From 4b93ce179a3777c8461f3b5843dc3802bddc739c Mon Sep 17 00:00:00 2001
From: Alex Auvolat <alex@adnab.me>
Date: Fri, 20 Oct 2023 12:56:45 +0200
Subject: [PATCH] jepsen: errors in reg2 workload under investigation

---
 script/jepsen.garage/README.md                | 25 ++++++++++++----
 script/jepsen.garage/src/jepsen/garage.clj    |  3 +-
 .../jepsen.garage/src/jepsen/garage/reg.clj   | 30 ++++++++++++-------
 3 files changed, 41 insertions(+), 17 deletions(-)

diff --git a/script/jepsen.garage/README.md b/script/jepsen.garage/README.md
index 8dcd3766..762901fe 100644
--- a/script/jepsen.garage/README.md
+++ b/script/jepsen.garage/README.md
@@ -35,7 +35,7 @@ lein run test --nodes-file nodes.vagrant --time-limit 64 --rate 50  --concurrenc
 
 ### Register linear, without timestamp patch
 
-Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 20  --concurrency 20 --workload reg --ops-per-key 100`
+Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 20  --concurrency 20 --workload reg1 --ops-per-key 100`
 
 Results: fails with a simple clock-scramble nemesis.
 
@@ -45,7 +45,7 @@ clocks are scrambled.
 
 ### Register linear, with timestamp patch
 
-Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 20  --concurrency 20 --workload reg --ops-per-key 100 -I`
+Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 20  --concurrency 20 --workload reg1 --ops-per-key 100 -I`
 
 Results:
 
@@ -54,9 +54,23 @@ Results:
 
 Explanation: S3 objects are not meant to behave like linearizable registers. TODO explain using a counter-example
 
-### Read-after-write CRDT register model
+### Read-after-write CRDT register model, without timestamp patch
+
+Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 100  --concurrency 100 --workload reg2 --ops-per-key 100`
+
+Results: fails with a simple clock-scramble nemesis.
+
+Explanation: old values are not overwritten correctly when their timestamps are in the future.
+
+### Read-after-write CRDT register model, with timestamp patch
+
+Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 100  --concurrency 100 --workload reg2 --ops-per-key 100 -I`
+
+Results:
+
+- Failures with clock-scramble nemesis + partition nemesis ???? TODO INVESTIGATE
+- TODO: layout reconfiguration nemesis
 
-TODO: determine the expected semantics of such a register, code a checker and show that results are correct
 
 ### Set, basic test (write some items, then read)
 
@@ -65,13 +79,12 @@ Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 100  -
 Results:
 
 - For now, no failures with clock-scramble nemesis + partition nemesis
+- TODO: layout reconfiguration nemesis
 
 ### Set, continuous test (interspersed reads and writes)
 
 TODO
 
-TODO: nemesis that reconfigures the cluster with a different subset of nodes, to have requests that occur during a resync period.
-
 
 ## Investigating (and fixing) wierd behavior
 
diff --git a/script/jepsen.garage/src/jepsen/garage.clj b/script/jepsen.garage/src/jepsen/garage.clj
index c8865248..be192a7f 100644
--- a/script/jepsen.garage/src/jepsen/garage.clj
+++ b/script/jepsen.garage/src/jepsen/garage.clj
@@ -15,7 +15,8 @@
 
 (def workloads
   "A map of workload names to functions that construct workloads, given opts."
-  {"reg"  reg/workload
+  {"reg1" reg/workload1
+   "reg2" reg/workload2
    "set1" set/workload1
    "set2" set/workload2})
 
diff --git a/script/jepsen.garage/src/jepsen/garage/reg.clj b/script/jepsen.garage/src/jepsen/garage/reg.clj
index b5bf28ff..6772abfe 100644
--- a/script/jepsen.garage/src/jepsen/garage/reg.clj
+++ b/script/jepsen.garage/src/jepsen/garage/reg.clj
@@ -103,18 +103,10 @@
             valid? (empty? (:bad-reads final))]
         (assoc final :valid? valid?)))))
 
-(defn workload
-  "Tests linearizable reads and writes"
+(defn workload-common
+  "Common parts of workload"
   [opts]
   {:client           (RegClient. nil)
-   :checker          (independent/checker
-                       (checker/compose
-                         {:reg-read-after-write (reg-read-after-write)
-                          ; linear test is desactivated, indeed Garage is not linear
-                          ;:linear (checker/linearizable
-                          ;          {:model     (model/register)
-                          ;           :algorithm :linear})
-                          :timeline (timeline/html)}))
    :generator        (independent/concurrent-generator
                        10
                        (range)
@@ -123,4 +115,22 @@
                            (gen/mix [op-get op-put op-del])
                            (gen/limit (:ops-per-key opts)))))})
 
+(defn workload1
+  "Tests linearizable reads and writes"
+  [opts]
+  (assoc (workload-common opts)
+         :checker (independent/checker
+                    (checker/compose
+                      {:linear (checker/linearizable
+                                 {:model     (model/register)
+                                  :algorithm :linear})
+                       :timeline (timeline/html)}))))
 
+(defn workload2
+  "Tests CRDT reads and writes"
+  [opts]
+  (assoc (workload-common opts)
+         :checker (independent/checker
+                    (checker/compose
+                      {:reg-read-after-write (reg-read-after-write)
+                       :timeline (timeline/html)}))))