added retry policy to gbcs-client

2025-01-27 13:12:12 +08:00
parent 1823d0b9ca
commit 90a5834f5f
9 changed files with 385 additions and 35 deletions
@@ -0,0 +1,75 @@
+package net.woggioni.gbcs.client
+
+import io.netty.util.concurrent.EventExecutorGroup
+import java.util.concurrent.CompletableFuture
+import java.util.concurrent.TimeUnit
+
+sealed class OperationOutcome<T> {
+    class Success<T>(val result: T) : OperationOutcome<T>()
+    class Failure<T>(val ex: Throwable) : OperationOutcome<T>()
+}
+
+sealed class OutcomeHandlerResult {
+    class Retry(val suggestedDelayMillis: Long? = null) : OutcomeHandlerResult()
+    class DoNotRetry : OutcomeHandlerResult()
+}
+
+fun interface OutcomeHandler<T> {
+    fun shouldRetry(result: OperationOutcome<T>): OutcomeHandlerResult
+}
+
+fun <T> executeWithRetry(
+    eventExecutorGroup: EventExecutorGroup,
+    maxAttempts: Int,
+    initialDelay: Double,
+    exp: Double,
+    outcomeHandler: OutcomeHandler<T>,
+    cb: () -> CompletableFuture<T>
+): CompletableFuture<T> {
+    val finalResult = cb()
+    var future = finalResult
+    var shortCircuit = false
+    for (i in 1 until maxAttempts) {
+        future = future.handle { result, ex ->
+            val operationOutcome = if (ex == null) {
+                OperationOutcome.Success(result)
+            } else {
+                OperationOutcome.Failure(ex.cause ?: ex)
+            }
+            if (shortCircuit) {
+                when(operationOutcome) {
+                    is OperationOutcome.Failure -> throw operationOutcome.ex
+                    is OperationOutcome.Success -> CompletableFuture.completedFuture(operationOutcome.result)
+                }
+            } else {
+                when(val outcomeHandlerResult = outcomeHandler.shouldRetry(operationOutcome)) {
+                    is OutcomeHandlerResult.Retry -> {
+                        val res = CompletableFuture<T>()
+                        val delay = run {
+                            val scheduledDelay = (initialDelay * Math.pow(exp, i.toDouble())).toLong()
+                            outcomeHandlerResult.suggestedDelayMillis?.coerceAtMost(scheduledDelay) ?: scheduledDelay
+                        }
+                        eventExecutorGroup.schedule({
+                            cb().handle { result, ex ->
+                                if (ex == null) {
+                                    res.complete(result)
+                                } else {
+                                    res.completeExceptionally(ex)
+                                }
+                            }
+                        }, delay, TimeUnit.MILLISECONDS)
+                        res
+                    }
+                    is OutcomeHandlerResult.DoNotRetry -> {
+                        shortCircuit = true
+                        when(operationOutcome) {
+                            is OperationOutcome.Failure -> throw operationOutcome.ex
+                            is OperationOutcome.Success -> CompletableFuture.completedFuture(operationOutcome.result)
+                        }
+                    }
+                }
+            }
+        }.thenCompose { it }
+    }
+    return future
+}