Add element type argument to ListFlag

6 files changed, 43 insertions, 16 deletions

diff --git a/flags/src/main/java/com/yahoo/vespa/flags/Flags.java b/flags/src/main/java/com/yahoo/vespa/flags/Flags.java
index 20ce7fe2578..527d53dc830 100644
--- a/flags/src/main/java/com/yahoo/vespa/flags/Flags.java
+++ b/flags/src/main/java/com/yahoo/vespa/flags/Flags.java
@@ -52,7 +52,7 @@ public class Flags {
             HOSTNAME);
 
     public static final UnboundListFlag<String> DISABLED_HOST_ADMIN_TASKS = defineListFlag(
-            "disabled-host-admin-tasks", List.of(),
+            "disabled-host-admin-tasks", List.of(), String.class,
             "List of host-admin task names (as they appear in the log, e.g. root>main>UpgradeTask) that should be skipped",
             "Takes effect on next host admin tick",
             HOSTNAME, NODE_TYPE);
@@ -112,7 +112,7 @@ public class Flags {
             APPLICATION_ID);
 
     public static final UnboundListFlag<String> DISABLED_DYNAMIC_PROVISIONING_FLAVORS = defineListFlag(
-            "disabled-dynamic-provisioning-flavors", List.of(),
+            "disabled-dynamic-provisioning-flavors", List.of(), String.class,
             "List of disabled Vespa flavor names that cannot be used for dynamic provisioning",
             "Takes effect on next provisioning");
 
@@ -195,9 +195,10 @@ public class Flags {
     }
 
     /** WARNING: public for testing: All flags should be defined in {@link Flags}. */
-    public static <T> UnboundListFlag<T> defineListFlag(String flagId, List<T> defaultValue, String description,
-                                                        String modificationEffect, FetchVector.Dimension... dimensions) {
-        return define(UnboundListFlag::new, flagId, defaultValue, description, modificationEffect, dimensions);
+    public static <T> UnboundListFlag<T> defineListFlag(String flagId, List<T> defaultValue, Class<T> elementClass,
+                                                        String description, String modificationEffect, FetchVector.Dimension... dimensions) {
+        return define((fid, dval, fvec) -> new UnboundListFlag<>(fid, dval, elementClass, fvec),
+                flagId, defaultValue, description, modificationEffect, dimensions);
     }
 
     @FunctionalInterface
diff --git a/flags/src/main/java/com/yahoo/vespa/flags/InMemoryFlagSource.java b/flags/src/main/java/com/yahoo/vespa/flags/InMemoryFlagSource.java
index b6e716fc912..6565ada98b0 100644
--- a/flags/src/main/java/com/yahoo/vespa/flags/InMemoryFlagSource.java
+++ b/flags/src/main/java/com/yahoo/vespa/flags/InMemoryFlagSource.java
@@ -41,8 +41,14 @@ public class InMemoryFlagSource implements FlagSource {
         return withRawFlag(flagId, new UnboundJacksonFlag<>(flagId, value, jacksonClass).serializer().serialize(value));
     }
 
-    public <T> InMemoryFlagSource withListFlag(FlagId flagId, List<T> value) {
-        return withRawFlag(flagId, new UnboundListFlag<T>(flagId, value).serializer().serialize(value));
+    /** use {@link #withListFlag(FlagId, List, Class)} instead */
+    @Deprecated
+    public InMemoryFlagSource withListFlag(FlagId flagId, List<String> value) {
+        return withListFlag(flagId, value, String.class);
+    }
+
+    public <T> InMemoryFlagSource withListFlag(FlagId flagId, List<T> value, Class<T> elementClass) {
+        return withRawFlag(flagId, new UnboundListFlag<T>(flagId, value, elementClass).serializer().serialize(value));
     }
 
     public InMemoryFlagSource removeFlag(FlagId flagId) {
diff --git a/flags/src/main/java/com/yahoo/vespa/flags/JacksonArraySerializer.java b/flags/src/main/java/com/yahoo/vespa/flags/JacksonArraySerializer.java
index 5716582e0aa..3c509703668 100644
--- a/flags/src/main/java/com/yahoo/vespa/flags/JacksonArraySerializer.java
+++ b/flags/src/main/java/com/yahoo/vespa/flags/JacksonArraySerializer.java
@@ -1,17 +1,23 @@
 // Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.vespa.flags;
 
+import com.fasterxml.jackson.databind.JavaType;
+
 import java.util.List;
 
 /**
  * @author freva
  */
 public class JacksonArraySerializer<T> implements FlagSerializer<List<T>> {
+    private final JavaType type;
+
+    public JacksonArraySerializer(Class<T> clazz) {
+        type = JsonNodeRawFlag.constructCollectionType(List.class, clazz);
+    }
 
-    @SuppressWarnings("unchecked")
     @Override
     public List<T> deserialize(RawFlag rawFlag) {
-        return (List<T>) JsonNodeRawFlag.fromJsonNode(rawFlag.asJsonNode()).toJacksonClass(List.class);
+        return JsonNodeRawFlag.fromJsonNode(rawFlag.asJsonNode()).toJacksonClass(type);
     }
 
     @Override
diff --git a/flags/src/main/java/com/yahoo/vespa/flags/JsonNodeRawFlag.java b/flags/src/main/java/com/yahoo/vespa/flags/JsonNodeRawFlag.java
index f41dd9f9e5c..92b7b3bc04d 100644
--- a/flags/src/main/java/com/yahoo/vespa/flags/JsonNodeRawFlag.java
+++ b/flags/src/main/java/com/yahoo/vespa/flags/JsonNodeRawFlag.java
@@ -1,9 +1,12 @@
 // Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.vespa.flags;
 
+import com.fasterxml.jackson.databind.JavaType;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
+import java.util.Collection;
+
 import static com.yahoo.yolean.Exceptions.uncheck;
 
 /**
@@ -36,6 +39,15 @@ public class JsonNodeRawFlag implements RawFlag {
         return uncheck(() -> mapper.treeToValue(jsonNode, jacksonClass));
     }
 
+    public <T> T toJacksonClass(JavaType jacksonClass) {
+        return uncheck(() -> mapper.readValue(jsonNode.toString(), jacksonClass));
+    }
+
+    @SuppressWarnings("rawtypes")
+    public static JavaType constructCollectionType(Class<? extends Collection> collectionClass, Class<?> elementClass) {
+        return mapper.getTypeFactory().constructCollectionType(collectionClass, elementClass);
+    }
+
     @Override
     public JsonNode asJsonNode() {
         return jsonNode;
diff --git a/flags/src/main/java/com/yahoo/vespa/flags/UnboundListFlag.java b/flags/src/main/java/com/yahoo/vespa/flags/UnboundListFlag.java
index f5150604231..a2230171454 100644
--- a/flags/src/main/java/com/yahoo/vespa/flags/UnboundListFlag.java
+++ b/flags/src/main/java/com/yahoo/vespa/flags/UnboundListFlag.java
@@ -9,14 +9,14 @@ import java.util.List;
  */
 @Immutable
 public class UnboundListFlag<T> extends UnboundFlagImpl<List<T>, ListFlag<T>, UnboundListFlag<T>> {
-    public UnboundListFlag(FlagId id, List<T> defaultValue) {
-        this(id, defaultValue, new FetchVector());
+    public UnboundListFlag(FlagId id, List<T> defaultValue, Class<T> clazz) {
+        this(id, defaultValue, clazz, new FetchVector());
     }
 
-    public UnboundListFlag(FlagId id, List<T> defaultValue, FetchVector defaultFetchVector) {
+    public UnboundListFlag(FlagId id, List<T> defaultValue, Class<T> clazz, FetchVector defaultFetchVector) {
         super(id, defaultValue, defaultFetchVector,
-                new JacksonArraySerializer<T>(),
-                UnboundListFlag::new,
+                new JacksonArraySerializer<T>(clazz),
+                (flagId, defVal, fetchVector) -> new UnboundListFlag<>(flagId, defVal, clazz, fetchVector),
                 ListFlag::new);
     }
 }
diff --git a/flags/src/test/java/com/yahoo/vespa/flags/FlagsTest.java b/flags/src/test/java/com/yahoo/vespa/flags/FlagsTest.java
index 284a4324a9e..750f0f414f9 100644
--- a/flags/src/test/java/com/yahoo/vespa/flags/FlagsTest.java
+++ b/flags/src/test/java/com/yahoo/vespa/flags/FlagsTest.java
@@ -8,7 +8,6 @@ import org.junit.Test;
 import org.mockito.ArgumentCaptor;
 
 import java.util.List;
-import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
 
@@ -90,7 +89,7 @@ public class FlagsTest {
 
     @Test
     public void testList() {
-        testGeneric(Flags.defineListFlag("list-id", List.of("a"), "desc", "mod"), List.of("a", "b", "c"));
+        testGeneric(Flags.defineListFlag("list-id", List.of("a"), String.class, "desc", "mod"), List.of("a", "b", "c"));
     }
 
     @Test
@@ -103,6 +102,9 @@ public class FlagsTest {
         testGeneric(Flags.defineJacksonFlag("jackson-id", defaultInstance, ExampleJacksonClass.class,
                 "description", "modification effect", FetchVector.Dimension.HOSTNAME),
                 instance);
+
+        testGeneric(Flags.defineListFlag("jackson-list-id", List.of(defaultInstance), ExampleJacksonClass.class, "desc", "mod"),
+                List.of(instance));
     }
 
     private <T> void testGeneric(UnboundFlag<T, ?, ?> unboundFlag, T value) {