hashed_keys[4];
  36
  37 void
  38 CacheDigest::init(uint64_t newCapacity)
  39 {
  40     const auto newMaskSz = CacheDigest::CalcMaskSize(newCapacity, bits_per_entry);
  41     assert(newCapacity > 0 && bits_per_entry > 0);
  42     assert(newMaskSz != 0);
  43     capacity = newCapacity;
  44     mask_size = newMaskSz;
  45     mask = static_cast<char *>(xcalloc(mask_size,1));
  46     debugs(70, 2, "capacity: " << capacity << " entries, bpe: " << bits_per_entry << "; size: "
  47            << mask_size << " bytes");
  48 }
  49
  50 CacheDigest::CacheDigest(uint64_t aCapacity, uint8_t bpe) :
  51     count(0),
  52     del_count(0),
  53     capacity(0),
  54     mask(nullptr),
  55     mask_size(0),
  56     bits_per_entry(bpe)
  57 {
  58     assert(SQUID_MD5_DIGEST_LENGTH == 16);  /* our hash functions rely on 16 byte keys */
  59     updateCapacity(aCapacity);
  60 }
  61
  62 CacheDigest::~CacheDigest()
  63 {
  64     xfree(mask);
  65 }
  66
  67 CacheDigest *
  68 CacheDigest::clone() const
  69 {
  70     CacheDigest *cl = new CacheDigest(capacity, bits_per_entry);
  71     cl->count = count;
  72     cl->del_count = del_count;
  73     assert(mask_size == cl->mask_size);
  74     memcpy(cl->mask, mask, mask_size);
  75     return cl;
  76 }
  77
  78 void
  79 CacheDigest::clear()
  80 {
  81     count = del_count = 0;
  82     memset(mask, 0, mask_size);
  83 }
  84
  85 void
  86 CacheDigest::updateCapacity(uint64_t newCapacity)
  87 {
  88     safe_free(mask);
  89     init(newCapacity); // will re-init mask and mask_size
  90 }
  91
  92 bool
  93 CacheDigest::contains(const cache_key * key) const
  94 {
  95     assert(key);
  96     /* hash */
  97     cacheDigestHashKey(this, key);
  98     /* test corresponding bits */
  99     return
 100         CBIT_TEST(mask, hashed_keys[0]) &&
 101         CBIT_TEST(mask, hashed_keys[1]) &&
 102         CBIT_TEST(mask, hashed_keys[2]) &&
 103         CBIT_TEST(mask, hashed_keys[3]);
 104 }
 105
 106 void
 107 CacheDigest::add(const cache_key * key)
 108 {
 109     assert(key);
 110     /* hash */
 111     cacheDigestHashKey(this, key);
 112     /* turn on corresponding bits */
 113     int on_xition_cnt = 0;
 114
 115     if (!CBIT_TEST(mask, hashed_keys[0])) {
 116         CBIT_SET(mask, hashed_keys[0]);
 117         ++on_xition_cnt;
 118     }
 119
 120     if (!CBIT_TEST(mask, hashed_keys[1])) {
 121         CBIT_SET(mask, hashed_keys[1]);
 122         ++on_xition_cnt;
 123     }
 124
 125     if (!CBIT_TEST(mask, hashed_keys[2])) {
 126         CBIT_SET(mask, hashed_keys[2]);
 127         ++on_xition_cnt;
 128     }
 129
 130     if (!CBIT_TEST(mask, hashed_keys[3])) {
 131         CBIT_SET(mask, hashed_keys[3]);
 132         ++on_xition_cnt;
 133     }
 134
 135     statCounter.cd.on_xition_count.count(on_xition_cnt);
 136     ++count;
 137 }
 138
 139 void
 140 CacheDigest::remove(const cache_key * key)
 141 {
 142     assert(key);
 143     ++del_count;
 144     /* we do not support deletions from the digest */
 145 }
 146
 147 /* returns mask utilization parameters */
 148 static void
 149 cacheDigestStats(const CacheDigest * cd, CacheDigestStats * stats)
 150 {
 151     int on_count = 0;
 152     int pos = cd->mask_size * 8;
 153     int seq_len_sum = 0;
 154     int seq_count = 0;
 155     int cur_seq_len = 0;
 156     int cur_seq_type = 1;
 157     assert(stats);
 158     memset(stats, 0, sizeof(*stats));
 159
 160     while (pos-- > 0) {
 161         const int is_on = 0 != CBIT_TEST(cd->mask, pos);
 162
 163         if (is_on)
 164             ++on_count;
 165
 166         if (is_on != cur_seq_type || !pos) {
 167             seq_len_sum += cur_seq_len;
 168             ++seq_count;
 169             cur_seq_type = is_on;
 170             cur_seq_len = 0;
 171         }
 172
 173         ++cur_seq_len;
 174     }
 175
 176     stats->bit_count = cd->mask_size * 8;
 177     stats->bit_on_count = on_count;
 178     stats->bseq_len_sum = seq_len_sum;
 179     stats->bseq_count = seq_count;
 180 }
 181
 182 double
 183 CacheDigest::usedMaskPercent() const
 184 {
 185     CacheDigestStats stats;
 186     cacheDigestStats(this, &stats);
 187     return xpercent(stats.bit_on_count, stats.bit_count);
 188 }
 189
 190 void
 191 cacheDigestGuessStatsUpdate(CacheDigestGuessStats * stats, int real_hit, int guess_hit)
 192 {
 193     assert(stats);
 194
 195     if (real_hit) {
 196         if (guess_hit)
 197             ++stats->trueHits;
 198         else
 199             ++stats->falseMisses;
 200     } else {
 201         if (guess_hit)
 202             ++stats->falseHits;
 203         else
 204             ++stats->trueMisses;
 205     }
 206 }
 207
 208 void
 209 cacheDigestGuessStatsReport(const CacheDigestGuessStats * stats, StoreEntry * sentry, const SBuf &label)
 210 {
 211     const int true_count = stats->trueHits + stats->trueMisses;
 212     const int false_count = stats->falseHits + stats->falseMisses;
 213     const int hit_count = stats->trueHits + stats->falseHits;
 214     const int miss_count = stats->trueMisses + stats->falseMisses;
 215     const int tot_count = true_count + false_count;
 216
 217     assert(!label.isEmpty());
 218     assert(tot_count == hit_count + miss_count);    /* paranoid */
 219
 220     if (!tot_count) {
 221         storeAppendPrintf(sentry, "no guess stats for " SQUIDSBUFPH " available\n", SQUIDSBUFPRINT(label));
 222         return;
 223     }
 224
 225     storeAppendPrintf(sentry, "Digest guesses stats for " SQUIDSBUFPH ":\n", SQUIDSBUFPRINT(label));
 226     storeAppendPrintf(sentry, "guess\t hit\t\t miss\t\t total\t\t\n");
 227     storeAppendPrintf(sentry, " \t #\t %%\t #\t %%\t #\t %%\t\n");
 228     storeAppendPrintf(sentry, "true\t %d\t %.2f\t %d\t %.2f\t %d\t %.2f\n",
 229                       stats->trueHits, xpercent(stats->trueHits, tot_count),
 230                       stats->trueMisses, xpercent(stats->trueMisses, tot_count),
 231                       true_count, xpercent(true_count, tot_count));
 232     storeAppendPrintf(sentry, "false\t %d\t %.2f\t %d\t %.2f\t %d\t %.2f\n",
 233                       stats->falseHits, xpercent(stats->falseHits, tot_count),
 234                       stats->falseMisses, xpercent(stats->falseMisses, tot_count),
 235                       false_count, xpercent(false_count, tot_count));
 236     storeAppendPrintf(sentry, "all\t %d\t %.2f\t %d\t %.2f\t %d\t %.2f\n",
 237                       hit_count, xpercent(hit_count, tot_count),
 238                       miss_count, xpercent(miss_count, tot_count),
 239                       tot_count, xpercent(tot_count, tot_count));
 240     storeAppendPrintf(sentry, "\tclose_hits: %d ( %d%%) /* cd said hit, doc was in the peer cache, but we got a miss */\n",
 241                       stats->closeHits, xpercentInt(stats->closeHits, stats->falseHits));
 242 }
 243
 244 void
 245 cacheDigestReport(CacheDigest * cd, const SBuf &label, StoreEntry * e)
 246 {
 247     CacheDigestStats stats;
 248     assert(cd && e);
 249     cacheDigestStats(cd, &stats);
 250     storeAppendPrintf(e, SQUIDSBUFPH " digest: size: %d bytes\n",
 251                       SQUIDSBUFPRINT(label), stats.bit_count / 8
 252                      );
 253     storeAppendPrintf(e, "\t entries: count: %" PRIu64 " capacity: %" PRIu64 " util: %d%%\n",
 254                       cd->count,
 255                       cd->capacity,
 256                       xpercentInt(cd->count, cd->capacity)
 257                      );
 258     storeAppendPrintf(e, "\t deletion attempts: %" PRIu64 "\n",
 259                       cd->del_count
 260                      );
 261     storeAppendPrintf(e, "\t bits: per entry: %d on: %d capacity: %d util: %d%%\n",
 262                       cd->bits_per_entry,
 263                       stats.bit_on_count, stats.bit_count,
 264                       xpercentInt(stats.bit_on_count, stats.bit_count)
 265                      );
 266     storeAppendPrintf(e, "\t bit-seq: count: %d avg.len: %.2f\n",
 267                       stats.bseq_count,
 268                       xdiv(stats.bseq_len_sum, stats.bseq_count)
 269                      );
 270 }
 271
 272 uint32_t
 273 CacheDigest::CalcMaskSize(uint64_t cap, uint8_t bpe)
 274 {
 275     uint64_t bitCount = (cap * bpe) + 7;
 276     assert(bitCount < INT_MAX); // do not 31-bit overflow later
 277     return static_cast<uint32_t>(bitCount / 8);
 278 }
 279
 280 static void
 281 cacheDigestHashKey(const CacheDigest * cd, const cache_key * key)
 282 {
 283     const uint32_t bit_count = cd->mask_size * 8;
 284     unsigned int tmp_keys[4];
 285     /* we must memcpy to ensure alignment */
 286     memcpy(tmp_keys, key, sizeof(tmp_keys));
 287     hashed_keys[0] = htonl(tmp_keys[0]) % bit_count;
 288     hashed_keys[1] = htonl(tmp_keys[1]) % bit_count;
 289     hashed_keys[2] = htonl(tmp_keys[2]) % bit_count;
 290     hashed_keys[3] = htonl(tmp_keys[3]) % bit_count;
 291     debugs(70, 9, "cacheDigestHashKey: " << storeKeyText(key) << " -(" <<
 292            bit_count << ")-> " << hashed_keys[0] << " " << hashed_keys[1] <<
 293            " " << hashed_keys[2] << " " << hashed_keys[3]);
 294 }
 295
 296 #endif
 297