Reporting of information pertaining to queuing of requests
Various approaches for capturing context data in a data processing arrangement are described. In one approach, a method controls shared access to an object for a plurality of requestors. An access control routine receives an access control request from a first routine of one of the requestors. The access control request specifies a type of control over access to the object and specifies a role descriptor that describes a processing context in the first routine of the requested access control to the object. The context is not visible to the access control routine without the role descriptor. The method determines whether the type of control can or cannot be immediately granted to the requestor. If the type of control cannot be immediately granted to the one of the requestors, the specified type of requested control and role descriptor are stored by the access control routine.
1 . A processor-implemented method for capturing context data, comprising:
controlling with an access control routine, shared access to an object by a plurality of requesters; inputting an access control request from a first routine of one of the requestors to the access control routine, wherein the access control request specifies a type of control over access to the object and specifies a role descriptor that describes a processing context in the first routine of the requested access control to the object, wherein the context is not visible to the access control routine without the role descriptor; determining whether the type of control can or cannot be immediately granted to one of the requesters; and storing the specified type of requested control and role descriptor by the access control routine in response to determining that the type of control cannot be immediately granted to the one of the requestors.
2 . The method of claim 1 , further comprising queuing the access control request in response to determining that the type of control cannot be immediately granted to the one of the requestors.
3 . The method of claim 1 , further comprising reading and outputting the stored type of requested control and role descriptor.
4 . The method of claim 2 , further comprising:
determining whether or not queuing the access control request would cause deadlock; and in response to determining that queuing the access control request would cause deadlock, unconditionally storing the specified type of requested control and role descriptor and denying the queuing of the access control request; and in response to determining that queuing the access control request would not cause deadlock, queuing the access control request and storing the specified type of requested control and role descriptor.
5 . The method of claim 4 , wherein the storing of the specified type of requested control and role descriptor is conditional in response to a state of a configuration parameter.
6 . The method of claim 1 , wherein the type of control is one of a read lock and an update lock and the object is one of an index page and a data page of a B+tree
7 . The method of claim 5 , wherein the processing context is an insert to a right-most page of the B+tree.
8 . The method of claim 5 , wherein the processing context indicates requested control over an interior index page in the B+tree.
9 . The method of claim 5 , wherein the processing context indicates requested control over a root page of the B+tree.
10 . The method of claim 1 , wherein the storing comprises storing the specified type and role descriptor in a circular table.
11 . An apparatus for capturing diagnostic information, comprising:
means for managing shared access to an object by a plurality of requestors with an access control routine; means for receiving an access control request from a first routine of one of the requesters to the access control routine, wherein the access control request specifies a type of control over access to the object and specifies a role descriptor that describes a processing context in the first routine of the requested access control to the object, wherein the context is not visible to the access control routine without the role descriptor; means for evaluating whether the type of control can or cannot be immediately granted to one of the requestors; and means, responsive to finding that the type of control cannot be immediately granted to the one of the requesters, for storing the specified type of requested control and role descriptor by the access control routine.
12 . A data processing system, comprising: a processor arrangement; a memory coupled to the processor arrangement, the memory configured with instructions executable by the processor arrangement for capturing context data;a persistent storage arrangement coupled to the memory and to the processor arrangement for retentive storage of an object to which access is shared by a plurality of requesters;
wherein the processor arrangement in executing the instructions, controls access to the object with an access control routine; receives from one of the plurality of requestors an access control request, wherein the access control request specifies one of a read lock and an update lock on the object and specifies a role descriptor that describes a processing context in the requestor of the requested access control to the object, wherein the context is not visible to the access control routine without the role descriptor; determines whether the type of control can or cannot be immediately granted to one of the requesters; and stores the specified type of requested control and role descriptor by the access control routine in response to determining that the type of control cannot be immediately granted to the one of the requestors.
13 . The system of claim 12 , wherein the processor arrangement in executing the instructions further queues the access control request in response to determining that the type of control cannot be immediately granted to the one of the requestors.
14 . The system of claim 12 , wherein the processor arrangement in executing the instructions further reads and outputs the stored type of requested control and role descriptor.
15 . The system of claim 13 , wherein the processor arrangement in executing the instructions further: determines whether queuing the access control request would cause deadlock; and in response to determining that queuing the access control request would cause deadlock, unconditionally stores the specified type of requested control and role descriptor and denying the queuing of the access control request; and in response to determining that queuing the access control request would not cause deadlock, queues the access control request and stores the specified type of requested control and role descriptor.
16 . The system of claim 15 , wherein the storing of the specified type of requested control and role descriptor is conditional in response to a state of a configuration parameter and queuing of the access control request.
17 . The system of claim 1 , wherein the object is one of an index page and a data page of a B+tree.
18 . The system of claim 16 , wherein the processing context is an insert to a right-most page of the B+tree.
19 . The system of claim 16 , wherein the processing context indicates requested control over an interior index page in the B+tree.
20 . The system of claim 16 , wherein the processing context indicates requested control over a root page of the B+tree.