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A new Jepsen checker for READ_YOUR_WRITES scan mode

This patch adds a new Jepsen checker to validate READ_YOUR_WRITES scan
mode. In this validation mode, each Jepsen client writes unique values
in a shared table concurrently. The checker generates two kind of
operations: 'count' which counts the number of rows of the table, 'add'
which inserts a unique value to the table. It validates that the total
row count of the table read by the client is always greater than or
equal to the count of previous writes by the same client, and the row
count never go down from the previous reads.

Change-Id: I92d5c0e3b91af58576eb6cd408d922ec7c0fef6c
Reviewed-by: David Ribeiro Alves <>
Tested-by: Hao Hao <>
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haohaoc committed Mar 26, 2018
1 parent ee0a75c commit ba0a8126fb95778a9964864b55fc189441393052
@@ -0,0 +1,217 @@
;; Licensed to the Apache Software Foundation (ASF) under one
;; or more contributor license agreements. See the NOTICE file
;; distributed with this work for additional information
;; regarding copyright ownership. The ASF licenses this file
;; to you under the Apache License, Version 2.0 (the
;; "License"); you may not use this file except in compliance
;; with the License. You may obtain a copy of the License at
;; Unless required by applicable law or agreed to in writing,
;; software distributed under the License is distributed on an
;; KIND, either express or implied. See the License for the
;; specific language governing permissions and limitations
;; under the License.
;; The 'sets' checker validates that:
;; 1) the total row count of a shared table read by a client is
;; greater than or equal to the count of successful writes
;; performed by that client.
;; 2) the row count never goes down from the previous reads of
;; the same client.
;; For example, sets' checker considers a history as follows valid:
;; [{:type :invoke, :f :add, :value 1, :process 0}
;; {:type :ok, :f :add, :value 1, :process 0}
;; {:type :invoke, :f :count, :value nil, :process 1}
;; {:type :ok, :f :count, :value 2, :process 1}
;; {:type :invoke, :f :add, :value 22, :process 0}
;; {:type :ok, :f :add, :value 22, :process 0}
;; {:type :invoke, :f :count, :value nil, :process 0}
;; {:type :ok, :f :count, :value 2, :process 0}]
;; while the following sequence as invalid. Since after process 0
;; successfully inserted three rows, the total number of rows
;; returned from the count operation of the same process is two,
;; which conflicts with the validation constraints:
;; [{:type :invoke, :f :add, :value 1, :process 0}
;; {:type :ok, :f :add, :value 1, :process 0}
;; {:type :invoke, :f :add, :value 2, :process 0}
;; {:type :ok, :f :add, :value 2, :process 0}
;; {:type :invoke, :f :count, :value nil, :process 0}
;; {:type :ok, :f :count, :value 2, :process 0}
;; {:type :invoke, :f :count, :value nil, :process 1}
;; {:type :ok, :f :count, :value 2, :process 1}
;; {:type :invoke, :f :add, :value 13, :process 1}
;: {:type :ok, :f :add, :value 13, :process 1}
;; {:type :invoke, :f :add, :value 22, :process 0}
;; {:type :ok, :f :add, :value 22, :process 0}
;; {:type :invoke, :f :count, :value nil, :process 0}
;; {:type :ok, :f :count, :value 2, :process 0}
;; {:type :invoke, :f :add, :value 250, :process 1}
;; {:type :ok, :f :add, :value 250, :process 1}]
;; This checker model is a variation of cockroach 'sets' checker,
;; see
(ns jepsen.kudu.sets
"Set test"
(:refer-clojure :exclude [test])
(:require [jepsen [kudu :as kudu]
[client :as client]
[checker :as checker]
[generator :as gen]
[nemesis :as nemesis]]
[jepsen.kudu.client :as kc]
[jepsen.kudu.table :as kt]
[clojure.core.reducers :as r]
[knossos.op :as op])
(:import [org.apache.kudu.client AsyncKuduScanner$ReadMode]))
(defn add-op []
"The add operation to be performed by the processes."
(->> (range)
(map (partial array-map
:type :invoke
:f :add
(defn count-op []
"The count operation to be performed by the processes."
{:type :invoke, :f :count, :value nil})
(defn count-by-set
"Given a set of :add operations or a :count operation, count the number
of successful :add operations or get the value from the :count operation."
(let [adds (->> history
(r/filter op/ok?)
(r/filter #(= :add (:f %)))
(r/map :value)
(into #{}))
counts (->> history
(r/filter op/ok?)
(r/filter #(= :count (:f %)))
(r/map :value)
(reduce (fn [_ x] x) nil))]
{:counts counts :adds (count adds)}))
(defn validate-counts
"Validate a series of :add and :count operations, making sure that:
1) the total row count of the table read is greater than or equal
to the count of successful writes.
2) the count never goes down from the previous counts."
(let [results (reduce-kv
(fn [coll key value]
(let [last-coll (last coll)
last-count (:total-counts last-coll)
adds (+ (:total-adds last-coll 0) (:adds value))]
(if (= (:counts value) nil)
(conj coll (assoc value :total-counts last-count :total-adds adds
:valid? (:valid? last-coll)))
;; validates the total row count is greater than or equal
;; to the count of writes, and the row count never goes down.
(let [is-valid (and (<= adds (:counts value))
(<= last-count (:counts value)))]
(conj coll (assoc value :total-counts (:counts value) :total-adds adds
:valid? (and is-valid (:valid? last-coll))))))))
[{:valid? true :total-counts 0 :total-adds 0 }]
(defn partition-by-set
"Given a history of operations, partition it to multiple groups of
sets. Each set is composed of a set of :add operations followed by
a :count operation. And validate each set."
(let [partition-history (->> history
(partition-by #(and (= :count (:f %))
(= :ok (:type %))))
(into []))]
(let [count-map (reduce-kv
(fn [coll key value]
(assoc coll key (count-by-set value)))
(let [result (->> count-map
(remove #(and (= (:counts %) nil) (= (:adds %) 0)))
(into [])
{:valid? result}))))
(defn check-sets
"Given the history of all processes/clients, validate the history per
(reify checker/Checker
(check [this test model history opts]
(let [results (reduce-kv
(fn [coll key val]
(assoc coll key (partition-by-set val))) {} (group-by :process history))]
(assoc results :valid? (jepsen.checker/merge-valid (mapcat vals (vals results))))))))
(defn client
"Create a shared table if it doesn't exist. The client can perform
two kinds of operations, :add that inserts a unique row into the
table, :count that counts the number of rows of the table."
[table-created? kclient ktable read-mode]
(reify client/Client
(setup! [_ test _]
(let [kclient (kc/sync-client (:master-addresses test))
table-name (:table-name test)
ktable (locking table-created?
(when (compare-and-set! table-created? false true)
(kc/create-table kclient table-name kt/kv-table-schema
(let [ranges (:table-ranges test)
rep-factor (:num-replicas test)]
(if (nil? ranges)
(kt/kv-table-options-hash rep-factor (count (:tservers test)))
(kt/kv-table-options-range rep-factor ranges)))))
(kc/open-table kclient table-name))]
(client table-created? kclient ktable read-mode)))
(invoke! [_ _ op]
(case (:f op)
:count (assoc op :type :ok,
:value (kt/count-rows kclient ktable read-mode))
:add (do (kt/kv-write kclient ktable (str (:value op)) (:value op))
(assoc op :type :ok))))
(teardown! [_ _]
(kc/close-client kclient))))
(defn sets-test
"This test creates multiple clients. Each client either writes a
unique value in a shared table or counts the number of rows for that
table concurrently. It uses 'sets' checker to validate Read-Your-Writes
and Read-Your-Reads consistency."
{:name "sets"
:client (client (atom false) nil nil AsyncKuduScanner$ReadMode/READ_YOUR_WRITES)
:concurrency 10
:num-replicas 5
:nemesis nemesis/noop
;; generator take a random mixture of add operations (that inserts
;; a sequence of values) and count operations.
:generator (->> (gen/mix [(->> (add-op)
(gen/stagger 1)) count-op])
(gen/stagger 1/3)
(gen/seq (cycle [(gen/sleep 5)
{:type :info, :f :start}
(gen/sleep 5)
{:type :info, :f :stop}])))
(gen/time-limit 60))
:checker (check-sets)}
@@ -36,6 +36,7 @@
@@ -104,3 +105,12 @@
0 nil
1 (:value (get rows 0))
(assert false (str "Expected 0 or 1 rows. Got: " (count rows)))))))
(defn count-rows
"Count the rows of the given table."
[sync-client table read-mode]
(let [scanner-builder (.newScannerBuilder sync-client table)]
(.readMode scanner-builder read-mode)
(.replicaSelection scanner-builder ReplicaSelection/CLOSEST_REPLICA)
(let [rows (c/drain-scanner-to-tuples (.build scanner-builder))]
(count rows))))
@@ -22,7 +22,8 @@
[jepsen.tests :as tests]
[jepsen.kudu :as kudu]
[jepsen.kudu.nemesis :as kn]
[jepsen.kudu.register :as kudu-register]))
[jepsen.kudu.register :as kudu-register]
[jepsen.kudu.sets :as kudu-sets]))
(defn check
[tcasefun opts]
@@ -51,7 +52,8 @@
;; Configurations for tests. Every configuration corresponds to running
;; a test with particular nemesis (let's call it "scenario").
(def register-test kudu-register/register-test)
(def register-test-configs
(def sets-test kudu-sets/sets-test)
(def test-configs
{:scenario "noop-nemesis"
:nemesis '((fn [] jn/noop))}
@@ -79,6 +81,8 @@
(defmacro instantiate-all-kudu-tests
`(instantiate-tests register-test register-test-configs ~opts))
(instantiate-tests register-test test-configs ~opts)
(instantiate-tests sets-test test-configs ~opts)))
(instantiate-all-kudu-tests {})

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