fix(flagd): Extended retry logic for SyncFlags

Signed-off-by: Guido Breitenhuber <[email protected]>

Author: guidobrei

providers/flagd/src/main/java/dev/openfeature/contrib/providers/flagd/resolver/common/ChannelBuilder.java

@@ -26,17 +26,38 @@
 /** gRPC channel builder helper. */
 public class ChannelBuilder {
 
+    @SuppressWarnings({"unchecked", "rawtypes"})
+    private static final Map<String, ?> DEFAULT_RETRY_POLICY = new HashMap() {
+        {
+            // 1 + 2 + 4
+            put("maxAttempts", 3.0); // types used here are important, need to be doubles
+            put("initialBackoff", "1s");
+            put("maxBackoff", "5s");
+            put("backoffMultiplier", 2.0);
+            // status codes to retry on:
+            put("retryableStatusCodes",
+                Arrays.asList(
+                        /*
+                         * Only states UNAVAILABLE and UNKNOWN should be retried. All
+                         * other failure states will probably not be resolved with a simple retry.
+                         */
+                        Code.UNAVAILABLE.toString(),
+                        Code.UNKNOWN.toString()
+                )
+            );
+        }
+    };
+
     /**
      * Controls retry (not-reconnection) policy for failed RPCs.
      */
     @SuppressWarnings({"unchecked", "rawtypes"})
     static final Map<String, ?> SERVICE_CONFIG_WITH_RETRY = new HashMap() {
         {
-            put("methodConfig", Arrays.asList(new HashMap() {
-                {
-                    put(
-                            "name",
-                            Arrays.asList(
+            put("methodConfig", Arrays.asList(
+                    new HashMap() {
+                        {
+                            put("name", Arrays.asList(
                                     new HashMap() {
                                         {
                                             put("service", "flagd.sync.v1.FlagSyncService");
@@ -46,29 +67,56 @@ public class ChannelBuilder {
                                         {
                                             put("service", "flagd.evaluation.v1.Service");
                                         }
-                                    }));
-                    put("retryPolicy", new HashMap() {
+                                    }
+                                ));
+                            put("retryPolicy", DEFAULT_RETRY_POLICY);
+                        }
+
                         {
-                            // 1 + 2 + 4
-                            put("maxAttempts", 3.0); // types used here are important, need to be doubles
-                            put("initialBackoff", "1s");
-                            put("maxBackoff", "5s");
-                            put("backoffMultiplier", 2.0);
-                            // status codes to retry on:
-                            put(
-                                    "retryableStatusCodes",
-                                    Arrays.asList(
-                                            /*
-                                             * Only states UNAVAILABLE and UNKNOWN should be retried. All
-                                             * other failure states will probably not be resolved with a simple retry.
-                                             */
-                                            Code.UNAVAILABLE.toString(),
-                                            Code.UNKNOWN.toString())
-                            );
+                            put("name", Arrays.asList(
+                                    new HashMap() {
+                                        {
+                                            put("service", "flagd.sync.v1.FlagSyncService");
+                                            put("method", "SyncFlags");
+                                        }
+                                    }
+                                ));
+                            put("retryPolicy", new HashMap(DEFAULT_RETRY_POLICY) {
+                                {
+                                    // 1 + 2 + 4 + 5 + 5 + 5 + 5 + 5 + 5 + 5
+                                    put("maxAttempts", 12.0);
+                                    // for streaming Retry on more status codes
+                                    put("retryableStatusCodes",
+                                            Arrays.asList(
+                                                    /*
+                                                     * All codes are retryable except OK and DEADLINE_EXCEEDED since
+                                                     * any others not listed here cause a very tight loop of retries.
+                                                     * DEADLINE_EXCEEDED is typically a result of a client specified
+                                                     * deadline,and definitionally should not result in a tight loop
+                                                     * (it's a timeout).
+                                                     */
+                                                    Code.CANCELLED.toString(),
+                                                    Code.UNKNOWN.toString(),
+                                                    Code.INVALID_ARGUMENT.toString(),
+                                                    Code.NOT_FOUND.toString(),
+                                                    Code.ALREADY_EXISTS.toString(),
+                                                    Code.PERMISSION_DENIED.toString(),
+                                                    Code.RESOURCE_EXHAUSTED.toString(),
+                                                    Code.FAILED_PRECONDITION.toString(),
+                                                    Code.ABORTED.toString(),
+                                                    Code.OUT_OF_RANGE.toString(),
+                                                    Code.UNIMPLEMENTED.toString(),
+                                                    Code.INTERNAL.toString(),
+                                                    Code.UNAVAILABLE.toString(),
+                                                    Code.DATA_LOSS.toString(),
+                                                    Code.UNAUTHENTICATED.toString()
+                                            )
+                                    );
+                                }
+                            });
                         }
-                    });
-                }
-            }));
+                    }
+            ));
         }
     };