add TransactionsDSL

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 * `Coroutines`:
   * Add extensions `SmartRWLocker.alsoWithUnlockingOnSuccessAsync` and `SmartRWLocker.alsoWithUnlockingOnSuccess`
+* `Transactions`:
+  * Add `TransactionsDSL`
 
 ## 0.25.2
 

settings.gradle

@@ -3,6 +3,7 @@ rootProject.name='micro_utils'
 String[] includes = [
     ":common",
     ":common:compose",
+    ":transactions",
     ":matrix",
     ":safe_wrapper",
     ":crypto",

transactions/build.gradle

@@ -0,0 +1,7 @@
+plugins {
+    id "org.jetbrains.kotlin.multiplatform"
+    id "org.jetbrains.kotlin.plugin.serialization"
+    id "com.android.library"
+}
+
+apply from: "$mppJvmJsAndroidLinuxMingwLinuxArm64Project"

transactions/src/commonMain/kotlin/TransactionsDSL.kt

@@ -0,0 +1,82 @@
+package dev.inmo.micro_utils.transactions
+
+typealias TransactionDSLRollbackLambda = suspend (Throwable) -> Unit
+class TransactionsDSL internal constructor() {
+    internal val rollbackActions = LinkedHashSet<TransactionDSLRollbackLambda>()
+
+    internal fun addRollbackAction(rollbackAction: TransactionDSLRollbackLambda) {
+        rollbackActions.add(rollbackAction)
+    }
+}
+class RollbackContext<T> internal constructor (
+    val actionResult: T,
+    val error: Throwable
+)
+
+/**
+ * Calls [action] and, if it succeeded - saving [rollback] action for future usage for cases when some other
+ * action or even main one throwing an error
+ *
+ * @param rollback Will be called if
+ */
+suspend fun <T> TransactionsDSL.rollbackableOperation(
+    rollback: suspend RollbackContext<T>.() -> Unit,
+    action: suspend () -> T
+): T {
+    return runCatching { action() }
+        .onSuccess {
+            addRollbackAction { e ->
+                val context = RollbackContext(it, e)
+                context.rollback()
+            }
+        }
+        .getOrThrow()
+}
+
+/**
+ * Starts transaction with opportunity to add actions [rollbackableOperation]. How to use:
+ *
+ * ```kotlin
+ * doSuspendTransaction {
+ *     println("start of action")
+ *
+ *     withRollback({ // it - result of action
+ *         // some rollback action
+ *     }) {
+ *         // Some action with rollback
+ *     }
+ *
+ *     withRollback({
+ *          repository.delete(it) // it - result of createSomething, if it completes successfully
+ *     }) {
+ *          repository.createSomething()
+ *     }
+ *
+ *     withRollback({
+ *         // will not be triggered due to error in action
+ *     }) {
+ *         error("It is just a simple error") // Will trigger rolling back previously successfully completed actions
+ *     }
+ * }
+ * ```
+ *
+ * @param onRollbackStepError Will be called if rollback action throwing some error
+ */
+suspend fun <T> doSuspendTransaction(
+    onRollbackStepError: suspend (TransactionDSLRollbackLambda, Throwable) -> Unit = { _, _ -> },
+    block: suspend TransactionsDSL.() -> T
+): Result<T> {
+    val transactionsDSL = TransactionsDSL()
+
+    return runCatching {
+        transactionsDSL.block()
+    }.onFailure { e ->
+        transactionsDSL.rollbackActions.forEach {
+            runCatching {
+                it.invoke(e)
+            }.onFailure { ee ->
+                onRollbackStepError(it, ee)
+            }
+        }
+    }
+}