From afe431d71c2fa70f3b64a4eeafa836de44ede253 Mon Sep 17 00:00:00 2001
From: aleksanderkotbury <aleksanderkotbury@gmail.com>
Date: Fri, 9 Feb 2024 17:14:43 +0100
Subject: [PATCH] added retryRaise and retryEither functions

---
 .../kotlin/arrow/resilience/ScheduleEither.kt | 38 +++++++++++
 .../arrow/resilience/ScheduleEitherTest.kt    | 68 +++++++++++++++++++
 2 files changed, 106 insertions(+)
 create mode 100644 arrow-libs/resilience/arrow-resilience/src/commonMain/kotlin/arrow/resilience/ScheduleEither.kt
 create mode 100644 arrow-libs/resilience/arrow-resilience/src/commonTest/kotlin/arrow/resilience/ScheduleEitherTest.kt

diff --git a/arrow-libs/resilience/arrow-resilience/src/commonMain/kotlin/arrow/resilience/ScheduleEither.kt b/arrow-libs/resilience/arrow-resilience/src/commonMain/kotlin/arrow/resilience/ScheduleEither.kt
new file mode 100644
index 00000000000..702efed1dd6
--- /dev/null
+++ b/arrow-libs/resilience/arrow-resilience/src/commonMain/kotlin/arrow/resilience/ScheduleEither.kt
@@ -0,0 +1,38 @@
+@file:OptIn(ExperimentalTypeInference::class)
+
+import arrow.core.Either
+import arrow.core.raise.Raise
+import arrow.core.raise.either
+import arrow.resilience.Schedule
+import arrow.resilience.ScheduleStep
+import kotlinx.coroutines.currentCoroutineContext
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.ensureActive
+import kotlin.experimental.ExperimentalTypeInference
+import kotlin.time.Duration
+
+public suspend inline fun <Error, Result, Output> Schedule<Error, Output>.retryRaise(
+  @BuilderInference action: Raise<Error>.() -> Result,
+): Either<Error, Result> = retryEither { either(action) }
+
+public suspend inline fun <Error, Result, Output> Schedule<Error, Output>.retryEither(
+  @BuilderInference action: () -> Either<Error, Result>,
+): Either<Error, Result> {
+  var step: ScheduleStep<Error, Output> = step
+
+  while (true) {
+    currentCoroutineContext().ensureActive()
+    when (val result = action()) {
+      is Either.Left -> when (val decision = step(result.value)) {
+        is Schedule.Decision.Continue -> {
+          if (decision.delay != Duration.ZERO) delay(decision.delay)
+          step = decision.step
+        }
+
+        is Schedule.Decision.Done -> return result
+      }
+
+      is Either.Right -> return result
+    }
+  }
+}
diff --git a/arrow-libs/resilience/arrow-resilience/src/commonTest/kotlin/arrow/resilience/ScheduleEitherTest.kt b/arrow-libs/resilience/arrow-resilience/src/commonTest/kotlin/arrow/resilience/ScheduleEitherTest.kt
new file mode 100644
index 00000000000..a7a17092acb
--- /dev/null
+++ b/arrow-libs/resilience/arrow-resilience/src/commonTest/kotlin/arrow/resilience/ScheduleEitherTest.kt
@@ -0,0 +1,68 @@
+package arrow.resilience
+
+import arrow.atomic.AtomicLong
+import arrow.core.Either
+import arrow.core.left
+import arrow.core.right
+import kotlinx.coroutines.test.TestResult
+import kotlinx.coroutines.test.runTest
+import retryEither
+import retryRaise
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+
+class ScheduleEitherTest {
+
+  @Test
+  fun retryRaiseIsStackSafe(): TestResult = runTest {
+    val count = AtomicLong(0)
+    val iterations = 20_000L
+
+    suspend fun increment() {
+      count.incrementAndGet()
+    }
+
+    val result = Schedule.recurs<CustomError>(iterations).retryRaise {
+      increment()
+      raise(CustomError)
+    }
+
+    assertTrue { result is Either.Left }
+    assertEquals(iterations + 1, count.get())
+  }
+
+  @Test
+  fun retryRaiseSucceedsIfErrorIsNotRaised(): TestResult = runTest {
+    val result = Schedule.recurs<CustomError>(0).retryRaise { 1 }
+
+    assertTrue { result is Either.Right && result.value == 1 }
+  }
+
+  @Test
+  fun retryEitherIsStackSafe(): TestResult = runTest {
+    val count = AtomicLong(0)
+    val iterations = 20_000L
+
+    suspend fun increment() {
+      count.incrementAndGet()
+    }
+
+    val result = Schedule.recurs<CustomError>(iterations).retryEither {
+      increment()
+      CustomError.left()
+    }
+
+    assertTrue { result is Either.Left }
+    assertEquals(iterations + 1, count.get())
+  }
+
+  @Test
+  fun retryEitherSucceedsIfErrorIsNotRaised(): TestResult = runTest {
+    val result = Schedule.recurs<CustomError>(0).retryEither { 1.right() }
+
+    assertTrue { result is Either.Right && result.value == 1 }
+  }
+}
+
+private object CustomError