1 files changed, 114 insertions, 0 deletions
diff --git a/common-parameters/src/main/java/org/onap/policy/common/parameters/ParameterService.java b/common-parameters/src/main/java/org/onap/policy/common/parameters/ParameterService.java
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+++ b/common-parameters/src/main/java/org/onap/policy/common/parameters/ParameterService.java
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+package org.onap.policy.common.parameters;
+/*
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2018 Ericsson. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * 
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * The parameter service makes ONAP PF parameters available to all classes in a JVM.
+ *
+ * The reason for having a parameter service is to avoid having to pass parameters down long call chains in modules such
+ * as PDPs and editors. The parameter service makes correct and verified parameters available statically.
+ *
+ * The parameter service must be used with care because changing a parameter set anywhere in a JVM will affect all users
+ * of those parameters anywhere in the JVM.
+ *
+ * @author Liam Fallon (liam.fallon@ericsson.com)
+ */
+public abstract class ParameterService {
+    // The map holding the parameters
+    private static Map<Class<? extends AbstractParameters>, AbstractParameters> parameterMap = new ConcurrentHashMap<>();
+
+    /**
+     * This class is an abstract static class that cannot be extended.
+     */
+    private ParameterService() {
+    }
+
+    /**
+     * Register parameters with the parameter service.
+     *
+     * @param <P> the generic type
+     * @param parametersClass the class of the parameter, used to index the parameter
+     * @param parameters the parameters
+     */
+    public static <P extends AbstractParameters> void registerParameters(final P parameters) {
+        parameterMap.put(parameters.getClass(), parameters);
+    }
+
+    /**
+     * Remove parameters from the parameter service.
+     *
+     * @param <P> the generic type
+     * @param parametersClass the class of the parameter, used to index the parameter
+     */
+    public static <P extends AbstractParameters> void deregisterParameters(final Class<P> parametersClass) {
+        parameterMap.remove(parametersClass);
+    }
+
+    /**
+     * Get parameters from the parameter service.
+     *
+     * @param <P> the generic type
+     * @param parametersClass the class of the parameter, used to index the parameter
+     * @return The parameter
+     */
+    @SuppressWarnings("unchecked")
+    public static <P extends AbstractParameters> P getParameters(final Class<P> parametersClass) {
+        final P parameter = (P) parameterMap.get(parametersClass);
+
+        if (parameter == null) {
+            throw new ParameterRuntimeException(
+                            "Parameters for " + parametersClass.getCanonicalName() + " not found in parameter service");
+        }
+
+        return parameter;
+    }
+
+    /**
+     * Check if parameters is defined on the parameter service.
+     *
+     * @param <P> the generic type
+     * @param parametersClass the class of the parameter, used to index the parameter
+     * @return true if the parameter is defined
+     */
+    public static <P extends AbstractParameters> boolean existsParameters(final Class<P> parametersClass) {
+        return parameterMap.get(parametersClass) != null;
+    }
+
+    /**
+     * Get all the entries in the parameters map.
+     *
+     * @return The entries
+     */
+    public static Set<Entry<Class<? extends AbstractParameters>, AbstractParameters>> getAll() {
+        return parameterMap.entrySet();
+    }
+
+    /**
+     * Clear all parameters in the parameter service.
+     */
+    public static void clear() {
+        parameterMap.clear();
+    }
+}