Merging upstream version 0.7.1 (Closes: #991419).

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 204 insertions, 0 deletions

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+### Continuous Integration
+
+| Drone | Travis | Cirrus |
+| -------- | ------ | ------- |
+| [![Build Status](https://cloud.drone.io/api/badges/concurrencykit/ck/status.svg)](https://cloud.drone.io/concurrencykit/ck) | [![Build Status](https://travis-ci.org/concurrencykit/ck.svg)](https://travis-ci.org/concurrencykit/ck) | [![Build Status](https://api.cirrus-ci.com/github/concurrencykit/ck.svg?branch=master)](https://cirrus-ci.com/github/concurrencykit/ck) |
+
+Compilers tested in the past include gcc, clang, cygwin, icc, mingw32, mingw64 and suncc across all supported architectures. All new architectures are required to pass the integration test and under-go extensive code review.
+
+Continuous integration is currently enabled for the following targets:
+ * `darwin/clang/x86-64`
+ * `freebsd/clang/x86-64`
+ * `linux/gcc/arm64`
+ * `linux/gcc/x86-64`
+ * `linux/clang/x86-64`
+ * `linux/clang/ppc64le`
+
+### Compile and Build
+
+* Step 1.
+        `./configure`
+        For additional options try `./configure --help`
+
+* Step 2.
+        In order to compile regressions (requires POSIX threads) use
+        `make regressions`. In order to compile libck use `make all` or `make`.
+
+* Step 3.
+	In order to install use `make install`
+	To uninstall use `make uninstall`.
+
+See http://concurrencykit.org/ for more information.
+
+### Supported Architectures
+
+Concurrency Kit supports any architecture using compiler built-ins as a fallback. There is usually a performance degradation associated with this.
+
+Concurrency Kit has specialized assembly for the following architectures:
+ * `aarch64`
+ * `arm`
+ * `ppc`
+ * `ppc64`
+ * `s390x`
+ * `sparcv9+`
+ * `x86`
+ * `x86_64`
+ 
+### Features
+
+#### Concurrency Primitives
+
+##### ck_pr
+
+Concurrency primitives as made available by the underlying architecture, includes support for all atomic operations (natively), transactional memory, pipeline control, read-for-ownership and more.
+
+##### ck_backoff
+
+A simple and efficient (minimal noise) backoff function.
+
+##### ck_cc
+
+Abstracted compiler builtins when writing efficient concurrent data structures.
+
+#### Safe Memory Reclamation
+
+##### ck_epoch
+
+A scalable safe memory reclamation mechanism with support idle threads and various optimizations that make it better than or competitive with many state-of-the-art solutions.
+
+##### ck_hp
+
+Implements support for hazard pointers, a simple and efficient lock-free safe memory reclamation mechanism.
+
+#### Data Structures
+
+##### ck_array
+
+A simple concurrently-readable pointer array structure.
+
+##### ck_bitmap
+
+An efficient multi-reader and multi-writer concurrent bitmap structure.
+
+##### ck_ring
+
+Efficient concurrent bounded FIFO data structures with various performance trade-off. This includes specialization for single-reader, many-reader, single-writer and many-writer.
+
+##### ck_fifo
+
+A reference implementation of the first published lock-free FIFO algorithm, with specialization for single-enqueuer-single-dequeuer and many-enqueuer-single-dequeuer and extensions to allow for node re-use.
+
+##### ck_hp_fifo
+
+A reference implementation of the above algorithm, implemented with safe memory reclamation using hazard pointers.
+
+##### ck_hp_stack
+
+A reference implementation of a Treiber stack with support for hazard pointers.
+
+##### ck_stack
+
+A reference implementation of an efficient lock-free stack, with specialized variants for a variety of memory management strategies and bounded concurrency.
+
+##### ck_queue
+
+A concurrently readable friendly derivative of the BSD-queue interface. Coupled with a safe memory reclamation mechanism, implement scalable read-side queues with a simple search and replace.
+
+##### ck_hs
+
+An extremely efficient single-writer-many-reader hash set, that satisfies lock-freedom with bounded concurrency without any usage of atomic operations and allows for recycling of unused or deleted slots. This data structure is recommended for use as a general hash-set if it is possible to compute values from keys. Learn more at https://engineering.backtrace.io/workload-specialization/ and http://concurrencykit.org/articles/ck_hs.html.
+
+##### ck_ht
+
+A specialization of the `ck_hs` algorithm allowing for disjunct key-value pairs.
+
+##### ck_rhs
+
+A variant of `ck_hs` that utilizes robin-hood hashing to allow for improved performance with higher load factors and high deletion rates.
+
+#### Synchronization Primitives
+
+##### ck_ec
+
+An extremely efficient event counter implementation, a better alternative to condition variables.
+
+##### ck_barrier
+
+A plethora of execution barriers including: centralized barriers, combining barriers, dissemination barriers, MCS barriers, tournament barriers.
+
+##### ck_brlock
+
+A simple big-reader lock implementation, write-biased reader-writer lock with scalable read-side locking.
+
+##### ck_bytelock
+
+An implementation of bytelocks, for research purposes, allowing for (in theory), fast read-side acquisition without the use of atomic operations. In reality, memory barriers are required on the fast path.
+
+##### ck_cohort
+
+A generic lock cohorting interface, allows you to turn any lock into a NUMA-friendly scalable NUMA lock. There is a significant trade-off in fast path acquisition cost. Specialization is included for all relevant lock implementations in Concurrency Kit. Learn more by reading "Lock Cohorting: A General Technique for Designing NUMA Locks".
+
+##### ck_elide
+
+A generic lock elision framework, allows you to turn any lock implementation into an elision-aware implementation. This requires support for restricted transactional memory by the underlying hardware.
+
+##### ck_pflock
+
+Phase-fair reader-writer mutex that provides strong fairness guarantees between readers and writers. Learn more by reading "Spin-Based Reader-Writer Synchronization for Multiprocessor Real-Time Systems".
+
+##### ck_rwcohort
+
+A generic read-write lock cohorting interface, allows you to turn any read-write lock into a NUMA-friendly scalable NUMA lock. There is a significant trade-off in fast path acquisition cost. Specialization is included for all relevant lock implementations in Concurrency Kit. Learn more by reading "Lock Cohorting: A General Technique for Designing NUMA Locks".
+
+##### ck_rwlock
+
+A simple centralized write-biased read-write lock.
+
+##### ck_sequence
+
+A sequence counter lock, popularized by the Linux kernel, allows for very fast read and write synchronization for simple data structures where deep copy is permitted.
+
+##### ck_swlock
+
+A single-writer specialized read-lock that is copy-safe, useful for data structures that must remain small, be copied and contain in-band mutexes.
+
+##### ck_tflock
+
+Task-fair locks are fair read-write locks, derived from "Scalable reader-writer synchronization for shared-memory multiprocessors".
+
+##### ck_spinlock
+
+A basic but very fast spinlock implementation.
+
+##### ck_spinlock_anderson
+
+Scalable and fast anderson spinlocks. This is here for reference, one of the earliest scalable and fair lock implementations.
+
+##### ck_spinlock_cas
+
+A basic spinlock utilizing compare_and_swap.
+
+##### ck_spinlock_dec
+
+A basic spinlock, a C adaption of the older optimized Linux kernel spinlock for x86. Primarily here for reference.
+
+##### ck_spinlock_fas
+
+A basic spinlock utilizing atomic exchange.
+
+##### ck_spinlock_clh
+
+An efficient implementation of the scalable CLH lock, providing many of the same performance properties of MCS with a better fast-path.
+
+##### ck_spinlock_hclh
+
+A NUMA-friendly CLH lock.
+
+##### ck_spinlock_mcs
+
+An implementation of the seminal scalable and fair MCS lock.
+
+##### ck_spinlock_ticket
+
+An implementation of fair centralized locks.
+