Contribute a new experimental storage engine PSKIPLIST

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "src/engines-experimental/pskiplist"]
+	path = src/engines-experimental/pskiplist
+	url = https://github.com/4paradigm/pskiplist.git

CMakeLists.txt

@@ -39,6 +39,8 @@ option(ENGINE_RADIX "enable experimental radix engine" OFF)
 option(ENGINE_ROBINHOOD "enable experimental robinhood engine (requires CXX_STANDARD to be set to value >= 14)" OFF)
 option(ENGINE_DRAM_VCMAP "enable testing dram_vcmap engine" OFF)
 
+option(ENGINE_PSKIPLIST "enable experimental pskiplist engine" OFF)
+
 # ----------------------------------------------------------------- #
 ## Set required and useful variables
 # ----------------------------------------------------------------- #
@@ -140,6 +142,27 @@ if(ENGINE_RADIX)
 		src/engines-experimental/radix.cc
 	)
 endif()
+# checkout submodule for ENGINE_PSKIPLIST
+find_package(Git QUIET)
+option(GIT_SUBMODULE "Check submodules during build" ON)
+if(GIT_SUBMODULE)
+	message(STATUS "Submodule update for ENGINE_PSKIPLIST")
+	execute_process(COMMAND ${GIT_EXECUTABLE} submodule update --init --recursive
+					WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+					RESULT_VARIABLE GIT_SUBMOD_PSKIPLIST)
+endif()
+if(ENGINE_PSKIPLIST)
+	if(NOT GIT_SUBMOD_PSKIPLIST EQUAL "0")
+		message(FATAL_ERROR "git submodule update for ENGINE_PSKIPLIST failed with ${GIT_SUBMOD_RESULT}, please checkout submodules")
+	endif()
+	list(APPEND SOURCE_FILES
+		src/engines-experimental/pskiplist.h
+		src/engines-experimental/pskiplist.cc
+		src/engines-experimental/pskiplist/persistent_skiplist.h
+		src/engines-experimental/pskiplist/smartpptr.h
+		src/engines-experimental/pskiplist/log4p.h
+	)
+endif()
 if(ENGINE_ROBINHOOD)
 	list(APPEND SOURCE_FILES
 		src/engines-experimental/robinhood.h
@@ -205,6 +228,12 @@ if(ENGINE_RADIX)
 else()
 	message(STATUS "RADIX engine is OFF")
 endif()
+if(ENGINE_PSKIPLIST)
+	add_definitions(-DENGINE_PSKIPLIST)
+	message(STATUS "PSKIPLIST engine is ON")
+else()
+	message(STATUS "PSKIPLIST engine is OFF")
+endif()
 if(ENGINE_ROBINHOOD)
 	add_definitions(-DENGINE_ROBINHOOD)
 	message(STATUS "ROBINHOOD engine is ON")

README.md

@@ -81,6 +81,7 @@ all language bindings and utilities. Engines are loaded by name at runtime.
 | [tree3](doc/ENGINES-experimental.md#tree3) | Persistent B+ tree | Yes | No | No |
 | [stree](doc/ENGINES-experimental.md#stree) | Sorted persistent B+ tree | Yes | No | Yes |
 | [robinhood](doc/ENGINES-experimental.md#robinhood) | Persistent hash map with Robin Hood hashing | Yes | Yes | No |
+| [pskiplist](doc/ENGINES-experimental.md#pskiplist) | Sorted persistent skiplist (contributed by [4Paradigm](https://github.com/4paradigm/pskiplist))| Yes | Yes | Yes |
 | [dram_vcmap](doc/ENGINES-testing.md#dram_vcmap) | Volatile concurrent hash map placed entirely on DRAM | Yes | Yes | No |
 
 The production quality engines are described in the [libpmemkv(7)](doc/libpmemkv.7.md#engines) manual

doc/ENGINES-experimental.md

@@ -5,6 +5,7 @@
 - [radix](#radix)
 - [stree](#stree)
 - [robinhood](#robinhood)
+- [pskiplist](#pskiplist)
 
 # tree3
 
@@ -178,6 +179,28 @@ There are two parameters to be optionally modified by env variables:
 
 No additional packages are required.
 
+# pskiplist
+
+A persistent and concurrent engine, backed by a skiplist implemented using Persistent Compare and Swap (PCAS), contributed by [4Paradigm Inc.](http://www.4paradigm.com/). The skiplist data structure is firstly introduced in a [VLDB paper](http://vldb.org/pvldb/vol14/p799-chen.pdf) **("Optimizing In-memory Database Engine for AI-powered On-line Decision Augmentation Using Persistent Memory". Cheng Chen, Jun Yang, Mian Lu, Taize Wang, Zhao Zheng, Yuqiang Chen, Wenyuan Dai, Bingsheng He, Weng-Fai Wong, Guoan Wu, Yuping Zhao, Andy Rudoff)**. It can be enabled in CMakeLists.txt using the `ENGINE_PSKIPLIST` option.
+
+### Configuration
+
+* **path** -- Path to the database file (layout "pmemkv_stree")
+	+ type: string
+* **force_create** -- If 0, pmemkv opens file specified by 'path', otherwise it creates it
+	+ type: uint64_t
+	+ default value: 0
+* **size** --  Only needed when force_create is not 0, specifies size of the database [in bytes]
+	+ type: uint64_t
+
+### Internals
+
+(TBD)
+
+### Prerequisites
+
+No additional packages are required.
+
 # Related Work
 ---------