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AVRO-4069: Remove Reader String Cache from Generic Datum Reader #3194

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AVRO-4069: Remove Reader String Cache from Generic Datum Reader #3194

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17da90b
AVRO-4069: Remove Reader String Cache from Generic Datum Reader
belugabehr Oct 1, 2024
5b2fdf6
AVRO-4069: Remove Reader String Cache from Generic Datum Reader
belugabehr Oct 1, 2024
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31 changes: 20 additions & 11 deletions lang/java/avro/src/main/java/org/apache/avro/generic/GenericData.java
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Original file line number Diff line number Diff line change
Expand Up @@ -73,15 +73,24 @@ public class GenericData {

private static final GenericData INSTANCE = new GenericData();

private static final Map<Class<?>, String> PRIMITIVE_DATUM_TYPES = new IdentityHashMap<>();
/**
* The size of this map was specifically selected. This map services as a cache
* and there are many negative hits (misses). For negative hits, the best
* performance outcome is achieved when the key hits an empty bucket in the
* HashMap. Selecting a larger map of size 64 seems to be a sufficient size in
* benchmarks. Also, for many JDK implementations, none of the cached items
* collide and share a bucket, therefore there are never any linear scans
* involved in a lookup.
*/
private static final Map<String, String> PRIMITIVE_DATUM_TYPES = new HashMap<>(64);
static {
PRIMITIVE_DATUM_TYPES.put(Integer.class, Type.INT.getName());
PRIMITIVE_DATUM_TYPES.put(Long.class, Type.LONG.getName());
PRIMITIVE_DATUM_TYPES.put(Float.class, Type.FLOAT.getName());
PRIMITIVE_DATUM_TYPES.put(Double.class, Type.DOUBLE.getName());
PRIMITIVE_DATUM_TYPES.put(Boolean.class, Type.BOOLEAN.getName());
PRIMITIVE_DATUM_TYPES.put(String.class, Type.STRING.getName());
PRIMITIVE_DATUM_TYPES.put(Utf8.class, Type.STRING.getName());
PRIMITIVE_DATUM_TYPES.put(Integer.class.getName(), Type.INT.getName());
PRIMITIVE_DATUM_TYPES.put(Long.class.getName(), Type.LONG.getName());
PRIMITIVE_DATUM_TYPES.put(Float.class.getName(), Type.FLOAT.getName());
PRIMITIVE_DATUM_TYPES.put(Double.class.getName(), Type.DOUBLE.getName());
PRIMITIVE_DATUM_TYPES.put(Boolean.class.getName(), Type.BOOLEAN.getName());
PRIMITIVE_DATUM_TYPES.put(String.class.getName(), Type.STRING.getName());
PRIMITIVE_DATUM_TYPES.put(Utf8.class.getName(), Type.STRING.getName());
}

/** Used to specify the Java type for a string schema. */
Expand All @@ -95,7 +104,7 @@ public enum StringType {
private final ClassLoader classLoader;

/**
* Set the Java type to be used when reading this schema. Meaningful only only
* Set the Java type to be used when reading this schema. Meaningful only for
* string schemas and map schemas (for the keys).
*/
public static void setStringType(Schema s, StringType stringType) {
Expand Down Expand Up @@ -945,7 +954,7 @@ public int resolveUnion(Schema union, Object datum) {
protected String getSchemaName(Object datum) {
if (datum == null || datum == JsonProperties.NULL_VALUE)
return Type.NULL.getName();
String primativeType = getPrimitiveTypeCache().get(datum.getClass());
final String primativeType = getPrimitiveTypeCache().get(datum.getClass().getName());
if (primativeType != null)
return primativeType;
if (isRecord(datum))
Expand Down Expand Up @@ -979,7 +988,7 @@ protected String getSchemaName(Object datum) {
* Called to obtain the primitive type cache. May be overridden for alternate
* record representations.
*/
protected Map<Class<?>, String> getPrimitiveTypeCache() {
protected Map<String, String> getPrimitiveTypeCache() {
return PRIMITIVE_DATUM_TYPES;
}

Expand Down
116 changes: 33 additions & 83 deletions lang/java/avro/src/main/java/org/apache/avro/generic/GenericDatumReader.java
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Original file line number Diff line number Diff line change
Expand Up @@ -23,8 +23,6 @@
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Function;

import org.apache.avro.AvroRuntimeException;
import org.apache.avro.Conversion;
Expand All @@ -46,8 +44,8 @@
private Schema actual;
private Schema expected;
private DatumReader<D> fastDatumReader = null;

private ResolvingDecoder creatorResolver = null;
private final Map<Class, Constructor> stringCtorCache;
private final Thread creator;

public GenericDatumReader() {
Expand All @@ -73,6 +71,7 @@
protected GenericDatumReader(GenericData data) {
this.data = data;
this.creator = Thread.currentThread();
this.stringCtorCache = new HashMap<>();
}

/** Return the {@link GenericData} implementation. */
Expand Down Expand Up @@ -452,13 +451,15 @@
* representation. By default, this calls {@link #readString(Object,Decoder)}.
*/
protected Object readString(Object old, Schema expected, Decoder in) throws IOException {
Class stringClass = this.getReaderCache().getStringClass(expected);
if (stringClass == String.class) {
return in.readString();
}
Class stringClass = this.findStringClass(expected);

// Default is CharSequence / UTF8 so check it first
if (stringClass == CharSequence.class) {
return readString(old, in);
}
if (stringClass == String.class) {
return in.readString();
}
return this.newInstanceFromString(stringClass, in.readString());
}

Expand Down Expand Up @@ -487,99 +488,48 @@
*/
protected Class findStringClass(Schema schema) {
String name = schema.getProp(GenericData.STRING_PROP);
if (name == null)
if (name == null) {
return CharSequence.class;

switch (GenericData.StringType.valueOf(name)) {
case String:
}
if (GenericData.StringType.String.name().equals(name)) {
return String.class;
default:
return CharSequence.class;
}
return CharSequence.class;
}

/**
* This class is used to reproduce part of IdentityHashMap in ConcurrentHashMap
* code.
*/
private static final class IdentitySchemaKey {
private final Schema schema;

private final int hashcode;

public IdentitySchemaKey(Schema schema) {
this.schema = schema;
this.hashcode = System.identityHashCode(schema);
}

@Override
public int hashCode() {
return this.hashcode;
@SuppressWarnings("unchecked")
protected Object newInstanceFromString(Class c, String s) {
// For some of the more common classes, implement specific routines.
// For more complex classes, use reflection.
if (c == Integer.class) {
return Integer.parseInt(s, 10);

Check notice

Code scanning / CodeQL

Missing catch of NumberFormatException Note

Potential uncaught 'java.lang.NumberFormatException'.
}

@Override
public boolean equals(Object obj) {
if (obj == null || !(obj instanceof GenericDatumReader.IdentitySchemaKey)) {
return false;
}
IdentitySchemaKey key = (IdentitySchemaKey) obj;
return this == key || this.schema == key.schema;
if (c == Long.class) {
return Long.parseLong(s, 10);

Check notice

Code scanning / CodeQL

Missing catch of NumberFormatException Note

Potential uncaught 'java.lang.NumberFormatException'.
}
}

// VisibleForTesting
static class ReaderCache {
private final Map<IdentitySchemaKey, Class> stringClassCache = new ConcurrentHashMap<>();

private final Map<Class, Function<String, Object>> stringCtorCache = new ConcurrentHashMap<>();

private final Function<Schema, Class> findStringClass;

public ReaderCache(Function<Schema, Class> findStringClass) {
this.findStringClass = findStringClass;
if (c == Float.class) {
return Float.parseFloat(s);

Check notice

Code scanning / CodeQL

Missing catch of NumberFormatException Note

Potential uncaught 'java.lang.NumberFormatException'.
}

public Object newInstanceFromString(Class c, String s) {
final Function<String, Object> ctor = stringCtorCache.computeIfAbsent(c, this::buildFunction);
return ctor.apply(s);
if (c == Double.class) {
return Double.parseDouble(s);

Check notice

Code scanning / CodeQL

Missing catch of NumberFormatException Note

Potential uncaught 'java.lang.NumberFormatException'.
}

private Function<String, Object> buildFunction(Class c) {
final Constructor cachedCtor = stringCtorCache.computeIfAbsent(c, clazz -> {
final Constructor ctor;
try {
ctor = c.getDeclaredConstructor(String.class);
ctor = clazz.getDeclaredConstructor(String.class);
ctor.setAccessible(true);
} catch (NoSuchMethodException e) {
throw new AvroRuntimeException(e);
}
ctor.setAccessible(true);

return (String s) -> {
try {
return ctor.newInstance(s);
} catch (ReflectiveOperationException e) {
throw new AvroRuntimeException(e);
}
};
}

public Class getStringClass(final Schema s) {
final IdentitySchemaKey key = new IdentitySchemaKey(s);
return this.stringClassCache.computeIfAbsent(key, (IdentitySchemaKey k) -> this.findStringClass.apply(k.schema));
return ctor;
});
try {
return cachedCtor.newInstance(s);
} catch (ReflectiveOperationException e) {
throw new AvroRuntimeException(e);
}
}

private final ReaderCache readerCache = new ReaderCache(this::findStringClass);

// VisibleForTesting
ReaderCache getReaderCache() {
return readerCache;
}

@SuppressWarnings("unchecked")
protected Object newInstanceFromString(Class c, String s) {
return this.getReaderCache().newInstanceFromString(c, s);
}

/**
* Called to read byte arrays. Subclasses may override to use a different byte
* array representation. By default, this calls
Expand Down
37 changes: 1 addition & 36 deletions lang/java/avro/src/test/java/org/apache/avro/generic/TestGenericDatumReader.java
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Original file line number Diff line number Diff line change
Expand Up @@ -23,8 +23,6 @@
import java.util.Arrays;
import java.util.List;
import java.util.Random;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

import org.apache.avro.Schema;
import org.junit.jupiter.api.Test;
Expand All @@ -33,27 +31,9 @@ public class TestGenericDatumReader {

private static final Random r = new Random(System.currentTimeMillis());

@Test
void readerCache() {
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@martin-g martin-g Oct 9, 2024

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Why do you delete the test ?
Looking at it I think it should still work. You just need to remove the ctor parameter.

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@belugabehr belugabehr Jan 4, 2025

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I believe this is testing the thread-safe nature of the code. This code should not be considered thread-safe and therefore should be removed.

final GenericDatumReader.ReaderCache cache = new GenericDatumReader.ReaderCache(this::findStringClass);
List<Thread> threads = IntStream.rangeClosed(1, 200).mapToObj((int index) -> {
final Schema schema = TestGenericDatumReader.this.build(index);
final WithSchema s = new WithSchema(schema, cache);
return (Runnable) () -> s.test();
}).map(Thread::new).collect(Collectors.toList());
threads.forEach(Thread::start);
threads.forEach((Thread t) -> {
try {
t.join();
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
});
}

@Test
void newInstanceFromString() {
final GenericDatumReader.ReaderCache cache = new GenericDatumReader.ReaderCache(this::findStringClass);
final GenericDatumReader cache = new GenericDatumReader();

Object object = cache.newInstanceFromString(StringBuilder.class, "Hello");
assertEquals(StringBuilder.class, object.getClass());
Expand All @@ -62,21 +42,6 @@ void newInstanceFromString() {

}

static class WithSchema {
private final Schema schema;

private final GenericDatumReader.ReaderCache cache;

public WithSchema(Schema schema, GenericDatumReader.ReaderCache cache) {
this.schema = schema;
this.cache = cache;
}

public void test() {
this.cache.getStringClass(schema);
}
}

private List<Schema> list = new ArrayList<>();

private Schema build(int index) {
Expand Down
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