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• MongoReadPreference.java

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com.redhat.lightblue.mongo.config.MongoReadPreference Maven / Gradle / Ivy

/*
 Copyright 2013 Red Hat, Inc. and/or its affiliates.

 This file is part of lightblue.

 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program.  If not, see .
 */
package com.redhat.lightblue.mongo.config;

import java.util.Map;
import java.util.Iterator;
import java.util.List;
import java.util.ArrayList;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import com.fasterxml.jackson.databind.node.ArrayNode;

import com.mongodb.ReadPreference;
import com.mongodb.DBObject;
import com.mongodb.BasicDBObject;
import com.mongodb.TaggableReadPreference;
import com.mongodb.TagSet;
import com.mongodb.Tag;

import com.redhat.lightblue.util.JsonUtils;

/**
 *
 * The read preferences can be nearest, primary, primaryPreferred, secondary,
 * and secondaryPreferred, with optional tags. The tags are specified as:
 * 
 *    readPreference ( tags1, tags2,... )
 * 
 * where each 'tags' is a JSON string containing name/value pairs:
 * 
 *    { name:value, name:value, ... }
 * 
 */
public class MongoReadPreference {

    public static class InvalidReadPreference extends RuntimeException {
        public InvalidReadPreference(String s) {
            super(s);
        }
    }

    public static class InvalidReadPreferenceArgs extends RuntimeException {
        public InvalidReadPreferenceArgs(String s) {
            super(s);
        }
    }

    public static final String READ_PREFERENCE_NEAREST = "nearest";
    public static final String READ_PREFERENCE_PRIMARY = "primary";
    public static final String READ_PREFERENCE_PRIMARY_PREFERRED = "primaryPreferred";
    public static final String READ_PREFERENCE_SECONDARY = "secondary";
    public static final String READ_PREFERENCE_SECONDARY_PREFERRED = "secondaryPreferred";

    public static ReadPreference parse(String value) {
        value = value.trim();
        int paren = value.indexOf('(');
        String pref;
        List tags;
        if (paren != -1) {
            pref = value.substring(0, paren).trim();
            String argsStr = value.substring(paren + 1).trim();
            if (!argsStr.endsWith(")")) {
                throw new InvalidReadPreference(value);
            }
            tags = parseArgs(argsStr.substring(0, argsStr.length() - 1));
        } else {
            pref = value;
            tags = null;
        }
        switch (pref) {
            case READ_PREFERENCE_NEAREST:
                if (tags == null) {
                    return ReadPreference.nearest();
                } else {
                    return ReadPreference.nearest(tags);
                }
            case READ_PREFERENCE_PRIMARY:
                return ReadPreference.primary();
            case READ_PREFERENCE_PRIMARY_PREFERRED:
                if (tags == null) {
                    return ReadPreference.primaryPreferred();
                } else {
                    return ReadPreference.primaryPreferred(tags);
                }
            case READ_PREFERENCE_SECONDARY:
                if (tags == null) {
                    return ReadPreference.secondary();
                } else {
                    return ReadPreference.secondary(tags);
                }
            case READ_PREFERENCE_SECONDARY_PREFERRED:
                if (tags == null) {
                    return ReadPreference.secondaryPreferred();
                } else {
                    return ReadPreference.secondaryPreferred(tags);
                }
            default:
                throw new InvalidReadPreference(value);
        }
    }

    private static List parseArgs(String args) {
        args = args.trim();
        if (args.length() == 0) {
            return null;
        } else {
            try {
                return parseArgs(JsonUtils.json(args));
            } catch (InvalidReadPreferenceArgs x) {
                throw x;
            } catch (Exception e) {
                throw new InvalidReadPreferenceArgs(args);
            }
        }
    }

    private static List parseArgs(JsonNode args) {
        List list = new ArrayList<>();
        if (args instanceof ObjectNode) {
            list.add(parseArg((ObjectNode) args));
        } else if (args instanceof ArrayNode) {
            ArrayNode array = (ArrayNode) args;
            for (Iterator itr = array.elements(); itr.hasNext();) {
                list.add(parseArg((ObjectNode) itr.next()));
            }
        } else {
            throw new InvalidReadPreferenceArgs(args.toString());
        }
        return list;
    }

    private static TagSet parseArg(ObjectNode arg) {
        List tags = new ArrayList<>();
        for (Iterator> itr = arg.fields(); itr.hasNext();) {
            Map.Entry entry = itr.next();
            tags.add(new Tag(entry.getKey(), entry.getValue().asText()));
        }
        return new TagSet(tags);
    }
}