feat: add support for determining HTTP exception retryability (#82)

Author: ianbotsf

aws-crt-kotlin/api/android/aws-crt-kotlin.api

@@ -8,6 +8,7 @@ public final class aws/sdk/kotlin/crt/CRT {
 	public final fun errorString (I)Ljava/lang/String;
 	public final fun initRuntime (Lkotlin/jvm/functions/Function1;)V
 	public static synthetic fun initRuntime$default (Laws/sdk/kotlin/crt/CRT;Lkotlin/jvm/functions/Function1;ILjava/lang/Object;)V
+	public final fun isHttpErrorRetryable (I)Z
 	public final fun lastError ()I
 	public final fun nativeMemory ()J
 }

aws-crt-kotlin/api/jvm/aws-crt-kotlin.api

@@ -8,6 +8,7 @@ public final class aws/sdk/kotlin/crt/CRT {
 	public final fun errorString (I)Ljava/lang/String;
 	public final fun initRuntime (Lkotlin/jvm/functions/Function1;)V
 	public static synthetic fun initRuntime$default (Laws/sdk/kotlin/crt/CRT;Lkotlin/jvm/functions/Function1;ILjava/lang/Object;)V
+	public final fun isHttpErrorRetryable (I)Z
 	public final fun lastError ()I
 	public final fun nativeMemory ()J
 }

aws-crt-kotlin/common/src/aws/sdk/kotlin/crt/CRT.kt

@@ -18,21 +18,28 @@ public expect object CRT {
     public fun lastError(): Int
 
     /**
-     * Given an integer error code from an internal operation
+     * Given an integer error code from an internal operation, return the associated error message.
      * @param errorCode An error code returned from an exception or other native function call
      * @return A user-friendly description of the error
      */
     public fun errorString(errorCode: Int): String?
 
     /**
-     * Given an integer error code from an internal operation
+     * Given an integer error code from an internal operation, return the associated error name.
      *
      * @param errorCode An error code returned from an exception or other native
      * function call
      * @return A string identifier for the error
      */
     public fun errorName(errorCode: Int): String?
 
+    /**
+     * Given an integer HTTP error code from an internal operation, return whether the error is retryable.
+     * @param errorCode An error code returned from an exception or other native function call
+     * @return True if the given HTTP error is retryable; otherwise, false.
+     */
+    public fun isHttpErrorRetryable(errorCode: Int): Boolean
+
     /**
      * @return The number of bytes allocated in native resources. If aws.crt.memory.tracing is 1 or 2, this will
      * be a non-zero value. Otherwise, no tracing will be done, and the value will always be 0

aws-crt-kotlin/jvm/src/aws/sdk/kotlin/crt/CRT.kt

@@ -6,6 +6,8 @@
 package aws.sdk.kotlin.crt
 
 import software.amazon.awssdk.crt.Log
+import software.amazon.awssdk.crt.http.HttpClientConnection
+import software.amazon.awssdk.crt.http.HttpException
 import java.util.concurrent.atomic.AtomicInteger as AtomicInt
 import software.amazon.awssdk.crt.CRT as crtJni
 
@@ -53,6 +55,17 @@ public actual object CRT {
      */
     public actual fun errorName(errorCode: Int): String? = crtJni.awsErrorName(errorCode)
 
+    public actual fun isHttpErrorRetryable(errorCode: Int): Boolean {
+        // An exception subtype that doesn't create a stack, which saves a bunch of time
+        class StacklessHttpException(errorCode: Int) : HttpException(errorCode) {
+            // Changing `fillInStackTrace` to a no-op skips filling in the stack
+            override fun fillInStackTrace(): Throwable = this
+        }
+
+        val phonyException = StacklessHttpException(errorCode)
+        return HttpClientConnection.isErrorRetryable(phonyException)
+    }
+
     /**
      * @return The number of bytes allocated in native resources. If aws.crt.memory.tracing is 1 or 2, this will
      * be a non-zero value. Otherwise, no tracing will be done, and the value will always be 0

aws-crt-kotlin/native/src/aws/sdk/kotlin/crt/CRTNative.kt

@@ -34,11 +34,15 @@ public actual object CRT {
         TODO("Not yet implemented")
     }
 
+    public actual fun isHttpErrorRetryable(errorCode: Int): Boolean {
+        TODO("Not yet implemented")
+    }
+
     /**
      * @return The number of bytes allocated in native resources. If aws.crt.memory.tracing is 1 or 2, this will
      * be a non-zero value. Otherwise, no tracing will be done, and the value will always be 0
      */
     public actual fun nativeMemory(): Long {
         TODO("Not yet implemented")
     }
-}
+}