src/CacheDigest.h

   1 /*
   2  * Copyright (C) 1996-2018 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 #ifndef SQUID_CACHEDIGEST_H_
  12 #define SQUID_CACHEDIGEST_H_
  13
  14 #include "mem/forward.h"
  15 #include "store_key_md5.h"
  16
  17 class CacheDigestGuessStats;
  18 class StoreEntry;
  19
  20 class CacheDigest
  21 {
  22     MEMPROXY_CLASS(CacheDigest);
  23 public:
  24     CacheDigest(uint64_t capacity, uint8_t bpe);
  25     ~CacheDigest();
  26
  27     // NP: only used by broken unit-test
  28     /// produce a new identical copy of the digest object
  29     CacheDigest *clone() const;
  30
  31     /// reset the digest mask and counters
  32     void clear();
  33
  34     /// changes mask size to fit newCapacity, resets bits to 0
  35     void updateCapacity(uint64_t newCapacity);
  36
  37     void add(const cache_key * key);
  38     void remove(const cache_key * key);
  39
  40     /// \returns true if the key belongs to the digest
  41     bool contains(const cache_key * key) const;
  42
  43     /// percentage of mask bits which are used
  44     double usedMaskPercent() const;
  45
  46     /// calculate the size of mask required to digest up to
  47     /// a specified capacity and bitsize.
  48     static uint32_t CalcMaskSize(uint64_t cap, uint8_t bpe);
  49
  50 private:
  51     void init(uint64_t newCapacity);
  52
  53 public:
  54     /* public, read-only */
  55     uint64_t count;          /* number of digested entries */
  56     uint64_t del_count;      /* number of deletions performed so far */
  57     uint64_t capacity;       /* expected maximum for .count, not a hard limit */
  58     char *mask;              /* bit mask */
  59     uint32_t mask_size;      /* mask size in bytes */
  60     int8_t bits_per_entry;   /* number of bits allocated for each entry from capacity */
  61 };
  62
  63 void cacheDigestGuessStatsUpdate(CacheDigestGuessStats * stats, int real_hit, int guess_hit);
  64 void cacheDigestGuessStatsReport(const CacheDigestGuessStats * stats, StoreEntry * sentry, const char *label);
  65 void cacheDigestReport(CacheDigest * cd, const char *label, StoreEntry * e);
  66
  67 #endif /* SQUID_CACHEDIGEST_H_ */
  68