netwerk/cache2/CacheFileContextEvictor.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 CacheFileContextEvictor__h__
   6 #define CacheFileContextEvictor__h__
   7
   8 #include "mozilla/UniquePtr.h"
   9 #include "nsCOMPtr.h"
  10 #include "nsString.h"
  11 #include "nsTArray.h"
  12
  13 class nsIFile;
  14 class nsILoadContextInfo;
  15
  16 namespace mozilla {
  17 namespace net {
  18
  19 class CacheIndexIterator;
  20
  21 struct CacheFileContextEvictorEntry {
  22   nsCOMPtr<nsILoadContextInfo> mInfo;
  23   bool mPinned = false;
  24   nsString mOrigin;       // it can be empty
  25   PRTime mTimeStamp = 0;  // in milliseconds
  26   RefPtr<CacheIndexIterator> mIterator;
  27 };
  28
  29 class CacheFileContextEvictor {
  30  public:
  31   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CacheFileContextEvictor)
  32
  33   CacheFileContextEvictor();
  34
  35  private:
  36   virtual ~CacheFileContextEvictor();
  37
  38  public:
  39   nsresult Init(nsIFile* aCacheDirectory);
  40   void Shutdown();
  41
  42   // Returns number of contexts that are being evicted.
  43   uint32_t ContextsCount();
  44   // Start evicting given context and an origin, if not empty.
  45   nsresult AddContext(nsILoadContextInfo* aLoadContextInfo, bool aPinned,
  46                       const nsAString& aOrigin);
  47   // CacheFileIOManager calls this method when CacheIndex's state changes. We
  48   // check whether the index is up to date and start or stop evicting according
  49   // to index's state.
  50   void CacheIndexStateChanged();
  51   // CacheFileIOManager calls this method to check whether an entry file should
  52   // be considered as evicted. It returns true when there is a matching context
  53   // info to the given key and the last modified time of the entry file is
  54   // earlier than the time stamp of the time when the context was added to the
  55   // evictor.
  56   void WasEvicted(const nsACString& aKey, nsIFile* aFile,
  57                   bool* aEvictedAsPinned, bool* aEvictedAsNonPinned);
  58
  59  private:
  60   // Writes information about eviction of the given context to the disk. This is
  61   // done for every context added to the evictor to be able to recover eviction
  62   // after a shutdown or crash. When the context file is found after startup, we
  63   // restore mTimeStamp from the last modified time of the file.
  64   nsresult PersistEvictionInfoToDisk(nsILoadContextInfo* aLoadContextInfo,
  65                                      bool aPinned, const nsAString& aOrigin);
  66   // Once we are done with eviction for the given context, the eviction info is
  67   // removed from the disk.
  68   nsresult RemoveEvictInfoFromDisk(nsILoadContextInfo* aLoadContextInfo,
  69                                    bool aPinned, const nsAString& aOrigin);
  70   // Tries to load all contexts from the disk. This method is called just once
  71   // after startup.
  72   nsresult LoadEvictInfoFromDisk();
  73   nsresult GetContextFile(nsILoadContextInfo* aLoadContextInfo, bool aPinned,
  74                           const nsAString& aOrigin, nsIFile** _retval);
  75
  76   void CreateIterators();
  77   void CloseIterators();
  78   void StartEvicting();
  79   void EvictEntries();
  80
  81   // Whether eviction is in progress
  82   bool mEvicting{false};
  83   // Whether index is up to date. We wait with eviction until the index finishes
  84   // update process when it is outdated. NOTE: We also stop eviction in progress
  85   // when the index is found outdated, the eviction is restarted again once the
  86   // update process finishes.
  87   bool mIndexIsUpToDate{false};
  88   // Whether we already tried to restore unfinished jobs from previous run after
  89   // startup.
  90   static bool sDiskAlreadySearched;
  91   // Array of contexts being evicted.
  92   nsTArray<UniquePtr<CacheFileContextEvictorEntry>> mEntries;
  93   nsCOMPtr<nsIFile> mCacheDirectory;
  94   nsCOMPtr<nsIFile> mEntriesDir;
  95 };
  96
  97 }  // namespace net
  98 }  // namespace mozilla
  99
 100 #endif