1/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
2/* This Source Code Form is subject to the terms of the Mozilla Public
3 * License, v. 2.0. If a copy of the MPL was not distributed with this
4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
5
6#include "nsICacheInfoChannel.idl"
7
8interface nsIFile;
9
10/**
11 * A channel may optionally implement this interface to allow clients
12 * to affect its behavior with respect to how it uses the cache service.
13 *
14 * This interface provides:
15 *   1) Support for "stream as file" semantics (for JAR and plugins).
16 *   2) Support for "pinning" cached data in the cache (for printing and save-as).
17 *   3) Support for uniquely identifying cached data in cases when the URL
18 *      is insufficient (e.g., HTTP form submission).
19 */
20[scriptable, builtinclass, uuid(dd1d6122-5ecf-4fe4-8f0f-995e7ab3121a)]
21interface nsICachingChannel : nsICacheInfoChannel
22{
23    /**
24     * Set/get the cache token... uniquely identifies the data in the cache.
25     * Holding a reference to this token prevents the cached data from being
26     * removed.
27     *
28     * A cache token retrieved from a particular instance of nsICachingChannel
29     * could be set on another instance of nsICachingChannel provided the
30     * underlying implementations are compatible.  The implementation of
31     * nsICachingChannel would be expected to only read from the cache entry
32     * identified by the cache token and not try to validate it.
33     *
34     * The cache token can be QI'd to a nsICacheEntryInfo if more detail
35     * about the cache entry is needed (e.g., expiration time).
36     */
37    attribute nsISupports cacheToken;
38
39    /**
40     * Instructs the channel to only store the metadata of the entry, and not
41     * the content. When reading an existing entry, this automatically sets
42     * LOAD_ONLY_IF_MODIFIED flag.
43     * Must be called before asyncOpen().
44     */
45    attribute boolean cacheOnlyMetadata;
46
47    /**
48     * Tells the channel to use the pinning storage.
49     */
50    attribute boolean pin;
51
52    /**
53     * Overrides cache validation for a time specified in seconds.
54     *
55     * @param aSecondsToTheFuture
56     *
57     */
58    void forceCacheEntryValidFor(in unsigned long aSecondsToTheFuture);
59
60    /**************************************************************************
61     * Caching channel specific load flags:
62     */
63
64    /**
65     * This load flag inhibits fetching from the net.  An error of
66     * NS_ERROR_DOCUMENT_NOT_CACHED will be sent to the listener's
67     * onStopRequest if network IO is necessary to complete the request.
68     *
69     * This flag can be used to find out whether fetching this URL would
70     * cause validation of the cache entry via the network.
71     *
72     * Combining this flag with LOAD_BYPASS_LOCAL_CACHE will cause all
73     * loads to fail.
74     */
75    const unsigned long LOAD_NO_NETWORK_IO = 1 << 26;
76
77    /**
78     * This load flag causes the local cache to be skipped when fetching a
79     * request.  Unlike LOAD_BYPASS_CACHE, it does not force an end-to-end load
80     * (i.e., it does not affect proxy caches).
81     */
82    const unsigned long LOAD_BYPASS_LOCAL_CACHE = 1 << 28;
83
84    /**
85     * This load flag causes the local cache to be skipped if the request
86     * would otherwise block waiting to access the cache.
87     */
88    const unsigned long LOAD_BYPASS_LOCAL_CACHE_IF_BUSY = 1 << 29;
89
90    /**
91     * This load flag inhibits fetching from the net if the data in the cache
92     * has been evicted.  An error of NS_ERROR_DOCUMENT_NOT_CACHED will be sent
93     * to the listener's onStopRequest in this case.  This flag is set
94     * automatically when the application is offline.
95     */
96    const unsigned long LOAD_ONLY_FROM_CACHE = 1 << 30;
97
98    /**
99     * This load flag controls what happens when a document would be loaded
100     * from the cache to satisfy a call to AsyncOpen.  If this attribute is
101     * set to TRUE, then the document will not be loaded from the cache.  A
102     * stream listener can check nsICachingChannel::isFromCache to determine
103     * if the AsyncOpen will actually result in data being streamed.
104     *
105     * If this flag has been set, and the request can be satisfied via the
106     * cache, then the OnDataAvailable events will be skipped.  The listener
107     * will only see OnStartRequest followed by OnStopRequest.
108     */
109    const unsigned long LOAD_ONLY_IF_MODIFIED = 1 << 31;
110};
111