summaryrefslogtreecommitdiffstats
path: root/config/src/main/java/com/yahoo/config/subscription/ConfigInstanceUtil.java
blob: 3c36bf7f1058188c9ec429db2bc66f8f9d98103f (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.config.subscription;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;

import com.yahoo.config.ConfigBuilder;
import com.yahoo.config.ConfigInstance;
import com.yahoo.config.ConfigurationRuntimeException;
import com.yahoo.yolean.Exceptions;
import com.yahoo.vespa.config.*;

/**
 * @author gjoranv
 * @since 5.1.6
 */
public class ConfigInstanceUtil {

    /**
     * Copies all values that have been explicitly set on the source to the destination.
     * Values that have not been explicitly set in the source builder, will be left unchanged
     * in the destination.
     *
     * @param destination The builder to copy values into.
     * @param source The builder to copy values from. Unset values are not copied.
     * @param <BUILDER> The builder class.
     */
    public static<BUILDER extends ConfigBuilder> void setValues(BUILDER destination, BUILDER source) {
        try {
            Method setter = destination.getClass().getDeclaredMethod("override", destination.getClass());
            setter.setAccessible(true);
            setter.invoke(destination, source);
            setter.setAccessible(false);
        } catch (Exception e) {
            throw new ConfigurationRuntimeException("Could not set values on config builder."
                    + destination.getClass().getName(), e);
        }
    }

    public static <T extends ConfigInstance> T getNewInstance(Class<T> type,
                                                              String configId,
                                                              ConfigPayload payload) {
        T instance;
        try {
            ConfigTransformer<?> transformer = new ConfigTransformer<T>(type);
            ConfigBuilder instanceBuilder = transformer.toConfigBuilder(payload);
            Constructor<T> constructor = type.getConstructor(instanceBuilder.getClass());
            instance = constructor.newInstance((ConfigInstance.Builder) instanceBuilder);

            // Workaround for JDK7, where compilation fails due to fields being
            // private and not accessible from T. Reference it as a
            // ConfigInstance to work around it. See
            // http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7022052 for
            // more information.
            ConfigInstance i = instance;
            i.postInitialize(configId);
            setConfigId(i, configId);

        } catch (InstantiationException | InvocationTargetException | NoSuchMethodException |
                NoSuchFieldException | IllegalAccessException e) {
            throw new IllegalArgumentException("Failed creating new instance of '" + type.getCanonicalName() +
                    "' for config id '" + configId + "': " + Exceptions.toMessageString(e), e);
        }
        return instance;
    }

    private static void setConfigId(ConfigInstance instance, String configId)
            throws NoSuchFieldException, IllegalAccessException {
        Field configIdField = ConfigInstance.class.getDeclaredField("configId");
        configIdField.setAccessible(true);
        configIdField.set(instance, configId);
        configIdField.setAccessible(false);
    }

    /**
     * Gets the value of a private field on a Builder.
     * @param builder a {@link com.yahoo.config.ConfigBuilder}
     * @param fieldName a config field name
     * @return the value of the private field
     */
    public static Object getField(ConfigBuilder builder, String fieldName) {
        try {
            Field f = builder.getClass().getDeclaredField(fieldName);
            f.setAccessible(true);
            return f.get(builder);
        } catch (NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException e) {
            throw new RuntimeException(e);
        }
    }

}