1 files changed, 33 insertions, 0 deletions
diff --git a/config-provisioning/src/main/java/com/yahoo/config/provision/zone/ZoneFilter.java b/config-provisioning/src/main/java/com/yahoo/config/provision/zone/ZoneFilter.java
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index 00000000000..ab44fdcb05e
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+++ b/config-provisioning/src/main/java/com/yahoo/config/provision/zone/ZoneFilter.java
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+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config.provision.zone;
+
+import com.yahoo.config.provision.CloudName;
+
+/**
+ * A ZoneId list which can be filtered in various ways; elements can be accessed after at least one filter.
+ *
+ * The methods here return instances of {@link ZoneList}, which extends ZoneFilter, but with accessors and additional filters.
+ * This forces the developer to consider which of the filters in this class to apply, prior to accessing any zones.
+ *
+ * @author jonmv
+ */
+public interface ZoneFilter {
+
+    /** Negates the next filter. */
+    ZoneFilter not();
+
+    /** Zones which are upgraded by the controller. */
+    ZoneList controllerUpgraded();
+
+    /** Zones where config servers are up and running. */
+    ZoneList reachable();
+
+    /** All zones from the initial pool. */
+    ZoneList all();
+
+    /** Zones in the specified cloud */
+    default ZoneList ofCloud(CloudName cloud) {
+        return all(); // Not implemented in this repo.
+    }
+
+}