gecko-dev/netwerk/cache2/CacheFileUtils.h

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4.2 KiB
C++

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef CacheFileUtils__h__
#define CacheFileUtils__h__
#include "nsError.h"
#include "nsCOMPtr.h"
#include "nsString.h"
#include "nsTArray.h"
#include "mozilla/StaticMutex.h"
#include "mozilla/TimeStamp.h"
class nsILoadContextInfo;
class nsACString;
namespace mozilla {
namespace net {
namespace CacheFileUtils {
already_AddRefed<nsILoadContextInfo>
ParseKey(const nsCSubstring &aKey,
nsCSubstring *aIdEnhance = nullptr,
nsCSubstring *aURISpec = nullptr);
void
AppendKeyPrefix(nsILoadContextInfo *aInfo, nsACString &_retval);
void
AppendTagWithValue(nsACString & aTarget, char const aTag, nsCSubstring const & aValue);
nsresult
KeyMatchesLoadContextInfo(const nsACString &aKey,
nsILoadContextInfo *aInfo,
bool *_retval);
class ValidityPair {
public:
ValidityPair(uint32_t aOffset, uint32_t aLen);
ValidityPair& operator=(const ValidityPair& aOther);
// Returns true when two pairs can be merged, i.e. they do overlap or the one
// ends exactly where the other begins.
bool CanBeMerged(const ValidityPair& aOther) const;
// Returns true when aOffset is placed anywhere in the validity interval or
// exactly after its end.
bool IsInOrFollows(uint32_t aOffset) const;
// Returns true when this pair has lower offset than the other pair. In case
// both pairs have the same offset it returns true when this pair has a
// shorter length.
bool LessThan(const ValidityPair& aOther) const;
// Merges two pair into one.
void Merge(const ValidityPair& aOther);
uint32_t Offset() const { return mOffset; }
uint32_t Len() const { return mLen; }
private:
uint32_t mOffset;
uint32_t mLen;
};
class ValidityMap {
public:
// Prints pairs in the map into log.
void Log() const;
// Returns number of pairs in the map.
uint32_t Length() const;
// Adds a new pair to the map. It keeps the pairs ordered and merges pairs
// when possible.
void AddPair(uint32_t aOffset, uint32_t aLen);
// Removes all pairs from the map.
void Clear();
size_t SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const;
ValidityPair& operator[](uint32_t aIdx);
private:
nsTArray<ValidityPair> mMap;
};
class DetailedCacheHitTelemetry {
public:
enum ERecType {
HIT = 0,
MISS = 1
};
static void AddRecord(ERecType aType, TimeStamp aLoadStart);
private:
class HitRate {
public:
HitRate();
void AddRecord(ERecType aType);
// Returns the bucket index that the current hit rate falls into according
// to the given aNumOfBuckets.
uint32_t GetHitRateBucket(uint32_t aNumOfBuckets) const;
uint32_t Count();
void Reset();
private:
uint32_t mHitCnt;
uint32_t mMissCnt;
};
// Group the hits and misses statistics by cache files count ranges (0-5000,
// 5001-10000, ... , 95001- )
static const uint32_t kRangeSize = 5000;
static const uint32_t kNumOfRanges = 20;
// Use the same ranges to report an average hit rate. Report the hit rates
// (and reset the counters) every kTotalSamplesReportLimit samples.
static const uint32_t kTotalSamplesReportLimit = 1000;
// Report hit rate for a given cache size range only if it contains
// kHitRateSamplesReportLimit or more samples. This limit should avoid
// reporting a biased statistics.
static const uint32_t kHitRateSamplesReportLimit = 500;
// All hit rates are accumulated in a single telemetry probe, so to use
// a sane number of enumerated values the hit rate is divided into buckets
// instead of using a percent value. This constant defines number of buckets
// that we divide the hit rates into. I.e. we'll report ranges 0%-5%, 5%-10%,
// 10-%15%, ...
static const uint32_t kHitRateBuckets = 20;
// Protects sRecordCnt, sHitStats and Telemetry::Accumulated() calls.
static StaticMutex sLock;
// Counter of samples that is compared against kTotalSamplesReportLimit.
static uint32_t sRecordCnt;
// Hit rate statistics for every cache size range.
static HitRate sHRStats[kNumOfRanges];
};
} // CacheFileUtils
} // net
} // mozilla
#endif