File Management in a Computing Device
When reading a directory on a computing device, the file server adds unique tags to the listing when passing the listing to a client application. The file server keeps a list of the unique tags together with the physical addresses of the files to which they correspond. When a client wishes to open a file, it can do so by passing the tag to the file server. This enables the file server to load the file directly without having to undertake a second directory search to discover the physical location of the file from its filename.
1 . A method of file management in a computing device incorporating a directory structure, the method comprising
a. arranging a directory listing of a filesystem to include a uniquely identifiable tag for each entry in the directory;
b. when providing the directory listing to a client, retaining a copy of the listing comprising a tag for each entry in the listing indicative of the physical location of an object referred to by that entry;
c. accepting a request to open an object by reference to its tag; and
d. retrieving the physical location of the said object, and opening the object at its physical location.
2 . A method according to claim 1 wherein the filesystem is controlled by a file server for providing filesystem services to multiple clients arranged to maintain one or more distinct sessions with the file server.
3 . A method according to claim 1 wherein the objects are selected to comprise files or other directories or any other entities.
4 . A method according to claim 1 wherein the tags are maintained in a listing in the form of an array in which the tags act as an index for enabling the physical location of respective objects to be retrieved.
5 . A method according to claim 1 wherein the filesystem comprises a read-only filesystem.
6 . A method according to claim 5 wherein the read-only filesystem is used to boot the computing device.
7 . A method according to claim 1 wherein the filesystem comprises a writable filesystem.
8 . A method according to claim 7 wherein the retained listing is invalidated if any change is made to the directory from which it was originally derived; and, passing an error code back to a client requesting to open an object having a tag in an invalidated listing for causing the client to open the object by name.
9 . A method according to claim 7 wherein the retained copy of the listing further comprises respective names for objects; the retained list is invalidated if any change is made to the directory from which it is was originally derived; and a request to open an object in an invalidated list causes the object to be opened using the respective name in the retained list.
10 . A method according to claim 7 wherein the filesystem is arranged to accept a request for opening an object referred by tag and by object name; the retained listing of tags is invalidated if any change is made to the directory from which it is was originally derived; and a request to open an object by a tag in an invalidated listing causes the filesystem to open the object using the object name.
11 . A method according to claim 8 wherein the filesystem is arranged to update and revalidate its retained listing after an invalidated listing has caused an object to be opened by name.
12 . A method according to claim 8 in which the filesystem is arranged to monitor activity for causing changes to entries in a directory for which it has a retained directory listing, and in which a tag is invalidated whenever affected by a change instead of invalidating the retained listing, and objects are opened by name only when a request is made using an invalidated tag; or the filesystem is arranged to dynamically update entries which would otherwise have been invalidated.
13 . A method according to claim 1 wherein either
a. a single retained directory list is allowed for each logical drive on a system; or
b. a fixed number of retained directory lists is allowed per file server session; or
c. multiple retained directory lists are allowed per file server session by client request, up to a fixed or dynamic maximum.
14 . A method according to claim 5 in which read-only filesystem usage is profiled and one or more retained directory listings are predefined and included in a boot ROM for automatic use during the boot process or any other predicable and profitable sequence of operations for the computing device.
15 . A computing device arranged to operate in accordance with a method as defined in claim 1 .
16 . An operating system for a computing device for causing the computing device to operate in accordance with a method as defined in claim 1 .