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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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() {}
+
+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__