netwerk/cache2/CacheFileUtils.h

   1 /* This Source Code Form is subject to the terms of the Mozilla Public
   2  * License, v. 2.0. If a copy of the MPL was not distributed with this
   3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   4
   5 #ifndef CacheFileUtils__h__
   6 #define CacheFileUtils__h__
   7
   8 #include "nsError.h"
   9 #include "nsCOMPtr.h"
  10 #include "nsString.h"
  11 #include "nsTArray.h"
  12 #include "mozilla/Mutex.h"
  13 #include "mozilla/StaticMutex.h"
  14 #include "mozilla/TimeStamp.h"
  15
  16 class nsILoadContextInfo;
  17
  18 namespace mozilla {
  19 namespace net {
  20 namespace CacheFileUtils {
  21
  22 extern const char* kAltDataKey;
  23
  24 already_AddRefed<nsILoadContextInfo> ParseKey(const nsACString& aKey,
  25                                               nsACString* aIdEnhance = nullptr,
  26                                               nsACString* aURISpec = nullptr);
  27
  28 void AppendKeyPrefix(nsILoadContextInfo* aInfo, nsACString& _retval);
  29
  30 void AppendTagWithValue(nsACString& aTarget, char const aTag,
  31                         const nsACString& aValue);
  32
  33 nsresult KeyMatchesLoadContextInfo(const nsACString& aKey,
  34                                    nsILoadContextInfo* aInfo, bool* _retval);
  35
  36 class ValidityPair {
  37  public:
  38   ValidityPair(uint32_t aOffset, uint32_t aLen);
  39
  40   ValidityPair& operator=(const ValidityPair& aOther) = default;
  41
  42   // Returns true when two pairs can be merged, i.e. they do overlap or the one
  43   // ends exactly where the other begins.
  44   bool CanBeMerged(const ValidityPair& aOther) const;
  45
  46   // Returns true when aOffset is placed anywhere in the validity interval or
  47   // exactly after its end.
  48   bool IsInOrFollows(uint32_t aOffset) const;
  49
  50   // Returns true when this pair has lower offset than the other pair. In case
  51   // both pairs have the same offset it returns true when this pair has a
  52   // shorter length.
  53   bool LessThan(const ValidityPair& aOther) const;
  54
  55   // Merges two pair into one.
  56   void Merge(const ValidityPair& aOther);
  57
  58   uint32_t Offset() const { return mOffset; }
  59   uint32_t Len() const { return mLen; }
  60
  61  private:
  62   uint32_t mOffset;
  63   uint32_t mLen;
  64 };
  65
  66 class ValidityMap {
  67  public:
  68   // Prints pairs in the map into log.
  69   void Log() const;
  70
  71   // Returns number of pairs in the map.
  72   uint32_t Length() const;
  73
  74   // Adds a new pair to the map. It keeps the pairs ordered and merges pairs
  75   // when possible.
  76   void AddPair(uint32_t aOffset, uint32_t aLen);
  77
  78   // Removes all pairs from the map.
  79   void Clear();
  80
  81   size_t SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const;
  82
  83   ValidityPair& operator[](uint32_t aIdx);
  84
  85  private:
  86   nsTArray<ValidityPair> mMap;
  87 };
  88
  89 class DetailedCacheHitTelemetry {
  90  public:
  91   enum ERecType { HIT = 0, MISS = 1 };
  92
  93   static void AddRecord(ERecType aType, TimeStamp aLoadStart);
  94
  95  private:
  96   class HitRate {
  97    public:
  98     HitRate();
  99
 100     void AddRecord(ERecType aType);
 101     // Returns the bucket index that the current hit rate falls into according
 102     // to the given aNumOfBuckets.
 103     uint32_t GetHitRateBucket(uint32_t aNumOfBuckets) const;
 104     uint32_t Count();
 105     void Reset();
 106
 107    private:
 108     uint32_t mHitCnt = 0;
 109     uint32_t mMissCnt = 0;
 110   };
 111
 112   // Group the hits and misses statistics by cache files count ranges (0-5000,
 113   // 5001-10000, ... , 95001- )
 114   static const uint32_t kRangeSize = 5000;
 115   static const uint32_t kNumOfRanges = 20;
 116
 117   // Use the same ranges to report an average hit rate. Report the hit rates
 118   // (and reset the counters) every kTotalSamplesReportLimit samples.
 119   static const uint32_t kTotalSamplesReportLimit = 1000;
 120
 121   // Report hit rate for a given cache size range only if it contains
 122   // kHitRateSamplesReportLimit or more samples. This limit should avoid
 123   // reporting a biased statistics.
 124   static const uint32_t kHitRateSamplesReportLimit = 500;
 125
 126   // All hit rates are accumulated in a single telemetry probe, so to use
 127   // a sane number of enumerated values the hit rate is divided into buckets
 128   // instead of using a percent value. This constant defines number of buckets
 129   // that we divide the hit rates into. I.e. we'll report ranges 0%-5%, 5%-10%,
 130   // 10-%15%, ...
 131   static const uint32_t kHitRateBuckets = 20;
 132
 133   // Protects sRecordCnt, sHRStats and Telemetry::Accumulated() calls.
 134   static StaticMutex sLock;
 135
 136   // Counter of samples that is compared against kTotalSamplesReportLimit.
 137   static uint32_t sRecordCnt MOZ_GUARDED_BY(sLock);
 138
 139   // Hit rate statistics for every cache size range.
 140   static HitRate sHRStats[kNumOfRanges] MOZ_GUARDED_BY(sLock);
 141 };
 142
 143 class CachePerfStats {
 144  public:
 145   // perfStatTypes in displayRcwnStats() in toolkit/content/aboutNetworking.js
 146   // must match EDataType
 147   enum EDataType {
 148     IO_OPEN = 0,
 149     IO_READ = 1,
 150     IO_WRITE = 2,
 151     ENTRY_OPEN = 3,
 152     LAST = 4
 153   };
 154
 155   static void AddValue(EDataType aType, uint32_t aValue, bool aShortOnly);
 156   static uint32_t GetAverage(EDataType aType, bool aFiltered);
 157   static uint32_t GetStdDev(EDataType aType, bool aFiltered);
 158   static bool IsCacheSlow();
 159   static void GetSlowStats(uint32_t* aSlow, uint32_t* aNotSlow);
 160
 161  private:
 162   // This class computes average and standard deviation, it returns an
 163   // arithmetic avg and stddev until total number of values reaches mWeight.
 164   // Then it returns modified moving average computed as follows:
 165   //
 166   //   avg = (1-a)*avg + a*value
 167   //   avgsq = (1-a)*avgsq + a*value^2
 168   //   stddev = sqrt(avgsq - avg^2)
 169   //
 170   //   where
 171   //       avgsq is an average of the square of the values
 172   //       a = 1 / weight
 173   class MMA {
 174    public:
 175     MMA(uint32_t aTotalWeight, bool aFilter);
 176
 177     void AddValue(uint32_t aValue);
 178     uint32_t GetAverage();
 179     uint32_t GetStdDev();
 180
 181    private:
 182     uint64_t mSum;
 183     uint64_t mSumSq;
 184     uint32_t mCnt;
 185     uint32_t mWeight;
 186     bool mFilter;
 187   };
 188
 189   class PerfData {
 190    public:
 191     PerfData();
 192
 193     void AddValue(uint32_t aValue, bool aShortOnly);
 194     uint32_t GetAverage(bool aFiltered);
 195     uint32_t GetStdDev(bool aFiltered);
 196
 197    private:
 198     // Contains filtered data (i.e. times when we think the cache and disk was
 199     // not busy) for a longer time.
 200     MMA mFilteredAvg;
 201
 202     // Contains unfiltered average of few recent values.
 203     MMA mShortAvg;
 204   };
 205
 206   static StaticMutex sLock;
 207
 208   static PerfData sData[LAST] MOZ_GUARDED_BY(sLock);
 209   static uint32_t sCacheSlowCnt MOZ_GUARDED_BY(sLock);
 210   static uint32_t sCacheNotSlowCnt MOZ_GUARDED_BY(sLock);
 211 };
 212
 213 void FreeBuffer(void* aBuf);
 214
 215 nsresult ParseAlternativeDataInfo(const char* aInfo, int64_t* _offset,
 216                                   nsACString* _type);
 217
 218 void BuildAlternativeDataInfo(const char* aInfo, int64_t aOffset,
 219                               nsACString& _retval);
 220
 221 class CacheFileLock final {
 222  public:
 223   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CacheFileLock)
 224   CacheFileLock() = default;
 225
 226   mozilla::Mutex& Lock() MOZ_RETURN_CAPABILITY(mLock) { return mLock; }
 227
 228  private:
 229   ~CacheFileLock() = default;
 230
 231   mozilla::Mutex mLock{"CacheFile.mLock"};
 232 };
 233
 234 }  // namespace CacheFileUtils
 235 }  // namespace net
 236 }  // namespace mozilla
 237
 238 #endif