├── .gitignore ├── CHANGELOG.md ├── LICENSE ├── README.md ├── doc └── intro.md ├── project.clj ├── src └── ecdts │ └── core.clj └── test └── ecdts └── core_test.clj /.gitignore: -------------------------------------------------------------------------------- 1 | /target 2 | /classes 3 | /checkouts 4 | pom.xml 5 | pom.xml.asc 6 | *.jar 7 | *.class 8 | /.lein-* 9 | /.nrepl-port 10 | .hgignore 11 | .hg/ 12 | -------------------------------------------------------------------------------- /CHANGELOG.md: -------------------------------------------------------------------------------- 1 | # Change Log 2 | All notable changes to this project will be documented in this file. This change log follows the conventions of [keepachangelog.com](http://keepachangelog.com/). 3 | 4 | ## [Unreleased][unreleased] 5 | ### Changed 6 | - Add a new arity to `make-widget-async` to provide a different widget shape. 7 | 8 | ## [0.1.1] - 2016-04-21 9 | ### Changed 10 | - Documentation on how to make the widgets. 11 | 12 | ### Removed 13 | - `make-widget-sync` - we're all async, all the time. 14 | 15 | ### Fixed 16 | - Fixed widget maker to keep working when daylight savings switches over. 17 | 18 | ## 0.1.0 - 2016-04-21 19 | ### Added 20 | - Files from the new template. 21 | - Widget maker public API - `make-widget-sync`. 22 | 23 | [unreleased]: https://github.com/your-name/ecdts/compare/0.1.1...HEAD 24 | [0.1.1]: https://github.com/your-name/ecdts/compare/0.1.0...0.1.1 25 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | THE ACCOMPANYING PROGRAM IS PROVIDED UNDER THE TERMS OF THIS ECLIPSE PUBLIC 2 | LICENSE ("AGREEMENT"). 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No party to this 212 | Agreement will bring a legal action under this Agreement more than one year 213 | after the cause of action arose. Each party waives its rights to a jury trial 214 | in any resulting litigation. 215 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Eventually Consistent Datatypes 2 | 3 | This is an implementation of highly-scalable [eventually consistent 4 | datatypes](https://dl.acm.org/citation.cfm?id=2911158) for Clojure. 5 | When you do massively parallel updates on STM, the abort rate can 6 | become prohibitive and you don't want to wait until your transactions 7 | succeed. One example is the counter from the paper, where each thread 8 | increments the counter in some inner loop. And you asynchronously 9 | merge the thread-local var from time to time with the global state. 10 | 11 | 12 | While I haven't had a use case for them yet, I found the research 13 | interesting and wanted to benchmark the approach against the Clojure 14 | STM. Consider the implementation experimental for now. I think the 15 | datatypes become interesting in many-core scenarios where you have 16 | more than 10 (maybe 100+) threads hammering on a datastructure. Since 17 | massive parallelism is a primary design goal of Clojure, I think they 18 | are worth investigating then. 19 | 20 | ## Bag 21 | 22 | I am not sure about the access semantics for the bag, it would be very 23 | well possible to use something different than sequences there, 24 | e.g. sets or vectors, since I haven't used Cons cells (Clojure doesn't 25 | use them much), but Clojure's persistent lists which also have 26 | constant time concatenation due to lazyness. 27 | 28 | You will still have `O(#elements)` worse case access time for other 29 | collections though, but subsequent accesses could benefit from a 30 | different datatype. I haven't implemented the OR-set from the paper 31 | yet, as it is more complicated and I am not sure whether a binary tree 32 | would perform well. Feel free to add it though :) or open an issue, if 33 | you have a use-case. 34 | 35 | ## Usage 36 | 37 | [![Clojars Project](http://clojars.org/es.topiq/ecdts/latest-version.svg)](http://clojars.org/es.topiq/ecdts) 38 | 39 | The general idea is that you create a thread-local version of a 40 | datatype for each of you threads and a global version with which you 41 | merge in the desired intervals. 42 | 43 | Example benchmark for the counter. You always have a global version, 44 | similar to a Clojure atom, which you merge into from time to time. The 45 | datatypes are dereferable to retrieve the current thread-local 46 | value. Read the paper for details. 47 | 48 | ~~~clojure 49 | (require '[ecdts.core :refer :all]) 50 | 51 | (def g (counter)) 52 | 53 | ;; example benchmark for the counter 54 | (let [st (.getTime (java.util.Date.)) 55 | ta (Thread. (fn [] 56 | (let [a (counter)] 57 | (loop [i 0 58 | j 0] 59 | (when (< i 20000000) 60 | (inc! a) 61 | (if (> j 1000) 62 | (do 63 | (merge! g a) 64 | (recur (inc i) 1)) 65 | (recur (inc i) (inc j))))) 66 | (merge! g a) 67 | (println "Thread A" 68 | (- (.getTime (java.util.Date.)) 69 | st))))) 70 | tb (Thread. (fn [] 71 | (let [a (counter)] 72 | (loop [i 0 73 | j 0] 74 | (when (< i 20000000) 75 | (inc! a) 76 | (if (> j 1000) 77 | (do 78 | (merge! g a) 79 | (recur (inc i) 1)) 80 | (recur (inc i) (inc j))))) 81 | (merge! g a) 82 | (println "Thread B" 83 | (- (.getTime (java.util.Date.)) 84 | st))))) 85 | tc (Thread. (fn [] 86 | (let [a (counter)] 87 | (loop [i 0 88 | j 0] 89 | (when (< i 20000000) 90 | (inc! a) 91 | (if (> j 1000) 92 | (do 93 | (merge! g a) 94 | (recur (inc i) 1)) 95 | (recur (inc i) (inc j))))) 96 | (merge! g a) 97 | (println "Thread C" 98 | (- (.getTime (java.util.Date.)) 99 | st))))) 100 | td (Thread. (fn [] 101 | (let [a (counter)] 102 | (loop [i 0 103 | j 0] 104 | (when (< i 20000000) 105 | (inc! a) 106 | (if (> j 1000) 107 | (do 108 | (merge! g a) 109 | (recur (inc i) 1)) 110 | (recur (inc i) (inc j))))) 111 | (merge! g a) 112 | (println "Thread D" 113 | (- (.getTime (java.util.Date.)) 114 | st)))))] 115 | (.start ta) 116 | (.start tb) 117 | (.start tc) 118 | (.start td)) 119 | ~~~ 120 | 121 | It is roughly 3 times as fast as the STM on my machine. 122 | 123 | The bag works similarly. 124 | 125 | ~~~clojure 126 | (def g (add-only-bag)) 127 | 128 | (let [st (.getTime (java.util.Date.)) 129 | ta (Thread. (fn [] 130 | (let [a (add-only-bag)] 131 | (loop [i 0 132 | j 0] 133 | (when (< i 2000000) 134 | (conj! a i) 135 | (if (> j 1000) 136 | (do 137 | (merge! g a) 138 | (recur (inc i) 1)) 139 | (recur (inc i) (inc j))))) 140 | (merge! g a) 141 | (println "Thread A" 142 | (- (.getTime (java.util.Date.)) 143 | st))))) 144 | tb (Thread. (fn [] 145 | (let [a (add-only-bag)] 146 | (loop [i 0 147 | j 0] 148 | (when (< i 2000000) 149 | (conj! a i) 150 | (if (> j 1000) 151 | (do 152 | (merge! g a) 153 | (recur (inc i) 1)) 154 | (recur (inc i) (inc j))))) 155 | (merge! g a) 156 | (println "Thread B" 157 | (- (.getTime (java.util.Date.)) 158 | st))))) 159 | tc (Thread. (fn [] 160 | (let [a (add-only-bag)] 161 | (loop [i 0 162 | j 0] 163 | (when (< i 2000000) 164 | (conj! a i) 165 | (if (> j 1000) 166 | (do 167 | (merge! g a) 168 | (recur (inc i) 1)) 169 | (recur (inc i) (inc j))))) 170 | (merge! g a) 171 | (println "Thread C" 172 | (- (.getTime (java.util.Date.)) 173 | st))))) 174 | td (Thread. (fn [] 175 | (let [a (add-only-bag)] 176 | (loop [i 0 177 | j 0] 178 | (when (< i 2000000) 179 | (conj! a i) 180 | (if (> j 1000) 181 | (do 182 | (merge! g a) 183 | (recur (inc i) 1)) 184 | (recur (inc i) (inc j))))) 185 | (merge! g a) 186 | (println "Thread D" 187 | (- (.getTime (java.util.Date.)) 188 | st)))))] 189 | (.start ta) 190 | (.start tb) 191 | (.start tc) 192 | (.start td)) 193 | ~~~ 194 | 195 | It is roughly 4 times faster on my machine. 196 | 197 | ## License 198 | 199 | Copyright © 2016 Christian Weilbach 200 | 201 | Distributed under the Eclipse Public License either version 1.0 or (at 202 | your option) any later version. 203 | -------------------------------------------------------------------------------- /doc/intro.md: -------------------------------------------------------------------------------- 1 | # Introduction to ecdts 2 | 3 | TODO: write [great documentation](http://jacobian.org/writing/what-to-write/) 4 | -------------------------------------------------------------------------------- /project.clj: -------------------------------------------------------------------------------- 1 | (defproject es.topiq/ecdts "0.1.0" 2 | :description "Eventually consistent datatypes for Clojure." 3 | :url "https://github.com/whilo/ecdts" 4 | :license {:name "Eclipse Public License" 5 | :url "http://www.eclipse.org/legal/epl-v10.html"} 6 | :dependencies [[org.clojure/clojure "1.8.0"]]) 7 | -------------------------------------------------------------------------------- /src/ecdts/core.clj: -------------------------------------------------------------------------------- 1 | (ns ecdts.core 2 | (:refer-clojure :exclude [conj!])) 3 | 4 | (set! *warn-on-reflection* true) 5 | 6 | (defprotocol PIncrementable 7 | "Implementation detail. Needed because we can only mutate (set!) 8 | inside of deftype for thread safety reasons." 9 | (-inc [this])) 10 | 11 | (defprotocol PMergeable 12 | "Protocol to merge a thread-local version of a datatype into the global version" 13 | (-merge [global local])) 14 | 15 | (deftype ECCounter [^:volatile-mutable ^long a ;; keep the global value synchronized 16 | ^:unsynchronized-mutable ^long b] 17 | clojure.lang.IDeref 18 | (deref [this] (+ a b)) 19 | PIncrementable 20 | (-inc [this] (set! b (inc b))) 21 | PMergeable 22 | (-merge [this other] 23 | (locking this 24 | (locking other 25 | (let [other ^ECCounter other 26 | g (+ a (.-b other))] 27 | (set! a g) 28 | (set! (.-b other) 0) 29 | (set! (.-a other) g) 30 | g))))) 31 | 32 | (defn counter 33 | "Creates an eventual consistent increment only counter. Optionally 34 | you can initialize a thread-local version with a value. Derefencing 35 | and incrementing are not synchronized for performance reasons, so 36 | these operations are only valid in the thread-local context." 37 | ([] (counter 0)) 38 | ([init-value] 39 | (ECCounter. 0 init-value))) 40 | 41 | (defn inc! 42 | "Increment the counter. (in-place)" 43 | [^ECCounter counter] 44 | (-inc counter)) 45 | 46 | (defn merge! 47 | "Merge local state into global state and update local state to 48 | reflect global changes. (in-place)" 49 | [global local] 50 | (-merge global local)) 51 | 52 | 53 | (comment 54 | (def foo (ECCounter. 0 0)) 55 | 56 | (def bar (ECCounter. 0 0)) 57 | 58 | (-inc foo) 59 | (-inc bar) 60 | 61 | (-merge foo foo) 62 | (-merge foo bar) 63 | 64 | (-inc bar) 65 | 66 | (def g (counter)) 67 | 68 | (let [st (.getTime (java.util.Date.)) 69 | ta (Thread. (fn [] 70 | (let [a (counter)] 71 | (loop [i 0 72 | j 0] 73 | (when (< i 20000000) 74 | (inc! a) 75 | (if (> j 1000) 76 | (do 77 | (merge! g a) 78 | (recur (inc i) 1)) 79 | (recur (inc i) (inc j))))) 80 | (merge! g a) 81 | (println "Thread A" 82 | (- (.getTime (java.util.Date.)) 83 | st))))) 84 | tb (Thread. (fn [] 85 | (let [a (counter)] 86 | (loop [i 0 87 | j 0] 88 | (when (< i 20000000) 89 | (inc! a) 90 | (if (> j 1000) 91 | (do 92 | (merge! g a) 93 | (recur (inc i) 1)) 94 | (recur (inc i) (inc j))))) 95 | (merge! g a) 96 | (println "Thread B" 97 | (- (.getTime (java.util.Date.)) 98 | st))))) 99 | tc (Thread. (fn [] 100 | (let [a (counter)] 101 | (loop [i 0 102 | j 0] 103 | (when (< i 20000000) 104 | (inc! a) 105 | (if (> j 1000) 106 | (do 107 | (merge! g a) 108 | (recur (inc i) 1)) 109 | (recur (inc i) (inc j))))) 110 | (merge! g a) 111 | (println "Thread C" 112 | (- (.getTime (java.util.Date.)) 113 | st))))) 114 | td (Thread. (fn [] 115 | (let [a (counter)] 116 | (loop [i 0 117 | j 0] 118 | (when (< i 20000000) 119 | (inc! a) 120 | (if (> j 1000) 121 | (do 122 | (merge! g a) 123 | (recur (inc i) 1)) 124 | (recur (inc i) (inc j))))) 125 | (merge! g a) 126 | (println "Thread D" 127 | (- (.getTime (java.util.Date.)) 128 | st)))))] 129 | (.start ta) 130 | (.start tb) 131 | (.start tc) 132 | (.start td)) 133 | 134 | @g 135 | 136 | (let [g (atom 0) 137 | st (.getTime (java.util.Date.)) 138 | ta (Thread. (fn [] 139 | (loop [i 0] 140 | (when (< i 20000000) 141 | (swap! g inc) 142 | (recur (inc i)))) 143 | (println "Thread A" 144 | (- (.getTime (java.util.Date.)) 145 | st)))) 146 | tb (Thread. (fn [] 147 | (loop [i 0] 148 | (when (< i 20000000) 149 | (swap! g inc) 150 | (recur (inc i)))) 151 | (println "Thread B" 152 | (- (.getTime (java.util.Date.)) 153 | st)))) 154 | tc (Thread. (fn [] 155 | (loop [i 0] 156 | (when (< i 20000000) 157 | (swap! g inc) 158 | (recur (inc i)))) 159 | (println "Thread C" 160 | (- (.getTime (java.util.Date.)) 161 | st)))) 162 | td (Thread. (fn [] 163 | (loop [i 0] 164 | (when (< i 20000000) 165 | (swap! g inc) 166 | (recur (inc i)))) 167 | (println "Thread D" 168 | (- (.getTime (java.util.Date.)) 169 | st))))] 170 | (.start ta) 171 | (.start tb) 172 | (.start tc) 173 | (.start td))) 174 | 175 | 176 | (defprotocol PConjable 177 | "Implementation detail. Needed because we can only mutate (set!) 178 | inside of deftype for thread safety reasons." 179 | (-conj [this elem])) 180 | 181 | (defn conj! 182 | "Adds element to an AddOnlyBag." 183 | [bag elem] 184 | (-conj bag elem)) 185 | 186 | (deftype ECAddOnlyBag [^:volatile-mutable l 187 | ^:unsynchronized-mutable appender] 188 | clojure.lang.IDeref 189 | (deref [this] (concat appender l)) 190 | PMergeable 191 | (-merge [this other] 192 | (locking this 193 | (locking other 194 | (let [other ^ECAddOnlyBag other 195 | new-list (concat (.-appender other) l)] 196 | (set! l new-list) 197 | (set! (.-l other) new-list) 198 | (set! (.-appender other) '()) 199 | new-list)))) 200 | PConjable 201 | (-conj [this elem] (set! appender (conj appender elem)))) 202 | 203 | (defn add-only-bag 204 | "Creates an AddOnlyBag. Optionally you can initialize a thread-local 205 | version with a seq value. Derefencing and conjing are not 206 | synchronized for performance reasons, so these operations are only 207 | valid in the thread-local context." 208 | ([] (add-only-bag '())) 209 | ([init-values] 210 | (ECAddOnlyBag. '() init-values))) 211 | 212 | (comment 213 | (def foo (ECAddOnlyBag. '() '(1 2 3))) 214 | 215 | (def bar (ECAddOnlyBag. '() '())) 216 | 217 | (-conj foo 4) 218 | 219 | (-merge bar foo) 220 | 221 | (def g (add-only-bag)) 222 | 223 | (let [st (.getTime (java.util.Date.)) 224 | ta (Thread. (fn [] 225 | (let [a (add-only-bag)] 226 | (loop [i 0 227 | j 0] 228 | (when (< i 2000000) 229 | (conj! a i) 230 | (if (> j 1000) 231 | (do 232 | (merge! g a) 233 | (recur (inc i) 1)) 234 | (recur (inc i) (inc j))))) 235 | (merge! g a) 236 | (println "Thread A" 237 | (- (.getTime (java.util.Date.)) 238 | st))))) 239 | tb (Thread. (fn [] 240 | (let [a (add-only-bag)] 241 | (loop [i 0 242 | j 0] 243 | (when (< i 2000000) 244 | (conj! a i) 245 | (if (> j 1000) 246 | (do 247 | (merge! g a) 248 | (recur (inc i) 1)) 249 | (recur (inc i) (inc j))))) 250 | (merge! g a) 251 | (println "Thread B" 252 | (- (.getTime (java.util.Date.)) 253 | st))))) 254 | tc (Thread. (fn [] 255 | (let [a (add-only-bag)] 256 | (loop [i 0 257 | j 0] 258 | (when (< i 2000000) 259 | (conj! a i) 260 | (if (> j 1000) 261 | (do 262 | (merge! g a) 263 | (recur (inc i) 1)) 264 | (recur (inc i) (inc j))))) 265 | (merge! g a) 266 | (println "Thread C" 267 | (- (.getTime (java.util.Date.)) 268 | st))))) 269 | td (Thread. (fn [] 270 | (let [a (add-only-bag)] 271 | (loop [i 0 272 | j 0] 273 | (when (< i 2000000) 274 | (conj! a i) 275 | (if (> j 1000) 276 | (do 277 | (merge! g a) 278 | (recur (inc i) 1)) 279 | (recur (inc i) (inc j))))) 280 | (merge! g a) 281 | (println "Thread D" 282 | (- (.getTime (java.util.Date.)) 283 | st)))))] 284 | (.start ta) 285 | (.start tb) 286 | (.start tc) 287 | (.start td)) 288 | 289 | (count @g) 290 | 291 | (let [g (atom '()) 292 | st (.getTime (java.util.Date.)) 293 | ta (Thread. (fn [] 294 | (loop [i 0] 295 | (when (< i 2000000) 296 | (swap! g conj i) 297 | (recur (inc i)))) 298 | (println "Thread A" 299 | (- (.getTime (java.util.Date.)) 300 | st)))) 301 | tb (Thread. (fn [] 302 | (loop [i 0] 303 | (when (< i 2000000) 304 | (swap! g conj i) 305 | (recur (inc i)))) 306 | (println "Thread B" 307 | (- (.getTime (java.util.Date.)) 308 | st)))) 309 | tc (Thread. (fn [] 310 | (loop [i 0] 311 | (when (< i 2000000) 312 | (swap! g conj i) 313 | (recur (inc i)))) 314 | (println "Thread C" 315 | (- (.getTime (java.util.Date.)) 316 | st)))) 317 | td (Thread. (fn [] 318 | (loop [i 0] 319 | (when (< i 2000000) 320 | (swap! g conj i) 321 | (recur (inc i)))) 322 | (println "Thread D" 323 | (- (.getTime (java.util.Date.)) 324 | st))))] 325 | (.start ta) 326 | (.start tb) 327 | (.start tc) 328 | (.start td))) 329 | -------------------------------------------------------------------------------- /test/ecdts/core_test.clj: -------------------------------------------------------------------------------- 1 | (ns ecdts.core-test 2 | (:require [clojure.test :refer :all] 3 | [ecdts.core :refer :all])) 4 | 5 | (deftest a-test 6 | (testing "FIXME, I fail." 7 | (is (= 0 1)))) 8 | --------------------------------------------------------------------------------