feat: Extract metadata from GCS read channel #333
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,166 @@ | ||
| /* | ||
| * Copyright 2026 Google LLC | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
| package com.google.cloud.gcs.analyticscore.client; | ||
|
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||
| import com.google.cloud.ReadChannel; | ||
| import java.lang.reflect.Field; | ||
| import java.lang.reflect.Method; | ||
| import java.util.Collection; | ||
| import java.util.Map; | ||
| import java.util.concurrent.CancellationException; | ||
| import java.util.concurrent.ExecutionException; | ||
| import java.util.concurrent.Future; | ||
| import javax.annotation.Nullable; | ||
| import org.slf4j.Logger; | ||
| import org.slf4j.LoggerFactory; | ||
|
|
||
| /** | ||
| * Utility class to extract metadata from GCS SDK {@link ReadChannel} instances using reflection. | ||
| */ | ||
| final class GcsReadChannelMetadataExtractor { | ||
| private static final Logger LOG = LoggerFactory.getLogger(GcsReadChannelMetadataExtractor.class); | ||
|
|
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| private GcsReadChannelMetadataExtractor() {} | ||
|
|
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| static final class ExtractedMetadata { | ||
| private final long size; | ||
| private final long generation; | ||
|
|
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| ExtractedMetadata(long size, long generation) { | ||
| this.size = size; | ||
| this.generation = generation; | ||
| } | ||
|
|
||
| long getSize() { | ||
| return size; | ||
| } | ||
|
|
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| long getGeneration() { | ||
| return generation; | ||
| } | ||
| } | ||
|
|
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| @Nullable | ||
| static ExtractedMetadata extract(@Nullable ReadChannel sdkChannel) { | ||
| if (sdkChannel == null) { | ||
| return null; | ||
| } | ||
| Object resolvedMetadata = resolveMetadataObject(sdkChannel); | ||
| if (resolvedMetadata == null) { | ||
| return null; | ||
| } | ||
| long extractedSize = extractLongProperty(resolvedMetadata, "getSize", "size"); | ||
| if (extractedSize < 0) { | ||
| return null; | ||
| } | ||
| long extractedGen = extractLongProperty(resolvedMetadata, "getGeneration", "generation"); | ||
| return new ExtractedMetadata(extractedSize, extractedGen); | ||
| } | ||
|
|
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| @Nullable | ||
| private static Object resolveMetadataObject(ReadChannel sdkChannel) { | ||
| Class<?> clazz = sdkChannel.getClass(); | ||
| while (clazz != null) { | ||
| for (String methodName : | ||
| new String[] { | ||
|
Contributor
There was a problem hiding this comment. Can you please create these as static constants instead. |
||
| "getObject", "getResolvedObject", "getBlobInfo", "getBlob", "getStorageObject" | ||
| }) { | ||
| try { | ||
| Method method = clazz.getDeclaredMethod(methodName); | ||
| method.setAccessible(true); | ||
|
Contributor
There was a problem hiding this comment. This can throw SecurityException or ObjectInaccesible exception as well. Please modify the catch blocks to handle all RunTimeExceptions to be sure. |
||
| Object res = resolveFutureIfNeeded(method.invoke(sdkChannel)); | ||
| if (res != null) { | ||
| return res; | ||
| } | ||
| } catch (ReflectiveOperationException ignored) { | ||
| LOG.debug("Method {} not present on class {}", methodName, clazz.getName()); | ||
| } | ||
| } | ||
| for (String fieldName : new String[] {"storageObject", "blobInfo", "object", "result"}) { | ||
|
Contributor
There was a problem hiding this comment. can you please create these as static constants |
||
| try { | ||
| Field field = clazz.getDeclaredField(fieldName); | ||
| field.setAccessible(true); | ||
| Object val = resolveFutureIfNeeded(field.get(sdkChannel)); | ||
| if (val != null) { | ||
| return val; | ||
| } | ||
| } catch (ReflectiveOperationException ignored) { | ||
| LOG.debug("Field {} not present on class {}", fieldName, clazz.getName()); | ||
| } | ||
| } | ||
| clazz = clazz.getSuperclass(); | ||
| } | ||
| return null; | ||
| } | ||
|
|
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| @Nullable | ||
| private static Object resolveFutureIfNeeded(@Nullable Object obj) | ||
| throws ReflectiveOperationException { | ||
| if (!(obj instanceof Future)) { | ||
| return obj; | ||
| } | ||
| Future<?> future = (Future<?>) obj; | ||
| if (!future.isDone()) { | ||
| return null; | ||
| } | ||
| try { | ||
| return future.get(); | ||
| } catch (CancellationException | ExecutionException ignored) { | ||
| LOG.debug("Future execution failed or was cancelled", ignored); | ||
| return null; | ||
| } catch (InterruptedException e) { | ||
|
shrutisinghania marked this conversation as resolved.
|
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| Thread.currentThread().interrupt(); | ||
| return null; | ||
| } | ||
| } | ||
|
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| private static long extractLongProperty( | ||
| Object target, String primaryGetter, String fallbackGetter) { | ||
| for (Method m : target.getClass().getMethods()) { | ||
| if (m.getParameterCount() == 0 && m.getName().equals(primaryGetter)) { | ||
| long val = invokeLongGetter(target, m); | ||
| if (val >= 0) { | ||
| return val; | ||
| } | ||
| } | ||
| } | ||
| if (target instanceof Map || target instanceof Collection) { | ||
| return -1L; | ||
| } | ||
| for (Method m : target.getClass().getMethods()) { | ||
| if (m.getParameterCount() == 0 && m.getName().equals(fallbackGetter)) { | ||
| long val = invokeLongGetter(target, m); | ||
| if (val >= 0) { | ||
| return val; | ||
| } | ||
| } | ||
| } | ||
| return -1L; | ||
| } | ||
|
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| private static long invokeLongGetter(Object target, Method method) { | ||
| try { | ||
| method.setAccessible(true); | ||
| Object val = method.invoke(target); | ||
| if (val instanceof Number) { | ||
| return ((Number) val).longValue(); | ||
| } | ||
| } catch (ReflectiveOperationException ignored) { | ||
| LOG.debug("Getter invocation failed for method {} on target {}", method.getName(), target); | ||
| } | ||
| return -1L; | ||
| } | ||
| } | ||
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we can drop this