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authorRami Ylimäki <rami.ylimaki@vincit.fi>2010-12-31 14:21:08 +0200
committerAlan Coopersmith <alan.coopersmith@oracle.com>2011-05-24 15:02:12 -0700
commit1eb1d726921493db463b9b790bf25532fdc43287 (patch)
treefd6d8a0be0c2f9fbd76e52b5e37dd79a9758ae33 /resproto.txt
parent386946098f97b9137af3265b5608fdcf22c7d49a (diff)
Added protocol description for XRes v1.2
Version 1.2 of XResource protocol adds two requests: XResQueryClientIds and XResQueryResourceBytes. They can be used for more exactly determining which resources are used by which clients. This patch incorporates comments from the mailing list. Acked-by: Gaetan Nadon <memsize@videotron.ca> Reviewed-by: Erkki Seppälä <erkki.seppala@vincit.fi> Signed-off-by: Rami Ylimäki <rami.ylimaki@vincit.fi> Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
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+ DRAFT FOR REVIEW
+ The X Resource Extension
+ Version 1.2
+ Rami Ylimäki
+ rami.ylimaki@vincit.fi
+
+ ❧❧❧❧❧❧❧❧❧❧❧
+
+1. Introduction
+
+The protocol description of X Resource Extension version 1.1 has been
+either lost or has never been written. This specification documents
+version 1.0 based on reverse engineered library and server
+code. Version 1.1 has been accidentally released from the version
+control and while it doesn't have differences to version 1.0, this
+version is labeled 1.2 in order to remove the risk of confusion. In
+addition to the 1.0 description, this document introduces a new 1.2
+version of the extension.
+
+Version 1.2 is a minor release and therefore the changes are
+compatible with the previous version. Main enhancements over version
+1.0 are:
+
+- Client identification is now possible. For example, servers
+ supporting version 1.2 may report PID of local clients.
+
+- Size of any resource can be queried from the server. Servers may not
+ necessarily support size calculation for every resource. However,
+ clients have now at least the chance to let the server do resource
+ size estimation for them.
+
+ ❧❧❧❧❧❧❧❧❧❧❧
+
+2. Notations used in this document
+
+Notation for data types and requests follows the guidelines set in
+sections 2-4 of X Window System Protocol standard.
+
+ ❧❧❧❧❧❧❧❧❧❧❧
+
+3. Interoperability between version 1.1 and 1.2
+
+Version 1.2 only introduces two new requests. However, these requests
+could be seen as generalized versions of existing requests. Even
+though we aren't deprecating any old requests, libraries could
+implement some old requests using the new ones.
+
+The new XResQueryClientIds request could be used instead of
+XResQueryClients.
+
+The new XResQueryResourceBytes request could be used instead of
+XResQueryClientPixmapBytes.
+
+Using the old requests is still acceptable because we don't want to
+change the semantics of existing requests between version 1.1 and 1.2.
+
+ ❧❧❧❧❧❧❧❧❧❧❧
+
+4. Data types
+
+4.1 Types in version 1.0
+
+CLIENTXIDRANGE [ resource_base: CARD32
+ resource_mask: CARD32 ]
+
+This type is used for reply of XResQueryClients in version 1.1. It
+represents the range of resource allocated for a client and can be
+also used for client identification.
+
+resource_base
+ First resource ID reserved for a client. Used also to identify the
+ clients themselves.
+resource_mask
+ Mask that can be used to identify a client from some resource
+ ID. Just zero the bits indicated by this mask from any resource ID
+ to identify the client that owns the resource.
+
+CLIENTXID [ client: XID ]
+
+This type identifies a single client by a resource owned by that
+client or by the first resource ID allocated for the client
+(resource_base of CLIENTXIDRANGE). Whenever a resource ID is used, it
+is masked by resource_mask of CLIENTXIDRANGE to find out the client
+that owns the resource.
+
+CLIENTRESOURCETYPECOUNT [ resource_type: ATOM
+ count: CARD32 ]
+
+This type is used for reply of XResQueryClientResources in version
+1.1. It represents the number of certain type of resources that are
+owned by some client.
+
+resource_type
+ Atom specifying the type of a resource.
+count
+ Number of resources of the given type owned by a client.
+
+4.2 Types in version 1.2
+
+4.2.1 Types used by XResQueryClientIds
+
+CLIENTIDMASK { ClientXid = 0x1, LocalClientPid = 0x2 }
+
+A bitmask specifying a client identification method. Currently only
+the PID of local clients is supported in the form of
+LocalClientPid. ClientXid is provided for backward compatibility with
+version 1.0 so that the new 1.2 requests (XResQueryClientIds) can be
+used in place of the older ones (XResQueryClients).
+
+CLIENTIDSPEC [ client: CLIENTXID or None
+ mask: SETofCLIENTIDMASK or None ]
+
+A data structure for selecting client IDs.
+
+client
+ ID of a resource allocated for some client. Only the part
+ identifying a client is actually used. The resource_base of
+ CLIENTXIDRANGE can be used if the client doesn't own any
+ resources. However, any resource ID is accepted because that makes
+ identifying the owners of existing resources easy. The null
+ resource None can be used to select all clients.
+mask
+ Collection of identification methods that should be applied on the
+ client. The special value None can be used to apply all supported
+ identification methods.
+
+CLIENTIDVALUE [ spec: CLIENTIDSPEC
+ length: CARD32
+ value: LISTofCARD32 ]
+
+A data structure specifying a single client ID.
+
+spec
+ A unique identifier for a specific ID of some client. Wildcards
+ such as None and bitmask unions aren't allowed. The data structure
+ must always identify a single client and single ID type. However,
+ the client doesn't have to be specified as the resource_base of
+ CLIENTXIDRANGE and can be any resource owned by the client.
+length
+ Specifies the length of an ID in units of CARD32. The length
+ depends on the ID type. In version 1.2 the lengths are 0 for
+ ClientXid and 4 for LocalClientPid. The length of ClientXid is 0
+ because that is already stored in the spec field.
+value
+ Actual ID data. In version 1.2 this is missing for ClientXid and
+ consists of a single CARD32 for LocalClientPid.
+
+4.2.2 Types used by XResQueryResourceBytes
+
+To better understand how resources are related to each other, it's
+useful to introduce the concepts of main resource and cross
+reference. By main resource we just mean a normal resource that has a
+valid XID. By cross reference we mean a resource that is used by some
+other resource.
+
+The same resource may have both of these roles depending on the
+context. For example, there could be an ordinary pixmap resource. When
+we talk about this resource in isolation the term main resource is
+used. We call the exact same resource a cross reference when we are
+concentrating on some higher level resource, such as window or
+graphics context, that is using the lower level resource. Cross
+references may also be internal server resources that don't have a
+valid XID.
+
+RESOURCEIDSPEC [ resource: XID or None
+ type: ATOM or None/AnyPropertyType ]
+
+A data structure for selecting or identifying resources. The
+interpretation of fields changes depending on the context. The
+differences in interpretation are described below.
+
+resource
+ An XID of a resource. The null resource None can be used to select
+ all resources matching some type if the data structure is used in
+ XResQueryResourceBytes request. The null resource None can be used
+ to mark private server resources if the data structure is used in
+ a cross reference of XResQueryResourceBytes reply.
+type
+ An atom identifying the resource type. The null atom
+ None/AnyPropertyType can be used to select all resource types
+ matching some resource ID if the data structure is used in
+ XResQueryResourceBytes request.
+
+RESOURCESIZESPEC [ spec: RESOURCEIDSPEC
+ bytes: CARD32
+ ref_count: CARD32
+ use_count: CARD32 ]
+
+A data structure specifying the size of a single resource.
+
+spec
+ Uniquely identifies a single resource. Wildcards such as None and
+ AnyPropertyType aren't allowed for main resources. In cross
+ references, None is used to mark internal server resources.
+bytes
+ Number of bytes allocated for the resource. The size of a resource
+ is never divided by a reference count. This is the number of bytes
+ released in server when there are no more references left to the
+ resource.
+ref_count
+ Number of total users of the resource. Typically the reference
+ count is 1 but for pixmaps and other resources used from different
+ contexts the count may be larger.
+use_count
+ Number of times the resource is used by some other resource. For
+ main resources this is typically 1, because a resource doesn't
+ usually use itself recursively. For cross references this is the
+ number of times the resource is used and is also 1 usually.
+
+RESOURCESIZEVALUE [ size: RESOURCESIZESPEC
+ num_cross_references: CARD32
+ cross_references: LISTofRESOURCESIZESPEC ]
+
+A data structure specifying sizes of cross references to other
+resources in addition to the main resource size.
+
+size
+ Size of a main resource.
+num_cross_references
+ Number of cross references to other resources from the main
+ resource. Currently resources can only have pixmaps as cross
+ references but this can be extended to other types in the
+ future. For simple resources this field is therefore 0 and the
+ cross_references list is missing.
+cross_references:
+ Size specifications for cross references. Note that cross
+ references may contain resources that don't have a valid XID. For
+ example, a DRI2 drawable might have a cross reference to a private
+ pixmap that is used internally in the server only. These private
+ cross references are contained in this list also. This makes it
+ possible to emulate XResGetClientPixmapBytes with
+ XResGetResourceBytes.
+
+ ❧❧❧❧❧❧❧❧❧❧❧
+
+5. Requests
+
+5.1 Requests in version 1.0
+
+┌───
+ XResQueryVersion
+ client_major: CARD8
+ client_minor: CARD8
+ ▶
+ server_major: CARD16
+ server_minor: CARD16
+└───
+
+The client sends the highest supported version to the server and the
+server sends the highest version it supports, but no higher than the
+requested version. Major version changes can introduce
+incompatibilities in existing functionality, minor version changes
+introduce only backward compatible changes. It is the client's
+responsibility to ensure that the server supports a version which is
+compatible with its expectations.
+
+client_major
+ Major X Resource Extension version supported by client.
+client_minor
+ Minor X Resource Extension version supported by client.
+server_major
+ Highest version supported by server that is compatible with
+ client.
+server_minor
+ Highest version supported by server that is compatible with
+ client.
+
+┌───
+ XResQueryClients
+ ▶
+ num_clients: CARD32
+ clients: LISTofCLIENTXIDRANGE
+└───
+
+The request asks X server to return the list of all currently
+connected clients.
+
+num_clients
+ Number of currently connected clients.
+clients
+ List of XID ranges allocated for the connected clients.
+
+┌───
+ XResQueryClientResources
+ client: CLIENTXID
+ ▶
+ num_types: CARD32
+ types: LISTofCLIENTRESOURCETYPECOUNT
+
+ Errors: Value
+└───
+
+This request can be used to ask the number of resources owned by a
+client. The server will return the counts of each type of resource.
+
+client
+ An XID in the resource range of a client. This identifies the
+ client and not some specific resource.
+num_types
+ Number of different resource types owned by the client.
+types
+ A list of counts for each resource type.
+
+A value error is generated if invalid resource or client XID is given
+in the request.
+
+┌───
+ XResQueryClientPixmapBytes
+ client: CLIENTXID
+ ▶
+ bytes: CARD32
+ bytes_overflow: CARD32
+
+ Errors: Value
+└───
+
+This request is used to get the pixmap usage of some client. The
+returned number is a sum of memory usage of each pixmap that can be
+attributed to the given client. Ideally the server goes through all
+pixmaps and divides each pixmap size by the pixmap reference count to
+get a pixmap reference size. The reference size is then added to the
+returned sum if the client happens to be referencing that pixmap. In
+practice some pixmap references may be missed, because it would be too
+difficult to keep track of all pixmap references. However, the server
+will check the most important client resources that are using pixmaps
+and tries to estimate the pixmap usage as well as is possible. In
+other words, the server need only make a best-effort attempt to
+calculate resource source, so actual resource size may differ from
+that reported in practice.
+
+client
+ Identifies a client by an ID in its resource ID range.
+bytes:
+ Number of bytes attributed to pixmap references from the client
+ resources.
+bytes_overflow:
+ Higher order word for the bytes field in case the sum of pixmap
+ reference sizes doesn't fit in CARD32.
+
+A value error is generated if invalid resource or client XID is given
+in the request.
+
+5.2 Requests in version 1.2
+
+┌───
+ XResQueryClientIds
+ num_specs: CARD32
+ client_specs: LISTofCLIENTIDSPEC
+ ▶
+ num_ids: CARD32
+ client_ids: LISTofCLIENTIDVALUE
+
+ Errors: Value
+└───
+
+XResQueryClientIds can be used to identify a given set of clients with
+some identification method. The request sends a list of specifiers
+that select clients and identification methods to server. The server
+then tries to identify the chosen clients using the identification
+methods specified for each client. The server returns IDs for those
+clients that were successfully identified. It's not an error condition
+if some identification method couldn't be applied to a client. If the
+server is unable to identify some clients, they simply aren't included
+in the returned list.
+
+The request supports wildcards in the client specifications so that in
+the most general case all IDs of all clients can be queried with a
+single CLIENTIDSPEC.
+
+The CLIENTIDSPEC of request and CLIENTIDSPEC of CLIENTIDVALUE in reply
+usually match each other. For example, if a request selected a client
+by a resource ID owned by the client, then the client is identified by
+the same resource ID in the reply. This has been done so that it would
+be easy to identify an owner of some resource.
+
+However, the CLIENTIDSPEC of returned CLIENTIDVALUE never contains any
+wildcards. If the request used a wildcard to specify all clients in a
+single CLIENTIDSPEC, then the reply has expanded the wildcard and
+returns separate CLIENTIDVALUE records for each client. In this case
+wildcarded clients are identified by resource_base of CLIENTXIDRANGE.
+
+The LocalClientPid type of IDs are included in the reply list only if
+the client executing the request asked for it and was also a local
+client itself. It doesn't make sense for remote clients to ask PIDs of
+local clients.
+
+num_specs
+ Number of client ID specifications.
+client_specs
+ A list specifying identification methods for clients. Supports
+ multiple identification methods and clients in a single
+ specification. See CLIENTIDSPEC for details.
+num_ids
+ Number of IDs that were successfully determined. Can be different
+ from num_specs or even zero if the server didn't support any
+ identification methods for the given clients.
+client_ids
+ A list specifying ID information for successfully identified
+ clients. If wildcards were used in a single CLIENTIDSPEC of
+ client_specs, then multiple CLIENTIDVALUE records may be returned
+ for that CLIENTIDSPEC. See CLIENTIDVALUE for details.
+
+A Value error is returned if the request specifies an invalid client
+XID or invalid identification method type.
+
+┌───
+ XResQueryResourceBytes
+ client: CLIENTXID or None
+ num_specs: CARD32
+ resource_specs: LISTofRESOURCEIDSPEC
+ ▶
+ num_sizes: CARD32
+ sizes: LISTofRESOURCESIZEVALUE
+
+ Errors: Atom, Value
+└───
+
+XResQueryResourceBytes can be used to ask the sizes of resources from
+X server. The request sends a list of specifiers that selects
+resources for size calculation. The server tries to calculate the
+sizes of chosen resources and returns an estimate for a resource only
+if the size could be determined. It's not an error condition if a size
+couldn't be calculated. In that case the resources simply aren't
+included in the returned list.
+
+The request supports wildcards so that in the most general case sizes
+of all resources of all clients can be queried with a single
+RESOURCEIDSPEC. However, the reply has all wildcards expanded and
+reports a size of a single resource in each RESOURCESIZEVALUE.
+
+client
+ An ID of a client can be given to limit the query to resources of
+ that client. Just like in CLIENTIDSPEC, any resource ID can be
+ given to identify a client and None can be used if the query
+ shouldn't be limited to a specific client. Note that in some cases
+ this field is redundant because resource_specs already fully
+ determines which resources are selected. If the client ID doesn't
+ match the owner of any resource in resource_specs, no sizes are
+ returned and no error is generated.
+num_specs
+ Number of resource specifications.
+resource_specs
+ A list of resource specifications. Each specification can either
+ uniquely identify a single resource or multiple resources if
+ wildcarding is used. See RESOURCEIDSPEC for details.
+num_sizes
+ Number of resources whose size could be determined. Can be
+ different from num_specs or even zero if the server didn't support
+ size calculation for the given resources.
+sizes
+ A list of resource sizes. Each resource size is linked to a unique
+ resource. Wildcards are never used in the returned size
+ records. For example, it's not possible to receive a single
+ RESOURCESIZEVALUE that would specify the size of all pixmaps if
+ the sizes of pixmap type resources were asked. Instead, a single
+ RESOURCESIZEVALUE would be returned for each pixmap in that case.
+
+An Atom error is returned if the request specifies an invalid resource
+type. A Value error is returned if the request specifies an invalid
+XID for a client or a resource.
+
+ ❧❧❧❧❧❧❧❧❧❧❧