[schema] AutoConsume should use the schema associated with messages a…

…s both writer and reader schema (apache#4325)

* [schema] AutoConsume should use the schema associated with messages for both writer and reader schema

*Motivation*

AutoConsume should use the schema associated with the messages for decoding the schemas.

*Modifications*

- provide a flag enable or disable using the provided schema as the reader schema
- for AUTO_CONSUME schema, disable usnig the provided schema as the reader schema. so it can use the right
  schema version for decoding messages into right generic records
- provide a few util methods for displaying schema data

* Handle 64 bytes schema version

* Addressed review comments

pulsar-client-api/src/main/java/org/apache/pulsar/common/schema/SchemaInfo.java

@@ -18,6 +18,9 @@
  */
 package org.apache.pulsar.common.schema;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import java.util.Base64;
 import java.util.Collections;
 import java.util.Map;
 
@@ -52,4 +55,19 @@ public class SchemaInfo {
      * Additional properties of the schema definition (implementation defined)
      */
     private Map<String, String> properties = Collections.emptyMap();
+
+    public String getSchemaDefinition() {
+        if (null == schema) {
+            return "";
+        }
+
+        switch (type) {
+            case AVRO:
+            case JSON:
+            case PROTOBUF:
+                return new String(schema, UTF_8);
+            default:
+                return Base64.getEncoder().encodeToString(schema);
+        }
+    }
 }

pulsar-client/src/main/java/org/apache/pulsar/client/impl/PulsarClientImpl.java

@@ -730,13 +730,16 @@ protected void preProcessSchemaBeforeSubscribe(PulsarClientImpl pulsarClientImpl
 
             if (schema instanceof AutoConsumeSchema) {
                 SchemaInfo schemaInfo = schemaInfoProvider.getLatestSchema();
-                if (schemaInfo.getType() != SchemaType.AVRO){
+                if (schemaInfo.getType() != SchemaType.AVRO && schemaInfo.getType() != SchemaType.JSON){
                     throw new RuntimeException("Currently schema detection only works for topics with avro schemas");
-
                 }
-                GenericSchema genericSchema = GenericSchemaImpl.of(schemaInfoProvider.getLatestSchema());
+
+                // when using `AutoConsumeSchema`, we use the schema associated with the messages as schema reader
+                // to decode the messages.
+                GenericSchema genericSchema = GenericSchemaImpl.of(
+                    schemaInfoProvider.getLatestSchema(), false /*useProvidedSchemaAsReaderSchema*/);
                 log.info("Auto detected schema for topic {} : {}",
-                        topicName, new String(schemaInfo.getSchema(), UTF_8));
+                        topicName, schemaInfo.getSchemaDefinition());
                 ((AutoConsumeSchema) schema).setSchema(genericSchema);
             }
             schema.setSchemaInfoProvider(schemaInfoProvider);

pulsar-client/src/main/java/org/apache/pulsar/client/impl/schema/AvroSchema.java

@@ -102,11 +102,16 @@ public static <T> AvroSchema<T> of(Class<T> pojo, Map<String, String> properties
     protected SchemaReader<T> loadReader(byte[] schemaVersion) {
         SchemaInfo schemaInfo = schemaInfoProvider.getSchemaByVersion(schemaVersion);
         if (schemaInfo != null) {
-            return new AvroReader<>(parseAvroSchema(new String(schemaInfo.getSchema())), schema);
+            log.info("Load schema reader for version({}), schema is : {}",
+                SchemaUtils.getStringSchemaVersion(schemaVersion),
+                schemaInfo.getSchemaDefinition());
+            return new AvroReader<>(parseAvroSchema(schemaInfo.getSchemaDefinition()), schema);
         } else {
+            log.warn("No schema found for version({}), use latest schema : {}",
+                SchemaUtils.getStringSchemaVersion(schemaVersion),
+                this.schemaInfo.getSchemaDefinition());
             return reader;
         }
     }
 
-
 }

pulsar-client/src/main/java/org/apache/pulsar/client/impl/schema/JSONSchema.java

@@ -27,7 +27,6 @@
 import lombok.extern.slf4j.Slf4j;
 import org.apache.pulsar.client.api.schema.SchemaDefinition;
 import org.apache.pulsar.client.api.schema.SchemaReader;
-import org.apache.pulsar.client.api.schema.SchemaWriter;
 import org.apache.pulsar.client.impl.schema.reader.JsonReader;
 import org.apache.pulsar.client.impl.schema.writer.JsonWriter;
 import org.apache.pulsar.common.schema.SchemaInfo;

pulsar-client/src/main/java/org/apache/pulsar/client/impl/schema/ProtobufSchema.java

@@ -27,7 +27,6 @@
 import org.apache.avro.protobuf.ProtobufData;
 import org.apache.pulsar.client.api.schema.SchemaDefinition;
 import org.apache.pulsar.client.api.schema.SchemaReader;
-import org.apache.pulsar.client.api.schema.SchemaWriter;
 import org.apache.pulsar.client.impl.schema.reader.ProtobufReader;
 import org.apache.pulsar.client.impl.schema.writer.ProtobufWriter;
 import org.apache.pulsar.common.schema.SchemaInfo;
@@ -96,7 +95,8 @@ public void accept(Descriptors.FieldDescriptor fieldDescriptor) {
 
     @Override
     protected SchemaReader<T> loadReader(byte[] schemaVersion) {
-        throw new RuntimeException("ProtobufSchema don't support schema versioning");    }
+        throw new RuntimeException("ProtobufSchema don't support schema versioning");
+    }
 
     public static <T extends com.google.protobuf.GeneratedMessageV3> ProtobufSchema<T> of(Class<T> pojo) {
         return of(pojo, new HashMap<>());

pulsar-client/src/main/java/org/apache/pulsar/client/impl/schema/SchemaUtils.java

@@ -22,15 +22,17 @@
 import io.netty.buffer.ByteBufUtil;
 import java.nio.ByteBuffer;
 import java.util.Arrays;
+import java.util.Base64;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import org.apache.pulsar.common.schema.SchemaType;
+import org.apache.pulsar.common.schema.SchemaVersion;
 
 /**
  * Utils for schemas.
  */
-final class SchemaUtils {
+public final class SchemaUtils {
 
     private SchemaUtils() {}
 
@@ -149,4 +151,22 @@ public static Object toAvroObject(Object value) {
         }
     }
 
+    public static String getStringSchemaVersion(byte[] schemaVersionBytes) {
+        if (null == schemaVersionBytes) {
+            return "NULL";
+        } else if (
+            // the length of schema version is 8 bytes post 2.4.0
+            schemaVersionBytes.length == Long.BYTES
+            // the length of schema version is 64 bytes before 2.4.0
+            || schemaVersionBytes.length == Long.SIZE) {
+            ByteBuffer bb = ByteBuffer.wrap(schemaVersionBytes);
+            return String.valueOf(bb.getLong());
+        } else if (schemaVersionBytes.length == 0) {
+            return "EMPTY";
+        } else {
+            return Base64.getEncoder().encodeToString(schemaVersionBytes);
+        }
+
+    }
+
 }

pulsar-client/src/main/java/org/apache/pulsar/client/impl/schema/StructSchema.java

@@ -131,6 +131,12 @@ public void setSchemaInfoProvider(SchemaInfoProvider schemaInfoProvider) {
         this.schemaInfoProvider = schemaInfoProvider;
     }
 
+    /**
+     * Load the schema reader for reading messages encoded by the given schema version.
+     *
+     * @param schemaVersion the provided schema version
+     * @return the schema reader for decoding messages encoded by the provided schema version.
+     */
     protected abstract SchemaReader<T> loadReader(byte[] schemaVersion);
 
     protected void setWriter(SchemaWriter<T> writer) {

pulsar-client/src/main/java/org/apache/pulsar/client/impl/schema/generic/GenericAvroSchema.java

@@ -18,18 +18,27 @@
  */
 package org.apache.pulsar.client.impl.schema.generic;
 
+import lombok.extern.slf4j.Slf4j;
+import org.apache.avro.Schema;
 import org.apache.pulsar.client.api.schema.GenericRecord;
 import org.apache.pulsar.client.api.schema.GenericRecordBuilder;
 import org.apache.pulsar.client.api.schema.SchemaReader;
+import org.apache.pulsar.client.impl.schema.SchemaUtils;
 import org.apache.pulsar.common.schema.SchemaInfo;
 
 /**
  * A generic avro schema.
  */
+@Slf4j
 public class GenericAvroSchema extends GenericSchemaImpl {
 
     public GenericAvroSchema(SchemaInfo schemaInfo) {
-        super(schemaInfo);
+        this(schemaInfo, true);
+    }
+
+    GenericAvroSchema(SchemaInfo schemaInfo,
+                      boolean useProvidedSchemaAsReaderSchema) {
+        super(schemaInfo, useProvidedSchemaAsReaderSchema);
         setReader(new GenericAvroReader(schema));
         setWriter(new GenericAvroWriter(schema));
     }
@@ -48,11 +57,19 @@ public boolean supportSchemaVersioning() {
     protected SchemaReader<GenericRecord> loadReader(byte[] schemaVersion) {
          SchemaInfo schemaInfo = schemaInfoProvider.getSchemaByVersion(schemaVersion);
          if (schemaInfo != null) {
+             log.info("Load schema reader for version({}), schema is : {}",
+                 SchemaUtils.getStringSchemaVersion(schemaVersion),
+                 schemaInfo.getSchemaDefinition());
+             Schema writerSchema = parseAvroSchema(schemaInfo.getSchemaDefinition());
+             Schema readerSchema = useProvidedSchemaAsReaderSchema ? schema : writerSchema;
              return new GenericAvroReader(
-                     parseAvroSchema(new String(schemaInfo.getSchema())),
-                     schema,
+                     writerSchema,
+                     readerSchema,
                      schemaVersion);
          } else {
+             log.warn("No schema found for version({}), use latest schema : {}",
+                 SchemaUtils.getStringSchemaVersion(schemaVersion),
+                 this.schemaInfo.getSchemaDefinition());
              return reader;
          }
     }

pulsar-client/src/main/java/org/apache/pulsar/client/impl/schema/generic/GenericJsonSchema.java

@@ -20,21 +20,28 @@
 
 import java.util.stream.Collectors;
 
+import lombok.extern.slf4j.Slf4j;
+import org.apache.avro.Schema;
 import org.apache.pulsar.client.api.schema.Field;
 import org.apache.pulsar.client.api.schema.GenericRecord;
 import org.apache.pulsar.client.api.schema.GenericRecordBuilder;
 import org.apache.pulsar.client.api.schema.SchemaReader;
+import org.apache.pulsar.client.impl.schema.SchemaUtils;
 import org.apache.pulsar.common.schema.SchemaInfo;
 
-import static java.nio.charset.StandardCharsets.UTF_8;
-
 /**
  * A generic json schema.
  */
+@Slf4j
 class GenericJsonSchema extends GenericSchemaImpl {
 
     public GenericJsonSchema(SchemaInfo schemaInfo) {
-        super(schemaInfo);
+        this(schemaInfo, true);
+    }
+
+    GenericJsonSchema(SchemaInfo schemaInfo,
+                      boolean useProvidedSchemaAsReaderSchema) {
+        super(schemaInfo, useProvidedSchemaAsReaderSchema);
         setWriter(new GenericJsonWriter());
         setReader(new GenericJsonReader(fields));
     }
@@ -43,12 +50,24 @@ public GenericJsonSchema(SchemaInfo schemaInfo) {
     protected SchemaReader<GenericRecord> loadReader(byte[] schemaVersion) {
         SchemaInfo schemaInfo = schemaInfoProvider.getSchemaByVersion(schemaVersion);
         if (schemaInfo != null) {
+            log.info("Load schema reader for version({}), schema is : {}",
+                SchemaUtils.getStringSchemaVersion(schemaVersion),
+                schemaInfo.getSchemaDefinition());
+            Schema readerSchema;
+            if (useProvidedSchemaAsReaderSchema) {
+                readerSchema = schema;
+            } else {
+                readerSchema = parseAvroSchema(schemaInfo.getSchemaDefinition());
+            }
             return new GenericJsonReader(schemaVersion,
-                    (parseAvroSchema(new String(schemaInfo.getSchema(), UTF_8)).getFields()
+                    readerSchema.getFields()
                             .stream()
                             .map(f -> new Field(f.name(), f.pos()))
-                            .collect(Collectors.toList())));
+                            .collect(Collectors.toList()));
         } else {
+            log.warn("No schema found for version({}), use latest schema : {}",
+                SchemaUtils.getStringSchemaVersion(schemaVersion),
+                this.schemaInfo.getSchemaDefinition());
             return reader;
         }
     }

pulsar-client/src/main/java/org/apache/pulsar/client/impl/schema/generic/GenericSchemaImpl.java

@@ -33,14 +33,20 @@
 public abstract class GenericSchemaImpl extends StructSchema<GenericRecord> implements GenericSchema<GenericRecord> {
 
     protected final List<Field> fields;
+    // the flag controls whether to use the provided schema as reader schema
+    // to decode the messages. In `AUTO_CONSUME` mode, setting this flag to `false`
+    // allows decoding the messages using the schema associated with the messages.
+    protected final boolean useProvidedSchemaAsReaderSchema;
 
-    protected GenericSchemaImpl(SchemaInfo schemaInfo) {
+    protected GenericSchemaImpl(SchemaInfo schemaInfo,
+                                boolean useProvidedSchemaAsReaderSchema) {
         super(schemaInfo);
 
         this.fields = schema.getFields()
                 .stream()
                 .map(f -> new Field(f.name(), f.pos()))
                 .collect(Collectors.toList());
+        this.useProvidedSchemaAsReaderSchema = useProvidedSchemaAsReaderSchema;
     }
 
     @Override
@@ -55,11 +61,16 @@ public List<Field> getFields() {
      * @return a generic schema instance
      */
     public static GenericSchemaImpl of(SchemaInfo schemaInfo) {
+        return of(schemaInfo, true);
+    }
+
+    public static GenericSchemaImpl of(SchemaInfo schemaInfo,
+                                       boolean useProvidedSchemaAsReaderSchema) {
         switch (schemaInfo.getType()) {
             case AVRO:
-                return new GenericAvroSchema(schemaInfo);
+                return new GenericAvroSchema(schemaInfo, useProvidedSchemaAsReaderSchema);
             case JSON:
-                return new GenericJsonSchema(schemaInfo);
+                return new GenericJsonSchema(schemaInfo, useProvidedSchemaAsReaderSchema);
             default:
                 throw new UnsupportedOperationException("Generic schema is not supported on schema type "
                     + schemaInfo.getType() + "'");