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Commit 64f5823

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strubergstruberg
committed
add an access layer on top of the minimal configuration API
work in progress, API looks solid though
1 parent dfec238 commit 64f5823
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‎api/src/main/java/javx/config/Config.java‎

Copy file name to clipboardExpand all lines: api/src/main/java/javx/config/Config.java
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@@ -45,6 +45,13 @@ public interface Config {
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*/
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String getValue(String key);
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/**
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* Create a {@link ConfigValue} to access the underlying configuration.
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*
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* @param key the property key
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*/
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ConfigValue<String> access(String key);
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/**
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* Returns a Map of all properties from all scannable config sources. The values of the properties reflect the
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* values that would be obtained by a call to {@link #getValue(java.lang.String)}, that is, the value of the
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‎api/src/main/java/javx/config/ConfigValue.java‎

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package javx.config;
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import javx.config.spi.Converter;
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import java.util.concurrent.TimeUnit;
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/**
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* Accessor to a configured value.
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* It follows a builder pattern.
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*
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* Accessing the configured value is finally done via {@link #getValue()}
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*
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* @author <a href="mailto:struberg@apache.org">Mark Struberg</a>
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* @author <a href="mailto:gpetracek@apache.org">Gerhard Petracek</a>
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*/
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public interface ConfigValue<T> {
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/**
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* Sets the type of the configuration entry to the given class and returns this builder.
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* The default type of a ConfigValue is {@code String}.
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*
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* @param clazz The target type
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* @param <N> The target type
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* @return This builder as a typed ConfigValue
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*/
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<N> ConfigValue<N> as(Class<N> clazz);
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/**
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* Sets the type of the configuration entry to the given class, sets the converter to the one given and
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* returns this builder. If a converter is provided for one of the types supported by
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* default (see {@link #as(Class)} then the provided converter is used instead of the built-in one.
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*
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* @param clazz The target type
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* @param converter The converter for the target type
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* @param <N> The target type
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* @return This builder as a typed ConfigValue
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*/
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<N> ConfigValue<N> as(Class<N> clazz, Converter<N> converter);
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/**
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* Sets the default value to use in case the resolution returns null.
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* @param value the default value
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* @return This builder
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*/
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ConfigValue<T> withDefault(T value);
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/**
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* Sets the default value to use in case the resolution returns null. Converts the given String to the type of
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* this resolver using the same method as used for the configuration entries.
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* @param value string value to be converted and used as default
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* @return This builder
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*/
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ConfigValue<T> withStringDefault(String value);
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/**
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* Specify that a resolved value will get cached for a certain amount of time.
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* After the time expires the next {@link #getValue()} will again resolve the value
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* from the underlying {@link Config}.
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*
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* @param timeUnit the TimeUnit for the value
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* @param value the amount of the TimeUnit to wait
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* @return This builder
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*/
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ConfigValue<T> cacheFor(TimeUnit timeUnit, long value);
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/**
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* Whether to evaluate variables in configured values.
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* A variable starts with '${' and ends with '}', e.g.
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* <pre>
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* mycompany.some.url=${myserver.host}/some/path
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* myserver.host=http://localhost:8081
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* </pre>
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* If 'evaluateVariables' is enabled, the result for the above key
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* {@code "mycompany.some.url"} would be:
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* {@code "http://localhost:8081/some/path"}
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* @param evaluateVariables whether to evaluate variables in values or not
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* @return This builder
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*/
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ConfigValue<T> evaluateVariables(boolean evaluateVariables);
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/**
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* Appends the resolved value of the given property to the key of this builder.
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* TODO further explain.
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* @return This builder
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*/
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ConfigValue<T> withLookupChain(String... postfixNames);
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/**
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* Whether to log picking up any value changes as INFO.
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*
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* @return This builder
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*/
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ConfigValue<T> logChanges(boolean logChanges);
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/**
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* Returns the converted resolved filtered value.
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* @return the resolved value
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*/
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T getValue();
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/**
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* Returns the key given in {@link Config#access(String)}.
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* @return the original key
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*/
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String getKey();
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/**
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* Returns the actual key which led to successful resolution and corresponds to the resolved value. This applies
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* only when {@link #withLookupChain(String...)} is used.
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* Otherwise the resolved key should always be equal to the original key.
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* This method is provided for cases, when arameterized resolution is
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* requested but the value for such appended key is not found and some of the fallback keys is used.
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*
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* This should be called only after calling {@link #getValue()} otherwise the value is undefined (but likely
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* null).
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*/
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String getResolvedKey();
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/**
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* Returns the default value provided by {@link #withDefault(Object)} or {@link #withStringDefault(String)}.
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* Returns null if no default was provided.
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* @return the default value or {@code null}
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*/
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T getDefaultValue();
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}
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‎api/src/main/java/javx/config/spi/Converter.java‎

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package javx.config.spi;
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/**
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* A very simple interface for conversion of configuration values from String to any Java type.
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*
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* @author <a href="mailto:struberg@apache.org">Mark Struberg</a>
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* @author <a href="mailto:gpetracek@apache.org">Gerhard Petracek</a>
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*/
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public interface Converter<T> {
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/**
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* Returns the converted value of the configuration entry.
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* @param value The String property value to convert
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* @return Converted value
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*/
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T convert(String value);
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}
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‎impl/src/main/java/org/apache/geronimo/config/ConfigImpl.java‎

Copy file name to clipboardExpand all lines: impl/src/main/java/org/apache/geronimo/config/ConfigImpl.java
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@@ -27,6 +27,7 @@
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import java.util.logging.Logger;
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import javx.config.Config;
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import javx.config.ConfigValue;
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import javx.config.spi.ConfigFilter;
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import javx.config.spi.ConfigSource;
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@@ -56,6 +57,11 @@ public String getValue(String key) {
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return null;
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}
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@Override
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public ConfigValue<String> access(String key) {
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return null;
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}
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@Override
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public Map<String, String> getAllProperties() {
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Map<String, String> result = new HashMap<String, String>();
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‎impl/src/main/java/org/apache/geronimo/config/ConfigValueImpl.java‎

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package org.apache.geronimo.config;
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import javx.config.Config;
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import javx.config.ConfigValue;
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import javx.config.spi.Converter;
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import java.util.concurrent.TimeUnit;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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/**
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* @author <a href="mailto:struberg@apache.org">Mark Struberg</a>
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*/
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public class ConfigValueImpl<T> implements ConfigValue<T> {
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private static final Logger logger = Logger.getLogger(ConfigValueImpl.class.getName());
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private final ConfigImpl config;
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private String keyOriginal;
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private String keyResolved;
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private Class<?> configEntryType = String.class;
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private boolean withDefault = false;
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private T defaultValue;
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private String propertyParameter;
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private String parameterValue;
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private Converter<?> converter;
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private boolean evaluateVariables = false;
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private boolean logChanges = false;
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private long cacheTimeMs = -1;
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private volatile long reloadAfter = -1;
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private T lastValue = null;
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public ConfigValueImpl(ConfigImpl config) {
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this.config = config;
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}
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@Override
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public <N> ConfigValue<N> as(Class<N> clazz) {
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configEntryType = clazz;
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this.converter = null;
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return (ConfigValue<N>) this;
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}
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@Override
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public <N> ConfigValue<N> as(Class<N> clazz, Converter<N> converter) {
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configEntryType = clazz;
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this.converter = converter;
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return (ConfigValue<N>) this;
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}
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@Override
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public ConfigValue<T> withDefault(T value) {
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defaultValue = value;
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withDefault = true;
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return this;
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}
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@Override
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public ConfigValue<T> withStringDefault(String value) {
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if (value == null || value.isEmpty())
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{
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throw new RuntimeException("Empty String or null supplied as string-default value for property "
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+ keyOriginal);
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}
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defaultValue = convert(value);
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withDefault = true;
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return this;
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}
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@Override
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public ConfigValue<T> cacheFor(TimeUnit timeUnit, long value) {
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this.cacheTimeMs = timeUnit.toMillis(value);
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return this;
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}
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@Override
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public ConfigValue<T> evaluateVariables(boolean evaluateVariables) {
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this.evaluateVariables = evaluateVariables;
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return this;
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}
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@Override
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public ConfigValue<T> withLookupChain(String... postfixNames) {
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//X TODO
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return null;
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}
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@Override
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public ConfigValue<T> logChanges(boolean logChanges) {
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this.logChanges = logChanges;
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return this;
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}
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@Override
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public T getValue() {
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long now = -1;
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if (cacheTimeMs > 0)
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{
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now = System.currentTimeMillis();
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if (now <= reloadAfter)
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{
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return lastValue;
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}
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}
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String valueStr = resolveStringValue();
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T value = convert(valueStr);
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if (withDefault)
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{
121+
value = fallbackToDefaultIfEmpty(keyResolved, value, defaultValue);
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}
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if (logChanges && (value != null && !value.equals(lastValue) || (value == null && lastValue != null)) )
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{
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logger.log(Level.INFO, "New value {0} for key {1}.",
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new Object[]{config.filterConfigValueForLog(keyOriginal, valueStr), keyOriginal});
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}
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lastValue = value;
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if (cacheTimeMs > 0)
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{
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reloadAfter = now + cacheTimeMs;
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}
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return value;
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}
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private String resolveStringValue() {
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//X TODO implement lookupChain
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return config.getValue(keyOriginal);
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}
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@Override
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public String getKey() {
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return keyOriginal;
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}
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@Override
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public String getResolvedKey() {
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return keyResolved;
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}
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@Override
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public T getDefaultValue() {
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return defaultValue;
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}
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private T convert(String value) {
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//X TODO
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return null;
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}
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private T fallbackToDefaultIfEmpty(String key, T value, T defaultValue) {
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if (value == null || (value instanceof String && ((String)value).isEmpty()))
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{
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logger.log(Level.FINE, "no configured value found for key {0}, using default value {1}.",
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new Object[]{key, defaultValue});
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return defaultValue;
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}
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return value;
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}
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}
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‎impl/src/main/java/org/apache/geronimo/config/DefaultConfigProvider.java‎

Copy file name to clipboardExpand all lines: impl/src/main/java/org/apache/geronimo/config/DefaultConfigProvider.java
+3-2Lines changed: 3 additions & 2 deletions
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@@ -42,7 +42,8 @@
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*/
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public class DefaultConfigProvider implements ConfigProvider.SPI {
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protected static Map<ClassLoader, WeakReference<Config>> configs = Collections.synchronizedMap(new WeakHashMap<ClassLoader, WeakReference<Config>>());
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protected static Map<ClassLoader, WeakReference<Config>> configs
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= Collections.synchronizedMap(new WeakHashMap<ClassLoader, WeakReference<Config>>());
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@Override
@@ -127,7 +128,7 @@ private Collection<? extends ConfigSource> getCustomPropertyFiles(ClassLoader fo
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private void registerConfig(Config config, ClassLoader forClassLoader) {
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synchronized (DefaultConfigProvider.class) {
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configs.put(forClassLoader, new WeakReference<Config>(config));
131+
configs.put(forClassLoader, new WeakReference<>(config));
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}
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}
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