| 1 | Userspace RCU Concurrent Data Structures (CDS) API |
| 2 | ================================================== |
| 3 | |
| 4 | by Mathieu Desnoyers and Paul E. McKenney |
| 5 | |
| 6 | This document describes briefly the data structures contained with the |
| 7 | userspace RCU library. |
| 8 | |
| 9 | |
| 10 | Data structure files |
| 11 | -------------------- |
| 12 | |
| 13 | ### `urcu/list.h` |
| 14 | |
| 15 | Doubly-linked list, which requires mutual exclusion on |
| 16 | updates and reads. |
| 17 | |
| 18 | |
| 19 | ### `urcu/rculist.h` |
| 20 | |
| 21 | Doubly-linked list, which requires mutual exclusion on |
| 22 | updates, allows RCU read traversals. |
| 23 | |
| 24 | |
| 25 | ### `urcu/hlist.h` |
| 26 | |
| 27 | Doubly-linked list, with single pointer list head. Requires |
| 28 | mutual exclusion on updates and reads. Useful for implementing hash tables. |
| 29 | Downside over `list.h`: lookup of tail in O(n). |
| 30 | |
| 31 | |
| 32 | ### `urcu/rcuhlist.h` |
| 33 | |
| 34 | Doubly-linked list, with single pointer list head. |
| 35 | Requires mutual exclusion on updates, allows RCU read traversals. Useful |
| 36 | for implementing hash tables. Downside over rculist.h: lookup of tail in O(n). |
| 37 | |
| 38 | |
| 39 | ### `urcu/wfstack.h` |
| 40 | |
| 41 | Stack with wait-free push and wait-free pop_all. Both |
| 42 | blocking and non-blocking pop and traversal operations are provided. This |
| 43 | stack does _not_ specifically rely on RCU. Various synchronization techniques |
| 44 | can be used to deal with pop ABA. Those are detailed in the API. |
| 45 | |
| 46 | |
| 47 | ### `urcu/wfcqueue.h` |
| 48 | |
| 49 | Concurrent queue with wait-free enqueue. Both blocking and |
| 50 | non-blocking dequeue, splice (move all elements from one queue |
| 51 | to another), and traversal operations are provided. |
| 52 | |
| 53 | This queue does _not_ specifically rely on RCU. Mutual exclusion |
| 54 | is used to protect dequeue, splice (from source queue) and |
| 55 | traversal (see API for details). |
| 56 | |
| 57 | - Note: deprecates `urcu/wfqueue.h`. |
| 58 | |
| 59 | |
| 60 | ### `urcu/lfstack.h` |
| 61 | |
| 62 | Stack with lock-free push, lock-free pop, wait-free pop_all, |
| 63 | wait-free traversal. Various synchronization techniques can be |
| 64 | used to deal with pop ABA. Those are detailed in the API. |
| 65 | This stack does _not_ specifically rely on RCU. |
| 66 | |
| 67 | - Note: deprecates `urcu/rculfstack.h`. |
| 68 | |
| 69 | |
| 70 | ### `urcu/rculfqueue.h` |
| 71 | |
| 72 | RCU queue with lock-free enqueue, lock-free dequeue. |
| 73 | This queue relies on RCU for existence guarantees. |
| 74 | |
| 75 | |
| 76 | ### `urcu/rculfhash.h` |
| 77 | |
| 78 | Lock-Free Resizable RCU Hash Table. RCU used to provide |
| 79 | existence guarantees. Provides scalable updates, and scalable |
| 80 | RCU read-side lookups and traversals. Unique and duplicate keys |
| 81 | are supported. Provides "uniquify add" and "replace add" |
| 82 | operations, along with associated read-side traversal uniqueness |
| 83 | guarantees. Automatic hash table resize based on number of |
| 84 | elements is supported. See the API for more details. |