Fix to thread-safely load Thrift classes for old libthrift (< 0.9.3) (line#5497)

Motivation:

In old Thrift versions (< 0.9.3), the multi-threaded environment was not considered during the initialization process for the Thrift class. A workaround was committed at line#4688 but only applied to DocService.

This problem can occur not only in `DocService` but also when creating Thrift clients and other parts, so it would be desirable to use `ThriftMetadataAccess.getStructMetaDataMap()` for places where `FieldMetaData.getStructMetaDataMap()` is used.

```java
// When creating Thrift clients
java.lang.IllegalArgumentException: failed to retrieve function metadata: ...
	at com.linecorp.armeria.internal.common.thrift.ThriftServiceMetadata.registerFunction(ThriftServiceMetadata.java:239)
	at com.linecorp.armeria.internal.common.thrift.ThriftServiceMetadata.lambda$init$2(ThriftServiceMetadata.java:117)
	at java.base/java.util.HashMap.forEach(HashMap.java:1337)
	at java.base/java.util.Collections$UnmodifiableMap.forEach(Collections.java:1505)
	at com.linecorp.armeria.internal.common.thrift.ThriftServiceMetadata.init(ThriftServiceMetadata.java:116)
	at com.linecorp.armeria.internal.common.thrift.ThriftServiceMetadata.<init>(ThriftServiceMetadata.java:85)
	at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1705)
	at com.linecorp.armeria.internal.client.thrift.THttpClientDelegate.metadata(THttpClientDelegate.java:216)
	at com.linecorp.armeria.internal.client.thrift.THttpClientDelegate.execute(THttpClientDelegate.java:122)
	at com.linecorp.armeria.internal.client.thrift.THttpClientDelegate.execute(THttpClientDelegate.java:78)
Caused by: java.lang.NullPointerException: null
	at com.linecorp.armeria.internal.common.thrift.ThriftFunction.<init>(ThriftFunction.java:104)
	at com.linecorp.armeria.internal.common.thrift.ThriftFunction.<init>(ThriftFunction.java:66)
	at com.linecorp.armeria.internal.common.thrift.ThriftServiceMetadata.registerFunction(ThriftServiceMetadata.java:229)
	... 33 common frames omitted

// When creating DocService
Caused by: java.lang.NullPointerException: null
	at com.linecorp.armeria.internal.server.thrift.ThriftDescriptiveTypeInfoProvider.newStructInfo(ThriftDescriptiveTypeInfoProvider.java:322)
	at com.linecorp.armeria.internal.server.thrift.ThriftDescriptiveTypeInfoProvider.newDescriptiveTypeInfo(ThriftDescriptiveTypeInfoProvider.java:101)
	at com.linecorp.armeria.server.docs.DocService$SpecificationLoader.lambda$composeDescriptiveTypeInfoProvider$9(DocService.java:386)
```

Reference:
- https://issues.apache.org/jira/browse/THRIFT-1618
- apache/thrift@4a78c6e

Modifications:

- Replace `FieldMetaData.getStructMetaDataMap()` with `ThriftMetadataAccess.getStructMetaDataMap()` to thread-safely initialize Thrift classes.

Result:

You no longer see `NullPointerException` when creating Thrift clients in a multi-threaded environment.

Author: ikhoon

thrift/thrift0.13/src/main/java/com/linecorp/armeria/common/thrift/text/StructContext.java

@@ -58,6 +58,7 @@
 
 import com.linecorp.armeria.common.annotation.Nullable;
 import com.linecorp.armeria.common.util.SystemInfo;
+import com.linecorp.armeria.internal.common.thrift.ThriftMetadataAccess;
 
 /**
  * A struct parsing context. Builds a map from field name to TField.
@@ -170,7 +171,7 @@ private <T extends TBase<T, F>, F extends TFieldIdEnum> Map<String, TField> comp
             // Get the metaDataMap for this Thrift class
             @SuppressWarnings("unchecked")
             final Map<? extends TFieldIdEnum, FieldMetaData> metaDataMap =
-                    FieldMetaData.getStructMetaDataMap((Class<T>) clazz);
+                    ThriftMetadataAccess.getStructMetaDataMap((Class<T>) clazz);
 
             for (Entry<? extends TFieldIdEnum, FieldMetaData> e : metaDataMap.entrySet()) {
                 final String fieldName = e.getKey().getFieldName();

thrift/thrift0.13/src/main/java/com/linecorp/armeria/internal/common/thrift/ThriftFunction.java

@@ -106,7 +106,7 @@ private <T extends TBase<T, F>, F extends TFieldIdEnum> ThriftFunction(
             //noinspection RedundantCast
             @SuppressWarnings("unchecked")
             final Map<TFieldIdEnum, FieldMetaData> metaDataMap =
-                    (Map<TFieldIdEnum, FieldMetaData>) FieldMetaData.getStructMetaDataMap(
+                    (Map<TFieldIdEnum, FieldMetaData>) ThriftMetadataAccess.getStructMetaDataMap(
                             (Class<T>) resultType);
 
             for (Entry<TFieldIdEnum, FieldMetaData> e : metaDataMap.entrySet()) {

thrift/thrift0.13/src/main/java/com/linecorp/armeria/internal/server/thrift/ThriftMetadataAccess.java renamed to thrift/thrift0.13/src/main/java/com/linecorp/armeria/internal/common/thrift/ThriftMetadataAccess.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023 LINE Corporation
+ * Copyright 2024 LINE Corporation
  *
  * LINE Corporation licenses this file to you under the Apache License,
  * version 2.0 (the "License"); you may not use this file except in compliance
@@ -14,7 +14,7 @@
  * under the License.
  */
 
-package com.linecorp.armeria.internal.server.thrift;
+package com.linecorp.armeria.internal.common.thrift;
 
 import java.io.BufferedReader;
 import java.io.InputStreamReader;
@@ -30,7 +30,7 @@
 
 import com.google.common.annotations.VisibleForTesting;
 
-final class ThriftMetadataAccess {
+public final class ThriftMetadataAccess {
 
     private static final Logger logger = LoggerFactory.getLogger(ThriftMetadataAccess.class);
 
@@ -62,8 +62,8 @@ static boolean needsPreInitialization(Properties properties) {
     }
 
     @SuppressWarnings("unchecked")
-    public static <T extends TBase<T, F>, F extends TFieldIdEnum>
-    Map<?, FieldMetaData> getStructMetaDataMap(Class<?> clazz) {
+    public static synchronized <T extends TBase<T, F>, F extends TFieldIdEnum>
+    Map<? extends TFieldIdEnum, FieldMetaData> getStructMetaDataMap(Class<?> clazz) {
         // Pre-initialize classes if there is a jar in the classpath with armeria-thrift <= 0.14
         // See the following issue for the motivation of pre-initializing classes
         // https://issues.apache.org/jira/browse/THRIFT-5430

thrift/thrift0.13/src/main/java/com/linecorp/armeria/internal/server/thrift/ThriftDescriptiveTypeInfoProvider.java

@@ -48,6 +48,7 @@
 import com.google.common.annotations.VisibleForTesting;
 
 import com.linecorp.armeria.common.annotation.Nullable;
+import com.linecorp.armeria.internal.common.thrift.ThriftMetadataAccess;
 import com.linecorp.armeria.server.docs.DescriptiveTypeInfo;
 import com.linecorp.armeria.server.docs.DescriptiveTypeInfoProvider;
 import com.linecorp.armeria.server.docs.EnumInfo;

thrift/thrift0.13/src/main/java/com/linecorp/armeria/internal/server/thrift/ThriftDocServicePlugin.java

@@ -50,6 +50,7 @@
 import com.linecorp.armeria.common.HttpMethod;
 import com.linecorp.armeria.common.annotation.Nullable;
 import com.linecorp.armeria.common.thrift.ThriftProtocolFactories;
+import com.linecorp.armeria.internal.common.thrift.ThriftMetadataAccess;
 import com.linecorp.armeria.server.Route;
 import com.linecorp.armeria.server.RoutePathType;
 import com.linecorp.armeria.server.Service;

thrift/thrift0.13/src/main/java/com/linecorp/armeria/server/thrift/THttpService.java

@@ -34,7 +34,6 @@
 import org.apache.thrift.TBase;
 import org.apache.thrift.TException;
 import org.apache.thrift.TFieldIdEnum;
-import org.apache.thrift.meta_data.FieldMetaData;
 import org.apache.thrift.protocol.TMessage;
 import org.apache.thrift.protocol.TMessageType;
 import org.apache.thrift.protocol.TProtocol;
@@ -74,6 +73,7 @@
 import com.linecorp.armeria.internal.common.thrift.TByteBufTransport;
 import com.linecorp.armeria.internal.common.thrift.ThriftFieldAccess;
 import com.linecorp.armeria.internal.common.thrift.ThriftFunction;
+import com.linecorp.armeria.internal.common.thrift.ThriftMetadataAccess;
 import com.linecorp.armeria.internal.common.thrift.ThriftProtocolUtil;
 import com.linecorp.armeria.internal.server.annotation.DecoratorAnnotationUtil.DecoratorAndOrder;
 import com.linecorp.armeria.server.DecoratingService;
@@ -653,7 +653,7 @@ private static RpcRequest toRpcRequest(Class<?> serviceType, String method, TBas
         // NB: The map returned by FieldMetaData.getStructMetaDataMap() is an EnumMap,
         //     so the parameter ordering is preserved correctly during iteration.
         final Set<? extends TFieldIdEnum> fields =
-                FieldMetaData.getStructMetaDataMap(thriftArgs.getClass()).keySet();
+                ThriftMetadataAccess.getStructMetaDataMap(thriftArgs.getClass()).keySet();
 
         // Handle the case where the number of arguments is 0 or 1.
         final int numFields = fields.size();

thrift/thrift0.13/src/test/java/com/linecorp/armeria/internal/server/thrift/ThriftMetadataAccessTest.java renamed to thrift/thrift0.13/src/test/java/com/linecorp/armeria/internal/common/thrift/ThriftMetadataAccessTest.java

@@ -14,7 +14,7 @@
  * under the License.
  */
 
-package com.linecorp.armeria.internal.server.thrift;
+package com.linecorp.armeria.internal.common.thrift;
 
 import static org.assertj.core.api.Assertions.assertThat;