nsICacheInfoChannel
Last changed in Gecko 2.0 (Firefox 4 / Thunderbird 3.3 / SeaMonkey 2.1)This interface provides:
- Support for "stream as file" semantics (for JAR and plugins).
- Support for "pinning" cached data in the cache (for printing and save-as).
- Support for uniquely identifying cached data in cases when the URL is insufficient. For example a HTTP form submission.
A channel may optionally implement this interface to allow clients to affect its behavior with respect to how it uses the cache service.
Method overview
boolean isFromCache(); Obsolete since Gecko 2.0 |
Attributes
Attribute | Type | Description |
cacheAsFile | boolean | Specifies whether or not the data should be cached to a file. This may fail if the disk cache is not present. The value of this attribute is usually only settable during the processing of a channel's OnStartRequest . The default value of this attribute depends on the particular implementation of nsICachingChannel . |
cacheFile | nsIFile | Get the "file" where the cached data can be found. This is valid for as long as a reference to the cache token is held. This may return an error if cacheAsFile is false . Read only. |
cacheForOfflineUse | boolean | Specifies whether or not the data should be placed in the offline cache, in addition to normal memory/disk caching. This may fail if the offline cache is not present. The value of this attribute should be set before opening the channel. |
cacheKey | nsISupports | Uniquely identifies the data in the cache for this channel. Holding a reference to this key does not prevent the cached data from being removed. A cache key retrieved from a particular instance of null indicating that the URI of the channel is sufficient to locate the same cache entry. Setting a null cache key is likewise valid. |
cacheToken | nsISupports | Uniquely identifies the data in the cache. Holding a reference to this token prevents the cached data from being removed. A cache token retrieved from a particular instance of QueryInterface 'd to a nsICacheEntryInfo if more detail about the cache entry is needed. For example, expiration time. |
offlineCacheClientID | ACString | The session into which to cache offline data. If not specified, data will be placed in "HTTP-offline". |
offlineCacheToken | nsISupports | The same as cacheToken but accessing the offline app cache token if there is any. Exceptions thrown
|
Constants
Constant | Value | Description |
LOAD_NO_NETWORK_IO | 1 << 26 | This load flag inhibits fetching from the net. An error of This flag can be used to find out whether fetching this URL would cause validation of the cache entry via the network. Combining this flag withLOAD_BYPASS_LOCAL_CACHE will cause all loads to fail. This flag differs from LOAD_ONLY_FROM_CACHE in that this flag fails the load if validation is required while LOAD_ONLY_FROM_CACHE skips validation where possible. |
LOAD_CHECK_OFFLINE_CACHE | 1 << 27 | This load flag causes the offline cache to be checked when fetching a request. It will be set automatically if the browser is offline. This flag will not be transferred through a redirect. |
LOAD_BYPASS_LOCAL_CACHE | 1 << 28 | This load flag causes the local cache to be skipped when fetching a request. Unlike LOAD_BYPASS_CACHE , it does not force an end-to-end load (That is, it does not affect proxy caches). |
LOAD_BYPASS_LOCAL_CACHE_IF_BUSY | 1 << 29 | This load flag causes the local cache to be skipped if the request would otherwise block waiting to access the cache. |
LOAD_ONLY_FROM_CACHE | 1 << 30 | This load flag inhibits fetching from the net if the data in the cache has been evicted. An error of NS_ERROR_DOCUMENT_NOT_CACHED will be sent to the listener's onStopRequest in this case. This flag is set automatically when the application is offline. |
LOAD_ONLY_IF_MODIFIED | 1 << 31 | This load flag controls what happens when a document would be loaded from the cache to satisfy a call to OnDataAvailable events will be skipped. The listener will only see OnStartRequest followed by OnStopRequest . |
Methods
isFromCache()
This method finds out whether or not this channel's data is being loaded from the cache.
boolean isFromCache();
Parameters
None.
Return value
Returns true
if this channel's data is being loaded from the cache, otherwise returns false
. This value is undefined before the channel fires its OnStartRequest
notification and after the channel fires its OnStopRequest
notification.