From 0e98281fa3eb0a8433c84af0c351ce4f817efd96 Mon Sep 17 00:00:00 2001
From: InsanusMokrassar <ovsyannikov.alexey95@gmail.com>
Date: Wed, 23 Sep 2026 14:45:36 +0600
Subject: [PATCH] fixes in smart rw locker

---
 CHANGELOG.md                                  |  4 ++
 .../micro_utils/coroutines/SmartRWLocker.kt   | 17 +++---
 .../commonTest/kotlin/SmartRWLockerTests.kt   | 54 +++++++++++++++++++
 3 files changed, 69 insertions(+), 6 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 97084333ba5..9a1b333cb44 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## 0.25.8.3
 
+* `Coroutines`:
+  * `SmartRWLocker`:
+    * Fix of `unlockWrite`, `lockWrite` and `releaseRead` calls to pass correct number of permits
+
 ## 0.25.8.2
 
 * `Coroutines`:
diff --git a/coroutines/src/commonMain/kotlin/dev/inmo/micro_utils/coroutines/SmartRWLocker.kt b/coroutines/src/commonMain/kotlin/dev/inmo/micro_utils/coroutines/SmartRWLocker.kt
index aea220812cd..f1f74e7b59f 100644
--- a/coroutines/src/commonMain/kotlin/dev/inmo/micro_utils/coroutines/SmartRWLocker.kt
+++ b/coroutines/src/commonMain/kotlin/dev/inmo/micro_utils/coroutines/SmartRWLocker.kt
@@ -1,6 +1,8 @@
 package dev.inmo.micro_utils.coroutines
 
 import kotlinx.coroutines.CancellationException
+import kotlinx.coroutines.NonCancellable
+import kotlinx.coroutines.withContext
 import kotlin.contracts.ExperimentalContracts
 import kotlin.contracts.InvocationKind
 import kotlin.contracts.contract
@@ -21,6 +23,7 @@ class SmartRWLocker(private val readPermits: Int = Int.MAX_VALUE, writeIsLocked:
     val readSemaphore: SmartSemaphore.Immutable = _readSemaphore.immutable()
     val writeMutex: SmartMutex.Immutable = _writeMutex.immutable()
 
+
     /**
      * Do lock in [readSemaphore] inside of [writeMutex] locking
      */
@@ -32,8 +35,8 @@ class SmartRWLocker(private val readPermits: Int = Int.MAX_VALUE, writeIsLocked:
     /**
      * Release one read permit in [readSemaphore]
      */
-    suspend fun releaseRead(): Boolean {
-        return _readSemaphore.release()
+    suspend fun releaseRead(): Boolean = withContext(NonCancellable) {
+        _readSemaphore.release()
     }
 
     /**
@@ -44,7 +47,9 @@ class SmartRWLocker(private val readPermits: Int = Int.MAX_VALUE, writeIsLocked:
         try {
             _readSemaphore.acquire(readPermits)
         } catch (e: CancellationException) {
-            _writeMutex.unlock()
+            withContext(NonCancellable) {
+                _writeMutex.unlock()
+            }
             throw e
         }
     }
@@ -52,9 +57,9 @@ class SmartRWLocker(private val readPermits: Int = Int.MAX_VALUE, writeIsLocked:
     /**
      * Unlock [writeMutex]
      */
-    suspend fun unlockWrite(): Boolean {
-        return _writeMutex.unlock().also {
-            if (it) {
+    suspend fun unlockWrite(): Boolean = withContext(NonCancellable) {
+        _writeMutex.unlock().also { unlocked ->
+            if (unlocked) {
                 _readSemaphore.release(readPermits)
             }
         }
diff --git a/coroutines/src/commonTest/kotlin/SmartRWLockerTests.kt b/coroutines/src/commonTest/kotlin/SmartRWLockerTests.kt
index 210ce222b15..de4b374a9a3 100644
--- a/coroutines/src/commonTest/kotlin/SmartRWLockerTests.kt
+++ b/coroutines/src/commonTest/kotlin/SmartRWLockerTests.kt
@@ -9,6 +9,7 @@ import kotlin.test.assertEquals
 import kotlin.test.assertFails
 import kotlin.test.assertFalse
 import kotlin.test.assertTrue
+import kotlin.time.Duration.Companion.days
 import kotlin.time.Duration.Companion.seconds
 
 class SmartRWLockerTests {
@@ -109,6 +110,59 @@ class SmartRWLockerTests {
         }
     }
 
+    @Test
+    fun failureOnReadFreeingRead() = runTest {
+        val locker = SmartRWLocker()
+        val job = launch {
+            locker.withReadAcquire {
+                while (isActive) {
+                    delay(1.days)
+                }
+            }
+        }
+
+        locker.readSemaphore.permitsStateFlow.first {
+            it == locker.readSemaphore.maxPermits - 1
+        }
+        job.cancelAndJoin()
+        locker.readSemaphore.permitsStateFlow.first {
+            it == locker.readSemaphore.maxPermits
+        }
+    }
+
+    @Test
+    fun cancelledReaderReleasesPermitUnderContention() = runTest(timeout = 5.seconds) {
+        val locker = SmartRWLocker(readPermits = 2)
+        val reader = launch(Dispatchers.Unconfined) {
+            locker.withReadAcquire {
+                awaitCancellation()
+            }
+        }
+        assertEquals(1, locker.readSemaphore.freePermits)
+
+        // Observe the second acquisition synchronously while it still holds the
+        // semaphore's internal mutex. Cancelling the unconfined reader makes its
+        // cleanup contend for that mutex before the acquisition can release it.
+        val cancellation = launch(Dispatchers.Unconfined) {
+            locker.readSemaphore.permitsStateFlow.first { it == 0 }
+            reader.cancel()
+        }
+
+        // Keep this acquisition on the normal test dispatcher: making it
+        // unconfined would change the ordering that forces cleanup contention.
+        locker.withReadAcquire {
+            cancellation.join()
+            reader.join()
+            assertTrue(reader.isCancelled)
+            assertEquals(
+                1,
+                locker.readSemaphore.freePermits,
+                "The cancelled reader must release its permit while the other reader still holds one"
+            )
+        }
+        assertEquals(2, locker.readSemaphore.freePermits)
+    }
+
     @Test
     fun simpleWithReadAcquireTest() {
         val locker = SmartRWLocker()