STM implementation (#270)

* Initial implementation

* Remove transaction from waiting list when it resumes

* Add a few useful stm datastructures

TMap and TSet need some work

* Use 64bit numbers for ids and just ignore rollover

* Smarter lock acquisition and start docs

* Fixes

* 🔥 unused imports

* Align api's of datatypes with our non-stm types

Also removed TMap and TSet for now

* Start testing datatypes

Also fixed some bugs

* More tests and small bug fixes

* Linter and test registerDelay

* Move exception handling to catch

try catch does not work because it keeps side-effects made in try

* 🔥 unused import

* Fix tests after exception handling refractor

* Much smarter lock strategy

* Fix some issues with blocking retry introduced by lock rework

* Use a mutable list for waiting transactions

Should save some time spent copying the list...

* Lock and release tvars right away when retrying

Before it locked everything first and unlocked them again later, blocking all variables till all of them had transactions registered

* Add two example cases to the tests

* Documentation and a few TODO's with optimization ideas

* More documentation

* Fix TSem.checkNonNegative

* Fix ank example

* Add an article about managing shared state in concurrent settings

The article presents the problem (race-conditions) and various solutions and their downsides/tradeoffs.

* Change locking strategy to retry if we encounter a lock

In 99% of the cases trying to validate a locked TVar means it is being updated and thus invalid.

* Use a different List implementation for queues

This does not pressure the gc as much because it is sharing. It is also very fast for head access

* Add TMap/TSet and move some stuff around

Also removed the need for blocking locking and changed how nested transactions run

* Linter

* Handle colliding hash values better

* Fix TMVar for nullable values.

TMVar(null) is not empty!

* Update arrow-docs/docs/fx/managing-state/README.md

Co-authored-by: Simon Vergauwen <[email protected]>

* Update arrow-docs/docs/fx/managing-state/README.md

Co-authored-by: Simon Vergauwen <[email protected]>

* Update arrow-docs/docs/fx/managing-state/README.md

Co-authored-by: Simon Vergauwen <[email protected]>

* Remove managing state for now.

Gonna redo that at some point

* Remove suspend encoding

It was unnecessary to begin with and this allows easier interleaving with effects

* 🔥 Unused imports

* Move STM to its own module

* Fix doc build

* Override fillInStackTrace for RetryException

* Address a few now inaccurate doc bits

* Some more outdated docs + slight doc changes

* Update STM.kt

Co-authored-by: Simon Vergauwen <[email protected]>

Author: 1Jajen1

arrow-libs/fx/arrow-docs/build.gradle

@@ -28,6 +28,7 @@ dependencies {
     compile "io.arrow-kt:arrow-meta:$VERSION_NAME"
     compile project(":arrow-fx")
     compile project(":arrow-fx-coroutines")
+    compile project(":arrow-fx-stm")
     compile project(":arrow-fx-rx2")
     compile project(":arrow-fx-reactor")
     compile project(":arrow-fx-kotlinx-coroutines")

arrow-libs/fx/arrow-fx-stm/build.gradle

@@ -0,0 +1,17 @@
+plugins {
+    id "org.jetbrains.kotlin.jvm"
+    id "org.jlleitschuh.gradle.ktlint"
+}
+
+apply plugin: 'kotlinx-atomicfu'
+
+apply from: "$SUB_PROJECT"
+apply from: "$DOC_CREATION"
+
+dependencies {
+    compile project(":arrow-fx-coroutines")
+
+    testImplementation "io.kotest:kotest-runner-junit5-jvm:$KOTEST_VERSION" // for kotest framework
+    testImplementation "io.kotest:kotest-assertions-core-jvm:$KOTEST_VERSION" // for kotest core jvm assertions
+    testImplementation "io.kotest:kotest-property-jvm:$KOTEST_VERSION" // for kotest property test
+}

arrow-libs/fx/arrow-fx-stm/gradle.properties

@@ -0,0 +1,4 @@
+# Maven publishing configuration
+POM_NAME=Arrow-Fx-STM
+POM_ARTIFACT_ID=arrow-fx-stm
+POM_PACKAGING=jar