Java Record作为Apache Ignite Cache键的序列化异常问题

问题描述 #

我尝试将Java Record类型作为Apache Ignite Cache的键使用时触发了错误，当前环境是Java 17.0.12（openjdk version "17.0.12" 2024-07-16）和GridGain Ignite 8.8.39。想知道有没有其他开发者遇到过同样的问题，以及是否必须自定义序列化处理才能使用Record类型？

错误日志 #

java.lang.UnsupportedOperationException: can't get field offset on a
record class: private final long
***.TestIgniteCache$TestKey.ttlInMillis at
jdk.unsupported/sun.misc.Unsafe.objectFieldOffset(Unknown Source) at
org.apache.ignite.internal.util.GridUnsafe.objectFieldOffset(GridUnsafe.java:1193)
at
org.apache.ignite.internal.binary.BinaryFieldAccessor$AbstractPrimitiveAccessor.(BinaryFieldAccessor.java:223)
at
org.apache.ignite.internal.binary.BinaryFieldAccessor$LongPrimitiveAccessor.(BinaryFieldAccessor.java:387)
at
org.apache.ignite.internal.binary.BinaryFieldAccessor.create(BinaryFieldAccessor.java:75)
at
org.apache.ignite.internal.binary.BinaryClassDescriptor.(BinaryClassDescriptor.java:368)
at
org.apache.ignite.internal.binary.BinaryClassDescriptor.(BinaryClassDescriptor.java:155)
at
org.apache.ignite.internal.binary.BinaryContext.createDescriptorForClass(BinaryContext.java:648)
at
org.apache.ignite.internal.binary.BinaryContext.descriptorForClass(BinaryContext.java:606)
at
org.apache.ignite.internal.binary.BinaryWriterExImpl.marshal0(BinaryWriterExImpl.java:181)
at
org.apache.ignite.internal.binary.BinaryWriterExImpl.marshal(BinaryWriterExImpl.java:164)
at
org.apache.ignite.internal.binary.BinaryWriterExImpl.marshal(BinaryWriterExImpl.java:151)
at
org.apache.ignite.internal.binary.GridBinaryMarshaller.marshal(GridBinaryMarshaller.java:250)
at
org.apache.ignite.internal.processors.cache.binary.CacheObjectBinaryProcessorImpl.marshalToBinary(CacheObjectBinaryProcessorImpl.java:506)
at
org.apache.ignite.internal.processors.cache.binary.CacheObjectBinaryProcessorImpl.toBinary(CacheObjectBinaryProcessorImpl.java:1360)
at
org.apache.ignite.internal.processors.cache.binary.CacheObjectBinaryProcessorImpl.toCacheKeyObject(CacheObjectBinaryProcessorImpl.java:1137)
at
org.apache.ignite.internal.processors.cache.GridCacheContext.toCacheKeyObject(GridCacheContext.java:1841)
at
org.apache.ignite.internal.processors.cache.distributed.dht.atomic.GridDhtAtomicCache$12.apply(GridDhtAtomicCache.java:476)
at
org.apache.ignite.internal.processors.cache.distributed.dht.atomic.GridDhtAtomicCache$12.apply(GridDhtAtomicCache.java:474)
at
org.apache.ignite.internal.processors.cache.distributed.dht.atomic.GridDhtAtomicCache.asyncOp(GridDhtAtomicCache.java:766)
at
org.apache.ignite.internal.processors.cache.distributed.dht.atomic.GridDhtAtomicCache.getAsync(GridDhtAtomicCache.java:474)
at
org.apache.ignite.internal.processors.cache.GridCacheAdapter.get0(GridCacheAdapter.java:4376)
at
org.apache.ignite.internal.processors.cache.GridCacheAdapter.get(GridCacheAdapter.java:4357)
at
org.apache.ignite.internal.processors.cache.GridCacheAdapter.get(GridCacheAdapter.java:1432)
at
org.apache.ignite.internal.processors.cache.IgniteCacheProxyImpl.get(IgniteCacheProxyImpl.java:1116)
at
org.apache.ignite.internal.processors.cache.GatewayProtectedCacheProxy.get(GatewayProtectedCacheProxy.java:637)
at ***.cache.TestIgniteCache.get(TestIgniteCache.java:123)

Record类定义 #

public static record TestKey<K>(K k, long ttlInMillis) {

    // 默认TTL为5分钟
    private static final long defaultTTLInMillis = 300000L;

    /**
     * 指定TTL的构造方法
     * @param k 键值
     * @param ttlInMillis 毫秒级TTL
     */
    public TestKey {
        if (Objects.isNull(k)) { 
            throw new IllegalArgumentException("Key must not be null!");
        }
        if (0 >= ttlInMillis) { 
            throw new IllegalArgumentException("ttlInMillis must not be zero or negative!");
        }
    }

    /**
     * 使用默认TTL的构造方法
     * @param k 键值
     */
    public TestKey (K k) {
        this(k, defaultTTLInMillis);
    }

    /**
     * 获取默认TTL值
     * @return 默认毫秒级TTL
     */
    public static final long defaultTTLInMillis() {
        return defaultTTLInMillis;
    }

}

问题原因 #

Ignite的默认二进制序列化器依赖sun.misc.Unsafe.objectFieldOffset()方法获取字段偏移量，但Java Record的字段是隐式定义的，Unsafe API不支持直接获取Record字段的偏移量，这直接导致了报错。

解决方案 #

有两种可行的处理方式：

1. 自定义序列化器 #

为Record类实现BinarySerializer接口，手动控制序列化和反序列化逻辑，绕过Unsafe的字段偏移量获取逻辑。示例代码如下：

public class TestKeyBinarySerializer implements BinarySerializer {
    @Override
    public void writeBinary(Object obj, BinaryWriter writer) throws BinaryObjectException {
        TestKey<?> key = (TestKey<?>) obj;
        writer.writeObject("k", key.k());
        writer.writeLong("ttlInMillis", key.ttlInMillis());
    }

    @Override
    public void readBinary(Object obj, BinaryReader reader) throws BinaryObjectException {
        // Record是不可变类，反序列化时通过构造方法初始化，只需按写入顺序读取所有字段
        reader.readObject("k");
        reader.readLong("ttlInMillis");
    }
}

然后在Ignite配置中注册这个序列化器：

IgniteConfiguration cfg = new IgniteConfiguration();
BinaryConfiguration binaryCfg = new BinaryConfiguration();
BinaryTypeConfiguration typeCfg = new BinaryTypeConfiguration(TestKey.class.getName());
typeCfg.setSerializer(new TestKeyBinarySerializer());
binaryCfg.setTypeConfigurations(List.of(typeCfg));
cfg.setBinaryConfiguration(binaryCfg);

2. 改用普通不可变类替代Record #

将TestKey改为普通类，手动实现equals()和hashCode()方法（Ignite缓存键必须实现这两个方法保证正确性）：

public static class TestKey<K> {
    private final K k;
    private final long ttlInMillis;
    private static final long defaultTTLInMillis = 300000L;

    public TestKey(K k, long ttlInMillis) {
        if (Objects.isNull(k)) {
            throw new IllegalArgumentException("Key must not be null!");
        }
        if (0 >= ttlInMillis) {
            throw new IllegalArgumentException("ttlInMillis must not be zero or negative!");
        }
        this.k = k;
        this.ttlInMillis = ttlInMillis;
    }

    public TestKey(K k) {
        this(k, defaultTTLInMillis);
    }

    public static long defaultTTLInMillis() {
        return defaultTTLInMillis;
    }

    public K k() {
        return k;
    }

    public long ttlInMillis() {
        return ttlInMillis;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        TestKey<?> testKey = (TestKey<?>) o;
        return ttlInMillis == testKey.ttlInMillis && Objects.equals(k, testKey.k);
    }

    @Override
    public int hashCode() {
        return Objects.hash(k, ttlInMillis);
    }
}

补充说明 #

GridGain Ignite 8.8.x版本确实存在对Java Record的支持缺陷，后续版本可能会修复该问题。如果坚持使用Record，自定义序列化器是最直接的解决方式。

内容的提问来源于stack exchange，提问作者lmk