Quelle InputStreamLengthHelper.cpp Sprache: C

/* -*- 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 "InputStreamLengthHelper.h"
#include "mozilla/dom/WorkerCommon.h"
#include "nsIAsyncInputStream.h"
#include "nsIInputStream.h"
#include "nsNetCID.h"
#include "nsServiceManagerUtils.h"

namespace mozilla {

namespace {

class AvailableEvent final : public Runnable {
public:
  AvailableEvent(nsIInputStream* stream,
                 const std::function<void(int64_t aLength)>& aCallback)
      : Runnable("mozilla::AvailableEvent"),
        mStream(stream),
        mCallback(aCallback),
        mSize(-1) {
    mCallbackTarget = GetCurrentSerialEventTarget();
    MOZ_ASSERT(NS_IsMainThread());
  }

  NS_IMETHOD
  Run() override {
    // ping
    if (!NS_IsMainThread()) {
      uint64_t size = 0;
      if (NS_WARN_IF(NS_FAILED(mStream->Available(&size)))) {
        mSize = -1;
      } else {
        mSize = (int64_t)size;
      }

      mStream = nullptr;

      nsCOMPtr<nsIRunnable> self(this);  // overly cute
      mCallbackTarget->Dispatch(self.forget(), NS_DISPATCH_NORMAL);
      mCallbackTarget = nullptr;
      return NS_OK;
    }

    // pong
    std::function<void(int64_t aLength)> callback;
    callback.swap(mCallback);
    callback(mSize);
    return NS_OK;
  }

private:
  nsCOMPtr<nsIInputStream> mStream;
  std::function<void(int64_t aLength)> mCallback;
  nsCOMPtr<nsIEventTarget> mCallbackTarget;

  int64_t mSize;
};

}  // namespace

/* static */
bool InputStreamLengthHelper::GetSyncLength(nsIInputStream* aStream,
                                            int64_t* aLength) {
  MOZ_ASSERT(aStream);
  MOZ_ASSERT(aLength);

  *aLength = -1;

  // Sync length access.
  nsCOMPtr<nsIInputStreamLength> streamLength = do_QueryInterface(aStream);
  if (streamLength) {
    int64_t length = -1;
    nsresult rv = streamLength->Length(&length);

    // All good!
    if (NS_SUCCEEDED(rv)) {
      *aLength = length;
      return true;
    }

    // Already closed stream or an error occurred.
    if (rv == NS_BASE_STREAM_CLOSED ||
        NS_WARN_IF(rv == NS_ERROR_NOT_AVAILABLE) ||
        NS_WARN_IF(rv != NS_BASE_STREAM_WOULD_BLOCK)) {
      return true;
    }
  }

  nsCOMPtr<nsIAsyncInputStreamLength> asyncStreamLength =
      do_QueryInterface(aStream);
  if (asyncStreamLength) {
    // GetAsyncLength should be used.
    return false;
  }

  // We cannot calculate the length of an async stream.
  nsCOMPtr<nsIAsyncInputStream> asyncStream = do_QueryInterface(aStream);
  if (asyncStream) {
    return false;
  }

  // For main-thread only, we want to avoid calling ::Available() for blocking
  // streams.
  if (NS_IsMainThread()) {
    bool nonBlocking = false;
    if (NS_WARN_IF(NS_FAILED(aStream->IsNonBlocking(&nonBlocking)))) {
      // Let's return -1. There is nothing else we can do here.
      return true;
    }

    if (!nonBlocking) {
      return false;
    }
  }

  // Fallback using available().
  uint64_t available = 0;
  nsresult rv = aStream->Available(&available);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    // Let's return -1. There is nothing else we can do here.
    return true;
  }

  *aLength = (int64_t)available;
  return true;
}

/* static */
void InputStreamLengthHelper::GetAsyncLength(
    nsIInputStream* aStream,
    const std::function<void(int64_t aLength)>& aCallback) {
  MOZ_ASSERT(aStream);
  MOZ_ASSERT(aCallback);

  // We don't want to allow this class to be used on workers because we are not
  // using the correct Runnable types.
  MOZ_DIAGNOSTIC_ASSERT(NS_IsMainThread() ||
                        !dom::IsCurrentThreadRunningWorker());

  RefPtr<InputStreamLengthHelper> helper =
      new InputStreamLengthHelper(aStream, aCallback);

  // Let's be sure that we don't call ::Available() on main-thread.
  if (NS_IsMainThread()) {
    nsCOMPtr<nsIInputStreamLength> streamLength = do_QueryInterface(aStream);
    nsCOMPtr<nsIAsyncInputStreamLength> asyncStreamLength =
        do_QueryInterface(aStream);
    if (!streamLength && !asyncStreamLength) {
      // We cannot calculate the length of an async stream. We must fix the
      // caller if this happens.
#ifdef DEBUG
      nsCOMPtr<nsIAsyncInputStream> asyncStream = do_QueryInterface(aStream);
      MOZ_DIAGNOSTIC_ASSERT(!asyncStream);
#endif

      bool nonBlocking = false;
      if (NS_SUCCEEDED(aStream->IsNonBlocking(&nonBlocking)) && !nonBlocking) {
        nsCOMPtr<nsIEventTarget> target =
            do_GetService(NS_STREAMTRANSPORTSERVICE_CONTRACTID);
        MOZ_ASSERT(target);

        RefPtr<AvailableEvent> event = new AvailableEvent(aStream, aCallback);
        target->Dispatch(event.forget(), NS_DISPATCH_NORMAL);
        return;
      }
    }
  }

  // Let's go async in order to have similar behaviors for sync and async
  // nsIInputStreamLength implementations.
  GetCurrentSerialEventTarget()->Dispatch(helper, NS_DISPATCH_NORMAL);
}

InputStreamLengthHelper::InputStreamLengthHelper(
    nsIInputStream* aStream,
    const std::function<void(int64_t aLength)>& aCallback)
    : Runnable("InputStreamLengthHelper"),
      mStream(aStream),
      mCallback(aCallback) {
  MOZ_ASSERT(aStream);
  MOZ_ASSERT(aCallback);
}

InputStreamLengthHelper::~InputStreamLengthHelper() = default;

NS_IMETHODIMP
InputStreamLengthHelper::Run() {
  // Sync length access.
  nsCOMPtr<nsIInputStreamLength> streamLength = do_QueryInterface(mStream);
  if (streamLength) {
    int64_t length = -1;
    nsresult rv = streamLength->Length(&length);

    // All good!
    if (NS_SUCCEEDED(rv)) {
      ExecCallback(length);
      return NS_OK;
    }

    // Already closed stream or an error occurred.
    if (rv == NS_BASE_STREAM_CLOSED ||
        NS_WARN_IF(rv == NS_ERROR_NOT_AVAILABLE) ||
        NS_WARN_IF(rv != NS_BASE_STREAM_WOULD_BLOCK)) {
      ExecCallback(-1);
      return NS_OK;
    }
  }

  // Async length access.
  nsCOMPtr<nsIAsyncInputStreamLength> asyncStreamLength =
      do_QueryInterface(mStream);
  if (asyncStreamLength) {
    nsresult rv =
        asyncStreamLength->AsyncLengthWait(this, GetCurrentSerialEventTarget());
    if (NS_WARN_IF(NS_FAILED(rv))) {
      ExecCallback(-1);
    }

    return NS_OK;
  }

  // Fallback using available().
  uint64_t available = 0;
  nsresult rv = mStream->Available(&available);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    ExecCallback(-1);
    return NS_OK;
  }

  ExecCallback((int64_t)available);
  return NS_OK;
}

NS_IMETHODIMP
InputStreamLengthHelper::OnInputStreamLengthReady(
    nsIAsyncInputStreamLength* aStream, int64_t aLength) {
  ExecCallback(aLength);
  return NS_OK;
}

void InputStreamLengthHelper::ExecCallback(int64_t aLength) {
  MOZ_ASSERT(mCallback);

  std::function<void(int64_t aLength)> callback;
  callback.swap(mCallback);

  callback(aLength);
}

NS_IMPL_ISUPPORTS_INHERITED(InputStreamLengthHelper, Runnable,
                            nsIInputStreamLengthCallback)

}  // namespace mozilla

quality100%

¤ Dauer der Verarbeitung: 0.14 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.