聊聊rocketmq的KVConfigManager

序

本文主要研究一下rocketmq的KVConfigManager

KVConfigManager

org/apache/rocketmq/namesrv/kvconfig/KVConfigManager.java

public class KVConfigManager {
    private static final Logger log = LoggerFactory.getLogger(LoggerName.NAMESRV_LOGGER_NAME);

    private final NamesrvController namesrvController;

    private final ReadWriteLock lock = new ReentrantReadWriteLock();
    private final HashMap<String/* Namespace */, HashMap<String/* Key */, String/* Value */>> configTable =
        new HashMap<String, HashMap<String, String>>();

    public KVConfigManager(NamesrvController namesrvController) {
        this.namesrvController = namesrvController;
    }

    public void load() {
        String content = null;
        try {
            content = MixAll.file2String(this.namesrvController.getNamesrvConfig().getKvConfigPath());
        } catch (IOException e) {
            log.warn("Load KV config table exception", e);
        }
        if (content != null) {
            KVConfigSerializeWrapper kvConfigSerializeWrapper =
                KVConfigSerializeWrapper.fromJson(content, KVConfigSerializeWrapper.class);
            if (null != kvConfigSerializeWrapper) {
                this.configTable.putAll(kvConfigSerializeWrapper.getConfigTable());
                log.info("load KV config table OK");
            }
        }
    }

    public void putKVConfig(final String namespace, final String key, final String value) {
        try {
            this.lock.writeLock().lockInterruptibly();
            try {
                HashMap<String, String> kvTable = this.configTable.get(namespace);
                if (null == kvTable) {
                    kvTable = new HashMap<String, String>();
                    this.configTable.put(namespace, kvTable);
                    log.info("putKVConfig create new Namespace {}", namespace);
                }

                final String prev = kvTable.put(key, value);
                if (null != prev) {
                    log.info("putKVConfig update config item, Namespace: {} Key: {} Value: {}",
                        namespace, key, value);
                } else {
                    log.info("putKVConfig create new config item, Namespace: {} Key: {} Value: {}",
                        namespace, key, value);
                }
            } finally {
                this.lock.writeLock().unlock();
            }
        } catch (InterruptedException e) {
            log.error("putKVConfig InterruptedException", e);
        }

        this.persist();
    }

    public void persist() {
        try {
            this.lock.readLock().lockInterruptibly();
            try {
                KVConfigSerializeWrapper kvConfigSerializeWrapper = new KVConfigSerializeWrapper();
                kvConfigSerializeWrapper.setConfigTable(this.configTable);

                String content = kvConfigSerializeWrapper.toJson();

                if (null != content) {
                    MixAll.string2File(content, this.namesrvController.getNamesrvConfig().getKvConfigPath());
                }
            } catch (IOException e) {
                log.error("persist kvconfig Exception, "
                    + this.namesrvController.getNamesrvConfig().getKvConfigPath(), e);
            } finally {
                this.lock.readLock().unlock();
            }
        } catch (InterruptedException e) {
            log.error("persist InterruptedException", e);
        }

    }

    public void deleteKVConfig(final String namespace, final String key) {
        try {
            this.lock.writeLock().lockInterruptibly();
            try {
                HashMap<String, String> kvTable = this.configTable.get(namespace);
                if (null != kvTable) {
                    String value = kvTable.remove(key);
                    log.info("deleteKVConfig delete a config item, Namespace: {} Key: {} Value: {}",
                        namespace, key, value);
                }
            } finally {
                this.lock.writeLock().unlock();
            }
        } catch (InterruptedException e) {
            log.error("deleteKVConfig InterruptedException", e);
        }

        this.persist();
    }

    public byte[] getKVListByNamespace(final String namespace) {
        try {
            this.lock.readLock().lockInterruptibly();
            try {
                HashMap<String, String> kvTable = this.configTable.get(namespace);
                if (null != kvTable) {
                    KVTable table = new KVTable();
                    table.setTable(kvTable);
                    return table.encode();
                }
            } finally {
                this.lock.readLock().unlock();
            }
        } catch (InterruptedException e) {
            log.error("getKVListByNamespace InterruptedException", e);
        }

        return null;
    }

    public String getKVConfig(final String namespace, final String key) {
        try {
            this.lock.readLock().lockInterruptibly();
            try {
                HashMap<String, String> kvTable = this.configTable.get(namespace);
                if (null != kvTable) {
                    return kvTable.get(key);
                }
            } finally {
                this.lock.readLock().unlock();
            }
        } catch (InterruptedException e) {
            log.error("getKVConfig InterruptedException", e);
        }

        return null;
    }

    public void printAllPeriodically() {
        try {
            this.lock.readLock().lockInterruptibly();
            try {
                log.info("--------------------------------------------------------");

                {
                    log.info("configTable SIZE: {}", this.configTable.size());
                    Iterator<Entry<String, HashMap<String, String>>> it =
                        this.configTable.entrySet().iterator();
                    while (it.hasNext()) {
                        Entry<String, HashMap<String, String>> next = it.next();
                        Iterator<Entry<String, String>> itSub = next.getValue().entrySet().iterator();
                        while (itSub.hasNext()) {
                            Entry<String, String> nextSub = itSub.next();
                            log.info("configTable NS: {} Key: {} Value: {}", next.getKey(), nextSub.getKey(),
                                nextSub.getValue());
                        }
                    }
                }
            } finally {
                this.lock.readLock().unlock();
            }
        } catch (InterruptedException e) {
            log.error("printAllPeriodically InterruptedException", e);
        }
    }
}

• 这里使用HashMap，然后通过ReentrantReadWriteLock进行并发控制，map的key是namespace，而value是一个HashMap
• putKVConfig及deleteKVConfig使用的是写锁
• persist、getKVListByNamespace、getKVConfig、printAllPeriodically使用的是读锁

MixAll.string2File

org/apache/rocketmq/common/MixAll.java

public static void string2File(final String str, final String fileName) throws IOException {

        String tmpFile = fileName + ".tmp";
        string2FileNotSafe(str, tmpFile);

        String bakFile = fileName + ".bak";
        String prevContent = file2String(fileName);
        if (prevContent != null) {
            string2FileNotSafe(prevContent, bakFile);
        }

        File file = new File(fileName);
        file.delete();

        file = new File(tmpFile);
        file.renameTo(new File(fileName));
    }

    public static void string2FileNotSafe(final String str, final String fileName) throws IOException {
        File file = new File(fileName);
        File fileParent = file.getParentFile();
        if (fileParent != null) {
            fileParent.mkdirs();
        }
        FileWriter fileWriter = null;

        try {
            fileWriter = new FileWriter(file);
            fileWriter.write(str);
        } catch (IOException e) {
            throw e;
        } finally {
            if (fileWriter != null) {
                fileWriter.close();
            }
        }
    }

• 将文本内容写到指定路径的文件
• 这里先写到.tmp文件，然后备份上一个版本的内容，在删除上一个版本的文件，最后将tmp文件重命名为正式的文件名

RemotingSerializable

org/apache/rocketmq/remoting/protocol/RemotingSerializable.java

public abstract class RemotingSerializable {
    private final static Charset CHARSET_UTF8 = Charset.forName("UTF-8");

    public static byte[] encode(final Object obj) {
        final String json = toJson(obj, false);
        if (json != null) {
            return json.getBytes(CHARSET_UTF8);
        }
        return null;
    }

    public static String toJson(final Object obj, boolean prettyFormat) {
        return JSON.toJSONString(obj, prettyFormat);
    }

    public static <T> T decode(final byte[] data, Class<T> classOfT) {
        final String json = new String(data, CHARSET_UTF8);
        return fromJson(json, classOfT);
    }

    public static <T> T fromJson(String json, Class<T> classOfT) {
        return JSON.parseObject(json, classOfT);
    }

    public byte[] encode() {
        final String json = this.toJson();
        if (json != null) {
            return json.getBytes(CHARSET_UTF8);
        }
        return null;
    }

    public String toJson() {
        return toJson(false);
    }

    public String toJson(final boolean prettyFormat) {
        return toJson(this, prettyFormat);
    }
}

• 这里toJson使用的是fastjson的方法

小结

• rocketmq的KVConfigManager采用的是HashMap来存配置项，key为namespace，value为HashMap，存储的值采用的是String
• 采用ReentrantReadWriteLock进行并发控制，支持序列JSON到磁盘，也支持从磁盘文件加载到内存

doc

• KVConfigManager