[HWKMETRICS-185] Duplicate application configuration classes.

api/metrics-api-jaxrs-1.1/src/main/java/org/hawkular/metrics/api/jaxrs/config/Configurable.java

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+/*
+ * Copyright 2014-2015 Red Hat, Inc. and/or its affiliates
+ * and other contributors as indicated by the @author tags.
+ *
+ * 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.
+ */
+package org.hawkular.metrics.api.jaxrs.config;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import javax.inject.Qualifier;
+
+/**
+ * Qualifier for an injected field or parameter which value should be fetched from configuration. For example:
+ * <pre>
+ *     &#064;Configurable
+ *     &#064;ConfigurationProperty(ConfigurationKey.BACKEND)
+ *     &#064;Inject
+ *     String backendType;
+ * </pre>
+ * Configuration is a set of key/value pairs (configuration properties) defined by the following sources, in order of
+ * precedence:
+ * <ul>
+ *     <li>system properties (-Dkey=value)</li>
+ *     <li>external {@link java.util.Properties} file, which path is defined by the <em>metrics.conf</em> system
+ *     property; by default, <em>&lt;user.home&gt;/.metrics.conf</em> is used</li>
+ *     <li>internal {@link java.util.Properties} file (<em>META-INF/metrics.conf</em>)</li>
+ * </ul>
+ * Any field or parameter annotated with {@link Configurable} must also be annotated with {@link ConfigurationProperty}.
+ * The value of the latter specifies the configuration property key. Otherwise the configuration producer method will
+ * throw an instance of {@link java.lang.IllegalArgumentException}. In most cases, a configuration property should at
+ * least be defined in the internal properties file, in order to provide a default value.<br>
+ * <br>
+ * Configuration values may be modified at runtime (through JMX). When a bean can/should adapt to such changes, the
+ * injected field or parameter type can be wrapped with {@link javax.enterprise.inject.Instance}. The configuration
+ * value will be fetched on each call to {@link javax.enterprise.inject.Instance#get()}.
+ *
+ * @author Thomas Segismont
+ * @see ConfigurationProperty
+ * @see ConfigurableProducer
+ */
+@Qualifier
+@Retention(RUNTIME)
+@Target({ METHOD, FIELD, PARAMETER })
+@Documented
+public @interface Configurable {
+}

api/metrics-api-jaxrs-1.1/src/main/java/org/hawkular/metrics/api/jaxrs/config/ConfigurableProducer.java

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+/*
+ * Copyright 2014-2015 Red Hat, Inc. and/or its affiliates
+ * and other contributors as indicated by the @author tags.
+ *
+ * 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.
+ */
+package org.hawkular.metrics.api.jaxrs.config;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.EnumMap;
+import java.util.Properties;
+
+import javax.annotation.PostConstruct;
+import javax.enterprise.context.ApplicationScoped;
+import javax.enterprise.inject.Produces;
+import javax.enterprise.inject.spi.InjectionPoint;
+
+/**
+ * @author Thomas Segismont
+ * @see Configurable
+ */
+@ApplicationScoped
+public class ConfigurableProducer {
+    static final String METRICS_CONF = "metrics.conf";
+
+    private EnumMap<ConfigurationKey, String> effectiveConfig;
+
+    @PostConstruct
+    void init() {
+        effectiveConfig = new EnumMap<>(ConfigurationKey.class);
+
+        Properties configFileProperties = new Properties();
+        File configurationFile = findConfigurationFile();
+        if (configurationFile != null) {
+            load(configFileProperties, configurationFile);
+        }
+
+        for (ConfigurationKey configKey : ConfigurationKey.values()) {
+            String name = configKey.toString();
+            String envName = configKey.toEnvString();
+
+            String value = System.getProperty(name);
+            if (value == null && envName != null) {
+                value = System.getenv(envName);
+            }
+            if (value == null) {
+                value = configFileProperties.getProperty(name);
+            }
+
+            if (configKey.isFlag()) {
+                effectiveConfig.put(configKey, String.valueOf(value != null));
+            } else {
+                effectiveConfig.put(configKey, value != null ? value : configKey.defaultValue());
+            }
+        }
+    }
+
+    @Produces
+    @Configurable
+    String getConfigurationPropertyAsString(InjectionPoint injectionPoint) {
+        ConfigurationProperty configProp = injectionPoint.getAnnotated().getAnnotation(ConfigurationProperty.class);
+        if (configProp == null) {
+            String message = "Any field or parameter annotated with @" + Configurable.class.getSimpleName()
+                             + " must also be annotated with @" + ConfigurationProperty.class.getSimpleName();
+            throw new IllegalArgumentException(message);
+        }
+        return effectiveConfig.get(configProp.value());
+    }
+
+    private File findConfigurationFile() {
+        String configurationFilePath = System.getProperty(METRICS_CONF);
+        if (configurationFilePath != null) {
+            File file = new File(configurationFilePath);
+            checkExplicitConfigurationFile(file);
+            return file;
+        }
+        File file = new File(System.getProperty("user.home"), ".metrics.conf");
+        if (!file.exists()) {
+            return null;
+        }
+        checkConfigurationFile(file);
+        return file;
+    }
+
+    private void checkExplicitConfigurationFile(File file) {
+        if (!file.exists()) {
+            throw new IllegalArgumentException(file + " does not exist");
+        }
+        checkConfigurationFile(file);
+    }
+
+    private void checkConfigurationFile(File file) {
+        if (!file.isFile()) {
+            throw new IllegalArgumentException(file + " is not a regular file");
+        }
+        if (!file.canRead()) {
+            throw new IllegalArgumentException(file + " is not readable");
+        }
+    }
+
+    private void load(Properties properties, File file) {
+        try (InputStream input = new FileInputStream(file)) {
+            properties.load(input);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}

api/metrics-api-jaxrs-1.1/src/main/java/org/hawkular/metrics/api/jaxrs/config/ConfigurationKey.java

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+/*
+ * Copyright 2014-2015 Red Hat, Inc. and/or its affiliates
+ * and other contributors as indicated by the @author tags.
+ *
+ * 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.
+ */
+package org.hawkular.metrics.api.jaxrs.config;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+/**
+ * Parameter and flags definitions.
+ *
+ * @author Thomas Segismont
+ * @see Configurable
+ */
+public enum ConfigurationKey {
+
+    CASSANDRA_NODES("hawkular-metrics.cassandra-nodes", "127.0.0.1", "CASSANDRA_NODES", false),
+    CASSANDRA_CQL_PORT("hawkular-metrics.cassandra-cql-port", "9042", "CASSANDRA_CQL_PORT", false),
+    CASSANDRA_KEYSPACE("cassandra.keyspace", "hawkular_metrics", null, false),
+    CASSANDRA_RESETDB("cassandra.resetdb", null, null, true),
+    WAIT_FOR_SERVICE("hawkular.metrics.waitForService", null, null, true),
+    TASK_SCHEDULER_TIME_UNITS("hawkular.scheduler.time-units", "minutes", "SCHEDULER_TIME_UNITS", false);
+
+    private final String name;
+    private final String env;
+    private final String defaultValue;
+    private final boolean flag;
+
+    /**
+     * @param name         string representation when set in file or as system property
+     * @param defaultValue default value for parameters, null for flags
+     * @param env          string representation when set in environment
+     * @param flag         true if the value does not matter
+     */
+    ConfigurationKey(String name, String defaultValue, String env, boolean flag) {
+        checkArgument(name != null, "name is null");
+        checkArgument(!flag || defaultValue == null, "Config flags can't have a default value");
+        this.name = name;
+        this.env = env;
+        this.defaultValue = defaultValue;
+        this.flag = flag;
+    }
+
+    /**
+     * @return name when set in file or as system property
+     */
+    @Override
+    public String toString() {
+        return name;
+    }
+
+    /**
+     * @return the default value, or null if none, or the parameter is just a flag
+     */
+    public String defaultValue() {
+        return defaultValue;
+    }
+
+    /**
+     * @return name when set in environment, or null if env binding is not supported
+     */
+    public String toEnvString() {
+        return env;
+    }
+
+    /**
+     * @return true if the value does not matter
+     */
+    public boolean isFlag() {
+        return flag;
+    }
+}

api/metrics-api-jaxrs-1.1/src/main/java/org/hawkular/metrics/api/jaxrs/config/ConfigurationProperty.java

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+/*
+ * Copyright 2014-2015 Red Hat, Inc. and/or its affiliates
+ * and other contributors as indicated by the @author tags.
+ *
+ * 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.
+ */
+package org.hawkular.metrics.api.jaxrs.config;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Defines the {@link ConfigurationKey} for {@link Configurable} injection points.
+ *
+ * @author Thomas Segismont
+ * @see Configurable
+ */
+@Retention(RUNTIME)
+@Target({ METHOD, FIELD, PARAMETER })
+@Documented
+public @interface ConfigurationProperty {
+    ConfigurationKey value();
+}