1/* This Source Code Form is subject to the terms of the Mozilla Public 2 * License, v. 2.0. If a copy of the MPL was not distributed with this 3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ 4 5#include "nsIInputStream.idl" 6 7interface nsIInputStreamCallback; 8interface nsIEventTarget; 9 10/** 11 * If an input stream is non-blocking, it may return NS_BASE_STREAM_WOULD_BLOCK 12 * when read. The caller must then wait for the stream to have some data to 13 * read. If the stream implements nsIAsyncInputStream, then the caller can use 14 * this interface to request an asynchronous notification when the stream 15 * becomes readable or closed (via the AsyncWait method). 16 * 17 * While this interface is almost exclusively used with non-blocking streams, it 18 * is not necessary that nsIInputStream::isNonBlocking return true. Nor is it 19 * necessary that a non-blocking nsIInputStream implementation also implement 20 * nsIAsyncInputStream. 21 */ 22[scriptable, uuid(a5f255ab-4801-4161-8816-277ac92f6ad1)] 23interface nsIAsyncInputStream : nsIInputStream 24{ 25 /** 26 * This method closes the stream and sets its internal status. If the 27 * stream is already closed, then this method is ignored. Once the stream 28 * is closed, the stream's status cannot be changed. Any successful status 29 * code passed to this method is treated as NS_BASE_STREAM_CLOSED, which 30 * has an effect equivalent to nsIInputStream::close. 31 * 32 * NOTE: this method exists in part to support pipes, which have both an 33 * input end and an output end. If the input end of a pipe is closed, then 34 * writes to the output end of the pipe will fail. The error code returned 35 * when an attempt is made to write to a "broken" pipe corresponds to the 36 * status code passed in when the input end of the pipe was closed, which 37 * greatly simplifies working with pipes in some cases. 38 * 39 * @param aStatus 40 * The error that will be reported if this stream is accessed after 41 * it has been closed. 42 */ 43 void closeWithStatus(in nsresult aStatus); 44 45 /** 46 * Asynchronously wait for the stream to be readable or closed. The 47 * notification is one-shot, meaning that each asyncWait call will result 48 * in exactly one notification callback. After the OnInputStreamReady event 49 * is dispatched, the stream releases its reference to the 50 * nsIInputStreamCallback object. It is safe to call asyncWait again from the 51 * notification handler. 52 * 53 * This method may be called at any time (even if read has not been called). 54 * In other words, this method may be called when the stream already has 55 * data to read. It may also be called when the stream is closed. If the 56 * stream is already readable or closed when AsyncWait is called, then the 57 * OnInputStreamReady event will be dispatched immediately. Otherwise, the 58 * event will be dispatched when the stream becomes readable or closed. 59 * 60 * @param aCallback 61 * This object is notified when the stream becomes ready. This 62 * parameter may be null to clear an existing callback. 63 * @param aFlags 64 * This parameter specifies optional flags passed in to configure 65 * the behavior of this method. Pass zero to specify no flags. 66 * @param aRequestedCount 67 * Wait until at least this many bytes can be read. This is only 68 * a suggestion to the underlying stream; it may be ignored. The 69 * caller may pass zero to indicate no preference. 70 * @param aEventTarget 71 * Specify NULL to receive notification on ANY thread (possibly even 72 * recursively on the calling thread -- i.e., synchronously), or 73 * specify that the notification be delivered to a specific event 74 * target. 75 */ 76 void asyncWait(in nsIInputStreamCallback aCallback, 77 in unsigned long aFlags, 78 in unsigned long aRequestedCount, 79 in nsIEventTarget aEventTarget); 80 81 /** 82 * If passed to asyncWait, this flag overrides the default behavior, 83 * causing the OnInputStreamReady notification to be suppressed until the 84 * stream becomes closed (either as a result of closeWithStatus/close being 85 * called on the stream or possibly due to some error in the underlying 86 * stream). 87 */ 88 const unsigned long WAIT_CLOSURE_ONLY = (1<<0); 89}; 90 91/** 92 * This is a companion interface for nsIAsyncInputStream::asyncWait. 93 */ 94[function, scriptable, uuid(d1f28e94-3a6e-4050-a5f5-2e81b1fc2a43)] 95interface nsIInputStreamCallback : nsISupports 96{ 97 /** 98 * Called to indicate that the stream is either readable or closed. 99 * 100 * @param aStream 101 * The stream whose asyncWait method was called. 102 */ 103 void onInputStreamReady(in nsIAsyncInputStream aStream); 104}; 105