/* 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/. */

#include "CacheLog.h"
#include "CacheFileChunk.h"

#include "CacheFile.h"
#include "nsThreadUtils.h"

namespace mozilla {
namespace net {

#define kMinBufSize        512

class NotifyUpdateListenerEvent : public nsRunnable {
public:
  NotifyUpdateListenerEvent(CacheFileChunkListener *aCallback,
                            CacheFileChunk *aChunk)
    : mCallback(aCallback)
    , mChunk(aChunk)
  {
    LOG(("NotifyUpdateListenerEvent::NotifyUpdateListenerEvent() [this=%p]",
         this));
    MOZ_COUNT_CTOR(NotifyUpdateListenerEvent);
  }

protected:
  ~NotifyUpdateListenerEvent()
  {
    LOG(("NotifyUpdateListenerEvent::~NotifyUpdateListenerEvent() [this=%p]",
         this));
    MOZ_COUNT_DTOR(NotifyUpdateListenerEvent);
  }

public:
  NS_IMETHOD Run()
  {
    LOG(("NotifyUpdateListenerEvent::Run() [this=%p]", this));

    mCallback->OnChunkUpdated(mChunk);
    return NS_OK;
  }

protected:
  nsCOMPtr<CacheFileChunkListener> mCallback;
  RefPtr<CacheFileChunk>           mChunk;
};

bool
CacheFileChunk::DispatchRelease()
{
  if (NS_IsMainThread()) {
    return false;
  }

  RefPtr<nsRunnableMethod<CacheFileChunk, MozExternalRefCountType, false> > event =
    NS_NewNonOwningRunnableMethod(this, &CacheFileChunk::Release);
  NS_DispatchToMainThread(event);

  return true;
}

NS_IMPL_ADDREF(CacheFileChunk)
NS_IMETHODIMP_(MozExternalRefCountType)
CacheFileChunk::Release()
{
  nsrefcnt count = mRefCnt - 1;
  if (DispatchRelease()) {
    // Redispatched to the main thread.
    return count;
  }

  NS_PRECONDITION(0 != mRefCnt, "dup release");
  count = --mRefCnt;
  NS_LOG_RELEASE(this, count, "CacheFileChunk");

  if (0 == count) {
    mRefCnt = 1;
    delete (this);
    return 0;
  }

  // We can safely access this chunk after decreasing mRefCnt since we re-post
  // all calls to Release() happening off the main thread to the main thread.
  // I.e. no other Release() that would delete the object could be run before
  // we call CacheFile::DeactivateChunk().
  //
  // NOTE: we don't grab the CacheFile's lock, so the chunk might be addrefed
  // on another thread before CacheFile::DeactivateChunk() grabs the lock on
  // this thread. To make sure we won't deactivate chunk that was just returned
  // to a new consumer we check mRefCnt once again in
  // CacheFile::DeactivateChunk() after we grab the lock.
  if (mActiveChunk && count == 1) {
    mFile->DeactivateChunk(this);
  }

  return count;
}

NS_INTERFACE_MAP_BEGIN(CacheFileChunk)
  NS_INTERFACE_MAP_ENTRY(mozilla::net::CacheFileIOListener)
  NS_INTERFACE_MAP_ENTRY(nsISupports)
NS_INTERFACE_MAP_END_THREADSAFE

CacheFileChunk::CacheFileChunk(CacheFile *aFile, uint32_t aIndex,
                               bool aInitByWriter)
  : CacheMemoryConsumer(aFile->mOpenAsMemoryOnly ? MEMORY_ONLY : DONT_REPORT)
  , mIndex(aIndex)
  , mState(INITIAL)
  , mStatus(NS_OK)
  , mIsDirty(false)
  , mActiveChunk(false)
  , mDataSize(0)
  , mReportedAllocation(0)
  , mLimitAllocation(!aFile->mOpenAsMemoryOnly && aInitByWriter)
  , mIsPriority(aFile->mPriority)
  , mBuf(nullptr)
  , mBufSize(0)
  , mRWBuf(nullptr)
  , mRWBufSize(0)
  , mReadHash(0)
  , mFile(aFile)
{
  LOG(("CacheFileChunk::CacheFileChunk() [this=%p, index=%u, initByWriter=%d]",
       this, aIndex, aInitByWriter));
  MOZ_COUNT_CTOR(CacheFileChunk);
}

CacheFileChunk::~CacheFileChunk()
{
  LOG(("CacheFileChunk::~CacheFileChunk() [this=%p]", this));
  MOZ_COUNT_DTOR(CacheFileChunk);

  if (mBuf) {
    free(mBuf);
    mBuf = nullptr;
    mBufSize = 0;
    ChunkAllocationChanged();
  }

  if (mRWBuf) {
    free(mRWBuf);
    mRWBuf = nullptr;
    mRWBufSize = 0;
    ChunkAllocationChanged();
  }
}

void
CacheFileChunk::InitNew()
{
  mFile->AssertOwnsLock();

  LOG(("CacheFileChunk::InitNew() [this=%p]", this));

  MOZ_ASSERT(mState == INITIAL);
  MOZ_ASSERT(NS_SUCCEEDED(mStatus));
  MOZ_ASSERT(!mBuf);
  MOZ_ASSERT(!mRWBuf);
  MOZ_ASSERT(!mIsDirty);
  MOZ_ASSERT(mDataSize == 0);

  mState = READY;
}

nsresult
CacheFileChunk::Read(CacheFileHandle *aHandle, uint32_t aLen,
                     CacheHash::Hash16_t aHash,
                     CacheFileChunkListener *aCallback)
{
  mFile->AssertOwnsLock();

  LOG(("CacheFileChunk::Read() [this=%p, handle=%p, len=%d, listener=%p]",
       this, aHandle, aLen, aCallback));

  MOZ_ASSERT(mState == INITIAL);
  MOZ_ASSERT(NS_SUCCEEDED(mStatus));
  MOZ_ASSERT(!mBuf);
  MOZ_ASSERT(!mRWBuf);
  MOZ_ASSERT(aLen);

  nsresult rv;

  mState = READING;

  if (CanAllocate(aLen)) {
    mRWBuf = static_cast<char *>(malloc(aLen));
    if (mRWBuf) {
      mRWBufSize = aLen;
      ChunkAllocationChanged();
    }
  }

  if (!mRWBuf) {
    // Allocation was denied or failed
    SetError(NS_ERROR_OUT_OF_MEMORY);
    return mStatus;
  }

  DoMemoryReport(MemorySize());

  rv = CacheFileIOManager::Read(aHandle, mIndex * kChunkSize, mRWBuf, aLen,
                                this);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    rv = mIndex ? NS_ERROR_FILE_CORRUPTED : NS_ERROR_FILE_NOT_FOUND;
    SetError(rv);
  } else {
    mListener = aCallback;
    mDataSize = aLen;
    mReadHash = aHash;
  }

  return rv;
}

nsresult
CacheFileChunk::Write(CacheFileHandle *aHandle,
                      CacheFileChunkListener *aCallback)
{
  mFile->AssertOwnsLock();

  LOG(("CacheFileChunk::Write() [this=%p, handle=%p, listener=%p]",
       this, aHandle, aCallback));

  MOZ_ASSERT(mState == READY);
  MOZ_ASSERT(NS_SUCCEEDED(mStatus));
  MOZ_ASSERT(!mRWBuf);
  MOZ_ASSERT(mBuf);
  MOZ_ASSERT(mDataSize); // Don't write chunk when it is empty

  nsresult rv;

  mState = WRITING;
  mRWBuf = mBuf;
  mRWBufSize = mBufSize;
  mBuf = nullptr;
  mBufSize = 0;

  rv = CacheFileIOManager::Write(aHandle, mIndex * kChunkSize, mRWBuf,
                                 mDataSize, false, false, this);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    SetError(rv);
  } else {
    mListener = aCallback;
    mIsDirty = false;
  }

  return rv;
}

void
CacheFileChunk::WaitForUpdate(CacheFileChunkListener *aCallback)
{
  mFile->AssertOwnsLock();

  LOG(("CacheFileChunk::WaitForUpdate() [this=%p, listener=%p]",
       this, aCallback));

  MOZ_ASSERT(mFile->mOutput);
  MOZ_ASSERT(IsReady());

#ifdef DEBUG
  for (uint32_t i = 0 ; i < mUpdateListeners.Length() ; i++) {
    MOZ_ASSERT(mUpdateListeners[i]->mCallback != aCallback);
  }
#endif

  ChunkListenerItem *item = new ChunkListenerItem();
  item->mTarget = CacheFileIOManager::IOTarget();
  if (!item->mTarget) {
    LOG(("CacheFileChunk::WaitForUpdate() - Cannot get Cache I/O thread! Using "
         "main thread for callback."));
    item->mTarget = do_GetMainThread();
  }
  item->mCallback = aCallback;
  MOZ_ASSERT(item->mTarget);
  item->mCallback = aCallback;

  mUpdateListeners.AppendElement(item);
}

nsresult
CacheFileChunk::CancelWait(CacheFileChunkListener *aCallback)
{
  mFile->AssertOwnsLock();

  LOG(("CacheFileChunk::CancelWait() [this=%p, listener=%p]", this, aCallback));

  MOZ_ASSERT(IsReady());

  uint32_t i;
  for (i = 0 ; i < mUpdateListeners.Length() ; i++) {
    ChunkListenerItem *item = mUpdateListeners[i];

    if (item->mCallback == aCallback) {
      mUpdateListeners.RemoveElementAt(i);
      delete item;
      break;
    }
  }

#ifdef DEBUG
  for ( ; i < mUpdateListeners.Length() ; i++) {
    MOZ_ASSERT(mUpdateListeners[i]->mCallback != aCallback);
  }
#endif

  return NS_OK;
}

nsresult
CacheFileChunk::NotifyUpdateListeners()
{
  mFile->AssertOwnsLock();

  LOG(("CacheFileChunk::NotifyUpdateListeners() [this=%p]", this));

  MOZ_ASSERT(IsReady());

  nsresult rv, rv2;

  rv = NS_OK;
  for (uint32_t i = 0 ; i < mUpdateListeners.Length() ; i++) {
    ChunkListenerItem *item = mUpdateListeners[i];

    LOG(("CacheFileChunk::NotifyUpdateListeners() - Notifying listener %p "
         "[this=%p]", item->mCallback.get(), this));

    RefPtr<NotifyUpdateListenerEvent> ev;
    ev = new NotifyUpdateListenerEvent(item->mCallback, this);
    rv2 = item->mTarget->Dispatch(ev, NS_DISPATCH_NORMAL);
    if (NS_FAILED(rv2) && NS_SUCCEEDED(rv))
      rv = rv2;
    delete item;
  }

  mUpdateListeners.Clear();

  return rv;
}

uint32_t
CacheFileChunk::Index()
{
  return mIndex;
}

CacheHash::Hash16_t
CacheFileChunk::Hash()
{
  mFile->AssertOwnsLock();

  MOZ_ASSERT(!mListener);
  MOZ_ASSERT(IsReady());

  return CacheHash::Hash16(mDataSize ? BufForReading() : nullptr, mDataSize);
}

uint32_t
CacheFileChunk::DataSize()
{
  mFile->AssertOwnsLock();
  return mDataSize;
}

void
CacheFileChunk::UpdateDataSize(uint32_t aOffset, uint32_t aLen, bool aEOF)
{
  mFile->AssertOwnsLock();

  MOZ_ASSERT(!aEOF, "Implement me! What to do with opened streams?");
  MOZ_ASSERT(aOffset <= mDataSize);
  MOZ_ASSERT(aLen != 0);

  // UpdateDataSize() is called only when we've written some data to the chunk
  // and we never write data anymore once some error occurs.
  MOZ_ASSERT(NS_SUCCEEDED(mStatus));

  LOG(("CacheFileChunk::UpdateDataSize() [this=%p, offset=%d, len=%d, EOF=%d]",
       this, aOffset, aLen, aEOF));

  mIsDirty = true;

  int64_t fileSize = kChunkSize * mIndex + aOffset + aLen;
  bool notify = false;

  if (fileSize > mFile->mDataSize)
    mFile->mDataSize = fileSize;

  if (aOffset + aLen > mDataSize) {
    mDataSize = aOffset + aLen;
    notify = true;
  }

  if (mState == READY || mState == WRITING) {
    MOZ_ASSERT(mValidityMap.Length() == 0);

    if (notify) {
      NotifyUpdateListeners();
    }

    return;
  }

  // We're still waiting for data from the disk. This chunk cannot be used by
  // input stream, so there must be no update listener. We also need to keep
  // track of where the data is written so that we can correctly merge the new
  // data with the old one.

  MOZ_ASSERT(mUpdateListeners.Length() == 0);
  MOZ_ASSERT(mState == READING);

  mValidityMap.AddPair(aOffset, aLen);
  mValidityMap.Log();
}

nsresult
CacheFileChunk::OnFileOpened(CacheFileHandle *aHandle, nsresult aResult)
{
  MOZ_CRASH("CacheFileChunk::OnFileOpened should not be called!");
  return NS_ERROR_UNEXPECTED;
}

nsresult
CacheFileChunk::OnDataWritten(CacheFileHandle *aHandle, const char *aBuf,
                              nsresult aResult)
{
  LOG(("CacheFileChunk::OnDataWritten() [this=%p, handle=%p, result=0x%08x]",
       this, aHandle, aResult));

  nsCOMPtr<CacheFileChunkListener> listener;

  {
    CacheFileAutoLock lock(mFile);

    MOZ_ASSERT(mState == WRITING);
    MOZ_ASSERT(mListener);

    if (NS_WARN_IF(NS_FAILED(aResult))) {
      SetError(aResult);
    }

    mState = READY;

    if (!mBuf) {
      mBuf = mRWBuf;
      mBufSize = mRWBufSize;
      mRWBuf = nullptr;
      mRWBufSize = 0;
    } else {
      free(mRWBuf);
      mRWBuf = nullptr;
      mRWBufSize = 0;
      ChunkAllocationChanged();
    }


    DoMemoryReport(MemorySize());

    mListener.swap(listener);
  }

  listener->OnChunkWritten(aResult, this);

  return NS_OK;
}

nsresult
CacheFileChunk::OnDataRead(CacheFileHandle *aHandle, char *aBuf,
                           nsresult aResult)
{
  LOG(("CacheFileChunk::OnDataRead() [this=%p, handle=%p, result=0x%08x]",
       this, aHandle, aResult));

  nsCOMPtr<CacheFileChunkListener> listener;

  {
    CacheFileAutoLock lock(mFile);

    MOZ_ASSERT(mState == READING);
    MOZ_ASSERT(mListener);

    if (NS_SUCCEEDED(aResult)) {
      CacheHash::Hash16_t hash = CacheHash::Hash16(mRWBuf, mRWBufSize);
      if (hash != mReadHash) {
        LOG(("CacheFileChunk::OnDataRead() - Hash mismatch! Hash of the data is"
             " %hx, hash in metadata is %hx. [this=%p, idx=%d]",
             hash, mReadHash, this, mIndex));
        aResult = NS_ERROR_FILE_CORRUPTED;
      }
      else {
        if (!mBuf) {
          // Just swap the buffers if we don't have mBuf yet
          MOZ_ASSERT(mDataSize == mRWBufSize);
          mBuf = mRWBuf;
          mBufSize = mRWBufSize;
          mRWBuf = nullptr;
          mRWBufSize = 0;
        } else {
          LOG(("CacheFileChunk::OnDataRead() - Merging buffers. [this=%p]",
               this));

          // Merge data with write buffer
          if (mRWBufSize >= mBufSize) {
            // The new data will fit into the buffer that contains data read
            // from the disk. Simply copy the valid pieces.
            mValidityMap.Log();
            for (uint32_t i = 0; i < mValidityMap.Length(); i++) {
              if (mValidityMap[i].Offset() + mValidityMap[i].Len() > mBufSize) {
                MOZ_CRASH("Unexpected error in validity map!");
              }
              memcpy(mRWBuf + mValidityMap[i].Offset(),
                     mBuf + mValidityMap[i].Offset(), mValidityMap[i].Len());
            }
            mValidityMap.Clear();

            free(mBuf);
            mBuf = mRWBuf;
            mBufSize = mRWBufSize;
            mRWBuf = nullptr;
            mRWBufSize = 0;
            ChunkAllocationChanged();
          } else {
            // Buffer holding the new data is larger. Use it as the destination
            // buffer to avoid reallocating mRWBuf. We need to copy those pieces
            // from mRWBuf which are not valid in mBuf.
            uint32_t invalidOffset = 0;
            uint32_t invalidLength;
            mValidityMap.Log();
            for (uint32_t i = 0; i < mValidityMap.Length(); i++) {
              MOZ_ASSERT(invalidOffset <= mValidityMap[i].Offset());
              invalidLength = mValidityMap[i].Offset() - invalidOffset;
              if (invalidLength > 0) {
                if (invalidOffset + invalidLength > mRWBufSize) {
                  MOZ_CRASH("Unexpected error in validity map!");
                }
                memcpy(mBuf + invalidOffset, mRWBuf + invalidOffset,
                       invalidLength);
              }
              invalidOffset = mValidityMap[i].Offset() + mValidityMap[i].Len();
            }
            if (invalidOffset < mRWBufSize) {
              invalidLength = mRWBufSize - invalidOffset;
              memcpy(mBuf + invalidOffset, mRWBuf + invalidOffset,
                     invalidLength);
            }
            mValidityMap.Clear();

            free(mRWBuf);
            mRWBuf = nullptr;
            mRWBufSize = 0;
            ChunkAllocationChanged();
          }

          DoMemoryReport(MemorySize());
        }
      }
    }

    if (NS_FAILED(aResult)) {
      aResult = mIndex ? NS_ERROR_FILE_CORRUPTED : NS_ERROR_FILE_NOT_FOUND;
      SetError(aResult);
      mDataSize = 0;
    }

    mState = READY;
    mListener.swap(listener);
  }

  listener->OnChunkRead(aResult, this);

  return NS_OK;
}

nsresult
CacheFileChunk::OnFileDoomed(CacheFileHandle *aHandle, nsresult aResult)
{
  MOZ_CRASH("CacheFileChunk::OnFileDoomed should not be called!");
  return NS_ERROR_UNEXPECTED;
}

nsresult
CacheFileChunk::OnEOFSet(CacheFileHandle *aHandle, nsresult aResult)
{
  MOZ_CRASH("CacheFileChunk::OnEOFSet should not be called!");
  return NS_ERROR_UNEXPECTED;
}

nsresult
CacheFileChunk::OnFileRenamed(CacheFileHandle *aHandle, nsresult aResult)
{
  MOZ_CRASH("CacheFileChunk::OnFileRenamed should not be called!");
  return NS_ERROR_UNEXPECTED;
}

bool
CacheFileChunk::IsReady() const
{
  mFile->AssertOwnsLock();

  return (NS_SUCCEEDED(mStatus) && (mState == READY || mState == WRITING));
}

bool
CacheFileChunk::IsDirty() const
{
  mFile->AssertOwnsLock();

  return mIsDirty;
}

nsresult
CacheFileChunk::GetStatus()
{
  mFile->AssertOwnsLock();

  return mStatus;
}

void
CacheFileChunk::SetError(nsresult aStatus)
{
  MOZ_ASSERT(NS_FAILED(aStatus));

  if (NS_FAILED(mStatus)) {
    // Remember only the first error code.
    return;
  }

  mStatus = aStatus;
}

char *
CacheFileChunk::BufForWriting() const
{
  mFile->AssertOwnsLock();

  MOZ_ASSERT(mBuf); // Writer should always first call EnsureBufSize()

  MOZ_ASSERT(NS_SUCCEEDED(mStatus));
  MOZ_ASSERT((mState == READY && !mRWBuf) ||
             (mState == WRITING && mRWBuf) ||
             (mState == READING && mRWBuf));

  return mBuf;
}

const char *
CacheFileChunk::BufForReading() const
{
  mFile->AssertOwnsLock();

  MOZ_ASSERT((mState == READY && mBuf && !mRWBuf) ||
             (mState == WRITING && mRWBuf));

  return mBuf ? mBuf : mRWBuf;
}

MOZ_WARN_UNUSED_RESULT nsresult
CacheFileChunk::EnsureBufSize(uint32_t aBufSize)
{
  mFile->AssertOwnsLock();

  // EnsureBufSize() is called only when we want to write some data to the chunk
  // and we never write data anymore once some error occurs.
  MOZ_ASSERT(NS_SUCCEEDED(mStatus));

  if (mBufSize >= aBufSize) {
    return NS_OK;
  }

  bool copy = false;
  if (!mBuf && mState == WRITING) {
    // We need to duplicate the data that is being written on the background
    // thread, so make sure that all the data fits into the new buffer.
    copy = true;

    if (mRWBufSize > aBufSize)
      aBufSize = mRWBufSize;
  }

  // find smallest power of 2 greater than or equal to aBufSize
  aBufSize--;
  aBufSize |= aBufSize >> 1;
  aBufSize |= aBufSize >> 2;
  aBufSize |= aBufSize >> 4;
  aBufSize |= aBufSize >> 8;
  aBufSize |= aBufSize >> 16;
  aBufSize++;

  const uint32_t minBufSize = kMinBufSize;
  const uint32_t maxBufSize = kChunkSize;
  aBufSize = clamped(aBufSize, minBufSize, maxBufSize);

  if (!CanAllocate(aBufSize - mBufSize)) {
    SetError(NS_ERROR_OUT_OF_MEMORY);
    return mStatus;
  }

  char *newBuf = static_cast<char *>(realloc(mBuf, aBufSize));
  if (!newBuf) {
    SetError(NS_ERROR_OUT_OF_MEMORY);
    return mStatus;
  }

  mBuf = newBuf;
  mBufSize = aBufSize;
  ChunkAllocationChanged();

  if (copy)
    memcpy(mBuf, mRWBuf, mRWBufSize);

  DoMemoryReport(MemorySize());

  return NS_OK;
}

// Memory reporting

size_t
CacheFileChunk::SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const
{
  size_t n = 0;
  n += mallocSizeOf(mBuf);
  n += mallocSizeOf(mRWBuf);
  n += mValidityMap.SizeOfExcludingThis(mallocSizeOf);

  return n;
}

size_t
CacheFileChunk::SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const
{
  return mallocSizeOf(this) + SizeOfExcludingThis(mallocSizeOf);
}

bool
CacheFileChunk::CanAllocate(uint32_t aSize)
{
  if (!mLimitAllocation) {
    return true;
  }

  LOG(("CacheFileChunk::CanAllocate() [this=%p, size=%u]", this, aSize));

  uint32_t limit = CacheObserver::MaxDiskChunksMemoryUsage(mIsPriority);
  if (limit == 0) {
    return true;
  }

  uint32_t usage = ChunksMemoryUsage();
  if (usage + aSize > limit) {
    LOG(("CacheFileChunk::CanAllocate() - Returning false. [this=%p]", this));
    return false;
  }

  return true;
}

void
CacheFileChunk::ChunkAllocationChanged()
{
  if (!mLimitAllocation) {
    return;
  }

  ChunksMemoryUsage() -= mReportedAllocation;
  mReportedAllocation = mBufSize + mRWBufSize;
  ChunksMemoryUsage() += mReportedAllocation;
  LOG(("CacheFileChunk::ChunkAllocationChanged() - %s chunks usage %u "
       "[this=%p]", mIsPriority ? "Priority" : "Normal",
       static_cast<uint32_t>(ChunksMemoryUsage()), this));
}

mozilla::Atomic<uint32_t>& CacheFileChunk::ChunksMemoryUsage()
{
  static mozilla::Atomic<uint32_t> chunksMemoryUsage(0);
  static mozilla::Atomic<uint32_t> prioChunksMemoryUsage(0);
  return mIsPriority ? prioChunksMemoryUsage : chunksMemoryUsage;
}

} // namespace net
} // namespace mozilla