143 lines
6.5 KiB
Plaintext
143 lines
6.5 KiB
Plaintext
/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "nsISupports.idl"
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typedef long nsCacheStoragePolicy;
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typedef long nsCacheAccessMode;
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/**
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* nsICache is a namespace for various cache constants. It does not represent
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* an actual object.
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*/
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[scriptable, uuid(d6c67f38-b39a-4582-8a48-4c4f8a56dfd0)]
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interface nsICache
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{
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/**
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* Access Modes
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*
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*
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* Mode Requested | Not Cached | Cached
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* ------------------------------------------------------------------------
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* READ | KEY_NOT_FOUND | NS_OK
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* | Mode = NONE | Mode = READ
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* | No Descriptor | Descriptor
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* ------------------------------------------------------------------------
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* WRITE | NS_OK | NS_OK (Cache service
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* | Mode = WRITE | Mode = WRITE dooms existing
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* | Descriptor | Descriptor cache entry)
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* ------------------------------------------------------------------------
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* READ_WRITE | NS_OK | NS_OK
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* (1st req.) | Mode = WRITE | Mode = READ_WRITE
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* | Descriptor | Descriptor
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* ------------------------------------------------------------------------
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* READ_WRITE | N/A | NS_OK
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* (Nth req.) | | Mode = READ
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* | | Descriptor
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* ------------------------------------------------------------------------
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*
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*
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* Access Requested:
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*
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* READ - I only want to READ, if there isn't an entry just fail
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* WRITE - I have something new I want to write into the cache, make
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* me a new entry and doom the old one, if any.
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* READ_WRITE - I want to READ, but I'm willing to update an existing
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* entry if necessary, or create a new one if none exists.
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*
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*
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* Access Granted:
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*
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* NONE - No descriptor is provided. You get zilch. Nada. Nothing.
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* READ - You can READ from this descriptor.
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* WRITE - You must WRITE to this descriptor because the cache entry
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* was just created for you.
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* READ_WRITE - You can READ the descriptor to determine if it's valid,
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* you may WRITE if it needs updating.
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*
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*
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* Comments:
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*
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* If you think that you might need to modify cached data or meta data,
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* then you must open a cache entry requesting WRITE access. Only one
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* cache entry descriptor, per cache entry, will be granted WRITE access.
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*
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* Usually, you will request READ_WRITE access in order to first test the
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* meta data and informational fields to determine if a write (ie. going
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* to the net) may actually be necessary. If you determine that it is
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* not, then you would mark the cache entry as valid (using MarkValid) and
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* then simply read the data from the cache.
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*
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* A descriptor granted WRITE access has exclusive access to the cache
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* entry up to the point at which it marks it as valid. Once the cache
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* entry has been "validated", other descriptors with READ access may be
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* opened to the cache entry.
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*
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* If you make a request for READ_WRITE access to a cache entry, the cache
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* service will downgrade your access to READ if there is already a
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* cache entry descriptor open with WRITE access.
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*
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* If you make a request for only WRITE access to a cache entry and another
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* descriptor with WRITE access is currently open, then the existing cache
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* entry will be 'doomed', and you will be given a descriptor (with WRITE
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* access only) to a new cache entry.
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*
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*/
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const nsCacheAccessMode ACCESS_NONE = 0;
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const nsCacheAccessMode ACCESS_READ = 1;
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const nsCacheAccessMode ACCESS_WRITE = 2;
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const nsCacheAccessMode ACCESS_READ_WRITE = 3;
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/**
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* Storage Policy
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*
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* The storage policy of a cache entry determines the device(s) to which
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* it belongs. See nsICacheSession and nsICacheEntryDescriptor for more
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* details.
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*
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* STORE_ANYWHERE - Allows the cache entry to be stored in any device.
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* The cache service decides which cache device to use
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* based on "some resource management calculation."
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* STORE_IN_MEMORY - Requires the cache entry to reside in non-persistent
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* storage (ie. typically in system RAM).
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* STORE_ON_DISK - Requires the cache entry to reside in persistent
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* storage (ie. typically on a system's hard disk).
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* STORE_OFFLINE - Requires the cache entry to reside in persistent,
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* reliable storage for offline use.
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*/
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const nsCacheStoragePolicy STORE_ANYWHERE = 0;
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const nsCacheStoragePolicy STORE_IN_MEMORY = 1;
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const nsCacheStoragePolicy STORE_ON_DISK = 2;
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// value 3 was used by STORE_ON_DISK_AS_FILE which was removed
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const nsCacheStoragePolicy STORE_OFFLINE = 4;
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/**
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* All entries for a cache session are stored as streams of data or
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* as objects. These constant my be used to specify the type of entries
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* when calling nsICacheService::CreateSession().
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*/
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const long NOT_STREAM_BASED = 0;
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const long STREAM_BASED = 1;
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/**
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* The synchronous OpenCacheEntry() may be blocking or non-blocking. If a cache entry is
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* waiting to be validated by another cache descriptor (so no new cache descriptors for that
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* key can be created, OpenCacheEntry() will return NS_ERROR_CACHE_WAIT_FOR_VALIDATION in
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* non-blocking mode. In blocking mode, it will wait until the cache entry for the key has
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* been validated or doomed. If the cache entry is validated, then a descriptor for that
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* entry will be created and returned. If the cache entry was doomed, then a descriptor
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* will be created for a new cache entry for the key.
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*/
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const long NON_BLOCKING = 0;
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const long BLOCKING = 1;
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/**
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* Constant meaning no expiration time.
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*/
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const unsigned long NO_EXPIRATION_TIME = 0xFFFFFFFF;
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};
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