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AsyncApplyBufferingPolicyEvent

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/* 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 "nsAsyncStreamCopier.h"
#include "nsIOService.h"
#include "nsIEventTarget.h"
#include "nsStreamUtils.h"
#include "nsThreadUtils.h"
#include "nsNetUtil.h"
#include "nsNetCID.h"
#include "nsIBufferedStreams.h"
#include "nsIRequestObserver.h"
#include "mozilla/Logging.h"

using namespace mozilla;

#undef LOG
//
// MOZ_LOG=nsStreamCopier:5
//
static LazyLogModule gStreamCopierLog("nsStreamCopier");
#define LOG(args) MOZ_LOG(gStreamCopierLog, mozilla::LogLevel::Debug, args)

/**
 * An event used to perform initialization off the main thread.
 */
class AsyncApplyBufferingPolicyEvent final: public Runnable
{
public:
    /**
     * @param aCopier
     *        The nsAsyncStreamCopier requesting the information.
     */
    explicit AsyncApplyBufferingPolicyEvent(nsAsyncStreamCopier* aCopier)
        : mCopier(aCopier)
      , mTarget(NS_GetCurrentThread())
      { }
    NS_IMETHOD Run() override
    {
      nsresult rv = mCopier->ApplyBufferingPolicy();
      if (NS_FAILED(rv)) {
          mCopier->Cancel(rv);
          return NS_OK;
      }

      rv = mTarget->Dispatch(NewRunnableMethod(mCopier,
					       &nsAsyncStreamCopier::AsyncCopyInternal),
			     NS_DISPATCH_NORMAL);
      MOZ_ASSERT(NS_SUCCEEDED(rv));

      if (NS_FAILED(rv)) {
          mCopier->Cancel(rv);
      }
      return NS_OK;
    }
private:
      RefPtr<nsAsyncStreamCopier> mCopier;
      nsCOMPtr<nsIEventTarget> mTarget;
};



//-----------------------------------------------------------------------------

nsAsyncStreamCopier::nsAsyncStreamCopier()
    : mLock("nsAsyncStreamCopier.mLock")
    , mMode(NS_ASYNCCOPY_VIA_READSEGMENTS)
    , mChunkSize(nsIOService::gDefaultSegmentSize)
    , mStatus(NS_OK)
    , mIsPending(false)
    , mShouldSniffBuffering(false)
{
    LOG(("Creating nsAsyncStreamCopier @%p\n", this));
}

nsAsyncStreamCopier::~nsAsyncStreamCopier()
{
    LOG(("Destroying nsAsyncStreamCopier @%p\n", this));
}

bool
nsAsyncStreamCopier::IsComplete(nsresult *status)
{
    MutexAutoLock lock(mLock);
    if (status)
        *status = mStatus;
    return !mIsPending;
}

nsIRequest*
nsAsyncStreamCopier::AsRequest()
{
    return static_cast<nsIRequest*>(static_cast<nsIAsyncStreamCopier*>(this));
}

void
nsAsyncStreamCopier::Complete(nsresult status)
{
    LOG(("nsAsyncStreamCopier::Complete [this=%p status=%" PRIx32 "]\n", this,
         static_cast<uint32_t>(status)));

    nsCOMPtr<nsIRequestObserver> observer;
    nsCOMPtr<nsISupports> ctx;
    {
        MutexAutoLock lock(mLock);
        mCopierCtx = nullptr;

        if (mIsPending) {
            mIsPending = false;
            mStatus = status;

            // setup OnStopRequest callback and release references...
            observer = mObserver;
            mObserver = nullptr;
        }
    }

    if (observer) {
        LOG(("  calling OnStopRequest [status=%" PRIx32 "]\n",
             static_cast<uint32_t>(status)));
        observer->OnStopRequest(AsRequest(), ctx, status);
    }
}

void
nsAsyncStreamCopier::OnAsyncCopyComplete(void *closure, nsresult status)
{
    nsAsyncStreamCopier *self = (nsAsyncStreamCopier *) closure;
    self->Complete(status);
    NS_RELEASE(self); // addref'd in AsyncCopy
}

//-----------------------------------------------------------------------------
// nsISupports

// We cannot use simply NS_IMPL_ISUPPORTSx as both
// nsIAsyncStreamCopier and nsIAsyncStreamCopier2 implement nsIRequest

NS_IMPL_ADDREF(nsAsyncStreamCopier)
NS_IMPL_RELEASE(nsAsyncStreamCopier)
NS_INTERFACE_TABLE_HEAD(nsAsyncStreamCopier)
NS_INTERFACE_TABLE_BEGIN
NS_INTERFACE_TABLE_ENTRY(nsAsyncStreamCopier, nsIAsyncStreamCopier)
NS_INTERFACE_TABLE_ENTRY(nsAsyncStreamCopier, nsIAsyncStreamCopier2)
NS_INTERFACE_TABLE_ENTRY_AMBIGUOUS(nsAsyncStreamCopier, nsIRequest, nsIAsyncStreamCopier)
NS_INTERFACE_TABLE_ENTRY_AMBIGUOUS(nsAsyncStreamCopier, nsISupports, nsIAsyncStreamCopier)
NS_INTERFACE_TABLE_END
NS_INTERFACE_TABLE_TAIL

//-----------------------------------------------------------------------------
// nsIRequest

NS_IMETHODIMP
nsAsyncStreamCopier::GetName(nsACString &name)
{
    name.Truncate();
    return NS_OK;
}

NS_IMETHODIMP
nsAsyncStreamCopier::IsPending(bool *result)
{
    *result = !IsComplete();
    return NS_OK;
}

NS_IMETHODIMP
nsAsyncStreamCopier::GetStatus(nsresult *status)
{
    IsComplete(status);
    return NS_OK;
}

NS_IMETHODIMP
nsAsyncStreamCopier::Cancel(nsresult status)
{
    nsCOMPtr<nsISupports> copierCtx;
    {
        MutexAutoLock lock(mLock);
        if (!mIsPending)
            return NS_OK;
        copierCtx.swap(mCopierCtx);
    }

    if (NS_SUCCEEDED(status)) {
        NS_WARNING("cancel with non-failure status code");
        status = NS_BASE_STREAM_CLOSED;
    }

    if (copierCtx)
        NS_CancelAsyncCopy(copierCtx, status);

    return NS_OK;
}

NS_IMETHODIMP
nsAsyncStreamCopier::Suspend()
{
    NS_NOTREACHED("nsAsyncStreamCopier::Suspend");
    return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsAsyncStreamCopier::Resume()
{
    NS_NOTREACHED("nsAsyncStreamCopier::Resume");
    return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsAsyncStreamCopier::GetLoadFlags(nsLoadFlags *aLoadFlags)
{
    *aLoadFlags = LOAD_NORMAL;
    return NS_OK;
}

NS_IMETHODIMP
nsAsyncStreamCopier::SetLoadFlags(nsLoadFlags aLoadFlags)
{
    return NS_OK;
}

NS_IMETHODIMP
nsAsyncStreamCopier::GetLoadGroup(nsILoadGroup **aLoadGroup)
{
    *aLoadGroup = nullptr;
    return NS_OK;
}

NS_IMETHODIMP
nsAsyncStreamCopier::SetLoadGroup(nsILoadGroup *aLoadGroup)
{
    return NS_OK;
}

nsresult
nsAsyncStreamCopier::InitInternal(nsIInputStream *source,
                                  nsIOutputStream *sink,
                                  nsIEventTarget *target,
                                  uint32_t chunkSize,
                                  bool closeSource,
                                  bool closeSink)
{
    NS_ASSERTION(!mSource && !mSink, "Init() called more than once");
    if (chunkSize == 0) {
        chunkSize = nsIOService::gDefaultSegmentSize;
    }
    mChunkSize = chunkSize;

    mSource = source;
    mSink = sink;
    mCloseSource = closeSource;
    mCloseSink = closeSink;

    if (target) {
        mTarget = target;
    } else {
        nsresult rv;
        mTarget = do_GetService(NS_STREAMTRANSPORTSERVICE_CONTRACTID, &rv);
        if (NS_FAILED(rv)) {
            return rv;
        }
    }

    return NS_OK;
}

//-----------------------------------------------------------------------------
// nsIAsyncStreamCopier

NS_IMETHODIMP
nsAsyncStreamCopier::Init(nsIInputStream *source,
                          nsIOutputStream *sink,
                          nsIEventTarget *target,
                          bool sourceBuffered,
                          bool sinkBuffered,
                          uint32_t chunkSize,
                          bool closeSource,
                          bool closeSink)
{
    NS_ASSERTION(sourceBuffered || sinkBuffered, "at least one stream must be buffered");
    mMode = sourceBuffered ? NS_ASYNCCOPY_VIA_READSEGMENTS
                           : NS_ASYNCCOPY_VIA_WRITESEGMENTS;

    return InitInternal(source, sink, target, chunkSize, closeSource, closeSink);
}

//-----------------------------------------------------------------------------
// nsIAsyncStreamCopier2

NS_IMETHODIMP
nsAsyncStreamCopier::Init(nsIInputStream *source,
                          nsIOutputStream *sink,
                          nsIEventTarget *target,
                          uint32_t chunkSize,
                          bool closeSource,
                          bool closeSink)
{
    mShouldSniffBuffering = true;

    return InitInternal(source, sink, target, chunkSize, closeSource, closeSink);
}

/**
 * Detect whether the input or the output stream is buffered,
 * bufferize one of them if neither is buffered.
 */
nsresult
nsAsyncStreamCopier::ApplyBufferingPolicy()
{
    // This function causes I/O, it must not be executed on the main
    // thread.
    MOZ_ASSERT(!NS_IsMainThread());

    if (NS_OutputStreamIsBuffered(mSink)) {
      // Sink is buffered, no need to perform additional buffering
      mMode = NS_ASYNCCOPY_VIA_WRITESEGMENTS;
      return NS_OK;
    }
    if (NS_InputStreamIsBuffered(mSource)) {
      // Source is buffered, no need to perform additional buffering
      mMode = NS_ASYNCCOPY_VIA_READSEGMENTS;
      return NS_OK;
    }

    // No buffering, let's buffer the sink
    nsresult rv;
    nsCOMPtr<nsIBufferedOutputStream> sink =
      do_CreateInstance(NS_BUFFEREDOUTPUTSTREAM_CONTRACTID, &rv);
    if (NS_FAILED(rv)) {
      return rv;
    }

    rv = sink->Init(mSink, mChunkSize);
    if (NS_FAILED(rv)) {
      return rv;
    }

    mMode = NS_ASYNCCOPY_VIA_WRITESEGMENTS;
    mSink = sink;
    return NS_OK;
}

//-----------------------------------------------------------------------------
// Both nsIAsyncStreamCopier and nsIAsyncStreamCopier2

NS_IMETHODIMP
nsAsyncStreamCopier::AsyncCopy(nsIRequestObserver *observer, nsISupports *ctx)
{
    LOG(("nsAsyncStreamCopier::AsyncCopy [this=%p observer=%p]\n", this, observer));

    NS_ASSERTION(mSource && mSink, "not initialized");
    nsresult rv;

    if (observer) {
        // build proxy for observer events
        rv = NS_NewRequestObserverProxy(getter_AddRefs(mObserver), observer, ctx);
        if (NS_FAILED(rv)) return rv;
    }

    // from this point forward, AsyncCopy is going to return NS_OK.  any errors
    // will be reported via OnStopRequest.
    mIsPending = true;

    if (mObserver) {
        rv = mObserver->OnStartRequest(AsRequest(), nullptr);
        if (NS_FAILED(rv))
            Cancel(rv);
    }

    if (!mShouldSniffBuffering) {
        // No buffer sniffing required, let's proceed
        AsyncCopyInternal();
        return NS_OK;
    }

    if (NS_IsMainThread()) {
        // Don't perform buffer sniffing on the main thread
        nsCOMPtr<nsIRunnable> event = new AsyncApplyBufferingPolicyEvent(this);
        rv = mTarget->Dispatch(event, NS_DISPATCH_NORMAL);
        if (NS_FAILED(rv)) {
          Cancel(rv);
        }
        return NS_OK;
    }

    // We're not going to block the main thread, so let's sniff here
    rv = ApplyBufferingPolicy();
    if (NS_FAILED(rv)) {
        Cancel(rv);
    }
    AsyncCopyInternal();
    return NS_OK;
}

// Launch async copy.
// All errors are reported through the observer.
void
nsAsyncStreamCopier::AsyncCopyInternal()
{
  MOZ_ASSERT(mMode ==  NS_ASYNCCOPY_VIA_READSEGMENTS
             || mMode == NS_ASYNCCOPY_VIA_WRITESEGMENTS);

    nsresult rv;
    // we want to receive progress notifications; release happens in
    // OnAsyncCopyComplete.
    NS_ADDREF_THIS();
    {
      MutexAutoLock lock(mLock);
      rv = NS_AsyncCopy(mSource, mSink, mTarget, mMode, mChunkSize,
                        OnAsyncCopyComplete, this, mCloseSource, mCloseSink,
                        getter_AddRefs(mCopierCtx));
    }
    if (NS_FAILED(rv)) {
        NS_RELEASE_THIS();
        Cancel(rv);
    }
}