As discussed at

Question

As discussed at I m trying to make changes to Logger so that it can be used in multithreaded environments The main problem is using it from K N due to concurrency model when using the functionality to have a single logger based on name I have identified few approaches as follows 1 Loading the properties from file str in an immutable shared variable Remove option to set level and output in Logger effectively removing mutable variables from Logger and instead set them using props This would build a new object even for same name but as the props are immutable configuration is effectively the same 2 Use atomic references to hold Logger variables This would have minimal change in functionality but atomicfu dependency need to be added and would also have performance penalty as everytime we need to log atomic ref will be accessed 3 Using ThreadLocal Logger and SharedImmutable ThreadLocal Logger global variables Modifications to Logger in one thread won t be visible to Logger in another thread What are your thoughts < Deactivated User> If anyone has any suggestions I would be happy to have them

Deactivated User · Answer

I would vote for option 2

Mayank · Answer

I was considering option 1 but considering it requires more changes and would reduce some functionality option 2 looks better Thanks for your input

Mayank · Answer

I made the changes according to the discussion and raised the PR <https github com korlibs korge next pull 116> Out of curiosity is there any reason why `Logger levels` and `Logger outputs` were global variable instead of each Logger instance having its own `level` and `output`

Deactivated User · Answer

Thanks I will try to check it today

Mayank · Answer

Its strange that atomicfu requires reflection Thanks for updating Klogger smiley I noticed that instead of update set was used I am not sure if there is an issue or not but in edge case an entry might be missed What `update` did was use compareAndSet

Deactivated User · Answer

I believe that would only be an issue if there is lots of concurrent updates and you want to be sure that the new value depends on the previous one If happening two updates at once and there is no lock between the generation using the previous value the old value would be lost So without a lock you need that loop

Deactivated User · Answer

Maybe we can place a lock instead

Mayank · Answer

Lock will work but afaik locks are not available in common As you said it will happen rarely so loop solution doesn t look bad if implementing lock takes more time

Deactivated User · Answer

No need to have locks in common In the end we can provide one implementation for JVM and other for native JS doesn t require any of this

Mayank · Answer

Makes sense I would like to implement it and create a PR

Deactivated User · Answer

I m checking what you proposed

Deactivated User · Answer

let me verify if it works

Deactivated User · Answer

becayse I have noticed that Kotlin Native doesn t seems to provide locks directly And what it provides is atomics with compareAndSet so maybe the best option is to directly do that

Mayank · Answer

thumbsup

Deactivated User · Answer

```Index klogger src commonMain kotlin com soywiz klogger atomic KloggerAtomicRef kt IDEA additional info Subsystem com intellij openapi diff impl patch CharsetEP lt + gt UTF 8 =================================================================== diff git a klogger src commonMain kotlin com soywiz klogger atomic KloggerAtomicRef kt b klogger src commonMain kotlin com soywiz klogger atomic KloggerAtomicRef kt a klogger src commonMain kotlin com soywiz klogger atomic KloggerAtomicRef kt revision 41dd275d03f5e89e7a8792d415e26fbf5833b194 +++ b klogger src commonMain kotlin com soywiz klogger atomic KloggerAtomicRef kt date 1611326398353 2 19 +2 17 import kotlin reflect KProperty abstract class KloggerAtomicRef lt T gt abstract var value T inline fun update func T gt T value = func value operator fun setValue receiver Any prop KProperty lt gt newValue T value = newValue operator fun getValue receiver Any prop KProperty lt gt T return value +expect class KloggerAtomicRef lt T gt initial T + val value T + inline fun update block T gt T + + +operator fun lt T gt KloggerAtomicRef lt T gt setValue receiver Any prop KProperty lt gt newValue T + update newValue + +operator fun lt T gt KloggerAtomicRef lt T gt getValue receiver Any prop KProperty lt gt T + return value expect fun lt T gt kloggerAtomicRef initial T KloggerAtomicRef lt T gt + expect fun lt T gt kloggerAtomicRef initial T KloggerAtomicRef lt T gt +fun lt T gt kloggerAtomicRef initial T KloggerAtomicRef lt T gt = KloggerAtomicRef initial Index klogger src nativeCommonMain kotlin com soywiz klogger atomic KloggerAtomicRefNative kt IDEA additional info Subsystem com intellij openapi diff impl patch CharsetEP lt + gt UTF 8 =================================================================== diff git a klogger src nativeCommonMain kotlin com soywiz klogger atomic KloggerAtomicRefNative kt b klogger src nativeCommonMain kotlin com soywiz klogger atomic KloggerAtomicRefNative kt a klogger src nativeCommonMain kotlin com soywiz klogger atomic KloggerAtomicRefNative kt revision 41dd275d03f5e89e7a8792d415e26fbf5833b194 +++ b klogger src nativeCommonMain kotlin com soywiz klogger atomic KloggerAtomicRefNative kt date 1611326398355 2 10 +2 16 import kotlin native concurrent actual fun lt T gt kloggerAtomicRef initial T KloggerAtomicRef lt T gt = object KloggerAtomicRef lt T gt private val ref = FreezableAtomicReference lt T gt initial freeze +actual class KloggerAtomicRef lt T gt actual constructor initial T + PublishedApi + internal val ref = FreezableAtomicReference lt T gt initial freeze override var value T get = ref value set value ref value = value freeze + actual val value T get = ref value + actual inline fun update block T gt T + synchronized ref ref set ref get + do + val old = ref value + val new = block old freeze + while ref compareAndSet old new + Index klogger src commonMain kotlin com soywiz klogger Logger kt IDEA additional info Subsystem com intellij openapi diff impl patch CharsetEP lt + gt UTF 8 =================================================================== diff git a klogger src commonMain kotlin com soywiz klogger Logger kt b klogger src commonMain kotlin com soywiz klogger Logger kt a klogger src commonMain kotlin com soywiz klogger Logger kt revision 41dd275d03f5e89e7a8792d415e26fbf5833b194 +++ b klogger src commonMain kotlin com soywiz klogger Logger kt date 1611326398353 125 6 +125 6 private inline operator fun lt K V gt AtomicMap lt K V gt get key K = value key private inline operator fun lt K V gt AtomicMap lt K V gt set key K value V this value = HashMap this value also it key = value + this update HashMap it also nmap gt nmap key = value Index klogger src jsMain kotlin com soywiz klogger atomic KloggerAtomicRefJs kt IDEA additional info Subsystem com intellij openapi diff impl patch CharsetEP lt + gt UTF 8 =================================================================== diff git a klogger src jsMain kotlin com soywiz klogger atomic KloggerAtomicRefJs kt b klogger src jsMain kotlin com soywiz klogger atomic KloggerAtomicRefJs kt a klogger src jsMain kotlin com soywiz klogger atomic KloggerAtomicRefJs kt revision 41dd275d03f5e89e7a8792d415e26fbf5833b194 +++ b klogger src jsMain kotlin com soywiz klogger atomic KloggerAtomicRefJs kt date 1611326398354 1 5 +1 11 package com soywiz klogger atomic actual fun lt T gt kloggerAtomicRef initial T KloggerAtomicRef lt T gt = object KloggerAtomicRef lt T gt override var value T = initial +actual class KloggerAtomicRef lt T gt actual constructor initial T + PublishedApi + internal var value T = initial + actual val value T get = value + actual inline fun update block T gt T + value = block value + + Index klogger src jvmAndroidMain kotlin com soywiz klogger atomic KloggerAtomicRefJvm kt IDEA additional info Subsystem com intellij openapi diff impl patch CharsetEP lt + gt UTF 8 =================================================================== diff git a klogger src jvmAndroidMain kotlin com soywiz klogger atomic KloggerAtomicRefJvm kt b klogger src jvmAndroidMain kotlin com soywiz klogger atomic KloggerAtomicRefJvm kt a klogger src jvmAndroidMain kotlin com soywiz klogger atomic KloggerAtomicRefJvm kt revision 41dd275d03f5e89e7a8792d415e26fbf5833b194 +++ b klogger src jvmAndroidMain kotlin com soywiz klogger atomic KloggerAtomicRefJvm kt date 1611326398354 2 9 +2 16 import java util concurrent atomic AtomicReference actual fun lt T gt kloggerAtomicRef initial T KloggerAtomicRef lt T gt = object KloggerAtomicRef lt T gt private val ref = AtomicReference lt T gt initial override var value T get = ref get set value ref set value +actual class KloggerAtomicRef lt T gt actual constructor initial T + PublishedApi + internal val ref = AtomicReference lt T gt initial + + actual val value T get = ref get + actual inline fun update block T gt T + synchronized ref ref set ref get + do + val old = ref get + val new = block old + while ref compareAndSet old new + ```

Deactivated User · Answer

This is my proposal and seems to work the other day I tried something else and had problems on JS and Kotlin Native due to some bugs in the compiler

Deactivated User · Answer

Since it seems to work Can you make a PR in korge next with your proposed changes or those if you think that would work for your case

Deactivated User · Answer

I plan to make a release of all the libraries later this week maybe on sunday targeting 1 4 30 RC

Deactivated User · Answer

so if we can get this right would be awesome

Mayank · Answer

On a quick glance of your proposal it looks goods to me As you have already implemented it can you create a branch I can take an in depth look and can propose some changes on top if that if required

Deactivated User · Answer

Deactivated User · Answer

maybe the implementation should be internal I think the issue I had with compilers bugs was when the expect class was internal or something like that

Mayank · Answer

I can try to make it internal Was the build failing or was it a runtime error

Deactivated User · Answer

compile time when running tests

Deactivated User · Answer

but it was a different implementation with mixed expect external extensions

Mayank · Answer

Got it Let me see what I can do

Deactivated User · Answer

+1 thanks

Mayank · Answer

I tried adding internal modifier and all tests passed I also ran an example It also worked fine Sorry I m relatively new to KMM why not use an interface instead of expect actual for KloggerAtomicRef I m asking this because I saw that ```kloggerAtomicRef``` fun had expect implementation but it is commented so I was wondering if it is required anymore We can instead directly use the class instead of a function

Deactivated User · Answer

Not required anymore

Deactivated User · Answer

It is possible to call the constructor directly In fact I created the expect function to be able to use AtomicReference from JVM and Kotlin Native directly as typealiases and make it internal but in the end I had some compilers bugs so I ended simplifying stuff But with the current implementation only the expect class should be required Would be awesome if the expect classes allowed to provide default implementations for some methods and properties but since it is not the case I moved some stuff to extension members

Mayank · Answer

Yes support for default implementation would be awesome

Mayank · Answer

I have made some changes at <https github com korlibs korge next pull 130> Request you to do a commit wise review as it should be easier to understand why I took certain decisions and the flow of thought Please let me know if any changes are required