What is claimed is:
1. A method of operating a transaction system which supports bulk delegations of locks from one or more delegator transactions to one or more delegates transaction, the method comprising:
validating at least a subset of the bulk lock delegations by, for each delegated lock owned by a delegator transaction, testing validity of delegating the lock based, at least in part, on ignore conflicts relationships amongst the delegates transactions and between the delegatee transactions and otherwise incompatible-mode owners of locks, which would remain after completion of the bulk delegation.
2. A method, as recited in claim 1, further comprising:
performing the validated bulk lock delegations.
3. A method, as recited in claim 1, further comprising:
representing locks of identical value as references to a shared lock state encoding the value.
4. A method, as recited in claim 3, wherein a subset of the shared lock states is encoded in an associative table of shared lock states (TSLS).
5. A method, as recited in claim 1, further comprising:
obviating the testing of each lock for at least another subset of the bulk lock delegations by performing one or more conservative tests.
6. A method, as recited in claim 5,
wherein the one or more conservative tests include testing for disjunction of a set of delegator transactions and a wset.
7. A method, as recited in claim 6, further comprising:
adding a corresponding entry to the wset coincident with recording of a lock owned in a write mode; and
recomputing the wset by scanning the locks.
8. A method, as recited in claim 5, wherein the one or more conservative tests includes:
determining for each particular one of the delegator transactions, whether there are no delegatee transactions such that, for each type of conflict, a corresponding first set of transactions with which the delegatee can ignore conflicts is not a super-set of a second set of transactions that includes those transactions with which the particular delegator transaction can ignore conflicts of such type, excluding the delegator transactions themselves, and
if there is at least one write lock owned by at least one of the delegator transactions, then determining whether all delegatee can ignore conflicts with each other.
9. A method, as recited in claim 1, performed by a lock manager in a transaction processing system.
10. In a computational system wherein a value of a lock is encoded to identify (i) a set of one or more transactions that own the lock and (ii) respective one or more modes in which such transactions own the lock, and wherein at least some locks of equal value are represented using a same shared lock state, a method of validating bulk delegation of locks from one or more delegator transactions to one or more delegatee transactions, the method comprising:
for at least a subset of the bulk delegations, and for each shared lock state encoding having an associated owner set that includes at least one of the delegator transactions, testing validity of delegating a lock represented thereby based, at least in part, on ignore conflicts relationships amongst the delegatee transactions and between the delegatee transactions and otherwise incompatible-mode owners that would remain after completion of the bulk delegation.
11. A method, as recited in claim 10, further comprising:
for each of the bulk delegations, performing one or more conservative validation tests and thereby obviating, for another subset of the bulk delegations, the validity testing for each shared lock state encoding.
12. A method, as recited in claim 11,
wherein the one or more conservative tests include testing for disjunction of a set of delegator transactions and a wset.
13. A method, as recited in claim 12, further comprising:
adding a corresponding entry to the wset coincident with recording of a lock value held in a write mode; and
recomputing the wset upon each scan of the shared lock states.
14. A method, as recited in claim 11, wherein the one or more conservative tests includes:
determining for each particular one of the delegator transactions, whether there are no delegatee transactions such that, for each type of conflict, a corresponding first set of transactions with which the delegates can ignore conflicts is not a super-set of a second set of transactions that includes those transactions with which the particular delegator transaction can ignore conflicts of such type, excluding the delegator transactions themselves, and
if there is at least one write lock owned by at least one of the delegator transactions, then determining whether all delegatee can ignore conflicts with each other.
15. A method, as recited in claim 10,
wherein the shared lock states are at least partially encoded in an associative table of shared lock states (TSLS).
16. A method, as recited in claim 15,
wherein at least a subset of the shared lock states that represent locks owned by a single owner is encoded separately from the table of shared lock states (TSLS).
17. A method, as recited in claim 15,
wherein at least a frequently used subset of the shared lock states is encoded separately from the table of shared lock states (TSLS).
18. In a computational system wherein locks of identical value are represented as references to a shared lock state encoding of the value, a method of implementing a bulk delegation of locks from one or more delegator transactions to one or more delegatee transactions, the method comprising:
validating the bulk delegation based at least in part on ignore conflicts relationships amongst the delegatee transactions; and
if validated, performing the bulk delegation.
19. The method of claim 18,
wherein the performing of the bulk delegation includes, for each shared lock state encoding having an associated owner set that includes one of the delegator transactions, removing from the owner set each of the delegator transactions and adding thereto each of the delegatee transactions.
20. The method of claim 18,
wherein the validating is based on ignore conflicts relationships amongst the delegatee transactions and between the delegatee transactions and otherwise incompatible-mode owners that would remain after completion of the bulk delegation.
21. The method of claim 18,
wherein the validating is based on one or more conservative validation tests that, if successful, obviate validity testing for each shared lock state; and
wherein, if not obviated by the one or more conservative validation tests, the validating includes, for each shared lock state encoding having an associated owner set that includes at least one of the delegator transactions, testing validity of delegating a lock represented thereby based, at least in part, on ignore conflicts relationships amongst the delegatee transactions and between the delegatee transactions and otherwise incompatible-mode owners that would remain after completion of the bulk delegation.
22. A transaction processing system that supports bulk delegation of locks, the transaction processing system comprising:
a lock manager that associates locking capabilities with transactions and that allows specification of certain conflicts between locking capabilities to be ignored; and
an encoding of ignore conflicts relationships amongst the transactions, the lock manager implementing at least a subset of bulk delegation operations by first validating requests therefor based on encoded ignore conflicts relationships amongst the delegates transactions and between the delegatee transactions and otherwise incompatible-mode owners that which would remain after completion of the bulk delegation, and if the requests are validated by performing the bulk delegation operations.
23. The transaction processing system of claim 22,
wherein the transaction processing system implements a transaction model that supports a nested conflict serializability correctness criterion; and
wherein the bulk delegation operation is employed to support creation, commitment or abortion of a sub-database.
24. The transaction processing system of claim 22, wherein as part of an initial computationally-efficient, but conservative, validation, the lock manager:
verifies that, for each delegator transaction and type of conflict between lock modes, a set of transactions with which a particular delegatee transaction can ignore conflicts is a super-set of the set of transactions with which the delegator transaction can ignore conflicts; and
if at least one to-be-delegated lock is owned in a write mode by at least one of the delegator transactions, further verifies that each of the delegatee transactions can ignore conflicts with each other.
25. A lock manager that implements a bulk delegation operation by validating a bulk delegation request based, at least in part, on ignore conflicts relationships amongst delegatee transactions.
26. The lock manager of claim 25, embodied as software executable in an transaction processing environment that associates locking capabilities with transactions and that allows specification of certain conflicts between locking capabilities to be ignored.
27. A computer program product encoded in one or more computer readable media and comprising:
definition of a data structure instantiable in memory to represent plural locks having identical lock values using a single shared lock state encoding;
lock manager instructions executable by a processor to associate locking capabilities with transactions, to specify certain conflicts between locking capabilities to be ignored, to manage the shared lock state encoding, and to implement a bulk delegation of locks from one or more delegator transactions to one or more delegatee transactions, wherein the lock manager instructions validate a bulk delegation request based, at least in part, on ignore conflicts relationships amongst the delegatee transactions.
28. The computer program product of claim 27,
wherein, if the bulk delegation request is successfully validated, the bulk delegation is performed by the lock manager.
29. The computer program product of claim 27,
wherein the one or more computer readable media are selected from the set of a disk, tape or other magnetic, optical or electronic storage medium and a network, wireline, wireless or other communications medium.
30. An apparatus comprising:
means for representing plural locks having identical values using a single shared lock state encoding; and
means for validating a bulk delegation of locks from one or more delegator transactions to one or more delegatee transactions based, at least in part, on ignore conflicts relationships amongst the delegatee transactions.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for delivering anti-tachyarrhythmia therapy, comprising:
generating an electrogram signal representing electrical activity in a cardiac chamber;
detecting chamber senses and measuring a time interval between such senses to determine a current heart rate;
detecting a tachyarrhythmia when the heart rate exceeds a specified tachycardia detection rate (TDR);
upon detection of a tachyarrhythmia, delivering shock therapy if the heart rate is above a fibrillation detection rate (FDR);
upon detection of a tachyarrhythmia below the FDR, delivering a sequence of different therapies where the sequence is stopped whenever the tachyarrhythmia is terminated;
recording the successes and failures of each therapy of the sequence in terminating tachyarrhythmias for a plurality of heart rate ranges between the TDR and the FDR and computing a successfailure ratio for each therapy at each heart rate range; and,
discontinuing a therapy from the sequence for a particular heart rate range if the successfailure ratio for a particular therapy at that particular heart rate range drops below a specified threshold value.
2. The method of claim 1 further comprising discontinuing a therapy from the sequence for a particular heart rate range if the successfailure ratio for a particular therapy at that particular heart rate range drops below a specified threshold difference from that of another therapy in the therapy sequence.
3. The method of claim 2 further comprising accepting an input defining the number of heart rate ranges and the boundaries defining the ranges.
4. The method of claim 1 wherein the sequence of different therapies include delivery of neural stimulation.
5. The method of claim 1 wherein the sequence of different therapies include delivery of anti-tachycardia pacing (ATP).
6. The method of claim 1 wherein the sequence of different therapies include delivery of neural stimulation and anti-tachycardia pacing ATP.
7. The method of claim 1 wherein the sequence of different therapies include delivery of shock therapy.
8. The method of claim 1 further comprising delivering neural stimulation with shock therapy if the heart rate is above the FDR.
9. The method of claim 1 wherein the cardiac chamber is a ventricle.
10. The method of claim 1 wherein the cardiac chamber is an atrium.
11. A cardiac device, comprising:
a sensing amplifier for sensing an electrogram signal representing electrical activity in a cardiac chamber;
a pulse generator for delivering anti-tachycardia pacing (ATP);
a shock pulse generator for delivering shock therapy;
a pulse generator for delivering neural stimulation that augments parasympathetic balance by parasympathetic stimulation or sympathetic inhibition;
a controller, wherein the controller is programmed to:
detect chamber senses and measure a time interval between such senses to determine a current heart rate;
detect a tachyarrhythmia when the heart rate exceeds a specified tachycardia detection rate (TDR);
upon detection of a tachyarrhythmia, deliver shock therapy if the heart rate is above a fibrillation detection rate (FDR);
upon detection of a tachyarrhythmia below the FDR, deliver a sequence of different therapies where the sequence is stopped whenever the tachyarrhythmia is terminated;
record the successes and failures of each therapy of the sequence in terminating tachyarrhythmias for a plurality of heart rate ranges between the TDR and the FDR and compute a successfailure ratio for each therapy at each heart rate range; and,
discontinue a therapy from the sequence for a particular heart rate range if the successfailure ratio for a particular therapy at that particular heart rate range drops below a specified threshold value.
12. The device of claim 11 wherein the controller is further programmed to discontinue a therapy from the sequence for a particular heart rate range if the successfailure ratio for a particular therapy at that particular heart rate range drops below a specified threshold difference from that of another therapy in the therapy sequence.
13. The device of claim 12 wherein the controller is further programmed to accept an input defining the number of heart rate ranges and the boundaries defining the ranges.
14. The device of claim 11 wherein the sequence of different therapies include delivery of neural stimulation.
15. The device of claim 11 wherein the sequence of different therapies include delivery of anti-tachycardia pacing (ATP).
16. The device of claim 11 wherein the sequence of different therapies include delivery of neural stimulation and anti-tachycardia pacing ATP.
17. The device of claim 11 wherein the sequence of different therapies include delivery of shock therapy.
18. The device of claim 11 wherein the controller is further programmed to deliver neural stimulation with shock therapy if the heart rate is above the FDR.
19. The device of claim 11 wherein the cardiac chamber is a ventricle.
20. The device of claim 11 wherein the cardiac chamber is an atrium.