/* 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 CacheFileIOManager__h__
#define CacheFileIOManager__h__

#include "CacheIOThread.h"
#include "CacheStorageService.h"
#include "CacheHashUtils.h"
#include "nsIEventTarget.h"
#include "nsINamed.h"
#include "nsITimer.h"
#include "nsCOMPtr.h"
#include "mozilla/Atomics.h"
#include "mozilla/SHA1.h"
#include "mozilla/StaticPtr.h"
#include "mozilla/TimeStamp.h"
#include "nsTArray.h"
#include "nsString.h"
#include "nsTHashtable.h"
#include "prio.h"

//#define DEBUG_HANDLES 1

class nsIFile;
class nsITimer;
class nsIDirectoryEnumerator;
class nsILoadContextInfo;

namespace mozilla {
namespace net {

class CacheFile;
class CacheFileIOListener;

#ifdef DEBUG_HANDLES
class CacheFileHandlesEntry;
#endif

#define ENTRIES_DIR "entries"
#define DOOMED_DIR "doomed"
#define TRASH_DIR "trash"

class CacheFileHandle final : public nsISupports {
 public:
  enum class PinningStatus : uint32_t { UNKNOWN, NON_PINNED, PINNED };

  NS_DECL_THREADSAFE_ISUPPORTS
  bool DispatchRelease();

  CacheFileHandle(const SHA1Sum::Hash* aHash, bool aPriority,
                  PinningStatus aPinning);
  CacheFileHandle(const nsACString& aKey, bool aPriority,
                  PinningStatus aPinning);
  void Log();
  bool IsDoomed() const { return mIsDoomed; }
  const SHA1Sum::Hash* Hash() const { return mHash; }
  int64_t FileSize() const { return mFileSize; }
  uint32_t FileSizeInK() const;
  bool IsPriority() const { return mPriority; }
  bool FileExists() const { return mFileExists; }
  bool IsClosed() const { return mClosed; }
  bool IsSpecialFile() const { return mSpecialFile; }
  nsCString& Key() { return mKey; }

  // Returns false when this handle has been doomed based on the pinning state
  // update.
  bool SetPinned(bool aPinned);
  void SetInvalid() { mInvalid = true; }

  // Memory reporting
  size_t SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const;
  size_t SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const;

 private:
  friend class CacheFileIOManager;
  friend class CacheFileHandles;
  friend class ReleaseNSPRHandleEvent;

  virtual ~CacheFileHandle();

  const SHA1Sum::Hash* mHash;
  mozilla::Atomic<bool, ReleaseAcquire> mIsDoomed;
  mozilla::Atomic<bool, ReleaseAcquire> mClosed;

  // mPriority and mSpecialFile are plain "bool", not "bool:1", so as to
  // avoid bitfield races with the byte containing mInvalid et al.  See
  // bug 1278502.
  bool const mPriority;
  bool const mSpecialFile;

  mozilla::Atomic<bool, Relaxed> mInvalid;

  // These bit flags are all accessed only on the IO thread
  bool mFileExists : 1;  // This means that the file should exists,
                         // but it can be still deleted by OS/user
                         // and then a subsequent OpenNSPRFileDesc()
                         // will fail.

  // Both initially false.  Can be raised to true only when this handle is to be
  // doomed during the period when the pinning status is unknown.  After the
  // pinning status determination we check these flags and possibly doom. These
  // flags are only accessed on the IO thread.
  bool mDoomWhenFoundPinned : 1;
  bool mDoomWhenFoundNonPinned : 1;
  // Set when after shutdown AND:
  // - when writing: writing data (not metadata) OR the physical file handle is
  //   not currently open
  // - when truncating: the physical file handle is not currently open
  // When set it prevents any further writes or truncates on such handles to
  // happen immediately after shutdown and gives a chance to write metadata of
  // already open files quickly as possible (only that renders them actually
  // usable by the cache.)
  bool mKilled : 1;
  // For existing files this is always pre-set to UNKNOWN.  The status is
  // udpated accordingly after the matadata has been parsed. For new files the
  // flag is set according to which storage kind is opening the cache entry and
  // remains so for the handle's lifetime. The status can only change from
  // UNKNOWN (if set so initially) to one of PINNED or NON_PINNED and it stays
  // unchanged afterwards. This status is only accessed on the IO thread.
  PinningStatus mPinning;

  nsCOMPtr<nsIFile> mFile;

  // file size is atomic because it is used on main thread by
  // nsHttpChannel::ReportNetVSCacheTelemetry()
  Atomic<int64_t, Relaxed> mFileSize;
  PRFileDesc* mFD;  // if null then the file doesn't exists on the disk
  nsCString mKey;
};

class CacheFileHandles {
 public:
  CacheFileHandles();
  ~CacheFileHandles();

  nsresult GetHandle(const SHA1Sum::Hash* aHash, CacheFileHandle** _retval);
  already_AddRefed<CacheFileHandle> NewHandle(const SHA1Sum::Hash*,
                                              bool aPriority,
                                              CacheFileHandle::PinningStatus);
  void RemoveHandle(CacheFileHandle* aHandlle);
  void GetAllHandles(nsTArray<RefPtr<CacheFileHandle> >* _retval);
  void GetActiveHandles(nsTArray<RefPtr<CacheFileHandle> >* _retval);
  void ClearAll();
  uint32_t HandleCount();

#ifdef DEBUG_HANDLES
  void Log(CacheFileHandlesEntry* entry);
#endif

  // Memory reporting
  size_t SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const;
  size_t SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const;

  class HandleHashKey : public PLDHashEntryHdr {
   public:
    typedef const SHA1Sum::Hash& KeyType;
    typedef const SHA1Sum::Hash* KeyTypePointer;

    explicit HandleHashKey(KeyTypePointer aKey) {
      MOZ_COUNT_CTOR(HandleHashKey);
      mHash = MakeUnique<uint8_t[]>(SHA1Sum::kHashSize);
      memcpy(mHash.get(), aKey, sizeof(SHA1Sum::Hash));
    }
    HandleHashKey(const HandleHashKey& aOther) {
      MOZ_ASSERT_UNREACHABLE("HandleHashKey copy constructor is forbidden!");
    }
    MOZ_COUNTED_DTOR(HandleHashKey)

    bool KeyEquals(KeyTypePointer aKey) const {
      return memcmp(mHash.get(), aKey, sizeof(SHA1Sum::Hash)) == 0;
    }
    static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
    static PLDHashNumber HashKey(KeyTypePointer aKey) {
      return (reinterpret_cast<const uint32_t*>(aKey))[0];
    }

    void AddHandle(CacheFileHandle* aHandle);
    void RemoveHandle(CacheFileHandle* aHandle);
    already_AddRefed<CacheFileHandle> GetNewestHandle();
    void GetHandles(nsTArray<RefPtr<CacheFileHandle> >& aResult);

    SHA1Sum::Hash* Hash() const {
      return reinterpret_cast<SHA1Sum::Hash*>(mHash.get());
    }
    bool IsEmpty() const { return mHandles.Length() == 0; }

    enum { ALLOW_MEMMOVE = true };

#ifdef DEBUG
    void AssertHandlesState();
#endif

    // Memory reporting
    size_t SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const;
    size_t SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const;

   private:
    // We can't make this UniquePtr<SHA1Sum::Hash>, because you can't have
    // UniquePtrs with known bounds.  So we settle for this representation
    // and using appropriate casts when we need to access it as a
    // SHA1Sum::Hash.
    UniquePtr<uint8_t[]> mHash;
    // Use weak pointers since the hash table access is on a single thread
    // only and CacheFileHandle removes itself from this table in its dtor
    // that may only be called on the same thread as we work with the hashtable
    // since we dispatch its Release() to this thread.
    nsTArray<CacheFileHandle*> mHandles;
  };

 private:
  nsTHashtable<HandleHashKey> mTable;
};

////////////////////////////////////////////////////////////////////////////////

class OpenFileEvent;
class ReadEvent;
class WriteEvent;
class MetadataWriteScheduleEvent;
class CacheFileContextEvictor;

#define CACHEFILEIOLISTENER_IID                      \
  { /* dcaf2ddc-17cf-4242-bca1-8c86936375a5 */       \
    0xdcaf2ddc, 0x17cf, 0x4242, {                    \
      0xbc, 0xa1, 0x8c, 0x86, 0x93, 0x63, 0x75, 0xa5 \
    }                                                \
  }

class CacheFileIOListener : public nsISupports {
 public:
  NS_DECLARE_STATIC_IID_ACCESSOR(CACHEFILEIOLISTENER_IID)

  NS_IMETHOD OnFileOpened(CacheFileHandle* aHandle, nsresult aResult) = 0;
  NS_IMETHOD OnDataWritten(CacheFileHandle* aHandle, const char* aBuf,
                           nsresult aResult) = 0;
  NS_IMETHOD OnDataRead(CacheFileHandle* aHandle, char* aBuf,
                        nsresult aResult) = 0;
  NS_IMETHOD OnFileDoomed(CacheFileHandle* aHandle, nsresult aResult) = 0;
  NS_IMETHOD OnEOFSet(CacheFileHandle* aHandle, nsresult aResult) = 0;
  NS_IMETHOD OnFileRenamed(CacheFileHandle* aHandle, nsresult aResult) = 0;

  virtual bool IsKilled() { return false; }
};

NS_DEFINE_STATIC_IID_ACCESSOR(CacheFileIOListener, CACHEFILEIOLISTENER_IID)

class CacheFileIOManager final : public nsITimerCallback, public nsINamed {
 public:
  NS_DECL_THREADSAFE_ISUPPORTS
  NS_DECL_NSITIMERCALLBACK
  NS_DECL_NSINAMED

  enum {
    OPEN = 0U,
    CREATE = 1U,
    CREATE_NEW = 2U,
    PRIORITY = 4U,
    SPECIAL_FILE = 8U,
    PINNED = 16U
  };

  CacheFileIOManager();

  static nsresult Init();
  static nsresult Shutdown();
  static nsresult OnProfile();
  static already_AddRefed<nsIEventTarget> IOTarget();
  static already_AddRefed<CacheIOThread> IOThread();
  static bool IsOnIOThread();
  static bool IsOnIOThreadOrCeased();
  static bool IsShutdown();

  // Make aFile's WriteMetadataIfNeeded be called automatically after
  // a short interval.
  static nsresult ScheduleMetadataWrite(CacheFile* aFile);
  // Remove aFile from the scheduling registry array.
  // WriteMetadataIfNeeded will not be automatically called.
  static nsresult UnscheduleMetadataWrite(CacheFile* aFile);
  // Shuts the scheduling off and flushes all pending metadata writes.
  static nsresult ShutdownMetadataWriteScheduling();

  static nsresult OpenFile(const nsACString& aKey, uint32_t aFlags,
                           CacheFileIOListener* aCallback);
  static nsresult Read(CacheFileHandle* aHandle, int64_t aOffset, char* aBuf,
                       int32_t aCount, CacheFileIOListener* aCallback);
  static nsresult Write(CacheFileHandle* aHandle, int64_t aOffset,
                        const char* aBuf, int32_t aCount, bool aValidate,
                        bool aTruncate, CacheFileIOListener* aCallback);
  // PinningDoomRestriction:
  // NO_RESTRICTION
  //    no restriction is checked, the file is simply always doomed
  // DOOM_WHEN_(NON)_PINNED, we branch based on the pinning status of the
  // handle:
  //   UNKNOWN: the handle is marked to be doomed when later found (non)pinned
  //   PINNED/NON_PINNED: doom only when the restriction matches the pin status
  //      and the handle has not yet been required to doom during the UNKNOWN
  //      period
  enum PinningDoomRestriction {
    NO_RESTRICTION,
    DOOM_WHEN_NON_PINNED,
    DOOM_WHEN_PINNED
  };
  static nsresult DoomFile(CacheFileHandle* aHandle,
                           CacheFileIOListener* aCallback);
  static nsresult DoomFileByKey(const nsACString& aKey,
                                CacheFileIOListener* aCallback);
  static nsresult ReleaseNSPRHandle(CacheFileHandle* aHandle);
  static nsresult TruncateSeekSetEOF(CacheFileHandle* aHandle,
                                     int64_t aTruncatePos, int64_t aEOFPos,
                                     CacheFileIOListener* aCallback);
  static nsresult RenameFile(CacheFileHandle* aHandle,
                             const nsACString& aNewName,
                             CacheFileIOListener* aCallback);
  static nsresult EvictIfOverLimit();
  static nsresult EvictAll();
  static nsresult EvictByContext(nsILoadContextInfo* aLoadContextInfo,
                                 bool aPinning, const nsAString& aOrigin);

  static nsresult InitIndexEntry(CacheFileHandle* aHandle,
                                 OriginAttrsHash aOriginAttrsHash,
                                 bool aAnonymous, bool aPinning);
  static nsresult UpdateIndexEntry(CacheFileHandle* aHandle,
                                   const uint32_t* aFrecency,
                                   const bool* aHasAltData,
                                   const uint16_t* aOnStartTime,
                                   const uint16_t* aOnStopTime,
                                   const uint8_t* aContentType);

  static nsresult UpdateIndexEntry();

  enum EEnumerateMode { ENTRIES, DOOMED };

  static void GetCacheDirectory(nsIFile** result);
#if defined(MOZ_WIDGET_ANDROID)
  static void GetProfilelessCacheDirectory(nsIFile** result);
#endif

  // Calls synchronously OnEntryInfo for an entry with the given hash.
  // Tries to find an existing entry in the service hashtables first, if not
  // found, loads synchronously from disk file.
  // Callable on the IO thread only.
  static nsresult GetEntryInfo(
      const SHA1Sum::Hash* aHash,
      CacheStorageService::EntryInfoCallback* aCallback);

  // Memory reporting
  static size_t SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf);
  static size_t SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf);

 private:
  friend class CacheFileHandle;
  friend class CacheFileChunk;
  friend class CacheFile;
  friend class ShutdownEvent;
  friend class OpenFileEvent;
  friend class CloseHandleEvent;
  friend class ReadEvent;
  friend class WriteEvent;
  friend class DoomFileEvent;
  friend class DoomFileByKeyEvent;
  friend class ReleaseNSPRHandleEvent;
  friend class TruncateSeekSetEOFEvent;
  friend class RenameFileEvent;
  friend class CacheIndex;
  friend class MetadataWriteScheduleEvent;
  friend class CacheFileContextEvictor;

  virtual ~CacheFileIOManager();

  nsresult InitInternal();
  void ShutdownInternal();

  nsresult OpenFileInternal(const SHA1Sum::Hash* aHash, const nsACString& aKey,
                            uint32_t aFlags, CacheFileHandle** _retval);
  nsresult OpenSpecialFileInternal(const nsACString& aKey, uint32_t aFlags,
                                   CacheFileHandle** _retval);
  void CloseHandleInternal(CacheFileHandle* aHandle);
  nsresult ReadInternal(CacheFileHandle* aHandle, int64_t aOffset, char* aBuf,
                        int32_t aCount);
  nsresult WriteInternal(CacheFileHandle* aHandle, int64_t aOffset,
                         const char* aBuf, int32_t aCount, bool aValidate,
                         bool aTruncate);
  nsresult DoomFileInternal(
      CacheFileHandle* aHandle,
      PinningDoomRestriction aPinningStatusRestriction = NO_RESTRICTION);
  nsresult DoomFileByKeyInternal(const SHA1Sum::Hash* aHash);
  nsresult MaybeReleaseNSPRHandleInternal(CacheFileHandle* aHandle,
                                          bool aIgnoreShutdownLag = false);
  nsresult TruncateSeekSetEOFInternal(CacheFileHandle* aHandle,
                                      int64_t aTruncatePos, int64_t aEOFPos);
  nsresult RenameFileInternal(CacheFileHandle* aHandle,
                              const nsACString& aNewName);
  nsresult EvictIfOverLimitInternal();
  nsresult OverLimitEvictionInternal();
  nsresult EvictAllInternal();
  nsresult EvictByContextInternal(nsILoadContextInfo* aLoadContextInfo,
                                  bool aPinning, const nsAString& aOrigin);

  nsresult TrashDirectory(nsIFile* aFile);
  static void OnTrashTimer(nsITimer* aTimer, void* aClosure);
  nsresult StartRemovingTrash();
  nsresult RemoveTrashInternal();
  nsresult FindTrashDirToRemove();

  nsresult CreateFile(CacheFileHandle* aHandle);
  static void HashToStr(const SHA1Sum::Hash* aHash, nsACString& _retval);
  static nsresult StrToHash(const nsACString& aHash, SHA1Sum::Hash* _retval);
  nsresult GetFile(const SHA1Sum::Hash* aHash, nsIFile** _retval);
  nsresult GetSpecialFile(const nsACString& aKey, nsIFile** _retval);
  nsresult GetDoomedFile(nsIFile** _retval);
  nsresult IsEmptyDirectory(nsIFile* aFile, bool* _retval);
  nsresult CheckAndCreateDir(nsIFile* aFile, const char* aDir,
                             bool aEnsureEmptyDir);
  nsresult CreateCacheTree();
  nsresult OpenNSPRHandle(CacheFileHandle* aHandle, bool aCreate = false);
  void NSPRHandleUsed(CacheFileHandle* aHandle);

  // Removing all cache files during shutdown
  nsresult SyncRemoveDir(nsIFile* aFile, const char* aDir);
  void SyncRemoveAllCacheFiles();

  nsresult ScheduleMetadataWriteInternal(CacheFile* aFile);
  void UnscheduleMetadataWriteInternal(CacheFile* aFile);
  void ShutdownMetadataWriteSchedulingInternal();

  static nsresult CacheIndexStateChanged();
  void CacheIndexStateChangedInternal();

  // Smart size calculation. UpdateSmartCacheSize() must be called on IO thread.
  // It is called in EvictIfOverLimitInternal() just before we decide whether to
  // start overlimit eviction or not and also in OverLimitEvictionInternal()
  // before we start an eviction loop.
  nsresult UpdateSmartCacheSize(int64_t aFreeSpace);

  // Memory reporting (private part)
  size_t SizeOfExcludingThisInternal(mozilla::MallocSizeOf mallocSizeOf) const;

  static StaticRefPtr<CacheFileIOManager> gInstance;

  TimeStamp mStartTime;
  // Set true on the IO thread, CLOSE level as part of the internal shutdown
  // procedure.
  bool mShuttingDown;
  RefPtr<CacheIOThread> mIOThread;
  nsCOMPtr<nsIFile> mCacheDirectory;
#if defined(MOZ_WIDGET_ANDROID)
  // On Android we add the active profile directory name between the path
  // and the 'cache2' leaf name.  However, to delete any leftover data from
  // times before we were doing it, we still need to access the directory
  // w/o the profile name in the path.  Here it is stored.
  nsCOMPtr<nsIFile> mCacheProfilelessDirectory;
#endif
  bool mTreeCreated;
  bool mTreeCreationFailed;
  CacheFileHandles mHandles;
  nsTArray<CacheFileHandle*> mHandlesByLastUsed;
  nsTArray<CacheFileHandle*> mSpecialHandles;
  nsTArray<RefPtr<CacheFile> > mScheduledMetadataWrites;
  nsCOMPtr<nsITimer> mMetadataWritesTimer;
  bool mOverLimitEvicting;
  // When overlimit eviction is too slow and cache size reaches 105% of the
  // limit, this flag is set and no other content is cached to prevent
  // uncontrolled cache growing.
  bool mCacheSizeOnHardLimit;
  bool mRemovingTrashDirs;
  nsCOMPtr<nsITimer> mTrashTimer;
  nsCOMPtr<nsIFile> mTrashDir;
  nsCOMPtr<nsIDirectoryEnumerator> mTrashDirEnumerator;
  nsTArray<nsCString> mFailedTrashDirs;
  RefPtr<CacheFileContextEvictor> mContextEvictor;
  TimeStamp mLastSmartSizeTime;
};

}  // namespace net
}  // namespace mozilla

#endif