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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/. */
#ifndef nsBaseContentStream_h__
#define nsBaseContentStream_h__
#include "nsIAsyncInputStream.h"
#include "nsIEventTarget.h"
#include "nsCOMPtr.h"
//-----------------------------------------------------------------------------
// nsBaseContentStream is designed to be subclassed with the intention of being
// used to satisfy the nsBaseChannel::OpenContentStream method.
//
// The subclass typically overrides the default Available, ReadSegments and
// CloseWithStatus methods. By default, Read is implemented in terms of
// ReadSegments, and Close is implemented in terms of CloseWithStatus. If
// CloseWithStatus is overriden, then the subclass will usually want to call
// the base class' CloseWithStatus method before returning.
//
// If the stream is non-blocking, then readSegments may return the exception
// NS_BASE_STREAM_WOULD_BLOCK if there is no data available and the stream is
// not at the "end-of-file" or already closed. This error code must not be
// returned from the Available implementation. When the caller receives this
// error code, he may choose to call the stream's AsyncWait method, in which
// case the base stream will have a non-null PendingCallback. When the stream
// has data or encounters an error, it should be sure to dispatch a pending
// callback if one exists (see DispatchCallback). The implementation of the
// base stream's CloseWithStatus (and Close) method will ensure that any
// pending callback is dispatched. It is the responsibility of the subclass
// to ensure that the pending callback is dispatched when it wants to have its
// ReadSegments method called again.
class nsBaseContentStream : public nsIAsyncInputStream {
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSIINPUTSTREAM
NS_DECL_NSIASYNCINPUTSTREAM
explicit nsBaseContentStream(bool nonBlocking)
: mStatus(NS_OK), mNonBlocking(nonBlocking) {}
nsresult Status() { return mStatus; }
bool IsNonBlocking() { return mNonBlocking; }
bool IsClosed() { return NS_FAILED(mStatus); }
// Called to test if the stream has a pending callback.
bool HasPendingCallback() { return mCallback != nullptr; }
// The current dispatch target (may be null) for the pending callback if any.
nsIEventTarget* CallbackTarget() { return mCallbackTarget; }
// Called to dispatch a pending callback. If there is no pending callback,
// then this function does nothing. Pass true to this function to cause the
// callback to occur asynchronously; otherwise, the callback will happen
// before this function returns.
void DispatchCallback(bool async = true);
// Helper function to make code more self-documenting.
void DispatchCallbackSync() { DispatchCallback(false); }
protected:
virtual ~nsBaseContentStream() = default;
private:
// Called from the base stream's AsyncWait method when a pending callback
// is installed on the stream.
virtual void OnCallbackPending() {}
private:
nsCOMPtr<nsIInputStreamCallback> mCallback;
nsCOMPtr<nsIEventTarget> mCallbackTarget;
nsresult mStatus;
bool mNonBlocking;
};
#endif // nsBaseContentStream_h__