gecko-dev/netwerk/base/nsIInputStreamPump.idl

/* 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 "nsIRequest.idl"

interface nsIInputStream;
interface nsIStreamListener;

/**
 * nsIInputStreamPump
 *
 * This interface provides a means to configure and use a input stream pump
 * instance.  The input stream pump will asynchronously read from an input
 * stream, and push data to an nsIStreamListener instance.  It utilizes the
 * current thread's nsIEventTarget in order to make reading from the stream
 * asynchronous. A different thread can be used if the pump also implements
 * nsIThreadRetargetableRequest.
 *
 * If the given stream supports nsIAsyncInputStream, then the stream pump will
 * call the stream's AsyncWait method to drive the stream listener.  Otherwise,
 * the stream will be read on a background thread utilizing the stream
 * transport service.  More details are provided below.
 */
[scriptable, uuid(400F5468-97E7-4d2b-9C65-A82AECC7AE82)]
interface nsIInputStreamPump : nsIRequest
{
    /**
     * Initialize the input stream pump.
     *
     * @param aStream
     *        contains the data to be read.  if the input stream is non-blocking,
     *        then it will be QI'd to nsIAsyncInputStream.  if the QI succeeds
     *        then the stream will be read directly.  otherwise, it will be read
     *        on a background thread using the stream transport service.
     * @param aStreamPos
     *        specifies the stream offset from which to start reading.  the
     *        offset value is absolute.  pass -1 to specify the current offset.
     *        NOTE: this parameter is ignored if the underlying stream does not
     *        implement nsISeekableStream.
     * @param aStreamLen
     *        specifies how much data to read from the stream.  pass -1 to read
     *        all data available in the stream.
     * @param aSegmentSize
     *        if the stream transport service is used, then this parameter
     *        specifies the segment size for the stream transport's buffer.
     *        pass 0 to specify the default value.
     * @param aSegmentCount
     *        if the stream transport service is used, then this parameter
     *        specifies the segment count for the stream transport's buffer.
     *        pass 0 to specify the default value.
     * @param aCloseWhenDone
     *        if true, the input stream will be closed after it has been read.
     */
    void init(in nsIInputStream aStream,
              in long long      aStreamPos,
              in long long      aStreamLen,
              in unsigned long  aSegmentSize,
              in unsigned long  aSegmentCount,
              in boolean        aCloseWhenDone);

    /**
     * asyncRead causes the input stream to be read in chunks and delivered
     * asynchronously to the listener via OnDataAvailable.
     *
     * @param aListener
     *        receives notifications.
     * @param aListenerContext
     *        passed to listener methods.
     */
    void asyncRead(in nsIStreamListener aListener,
                   in nsISupports       aListenerContext);
};