gecko-dev/dom/file/MemoryBlobImpl.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "MemoryBlobImpl.h"
#include "mozilla/IntegerPrintfMacros.h"
#include "mozilla/SHA1.h"
#include "nsIIPCSerializableInputStream.h"
#include "nsPrintfCString.h"

namespace mozilla {
namespace dom {

// XXXkhuey the input stream that we pass out of a File
// can outlive the actual File object.  Thus, we must
// ensure that the buffer underlying the stream we get
// from NS_NewByteInputStream is held alive as long as the
// stream is.  We do that by passing back this class instead.
class DataOwnerAdapter final : public nsIInputStream,
                               public nsISeekableStream,
                               public nsIIPCSerializableInputStream
{
  typedef MemoryBlobImpl::DataOwner DataOwner;
public:
  static nsresult Create(DataOwner* aDataOwner,
                         uint32_t aStart,
                         uint32_t aLength,
                         nsIInputStream** _retval);

  NS_DECL_THREADSAFE_ISUPPORTS

  // These are mandatory.
  NS_FORWARD_NSIINPUTSTREAM(mStream->)
  NS_FORWARD_NSISEEKABLESTREAM(mSeekableStream->)

  // This is optional. We use a conditional QI to keep it from being called
  // if the underlying stream doesn't support it.
  NS_FORWARD_NSIIPCSERIALIZABLEINPUTSTREAM(mSerializableInputStream->)

private:
  ~DataOwnerAdapter() {}

  DataOwnerAdapter(DataOwner* aDataOwner,
                   nsIInputStream* aStream)
    : mDataOwner(aDataOwner), mStream(aStream),
      mSeekableStream(do_QueryInterface(aStream)),
      mSerializableInputStream(do_QueryInterface(aStream))
  {
    MOZ_ASSERT(mSeekableStream, "Somebody gave us the wrong stream!");
  }

  RefPtr<DataOwner> mDataOwner;
  nsCOMPtr<nsIInputStream> mStream;
  nsCOMPtr<nsISeekableStream> mSeekableStream;
  nsCOMPtr<nsIIPCSerializableInputStream> mSerializableInputStream;
};

NS_IMPL_ADDREF(DataOwnerAdapter)
NS_IMPL_RELEASE(DataOwnerAdapter)

NS_INTERFACE_MAP_BEGIN(DataOwnerAdapter)
  NS_INTERFACE_MAP_ENTRY(nsIInputStream)
  NS_INTERFACE_MAP_ENTRY(nsISeekableStream)
  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIIPCSerializableInputStream,
                                     mSerializableInputStream)
  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIInputStream)
NS_INTERFACE_MAP_END

nsresult DataOwnerAdapter::Create(DataOwner* aDataOwner,
                                  uint32_t aStart,
                                  uint32_t aLength,
                                  nsIInputStream** _retval)
{
  nsresult rv;
  MOZ_ASSERT(aDataOwner, "Uh ...");

  nsCOMPtr<nsIInputStream> stream;

  rv = NS_NewByteInputStream(getter_AddRefs(stream),
                             static_cast<const char*>(aDataOwner->mData) +
                             aStart,
                             (int32_t)aLength,
                             NS_ASSIGNMENT_DEPEND);
  NS_ENSURE_SUCCESS(rv, rv);

  NS_ADDREF(*_retval = new DataOwnerAdapter(aDataOwner, stream));

  return NS_OK;
}

NS_IMPL_ISUPPORTS_INHERITED0(MemoryBlobImpl, BlobImpl)

already_AddRefed<BlobImpl>
MemoryBlobImpl::CreateSlice(uint64_t aStart, uint64_t aLength,
                            const nsAString& aContentType,
                            ErrorResult& aRv)
{
  RefPtr<BlobImpl> impl =
    new MemoryBlobImpl(this, aStart, aLength, aContentType);
  return impl.forget();
}

void
MemoryBlobImpl::GetInternalStream(nsIInputStream** aStream, ErrorResult& aRv)
{
  if (mLength > INT32_MAX) {
    aRv.Throw(NS_ERROR_FAILURE);
    return;
  }

  aRv = DataOwnerAdapter::Create(mDataOwner, mStart, mLength, aStream);
}

/* static */ StaticMutex
MemoryBlobImpl::DataOwner::sDataOwnerMutex;

/* static */ StaticAutoPtr<LinkedList<MemoryBlobImpl::DataOwner>>
MemoryBlobImpl::DataOwner::sDataOwners;

/* static */ bool
MemoryBlobImpl::DataOwner::sMemoryReporterRegistered = false;

MOZ_DEFINE_MALLOC_SIZE_OF(MemoryFileDataOwnerMallocSizeOf)

class MemoryBlobImplDataOwnerMemoryReporter final
  : public nsIMemoryReporter
{
  ~MemoryBlobImplDataOwnerMemoryReporter() {}

public:
  NS_DECL_THREADSAFE_ISUPPORTS

  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
                            nsISupports* aData, bool aAnonymize) override
  {
    typedef MemoryBlobImpl::DataOwner DataOwner;

    StaticMutexAutoLock lock(DataOwner::sDataOwnerMutex);

    if (!DataOwner::sDataOwners) {
      return NS_OK;
    }

    const size_t LARGE_OBJECT_MIN_SIZE = 8 * 1024;
    size_t smallObjectsTotal = 0;

    for (DataOwner *owner = DataOwner::sDataOwners->getFirst();
         owner; owner = owner->getNext()) {

      size_t size = MemoryFileDataOwnerMallocSizeOf(owner->mData);

      if (size < LARGE_OBJECT_MIN_SIZE) {
        smallObjectsTotal += size;
      } else {
        SHA1Sum sha1;
        sha1.update(owner->mData, owner->mLength);
        uint8_t digest[SHA1Sum::kHashSize]; // SHA1 digests are 20 bytes long.
        sha1.finish(digest);

        nsAutoCString digestString;
        for (size_t i = 0; i < sizeof(digest); i++) {
          digestString.AppendPrintf("%02x", digest[i]);
        }

        aHandleReport->Callback(
          /* process */ NS_LITERAL_CSTRING(""),
          nsPrintfCString(
            "explicit/dom/memory-file-data/large/file(length=%" PRIu64 ", sha1=%s)",
            owner->mLength, aAnonymize ? "<anonymized>" : digestString.get()),
          KIND_HEAP, UNITS_BYTES, size,
          nsPrintfCString(
            "Memory used to back a memory file of length %" PRIu64 " bytes.  The file "
            "has a sha1 of %s.\n\n"
            "Note that the allocator may round up a memory file's length -- "
            "that is, an N-byte memory file may take up more than N bytes of "
            "memory.",
            owner->mLength, digestString.get()),
          aData);
      }
    }

    if (smallObjectsTotal > 0) {
      aHandleReport->Callback(
        /* process */ NS_LITERAL_CSTRING(""),
        NS_LITERAL_CSTRING("explicit/dom/memory-file-data/small"),
        KIND_HEAP, UNITS_BYTES, smallObjectsTotal,
        nsPrintfCString(
          "Memory used to back small memory files (i.e. those taking up less "
          "than %zu bytes of memory each).\n\n"
          "Note that the allocator may round up a memory file's length -- "
          "that is, an N-byte memory file may take up more than N bytes of "
          "memory.", LARGE_OBJECT_MIN_SIZE),
        aData);
    }

    return NS_OK;
  }
};

NS_IMPL_ISUPPORTS(MemoryBlobImplDataOwnerMemoryReporter, nsIMemoryReporter)

/* static */ void
MemoryBlobImpl::DataOwner::EnsureMemoryReporterRegistered()
{
  sDataOwnerMutex.AssertCurrentThreadOwns();
  if (sMemoryReporterRegistered) {
    return;
  }

  RegisterStrongMemoryReporter(new MemoryBlobImplDataOwnerMemoryReporter());

  sMemoryReporterRegistered = true;
}

} // namespace dom
} // namespace mozilla