gecko-dev/netwerk/cache/public/nsICache.idl

/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * The contents of this file are subject to the Mozilla Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/MPL/
 * 
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 * 
 * The Original Code is nsICache.idl, released February 23, 2001.
 * 
 * The Initial Developer of the Original Code is Netscape Communications
 * Corporation.  Portions created by Netscape are
 * Copyright (C) 2001 Netscape Communications Corporation.  All
 * Rights Reserved.
 * 
 * Contributor(s): 
 *    Gordon Sheridan <gordon@netscape.com>
 *    Patrick Beard   <beard@netscape.com>
 *    Darin Fisher    <darin@netscape.com>
 */

#include "nsISupports.idl"

typedef long nsCacheStoragePolicy;
typedef long nsCacheAccessMode;

/**
 * nsICache is a namespace for various cache constants.  It does not represent
 * an actual object.
 */
[scriptable, uuid(ec1c0063-197d-44bb-84ba-7525d50fc937)]
interface nsICache
{
    /**
     * Access Modes
     *
     *
     * Mode Requested | Not Cached          | Cached
     * ------------------------------------------------------------------------
     * READ           | KEY_NOT_FOUND       | NS_OK
     *                | Mode = NONE         | Mode = READ
     *                | No Descriptor       | Descriptor
     * ------------------------------------------------------------------------
     * WRITE          | NS_OK               | NS_OK            (Cache manager
     *                | Mode = WRITE        | Mode = WRITE      dooms existing
     *                | Descriptor          | Descriptor        cache entry)
     * ------------------------------------------------------------------------
     * READ_WRITE     | NS_OK               | NS_OK
     * (1st req.)     | Mode = WRITE        | Mode = READ_WRITE
     *                | Descriptor          | Descriptor
     * ------------------------------------------------------------------------
     * READ_WRITE     | N/A                 | NS_OK
     * (Nth req.)     |                     | Mode = READ
     *                |                     | Descriptor
     * ------------------------------------------------------------------------
     *
     *
     * Access Requested:
     *
     * READ	       - I only want to READ, if there isn't an entry just fail
     * WRITE       - I have something new I want to write into the cache, make
     *               me a new entry and doom the old one, if any.
     * READ_WRITE  - I want to READ, but I'm willing to update an existing
     *               entry if necessary, or create a new one if none exists.
     *
     *
     * Access Granted:
     *
     * NONE        - No descriptor is provided. You get zilch. Nada. Nothing.
     * READ		   - You can READ from this descriptor.
     * WRITE	   - You must WRITE to this descriptor because the cache entry
     *               was just created for you.
     * READ_WRITE  - You can READ the descriptor to determine if it's valid,
     *               you may WRITE if it needs updating.
     *
     *
     * Comments:
     *
     * If you think that you might need to modify cached data or meta data,
     * then you must open a cache entry requesting WRITE access.  Only one
     * cache entry descriptor, per cache entry, will be granted WRITE access.
     * 
     * Usually, you will request READ_WRITE access in order to first test the
     * meta data and informational fields to determine if a write (ie. going
     * to the net) may actually be necessary.  If you determine that it is 
     * not, then you would mark the cache entry as valid (using MarkValid) and
     * then simply read the data from the cache.
     *
     * A descriptor granted WRITE access has exclusive access to the cache
     * entry up to the point at which it marks it as valid.  Once the cache
     * entry has been "validated", other descriptors with READ access may be
     * opened to the cache entry.
     *
     * If you make a request for READ_WRITE access to a cache entry, the cache
     * service will downgrade your access to READ if there is already a
     * cache entry descriptor open with WRITE access.
     *
     * If you make a request for only WRITE access to a cache entry and another
     * descriptor with WRITE access is currently open, then the existing cache
     * entry will be 'doomed', and you will be given a descriptor (with WRITE
     * access only) to a new cache entry.
     *
     */
    const nsCacheAccessMode ACCESS_NONE       = 0;
    const nsCacheAccessMode ACCESS_READ       = 1;
    const nsCacheAccessMode ACCESS_WRITE      = 2;
    const nsCacheAccessMode ACCESS_READ_WRITE = 3;

    /**
     * Storage Policy
     *
     * The storage policy of a cache entry determines the device(s) to which
     * it belongs.  See nsICacheSession and nsICacheEntryDescriptor for more
     * details.
     *
     * STORE_ANYWHERE        - Allows the cache entry to be stored in any device.
     *                         The cache service decides which cache device to use
     *                         based on "some resource management calculation."
     * STORE_IN_MEMORY       - Requires the cache entry to reside in non-persistent
     *                         storage (ie. typically in system RAM).
     * STORE_ON_DISK         - Requires the cache entry to reside in persistent
     *                         storage (ie. typically on a system's hard disk).
     * STORE_ON_DISK_AS_DISK - Requires the cache entry to reside in persistent
     *                         storage, and in a specific file.
     */
    const nsCacheStoragePolicy STORE_ANYWHERE           = 0;
    const nsCacheStoragePolicy STORE_IN_MEMORY          = 1;
    const nsCacheStoragePolicy STORE_ON_DISK            = 2;
    const nsCacheStoragePolicy STORE_ON_DISK_AS_FILE    = 3;

    /**
     * All entries for a cache session are stored as streams of data or
     * as objects.  These constant my be used to specify the type of entries
     * when calling nsICacheService::CreateSession().
     */
    const long              NOT_STREAM_BASED = 0;
    const long              STREAM_BASED     = 1;
};


%{C++

/**
 * Cache specific nsresult error codes
 */
#define NS_ERROR_CACHE_KEY_NOT_FOUND        NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_NETWORK, 60)
#define NS_ERROR_CACHE_DATA_IS_STREAM       NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_NETWORK, 61)
#define NS_ERROR_CACHE_DATA_IS_NOT_STREAM   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_NETWORK, 62)
#define NS_ERROR_CACHE_WAIT_FOR_VALIDATION  NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_NETWORK, 63)
#define NS_ERROR_CACHE_ENTRY_DOOMED         NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_NETWORK, 64)
#define NS_ERROR_CACHE_READ_ACCESS_DENIED   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_NETWORK, 65)
#define NS_ERROR_CACHE_WRITE_ACCESS_DENIED  NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_NETWORK, 66)

%}