/* -*- 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 nsICacheSession.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"
#include "nsICache.idl"

interface nsICacheEntryDescriptor;
interface nsICacheListener;

[scriptable, uuid(b4b419ad-28b7-4d25-9988-20fa98505a19)]
interface nsICacheSession : nsISupports
{
    /**
     * Expired entries will be doomed or evicted if this attribute is set to
     * true.  If false, expired entries will be returned (useful for offline-
     * mode and clients, such as HTTP, that can update the valid lifetime of
     * cached content).  This attribute defaults to true.
     */
    attribute PRBool doomEntriesIfExpired;

    /**
     * A cache session can only give out one descriptor with WRITE access
     * to a given cache entry at a time.  Until the client calls MarkValid on
     * its descriptor, other attempts to open the same cache entry will block.
     */

    /**
     * Synchronous cache access.  This returns a unique descriptor each
     * time it is called, even if the same key is specified.  When
     * called by multiple threads for write access, only one writable
     * descriptor will be granted.  If 'blockingMode' is set to false, it will
     * return NS_ERROR_CACHE_WAIT_FOR_VALIDATION rather than block when another
     * descriptor has been given WRITE access but hasn't validated the entry yet.
     */
    nsICacheEntryDescriptor openCacheEntry(in string            key,
                                           in nsCacheAccessMode accessRequested,
                                           in boolean           blockingMode);

    /**
     * Asynchronous cache access. Does not block the calling thread.
     * Instead, the listener will be notified when the descriptor is
     * available.
     */
    void asyncOpenCacheEntry(in string            key,
                             in nsCacheAccessMode accessRequested,
                             in nsICacheListener  listener);

    /**
     * Evict all entries for this session's clientID according to its storagePolicy.
     */
    void evictEntries();
    
    /**
     * Return whether any of the cache devices implied by the session storage policy
     * are currently enabled for instantiation if they don't already exist.
     */
    PRBool isStorageEnabled();
};