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/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* 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 "nsISupports.idl"
typedef long nsCacheStoragePolicy;
typedef long nsCacheAccessMode;
/**
* nsICache is a namespace for various cache constants. It does not represent
* an actual object.
*/
[builtinclass, uuid(d6c67f38-b39a-4582-8a48-4c4f8a56dfd0)]
interface nsICache : nsISupports
{
/**
* 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 service
* | 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_OFFLINE - Requires the cache entry to reside in persistent,
* reliable storage for offline use.
*/
const nsCacheStoragePolicy STORE_ANYWHERE = 0;
const nsCacheStoragePolicy STORE_IN_MEMORY = 1;
const nsCacheStoragePolicy STORE_ON_DISK = 2;
// value 3 was used by STORE_ON_DISK_AS_FILE which was removed
const nsCacheStoragePolicy STORE_OFFLINE = 4;
/**
* 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;
/**
* The synchronous OpenCacheEntry() may be blocking or non-blocking. If a cache entry is
* waiting to be validated by another cache descriptor (so no new cache descriptors for that
* key can be created, OpenCacheEntry() will return NS_ERROR_CACHE_WAIT_FOR_VALIDATION in
* non-blocking mode. In blocking mode, it will wait until the cache entry for the key has
* been validated or doomed. If the cache entry is validated, then a descriptor for that
* entry will be created and returned. If the cache entry was doomed, then a descriptor
* will be created for a new cache entry for the key.
*/
const long NON_BLOCKING = 0;
const long BLOCKING = 1;
/**
* Constant meaning no expiration time.
*/
const unsigned long NO_EXPIRATION_TIME = 0xFFFFFFFF;
};
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