CacheFileContextEvictor.h

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/* 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 CacheFileContextEvictor__h__

#define CacheFileContextEvictor__h__

#include "mozilla/UniquePtr.h"

#include "nsCOMPtr.h"

#include "nsString.h"

#include "nsTArray.h"

class nsIFile;

class nsILoadContextInfo;

namespace mozilla {

namespace net {

class CacheIndexIterator;

struct CacheFileContextEvictorEntry {

  nsCOMPtr<nsILoadContextInfo> mInfo;

  bool mPinned = false;

  nsString mOrigin;       // it can be empty

  PRTime mTimeStamp = 0;  // in milliseconds

  RefPtr<CacheIndexIterator> mIterator;

};

class CacheFileContextEvictor {

 public:

  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CacheFileContextEvictor)

  CacheFileContextEvictor();

 private:

  virtual ~CacheFileContextEvictor();

 public:

  nsresult Init(nsIFile* aCacheDirectory);

  void Shutdown();

  // Returns number of contexts that are being evicted.

  uint32_t ContextsCount();

  // Start evicting given context and an origin, if not empty.

  nsresult AddContext(nsILoadContextInfo* aLoadContextInfo, bool aPinned,

                      const nsAString& aOrigin);

  // CacheFileIOManager calls this method when CacheIndex's state changes. We

  // check whether the index is up to date and start or stop evicting according

  // to index's state.

  void CacheIndexStateChanged();

  // CacheFileIOManager calls this method to check whether an entry file should

  // be considered as evicted. It returns true when there is a matching context

  // info to the given key and the last modified time of the entry file is

  // earlier than the time stamp of the time when the context was added to the

  // evictor.

  void WasEvicted(const nsACString& aKey, nsIFile* aFile,

                  bool* aEvictedAsPinned, bool* aEvictedAsNonPinned);

 private:

  // Writes information about eviction of the given context to the disk. This is

  // done for every context added to the evictor to be able to recover eviction

  // after a shutdown or crash. When the context file is found after startup, we

  // restore mTimeStamp from the last modified time of the file.

  nsresult PersistEvictionInfoToDisk(nsILoadContextInfo* aLoadContextInfo,

                                     bool aPinned, const nsAString& aOrigin);

  // Once we are done with eviction for the given context, the eviction info is

  // removed from the disk.

  nsresult RemoveEvictInfoFromDisk(nsILoadContextInfo* aLoadContextInfo,

                                   bool aPinned, const nsAString& aOrigin);

  // Tries to load all contexts from the disk. This method is called just once

  // after startup.

  nsresult LoadEvictInfoFromDisk();

  nsresult GetContextFile(nsILoadContextInfo* aLoadContextInfo, bool aPinned,

                          const nsAString& aOrigin, nsIFile** _retval);

  void CreateIterators();

  void CloseIterators();

  void StartEvicting();

  void EvictEntries();

  // Whether eviction is in progress

  bool mEvicting{false};

  // Whether index is up to date. We wait with eviction until the index finishes

  // update process when it is outdated. NOTE: We also stop eviction in progress

  // when the index is found outdated, the eviction is restarted again once the

  // update process finishes.

  bool mIndexIsUpToDate{false};

  // Whether we already tried to restore unfinished jobs from previous run after

  // startup.

  static bool sDiskAlreadySearched;

  // Array of contexts being evicted.

  nsTArray<UniquePtr<CacheFileContextEvictorEntry>> mEntries;

  nsCOMPtr<nsIFile> mCacheDirectory;

  nsCOMPtr<nsIFile> mEntriesDir;

};

}  // namespace net

}  // namespace mozilla

#endif