The Tor Browser: netwerk/cache2/CacheIndex.h@6474c204b198 (annotated)

netwerk/cache2/CacheIndex.h@6474c204b198 (annotated)

netwerk/cache2/CacheIndex.h

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* 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 CacheIndex__h__
 #define CacheIndex__h__
 #include "CacheLog.h"
 #include "CacheFileIOManager.h"
 #include "nsIRunnable.h"
 #include "CacheHashUtils.h"
 #include "nsICacheStorageService.h"
 #include "nsICacheEntry.h"
 #include "nsILoadContextInfo.h"
 #include "nsTHashtable.h"
 #include "nsThreadUtils.h"
 #include "nsWeakReference.h"
 #include "mozilla/SHA1.h"
 #include "mozilla/Mutex.h"
 #include "mozilla/Endian.h"
 #include "mozilla/TimeStamp.h"
 class nsIFile;
 class nsIDirectoryEnumerator;
 class nsITimer;
 #ifdef DEBUG
 #define DEBUG_STATS 1
 #endif
 namespace mozilla {
 namespace net {
 class CacheFileMetadata;
 class FileOpenHelper;
 class CacheIndexIterator;
 typedef struct {
   // Version of the index. The index must be ignored and deleted when the file
   // on disk was written with a newer version.
   uint32_t mVersion;
   // Timestamp of time when the last successful write of the index started.
   // During update process we use this timestamp for a quick validation of entry
   // files. If last modified time of the file is lower than this timestamp, we
   // skip parsing of such file since the information in index should be up to
   // date.
   uint32_t mTimeStamp;
   // We set this flag as soon as possible after parsing index during startup
   // and clean it after we write journal to disk during shutdown. We ignore the
   // journal and start update process whenever this flag is set during index
   // parsing.
   uint32_t mIsDirty;
 } CacheIndexHeader;
 struct CacheIndexRecord {
   SHA1Sum::Hash mHash;
   uint32_t      mFrecency;
   uint32_t      mExpirationTime;
   uint32_t      mAppId;
   /*
    *    1000 0000 0000 0000 0000 0000 0000 0000 : initialized
    *    0100 0000 0000 0000 0000 0000 0000 0000 : anonymous
    *    0010 0000 0000 0000 0000 0000 0000 0000 : inBrowser
    *    0001 0000 0000 0000 0000 0000 0000 0000 : removed
    *    0000 1000 0000 0000 0000 0000 0000 0000 : dirty
    *    0000 0100 0000 0000 0000 0000 0000 0000 : fresh
    *    0000 0011 0000 0000 0000 0000 0000 0000 : reserved
    *    0000 0000 1111 1111 1111 1111 1111 1111 : file size (in kB)
    */
   uint32_t      mFlags;
   CacheIndexRecord()
     : mFrecency(0)
     , mExpirationTime(nsICacheEntry::NO_EXPIRATION_TIME)
     , mAppId(nsILoadContextInfo::NO_APP_ID)
     , mFlags(0)
   {}
 };
 class CacheIndexEntry : public PLDHashEntryHdr
 {
 public:
   typedef const SHA1Sum::Hash& KeyType;
   typedef const SHA1Sum::Hash* KeyTypePointer;
   CacheIndexEntry(KeyTypePointer aKey)
   {
     MOZ_COUNT_CTOR(CacheIndexEntry);
     mRec = new CacheIndexRecord();
     LOG(("CacheIndexEntry::CacheIndexEntry() - Created record [rec=%p]", mRec.get()));
     memcpy(&mRec->mHash, aKey, sizeof(SHA1Sum::Hash));
   }
   CacheIndexEntry(const CacheIndexEntry& aOther)
   {
     NS_NOTREACHED("CacheIndexEntry copy constructor is forbidden!");
   }
   ~CacheIndexEntry()
   {
     MOZ_COUNT_DTOR(CacheIndexEntry);
     LOG(("CacheIndexEntry::~CacheIndexEntry() - Deleting record [rec=%p]",
          mRec.get()));
   }
   // KeyEquals(): does this entry match this key?
   bool KeyEquals(KeyTypePointer aKey) const
   {
     return memcmp(&mRec->mHash, aKey, sizeof(SHA1Sum::Hash)) == 0;
   }
   // KeyToPointer(): Convert KeyType to KeyTypePointer
   static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
   // HashKey(): calculate the hash number
   static PLDHashNumber HashKey(KeyTypePointer aKey)
   {
     return (reinterpret_cast<const uint32_t *>(aKey))[0];
   }
   // ALLOW_MEMMOVE can we move this class with memmove(), or do we have
   // to use the copy constructor?
   enum { ALLOW_MEMMOVE = true };
   bool operator==(const CacheIndexEntry& aOther) const
   {
     return KeyEquals(&aOther.mRec->mHash);
   }
   CacheIndexEntry& operator=(const CacheIndexEntry& aOther)
   {
     MOZ_ASSERT(memcmp(&mRec->mHash, &aOther.mRec->mHash,
                sizeof(SHA1Sum::Hash)) == 0);
     mRec->mFrecency = aOther.mRec->mFrecency;
     mRec->mExpirationTime = aOther.mRec->mExpirationTime;
     mRec->mAppId = aOther.mRec->mAppId;
     mRec->mFlags = aOther.mRec->mFlags;
     return *this;
   }
   void InitNew()
   {
     mRec->mFrecency = 0;
     mRec->mExpirationTime = nsICacheEntry::NO_EXPIRATION_TIME;
     mRec->mAppId = nsILoadContextInfo::NO_APP_ID;
     mRec->mFlags = 0;
   }
   void Init(uint32_t aAppId, bool aAnonymous, bool aInBrowser)
   {
     MOZ_ASSERT(mRec->mFrecency == 0);
     MOZ_ASSERT(mRec->mExpirationTime == nsICacheEntry::NO_EXPIRATION_TIME);
     MOZ_ASSERT(mRec->mAppId == nsILoadContextInfo::NO_APP_ID);
     // When we init the entry it must be fresh and may be dirty
     MOZ_ASSERT((mRec->mFlags & ~kDirtyMask) == kFreshMask);
     mRec->mAppId = aAppId;
     mRec->mFlags |= kInitializedMask;
     if (aAnonymous) {
       mRec->mFlags |= kAnonymousMask;
     }
     if (aInBrowser) {
       mRec->mFlags |= kInBrowserMask;
     }
   }
   const SHA1Sum::Hash * Hash() { return &mRec->mHash; }
   bool IsInitialized() { return !!(mRec->mFlags & kInitializedMask); }
   uint32_t AppId() { return mRec->mAppId; }
   bool     Anonymous() { return !!(mRec->mFlags & kAnonymousMask); }
   bool     InBrowser() { return !!(mRec->mFlags & kInBrowserMask); }
   bool IsRemoved() { return !!(mRec->mFlags & kRemovedMask); }
   void MarkRemoved() { mRec->mFlags |= kRemovedMask; }
   bool IsDirty() { return !!(mRec->mFlags & kDirtyMask); }
   void MarkDirty() { mRec->mFlags |= kDirtyMask; }
   void ClearDirty() { mRec->mFlags &= ~kDirtyMask; }
   bool IsFresh() { return !!(mRec->mFlags & kFreshMask); }
   void MarkFresh() { mRec->mFlags |= kFreshMask; }
   void     SetFrecency(uint32_t aFrecency) { mRec->mFrecency = aFrecency; }
   uint32_t GetFrecency() { return mRec->mFrecency; }
   void     SetExpirationTime(uint32_t aExpirationTime)
   {
     mRec->mExpirationTime = aExpirationTime;
   }
   uint32_t GetExpirationTime() { return mRec->mExpirationTime; }
   // Sets filesize in kilobytes.
   void     SetFileSize(uint32_t aFileSize)
   {
     if (aFileSize > kFileSizeMask) {
       LOG(("CacheIndexEntry::SetFileSize() - FileSize is too large, "
            "truncating to %u", kFileSizeMask));
       aFileSize = kFileSizeMask;
     }
     mRec->mFlags &= ~kFileSizeMask;
     mRec->mFlags |= aFileSize;
   }
   // Returns filesize in kilobytes.
   uint32_t GetFileSize() { return mRec->mFlags & kFileSizeMask; }
   bool     IsFileEmpty() { return GetFileSize() == 0; }
   void WriteToBuf(void *aBuf)
   {
     CacheIndexRecord *dst = reinterpret_cast<CacheIndexRecord *>(aBuf);
     // Copy the whole record to the buffer.
     memcpy(aBuf, mRec, sizeof(CacheIndexRecord));
     // Dirty and fresh flags should never go to disk, since they make sense only
     // during current session.
     dst->mFlags &= ~kDirtyMask;
     dst->mFlags &= ~kFreshMask;
 #if defined(IS_LITTLE_ENDIAN)
     // Data in the buffer are in machine byte order and we want them in network
     // byte order.
     NetworkEndian::writeUint32(&dst->mFrecency, dst->mFrecency);
     NetworkEndian::writeUint32(&dst->mExpirationTime, dst->mExpirationTime);
     NetworkEndian::writeUint32(&dst->mAppId, dst->mAppId);
     NetworkEndian::writeUint32(&dst->mFlags, dst->mFlags);
 #endif
   }
   void ReadFromBuf(void *aBuf)
   {
     CacheIndexRecord *src= reinterpret_cast<CacheIndexRecord *>(aBuf);
     MOZ_ASSERT(memcmp(&mRec->mHash, &src->mHash,
                sizeof(SHA1Sum::Hash)) == 0);
     mRec->mFrecency = NetworkEndian::readUint32(&src->mFrecency);
     mRec->mExpirationTime = NetworkEndian::readUint32(&src->mExpirationTime);
     mRec->mAppId = NetworkEndian::readUint32(&src->mAppId);
     mRec->mFlags = NetworkEndian::readUint32(&src->mFlags);
   }
   void Log() {
     LOG(("CacheIndexEntry::Log() [this=%p, hash=%08x%08x%08x%08x%08x, fresh=%u,"
          " initialized=%u, removed=%u, dirty=%u, anonymous=%u, inBrowser=%u, "
          "appId=%u, frecency=%u, expirationTime=%u, size=%u]",
          this, LOGSHA1(mRec->mHash), IsFresh(), IsInitialized(), IsRemoved(),
          IsDirty(), Anonymous(), InBrowser(), AppId(), GetFrecency(),
          GetExpirationTime(), GetFileSize()));
   }
   static bool RecordMatchesLoadContextInfo(CacheIndexRecord *aRec,
                                            nsILoadContextInfo *aInfo)
   {
     if (!aInfo->IsPrivate() &&
         aInfo->AppId() == aRec->mAppId &&
         aInfo->IsAnonymous() == !!(aRec->mFlags & kAnonymousMask) &&
         aInfo->IsInBrowserElement() == !!(aRec->mFlags & kInBrowserMask)) {
       return true;
     }
     return false;
   }
   // Memory reporting
   size_t SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const
   {
     return mallocSizeOf(mRec.get());
   }
   size_t SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const
   {
     return mallocSizeOf(this) + SizeOfExcludingThis(mallocSizeOf);
   }
 private:
   friend class CacheIndex;
   friend class CacheIndexEntryAutoManage;
   static const uint32_t kInitializedMask = 0x80000000;
   static const uint32_t kAnonymousMask   = 0x40000000;
   static const uint32_t kInBrowserMask   = 0x20000000;
   // This flag is set when the entry was removed. We need to keep this
   // information in memory until we write the index file.
   static const uint32_t kRemovedMask     = 0x10000000;
   // This flag is set when the information in memory is not in sync with the
   // information in index file on disk.
   static const uint32_t kDirtyMask       = 0x08000000;
   // This flag is set when the information about the entry is fresh, i.e.
   // we've created or opened this entry during this session, or we've seen
   // this entry during update or build process.
   static const uint32_t kFreshMask       = 0x04000000;
   static const uint32_t kReservedMask    = 0x03000000;
   // FileSize in kilobytes
   static const uint32_t kFileSizeMask    = 0x00FFFFFF;
   nsAutoPtr<CacheIndexRecord> mRec;
 };
 class CacheIndexStats
 {
 public:
   CacheIndexStats()
     : mCount(0)
     , mNotInitialized(0)
     , mRemoved(0)
     , mDirty(0)
     , mFresh(0)
     , mEmpty(0)
     , mSize(0)
 #ifdef DEBUG
     , mStateLogged(false)
     , mDisableLogging(false)
 #endif
   {
   }
   bool operator==(const CacheIndexStats& aOther) const
   {
     return
 #ifdef DEBUG
            aOther.mStateLogged == mStateLogged &&
 #endif
            aOther.mCount == mCount &&
            aOther.mNotInitialized == mNotInitialized &&
            aOther.mRemoved == mRemoved &&
            aOther.mDirty == mDirty &&
            aOther.mFresh == mFresh &&
            aOther.mEmpty == mEmpty &&
            aOther.mSize == mSize;
   }
 #ifdef DEBUG
   void DisableLogging() {
     mDisableLogging = true;
   }
 #endif
   void Log() {
     LOG(("CacheIndexStats::Log() [count=%u, notInitialized=%u, removed=%u, "
          "dirty=%u, fresh=%u, empty=%u, size=%u]", mCount, mNotInitialized,
          mRemoved, mDirty, mFresh, mEmpty, mSize));
   }
   void Clear() {
     MOZ_ASSERT(!mStateLogged, "CacheIndexStats::Clear() - state logged!");
     mCount = 0;
     mNotInitialized = 0;
     mRemoved = 0;
     mDirty = 0;
     mFresh = 0;
     mEmpty = 0;
     mSize = 0;
   }
 #ifdef DEBUG
   bool StateLogged() {
     return mStateLogged;
   }
 #endif
   uint32_t Count() {
     MOZ_ASSERT(!mStateLogged, "CacheIndexStats::Count() - state logged!");
     return mCount;
   }
   uint32_t Dirty() {
     MOZ_ASSERT(!mStateLogged, "CacheIndexStats::Dirty() - state logged!");
     return mDirty;
   }
   uint32_t Fresh() {
     MOZ_ASSERT(!mStateLogged, "CacheIndexStats::Fresh() - state logged!");
     return mFresh;
   }
   uint32_t ActiveEntriesCount() {
     MOZ_ASSERT(!mStateLogged, "CacheIndexStats::ActiveEntriesCount() - state "
                "logged!");
     return mCount - mRemoved - mNotInitialized - mEmpty;
   }
   uint32_t Size() {
     MOZ_ASSERT(!mStateLogged, "CacheIndexStats::Size() - state logged!");
     return mSize;
   }
   void BeforeChange(CacheIndexEntry *aEntry) {
 #ifdef DEBUG_STATS
     if (!mDisableLogging) {
       LOG(("CacheIndexStats::BeforeChange()"));
       Log();
     }
 #endif
     MOZ_ASSERT(!mStateLogged, "CacheIndexStats::BeforeChange() - state "
                "logged!");
 #ifdef DEBUG
     mStateLogged = true;
 #endif
     if (aEntry) {
       MOZ_ASSERT(mCount);
       mCount--;
       if (aEntry->IsDirty()) {
         MOZ_ASSERT(mDirty);
         mDirty--;
       }
       if (aEntry->IsFresh()) {
         MOZ_ASSERT(mFresh);
         mFresh--;
       }
       if (aEntry->IsRemoved()) {
         MOZ_ASSERT(mRemoved);
         mRemoved--;
       } else {
         if (!aEntry->IsInitialized()) {
           MOZ_ASSERT(mNotInitialized);
           mNotInitialized--;
         } else {
           if (aEntry->IsFileEmpty()) {
             MOZ_ASSERT(mEmpty);
             mEmpty--;
           } else {
             MOZ_ASSERT(mSize >= aEntry->GetFileSize());
             mSize -= aEntry->GetFileSize();
           }
         }
       }
     }
   }
   void AfterChange(CacheIndexEntry *aEntry) {
     MOZ_ASSERT(mStateLogged, "CacheIndexStats::AfterChange() - state not "
                "logged!");
 #ifdef DEBUG
     mStateLogged = false;
 #endif
     if (aEntry) {
       ++mCount;
       if (aEntry->IsDirty()) {
         mDirty++;
       }
       if (aEntry->IsFresh()) {
         mFresh++;
       }
       if (aEntry->IsRemoved()) {
         mRemoved++;
       } else {
         if (!aEntry->IsInitialized()) {
           mNotInitialized++;
         } else {
           if (aEntry->IsFileEmpty()) {
             mEmpty++;
           } else {
             mSize += aEntry->GetFileSize();
           }
         }
       }
     }
 #ifdef DEBUG_STATS
     if (!mDisableLogging) {
       LOG(("CacheIndexStats::AfterChange()"));
       Log();
     }
 #endif
   }
 private:
   uint32_t mCount;
   uint32_t mNotInitialized;
   uint32_t mRemoved;
   uint32_t mDirty;
   uint32_t mFresh;
   uint32_t mEmpty;
   uint32_t mSize;
 #ifdef DEBUG
   // We completely remove the data about an entry from the stats in
   // BeforeChange() and set this flag to true. The entry is then modified,
   // deleted or created and the data is again put into the stats and this flag
   // set to false. Statistics must not be read during this time since the
   // information is not correct.
   bool     mStateLogged;
   // Disables logging in this instance of CacheIndexStats
   bool     mDisableLogging;
 #endif
 };
 class CacheIndex : public CacheFileIOListener
                  , public nsIRunnable
 {
 public:
   NS_DECL_THREADSAFE_ISUPPORTS
   NS_DECL_NSIRUNNABLE
   CacheIndex();
   static nsresult Init(nsIFile *aCacheDirectory);
   static nsresult PreShutdown();
   static nsresult Shutdown();
   // Following methods can be called only on IO thread.
   // Add entry to the index. The entry shouldn't be present in index. This
   // method is called whenever a new handle for a new entry file is created. The
   // newly created entry is not initialized and it must be either initialized
   // with InitEntry() or removed with RemoveEntry().
   static nsresult AddEntry(const SHA1Sum::Hash *aHash);
   // Inform index about an existing entry that should be present in index. This
   // method is called whenever a new handle for an existing entry file is
   // created. Like in case of AddEntry(), either InitEntry() or RemoveEntry()
   // must be called on the entry, since the entry is not initizlized if the
   // index is outdated.
   static nsresult EnsureEntryExists(const SHA1Sum::Hash *aHash);
   // Initialize the entry. It MUST be present in index. Call to AddEntry() or
   // EnsureEntryExists() must precede the call to this method.
   static nsresult InitEntry(const SHA1Sum::Hash *aHash,
                             uint32_t             aAppId,
                             bool                 aAnonymous,
                             bool                 aInBrowser);
   // Remove entry from index. The entry should be present in index.
   static nsresult RemoveEntry(const SHA1Sum::Hash *aHash);
   // Update some information in entry. The entry MUST be present in index and
   // MUST be initialized. Call to AddEntry() or EnsureEntryExists() and to
   // InitEntry() must precede the call to this method.
   // Pass nullptr if the value didn't change.
   static nsresult UpdateEntry(const SHA1Sum::Hash *aHash,
                               const uint32_t      *aFrecency,
                               const uint32_t      *aExpirationTime,
                               const uint32_t      *aSize);
   // Remove all entries from the index. Called when clearing the whole cache.
   static nsresult RemoveAll();
   enum EntryStatus {
     EXISTS         = 0,
     DOES_NOT_EXIST = 1,
     DO_NOT_KNOW    = 2
   };
   // Returns status of the entry in index for the given key. It can be called
   // on any thread.
   static nsresult HasEntry(const nsACString &aKey, EntryStatus *_retval);
   // Returns a hash of the least important entry that should be evicted if the
   // cache size is over limit and also returns a total number of all entries in
   // the index.
   static nsresult GetEntryForEviction(SHA1Sum::Hash *aHash, uint32_t *aCnt);
   // Returns cache size in kB.
   static nsresult GetCacheSize(uint32_t *_retval);
   // Asynchronously gets the disk cache size, used for display in the UI.
   static nsresult AsyncGetDiskConsumption(nsICacheStorageConsumptionObserver* aObserver);
   // Returns an iterator that returns entries matching a given context that were
   // present in the index at the time this method was called. If aAddNew is true
   // then the iterator will also return entries created after this call.
   // NOTE: When some entry is removed from index it is removed also from the
   // iterator regardless what aAddNew was passed.
   static nsresult GetIterator(nsILoadContextInfo *aInfo, bool aAddNew,
                               CacheIndexIterator **_retval);
   // Returns true if we _think_ that the index is up to date. I.e. the state is
   // READY or WRITING and mIndexNeedsUpdate as well as mShuttingDown is false.
   static nsresult IsUpToDate(bool *_retval);
   // Memory reporting
   static size_t SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf);
   static size_t SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf);
 private:
   friend class CacheIndexEntryAutoManage;
   friend class CacheIndexAutoLock;
   friend class CacheIndexAutoUnlock;
   friend class FileOpenHelper;
   friend class CacheIndexIterator;
   virtual ~CacheIndex();
   NS_IMETHOD OnFileOpened(CacheFileHandle *aHandle, nsresult aResult);
   nsresult   OnFileOpenedInternal(FileOpenHelper *aOpener,
                                   CacheFileHandle *aHandle, nsresult aResult);
   NS_IMETHOD OnDataWritten(CacheFileHandle *aHandle, const char *aBuf,
                            nsresult aResult);
   NS_IMETHOD OnDataRead(CacheFileHandle *aHandle, char *aBuf, nsresult aResult);
   NS_IMETHOD OnFileDoomed(CacheFileHandle *aHandle, nsresult aResult);
   NS_IMETHOD OnEOFSet(CacheFileHandle *aHandle, nsresult aResult);
   NS_IMETHOD OnFileRenamed(CacheFileHandle *aHandle, nsresult aResult);
   void     Lock();
   void     Unlock();
   void     AssertOwnsLock();
   nsresult InitInternal(nsIFile *aCacheDirectory);
   void     PreShutdownInternal();
   // This method returns false when index is not initialized or is shut down.
   bool IsIndexUsable();
   // This method checks whether the entry has the same values of appId,
   // isAnonymous and isInBrowser. We don't expect to find a collision since
   // these values are part of the key that we hash and we use a strong hash
   // function.
   static bool IsCollision(CacheIndexEntry *aEntry,
                           uint32_t         aAppId,
                           bool             aAnonymous,
                           bool             aInBrowser);
   // Checks whether any of the information about the entry has changed.
   static bool HasEntryChanged(CacheIndexEntry *aEntry,
                               const uint32_t  *aFrecency,
                               const uint32_t  *aExpirationTime,
                               const uint32_t  *aSize);
   // Merge all pending operations from mPendingUpdates into mIndex.
   void ProcessPendingOperations();
   static PLDHashOperator UpdateEntryInIndex(CacheIndexEntry *aEntry,
                                             void* aClosure);
   // Following methods perform writing of the index file.
   //
   // The index is written periodically, but not earlier than once in
   // kMinDumpInterval and there must be at least kMinUnwrittenChanges
   // differences between index on disk and in memory. Index is always first
   // written to a temporary file and the old index file is replaced when the
   // writing process succeeds.
   //
   // Starts writing of index when both limits (minimal delay between writes and
   // minimum number of changes in index) were exceeded.
   bool WriteIndexToDiskIfNeeded();
   // Starts writing of index file.
   void WriteIndexToDisk();
   // Serializes part of mIndex hashtable to the write buffer a writes the buffer
   // to the file.
   void WriteRecords();
   // Finalizes writing process.
   void FinishWrite(bool aSucceeded);
   static PLDHashOperator CopyRecordsToRWBuf(CacheIndexEntry *aEntry,
                                             void* aClosure);
   static PLDHashOperator ApplyIndexChanges(CacheIndexEntry *aEntry,
                                            void* aClosure);
   // Following methods perform writing of the journal during shutdown. All these
   // methods must be called only during shutdown since they write/delete files
   // directly on the main thread instead of using CacheFileIOManager that does
   // it asynchronously on IO thread. Journal contains only entries that are
   // dirty, i.e. changes that are not present in the index file on the disk.
   // When the log is written successfully, the dirty flag in index file is
   // cleared.
   nsresult GetFile(const nsACString &aName, nsIFile **_retval);
   nsresult RemoveFile(const nsACString &aName);
   void     RemoveIndexFromDisk();
   // Writes journal to the disk and clears dirty flag in index header.
   nsresult WriteLogToDisk();
   static PLDHashOperator WriteEntryToLog(CacheIndexEntry *aEntry,
                                          void* aClosure);
   // Following methods perform reading of the index from the disk.
   //
   // Index is read at startup just after initializing the CacheIndex. There are
   // 3 files used when manipulating with index: index file, journal file and
   // a temporary file. All files contain the hash of the data, so we can check
   // whether the content is valid and complete. Index file contains also a dirty
   // flag in the index header which is unset on a clean shutdown. During opening
   // and reading of the files we determine the status of the whole index from
   // the states of the separate files. Following table shows all possible
   // combinations:
   //
   // index, journal, tmpfile
   // M      *        *       - index is missing    -> BUILD
   // I      *        *       - index is invalid    -> BUILD
   // D      *        *       - index is dirty      -> UPDATE
   // C      M        *       - index is dirty      -> UPDATE
   // C      I        *       - unexpected state    -> UPDATE
   // C      V        E       - unexpected state    -> UPDATE
   // C      V        M       - index is up to date -> READY
   //
   // where the letters mean:
   //   * - any state
   //   E - file exists
   //   M - file is missing
   //   I - data is invalid (parsing failed or hash didn't match)
   //   D - dirty (data in index file is correct, but dirty flag is set)
   //   C - clean (index file is clean)
   //   V - valid (data in journal file is correct)
   //
   // Note: We accept the data from journal only when the index is up to date as
   // a whole (i.e. C,V,M state).
   //
   // We rename the journal file to the temporary file as soon as possible after
   // initial test to ensure that we start update process on the next startup if
   // FF crashes during parsing of the index.
   //
   // Initiates reading index from disk.
   void ReadIndexFromDisk();
   // Starts reading data from index file.
   void StartReadingIndex();
   // Parses data read from index file.
   void ParseRecords();
   // Starts reading data from journal file.
   void StartReadingJournal();
   // Parses data read from journal file.
   void ParseJournal();
   // Merges entries from journal into mIndex.
   void MergeJournal();
   // In debug build this method checks that we have no fresh entry in mIndex
   // after we finish reading index and before we process pending operations.
   void EnsureNoFreshEntry();
   // In debug build this method is called after processing pending operations
   // to make sure mIndexStats contains correct information.
   void EnsureCorrectStats();
   static PLDHashOperator SumIndexStats(CacheIndexEntry *aEntry, void* aClosure);
   // Finalizes reading process.
   void FinishRead(bool aSucceeded);
   static PLDHashOperator ProcessJournalEntry(CacheIndexEntry *aEntry,
                                              void* aClosure);
   // Following methods perform updating and building of the index.
   // Timer callback that starts update or build process.
   static void DelayedUpdate(nsITimer *aTimer, void *aClosure);
   // Posts timer event that start update or build process.
   nsresult ScheduleUpdateTimer(uint32_t aDelay);
   nsresult SetupDirectoryEnumerator();
   void InitEntryFromDiskData(CacheIndexEntry *aEntry,
                              CacheFileMetadata *aMetaData,
                              int64_t aFileSize);
   // Returns true when either a timer is scheduled or event is posted.
   bool IsUpdatePending();
   // Iterates through all files in entries directory that we didn't create/open
   // during this session, parses them and adds the entries to the index.
   void BuildIndex();
   bool StartUpdatingIndexIfNeeded(bool aSwitchingToReadyState = false);
   // Starts update or build process or fires a timer when it is too early after
   // startup.
   void StartUpdatingIndex(bool aRebuild);
   // Iterates through all files in entries directory that we didn't create/open
   // during this session and theirs last modified time is newer than timestamp
   // in the index header. Parses the files and adds the entries to the index.
   void UpdateIndex();
   // Finalizes update or build process.
   void FinishUpdate(bool aSucceeded);
   static PLDHashOperator RemoveNonFreshEntries(CacheIndexEntry *aEntry,
                                                void* aClosure);
   enum EState {
     // Initial state in which the index is not usable
     // Possible transitions:
     //  -> READING
     INITIAL  = 0,
     // Index is being read from the disk.
     // Possible transitions:
     //  -> INITIAL  - We failed to dispatch a read event.
     //  -> BUILDING - No or corrupted index file was found.
     //  -> UPDATING - No or corrupted journal file was found.
     //              - Dirty flag was set in index header.
     //  -> READY    - Index was read successfully or was interrupted by
     //                pre-shutdown.
     //  -> SHUTDOWN - This could happen only in case of pre-shutdown failure.
     READING  = 1,
     // Index is being written to the disk.
     // Possible transitions:
     //  -> READY    - Writing of index finished or was interrupted by
     //                pre-shutdown..
     //  -> UPDATING - Writing of index finished, but index was found outdated
     //                during writing.
     //  -> SHUTDOWN - This could happen only in case of pre-shutdown failure.
     WRITING  = 2,
     // Index is being build.
     // Possible transitions:
     //  -> READY    - Building of index finished or was interrupted by
     //                pre-shutdown.
     //  -> SHUTDOWN - This could happen only in case of pre-shutdown failure.
     BUILDING = 3,
     // Index is being updated.
     // Possible transitions:
     //  -> READY    - Updating of index finished or was interrupted by
     //                pre-shutdown.
     //  -> SHUTDOWN - This could happen only in case of pre-shutdown failure.
     UPDATING = 4,
     // Index is ready.
     // Possible transitions:
     //  -> UPDATING - Index was found outdated.
     //  -> SHUTDOWN - Index is shutting down.
     READY    = 5,
     // Index is shutting down.
     SHUTDOWN = 6
   };
 #ifdef PR_LOGGING
   static char const * StateString(EState aState);
 #endif
   void ChangeState(EState aNewState);
   // Allocates and releases buffer used for reading and writing index.
   void AllocBuffer();
   void ReleaseBuffer();
   // Methods used by CacheIndexEntryAutoManage to keep the arrays up to date.
   void InsertRecordToFrecencyArray(CacheIndexRecord *aRecord);
   void InsertRecordToExpirationArray(CacheIndexRecord *aRecord);
   void RemoveRecordFromFrecencyArray(CacheIndexRecord *aRecord);
   void RemoveRecordFromExpirationArray(CacheIndexRecord *aRecord);
   // Methods used by CacheIndexEntryAutoManage to keep the iterators up to date.
   void AddRecordToIterators(CacheIndexRecord *aRecord);
   void RemoveRecordFromIterators(CacheIndexRecord *aRecord);
   void ReplaceRecordInIterators(CacheIndexRecord *aOldRecord,
                                 CacheIndexRecord *aNewRecord);
   // Memory reporting (private part)
   size_t SizeOfExcludingThisInternal(mozilla::MallocSizeOf mallocSizeOf) const;
   static CacheIndex *gInstance;
   nsCOMPtr<nsIFile> mCacheDirectory;
   mozilla::Mutex mLock;
   EState         mState;
   // Timestamp of time when the index was initialized. We use it to delay
   // initial update or build of index.
   TimeStamp      mStartTime;
   // Set to true in PreShutdown(), it is checked on variaous places to prevent
   // starting any process (write, update, etc.) during shutdown.
   bool           mShuttingDown;
   // When set to true, update process should start as soon as possible. This
   // flag is set whenever we find some inconsistency which would be fixed by
   // update process. The flag is checked always when switching to READY state.
   // To make sure we start the update process as soon as possible, methods that
   // set this flag should also call StartUpdatingIndexIfNeeded() to cover the
   // case when we are currently in READY state.
   bool           mIndexNeedsUpdate;
   // Set at the beginning of RemoveAll() which clears the whole index. When
   // removing all entries we must stop any pending reading, writing, updating or
   // building operation. This flag is checked at various places and it prevents
   // we won't start another operation (e.g. canceling reading of the index would
   // normally start update or build process)
   bool           mRemovingAll;
   // Whether the index file on disk exists and is valid.
   bool           mIndexOnDiskIsValid;
   // When something goes wrong during updating or building process, we don't
   // mark index clean (and also don't write journal) to ensure that update or
   // build will be initiated on the next start.
   bool           mDontMarkIndexClean;
   // Timestamp value from index file. It is used during update process to skip
   // entries that were last modified before this timestamp.
   uint32_t       mIndexTimeStamp;
   // Timestamp of last time the index was dumped to disk.
   // NOTE: The index might not be necessarily dumped at this time. The value
   // is used to schedule next dump of the index.
   TimeStamp      mLastDumpTime;
   // Timer of delayed update/build.
   nsCOMPtr<nsITimer> mUpdateTimer;
   // True when build or update event is posted
   bool               mUpdateEventPending;
   // Helper members used when reading/writing index from/to disk.
   // Contains number of entries that should be skipped:
   //  - in hashtable when writing index because they were already written
   //  - in index file when reading index because they were already read
   uint32_t                  mSkipEntries;
   // Number of entries that should be written to disk. This is number of entries
   // in hashtable that are initialized and are not marked as removed when writing
   // begins.
   uint32_t                  mProcessEntries;
   char                     *mRWBuf;
   uint32_t                  mRWBufSize;
   uint32_t                  mRWBufPos;
   nsRefPtr<CacheHash>       mRWHash;
   // Reading of journal succeeded if true.
   bool                      mJournalReadSuccessfully;
   // Handle used for writing and reading index file.
   nsRefPtr<CacheFileHandle> mIndexHandle;
   // Handle used for reading journal file.
   nsRefPtr<CacheFileHandle> mJournalHandle;
   // Used to check the existence of the file during reading process.
   nsRefPtr<CacheFileHandle> mTmpHandle;
   nsRefPtr<FileOpenHelper>  mIndexFileOpener;
   nsRefPtr<FileOpenHelper>  mJournalFileOpener;
   nsRefPtr<FileOpenHelper>  mTmpFileOpener;
   // Directory enumerator used when building and updating index.
   nsCOMPtr<nsIDirectoryEnumerator> mDirEnumerator;
   // Main index hashtable.
   nsTHashtable<CacheIndexEntry> mIndex;
   // We cannot add, remove or change any entry in mIndex in states READING and
   // WRITING. We track all changes in mPendingUpdates during these states.
   nsTHashtable<CacheIndexEntry> mPendingUpdates;
   // Contains information statistics for mIndex + mPendingUpdates.
   CacheIndexStats               mIndexStats;
   // When reading journal, we must first parse the whole file and apply the
   // changes iff the journal was read successfully. mTmpJournal is used to store
   // entries from the journal file. We throw away all these entries if parsing
   // of the journal fails or the hash does not match.
   nsTHashtable<CacheIndexEntry> mTmpJournal;
   // Arrays that keep entry records ordered by eviction preference. When looking
   // for an entry to evict, we first try to find an expired entry. If there is
   // no expired entry, we take the entry with lowest valid frecency. Zero
   // frecency is an initial value and such entries are stored at the end of the
   // array. Uninitialized entries and entries marked as deleted are not present
   // in these arrays.
   nsTArray<CacheIndexRecord *>  mFrecencyArray;
   nsTArray<CacheIndexRecord *>  mExpirationArray;
   nsTArray<CacheIndexIterator *> mIterators;
   class DiskConsumptionObserver : public nsRunnable
   {
   public:
     static DiskConsumptionObserver* Init(nsICacheStorageConsumptionObserver* aObserver)
     {
       nsWeakPtr observer = do_GetWeakReference(aObserver);
       if (!observer)
         return nullptr;
       return new DiskConsumptionObserver(observer);
     }
     void OnDiskConsumption(int64_t aSize)
     {
       mSize = aSize;
       NS_DispatchToMainThread(this);
     }
   private:
     DiskConsumptionObserver(nsWeakPtr const &aWeakObserver)
       : mObserver(aWeakObserver) { }
     virtual ~DiskConsumptionObserver() { }
     NS_IMETHODIMP Run()
     {
       MOZ_ASSERT(NS_IsMainThread());
       nsCOMPtr<nsICacheStorageConsumptionObserver> observer =
         do_QueryReferent(mObserver);
       if (observer) {
         observer->OnNetworkCacheDiskConsumption(mSize);
       }
       return NS_OK;
     }
     nsWeakPtr mObserver;
     int64_t mSize;
   };
   // List of async observers that want to get disk consumption information
   nsTArray<nsRefPtr<DiskConsumptionObserver> > mDiskConsumptionObservers;
 };
 class CacheIndexAutoLock {
 public:
   CacheIndexAutoLock(CacheIndex *aIndex)
     : mIndex(aIndex)
     , mLocked(true)
   {
     mIndex->Lock();
   }
   ~CacheIndexAutoLock()
   {
     if (mLocked) {
       mIndex->Unlock();
     }
   }
   void Lock()
   {
     MOZ_ASSERT(!mLocked);
     mIndex->Lock();
     mLocked = true;
   }
   void Unlock()
   {
     MOZ_ASSERT(mLocked);
     mIndex->Unlock();
     mLocked = false;
   }
 private:
   nsRefPtr<CacheIndex> mIndex;
   bool mLocked;
 };
 class CacheIndexAutoUnlock {
 public:
   CacheIndexAutoUnlock(CacheIndex *aIndex)
     : mIndex(aIndex)
     , mLocked(false)
   {
     mIndex->Unlock();
   }
   ~CacheIndexAutoUnlock()
   {
     if (!mLocked) {
       mIndex->Lock();
     }
   }
   void Lock()
   {
     MOZ_ASSERT(!mLocked);
     mIndex->Lock();
     mLocked = true;
   }
   void Unlock()
   {
     MOZ_ASSERT(mLocked);
     mIndex->Unlock();
     mLocked = false;
   }
 private:
   nsRefPtr<CacheIndex> mIndex;
   bool mLocked;
 };
 } // net
 } // mozilla
 #endif

The Tor Browser / annotate

netwerk/cache2/CacheIndex.h@6474c204b198 (annotated)

netwerk/cache2/CacheIndex.h