tenfourfox/dom/cache/CachePushStreamChild.cpp
Cameron Kaiser c9b2922b70 hello FPR
2017-04-19 00:56:45 -07:00

264 lines
6.5 KiB
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 "mozilla/dom/cache/CachePushStreamChild.h"
#include "mozilla/unused.h"
#include "nsIAsyncInputStream.h"
#include "nsICancelableRunnable.h"
#include "nsIThread.h"
#include "nsStreamUtils.h"
namespace mozilla {
namespace dom {
namespace cache {
class CachePushStreamChild::Callback final : public nsIInputStreamCallback
, public nsICancelableRunnable
{
public:
explicit Callback(CachePushStreamChild* aActor)
: mActor(aActor)
, mOwningThread(NS_GetCurrentThread())
{
MOZ_ASSERT(mActor);
}
NS_IMETHOD
OnInputStreamReady(nsIAsyncInputStream* aStream) override
{
// any thread
if (mOwningThread == NS_GetCurrentThread()) {
return Run();
}
// If this fails, then it means the owning thread is a Worker that has
// been shutdown. Its ok to lose the event in this case because the
// CachePushStreamChild listens for this event through the Feature.
nsresult rv = mOwningThread->Dispatch(this, nsIThread::DISPATCH_NORMAL);
if (NS_FAILED(rv)) {
NS_WARNING("Failed to dispatch stream readable event to owning thread");
}
return NS_OK;
}
NS_IMETHOD
Run() override
{
MOZ_ASSERT(mOwningThread == NS_GetCurrentThread());
if (mActor) {
mActor->OnStreamReady(this);
}
return NS_OK;
}
NS_IMETHOD
Cancel() override
{
// Cancel() gets called when the Worker thread is being shutdown. We have
// nothing to do here because CachePushStreamChild handles this case via
// the Feature.
return NS_OK;
}
void
ClearActor()
{
MOZ_ASSERT(mOwningThread == NS_GetCurrentThread());
MOZ_ASSERT(mActor);
mActor = nullptr;
}
private:
~Callback()
{
// called on any thread
// ClearActor() should be called before the Callback is destroyed
MOZ_ASSERT(!mActor);
}
CachePushStreamChild* mActor;
nsCOMPtr<nsIThread> mOwningThread;
NS_DECL_THREADSAFE_ISUPPORTS
};
NS_IMPL_ISUPPORTS(CachePushStreamChild::Callback, nsIInputStreamCallback,
nsIRunnable,
nsICancelableRunnable);
CachePushStreamChild::CachePushStreamChild(Feature* aFeature,
nsISupports* aParent,
nsIAsyncInputStream* aStream)
: mParent(aParent)
, mStream(aStream)
, mClosed(false)
{
MOZ_ASSERT(mParent);
MOZ_ASSERT(mStream);
MOZ_ASSERT_IF(!NS_IsMainThread(), aFeature);
SetFeature(aFeature);
}
CachePushStreamChild::~CachePushStreamChild()
{
NS_ASSERT_OWNINGTHREAD(CachePushStreamChild);
MOZ_ASSERT(mClosed);
MOZ_ASSERT(!mCallback);
}
void
CachePushStreamChild::Start()
{
DoRead();
}
void
CachePushStreamChild::StartDestroy()
{
// The worker has signaled its shutting down, but continue streaming. The
// Cache is now designed to hold the worker open until all async operations
// complete.
}
void
CachePushStreamChild::ActorDestroy(ActorDestroyReason aReason)
{
NS_ASSERT_OWNINGTHREAD(CachePushStreamChild);
// If the parent side runs into a problem then the actor will be destroyed.
// In this case we have not run OnEnd(), so still need to close the input
// stream.
if (!mClosed) {
mStream->CloseWithStatus(NS_ERROR_ABORT);
mClosed = true;
}
if (mCallback) {
mCallback->ClearActor();
mCallback = nullptr;
}
RemoveFeature();
}
void
CachePushStreamChild::DoRead()
{
NS_ASSERT_OWNINGTHREAD(CachePushStreamChild);
MOZ_ASSERT(!mClosed);
MOZ_ASSERT(!mCallback);
// The input stream (likely a pipe) probably uses a segment size of
// 4kb. If there is data already buffered it would be nice to aggregate
// multiple segments into a single IPC call. Conversely, don't send too
// too large of a buffer in a single call to avoid spiking memory.
static const uint64_t kMaxBytesPerMessage = 32 * 1024;
static_assert(kMaxBytesPerMessage <= static_cast<uint64_t>(UINT32_MAX),
"kMaxBytesPerMessage must cleanly cast to uint32_t");
while (!mClosed) {
// Use non-auto here as we're unlikely to hit stack storage with the
// sizes we are sending. Also, it would be nice to avoid another copy
// to the IPC layer which we avoid if we use COW strings. Unfortunately
// IPC does not seem to support passing dependent storage types.
nsCString buffer;
uint64_t available = 0;
nsresult rv = mStream->Available(&available);
if (NS_FAILED(rv)) {
OnEnd(rv);
return;
}
if (available == 0) {
Wait();
return;
}
uint32_t expectedBytes =
static_cast<uint32_t>(std::min(available, kMaxBytesPerMessage));
buffer.SetLength(expectedBytes);
uint32_t bytesRead = 0;
rv = mStream->Read(buffer.BeginWriting(), buffer.Length(), &bytesRead);
buffer.SetLength(bytesRead);
// If we read any data from the stream, send it across.
if (!buffer.IsEmpty()) {
Unused << SendBuffer(buffer);
}
if (rv == NS_BASE_STREAM_WOULD_BLOCK) {
Wait();
return;
}
// Any other error or zero-byte read indicates end-of-stream
if (NS_FAILED(rv) || buffer.IsEmpty()) {
OnEnd(rv);
return;
}
}
}
void
CachePushStreamChild::Wait()
{
NS_ASSERT_OWNINGTHREAD(CachePushStreamChild);
MOZ_ASSERT(!mClosed);
MOZ_ASSERT(!mCallback);
// Set mCallback immediately instead of waiting for success. Its possible
// AsyncWait() will callback synchronously.
mCallback = new Callback(this);
nsresult rv = mStream->AsyncWait(mCallback, 0, 0, nullptr);
if (NS_FAILED(rv)) {
OnEnd(rv);
return;
}
}
void
CachePushStreamChild::OnStreamReady(Callback* aCallback)
{
NS_ASSERT_OWNINGTHREAD(CachePushStreamChild);
MOZ_ASSERT(mCallback);
MOZ_ASSERT(aCallback == mCallback);
mCallback->ClearActor();
mCallback = nullptr;
DoRead();
}
void
CachePushStreamChild::OnEnd(nsresult aRv)
{
NS_ASSERT_OWNINGTHREAD(CachePushStreamChild);
MOZ_ASSERT(aRv != NS_BASE_STREAM_WOULD_BLOCK);
if (mClosed) {
return;
}
mClosed = true;
mStream->CloseWithStatus(aRv);
if (aRv == NS_BASE_STREAM_CLOSED) {
aRv = NS_OK;
}
// This will trigger an ActorDestroy() from the parent side
Unused << SendClose(aRv);
}
} // namespace cache
} // namespace dom
} // namespace mozilla