fix(profiling): Fix meta_length not serialized in Perfetto envelope header

SentryEnvelopeItemHeader.serialize() checked the raw metaLength field
instead of calling getMetaLength(), so the callable path used by
Perfetto profile chunks was never invoked and meta_length was never
written to the envelope header JSON.

Refactor SentryEnvelopeItemHeader to remove the metaLength field
entirely — all constructors now store a single calculateMetaLength
callable. Eager constructors (deserializer) wrap the Integer in a
lambda. All constructors delegate to one private primary constructor.

In fromPerfettoProfileChunk, replace the round-trip through
ProfileChunk.setMetaLength/getMetaLength with a local AtomicInteger
shared between the CachedItem lambda and the header callable, keeping
meta_length as an envelope transport concern rather than in
ProfileChunk

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: 43jay

sentry/src/main/java/io/sentry/ProfileChunk.java

@@ -138,20 +138,6 @@ public double getTimestamp() {
     return contentType;
   }
 
-  /**
-   * The length of the JSON metadata prefix in the binary envelope payload. Set during lazy
-   * serialization of Perfetto profile chunks so the envelope item header can read it.
-   */
-  private transient int metaLength = 0;
-
-  public int getMetaLength() {
-    return metaLength;
-  }
-
-  public void setMetaLength(final int metaLength) {
-    this.metaLength = metaLength;
-  }
-
   public @Nullable SentryProfile getSentryProfile() {
     return sentryProfile;
   }

sentry/src/main/java/io/sentry/SentryEnvelopeItem.java

@@ -28,6 +28,7 @@
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.concurrent.Callable;
+import java.util.concurrent.atomic.AtomicInteger;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -385,6 +386,12 @@ private static void ensureAttachmentSizeLimit(
               traceFile != null ? traceFile.getName() : "null"));
     }
 
+    // Perfetto profile chunks are serialized as [JSON metadata][raw .pftrace bytes] with no
+    // delimiter. The server needs meta_length in the envelope header to know where the JSON
+    // ends and the binary begins. meta_length is not known until the CachedItem payload lambda
+    // runs, so we track it here as an envelope serialization concern rather than on ProfileChunk.
+    final AtomicInteger metaLength = new AtomicInteger(-1);
+
     final CachedItem cachedItem =
         new CachedItem(
             () -> {
@@ -394,6 +401,7 @@ private static void ensureAttachmentSizeLimit(
                   final Writer writer = new BufferedWriter(new OutputStreamWriter(stream, UTF_8))) {
                 serializer.serialize(profileChunk, writer);
                 metadataBytes = stream.toByteArray();
+                metaLength.set(metadataBytes.length);
               } catch (IOException e) {
                 throw new SentryEnvelopeException(
                     String.format(
@@ -416,9 +424,6 @@ private static void ensureAttachmentSizeLimit(
               System.arraycopy(metadataBytes, 0, payload, 0, metadataBytes.length);
               System.arraycopy(traceBytes, 0, payload, metadataBytes.length, traceBytes.length);
 
-              // Store metaLength so the header callable can read it after lazy evaluation
-              profileChunk.setMetaLength(metadataBytes.length);
-
               return payload;
             });
 
@@ -431,7 +436,7 @@ private static void ensureAttachmentSizeLimit(
             null,
             profileChunk.getPlatform(),
             null,
-            (Callable<Integer>) () -> profileChunk.getMetaLength());
+            (Callable<Integer>) metaLength::get);
 
     // avoid method refs on Android due to some issues with older AGP setups
     // noinspection Convert2MethodRef

sentry/src/main/java/io/sentry/SentryEnvelopeItemHeader.java

@@ -21,8 +21,7 @@ public final class SentryEnvelopeItemHeader implements JsonSerializable, JsonUnk
   private final int length;
   @Nullable private final Callable<Integer> getLength;
   private final @Nullable String attachmentType;
-  private final @Nullable Integer metaLength;
-  @Nullable private final Callable<Integer> getMetaLength;
+  @Nullable private final Callable<Integer> calculateMetaLength;
 
   private @Nullable Map<String, Object> unknown;
 
@@ -54,31 +53,41 @@ public int getLength() {
     return platform;
   }
 
-  public @Nullable Integer getMetaLength() {
-    if (getMetaLength != null) {
+  @Nullable Integer getMetaLength() {
+    if (calculateMetaLength != null) {
       try {
-        return getMetaLength.call();
+        return calculateMetaLength.call();
       } catch (Throwable ignored) {
         return null;
       }
     }
-    return metaLength;
+    return null;
   }
 
-  @ApiStatus.Internal
-  public SentryEnvelopeItemHeader(
+  private SentryEnvelopeItemHeader(
       final @NotNull SentryItemType type,
       int length,
+      final @Nullable Callable<Integer> getLength,
       final @Nullable String contentType,
       final @Nullable String fileName,
       final @Nullable String attachmentType,
       final @Nullable String platform,
-      final @Nullable Integer itemCount) {
-    this(type, length, contentType, fileName, attachmentType, platform, itemCount, null);
+      final @Nullable Integer itemCount,
+      final @Nullable Callable<Integer> calculateMetaLength) {
+    this.type = Objects.requireNonNull(type, "type is required");
+    this.contentType = contentType;
+    this.length = length;
+    this.fileName = fileName;
+    this.getLength = getLength;
+    this.attachmentType = attachmentType;
+    this.platform = platform;
+    this.itemCount = itemCount;
+    this.calculateMetaLength = calculateMetaLength;
   }
 
+  /** Eager constructor used internally by {@link Deserializer#deserialize}. */
   @ApiStatus.Internal
-  public SentryEnvelopeItemHeader(
+  private SentryEnvelopeItemHeader(
       final @NotNull SentryItemType type,
       int length,
       final @Nullable String contentType,
@@ -87,44 +96,37 @@ public SentryEnvelopeItemHeader(
       final @Nullable String platform,
       final @Nullable Integer itemCount,
       final @Nullable Integer metaLength) {
-    this.type = Objects.requireNonNull(type, "type is required");
-    this.contentType = contentType;
-    this.length = length;
-    this.fileName = fileName;
-    this.getLength = null;
-    this.attachmentType = attachmentType;
-    this.platform = platform;
-    this.itemCount = itemCount;
-    this.metaLength = metaLength;
-    this.getMetaLength = null;
+    this(
+        type, length, null, contentType, fileName, attachmentType, platform, itemCount,
+        metaLength != null ? () -> metaLength : null);
   }
 
-  SentryEnvelopeItemHeader(
+  @ApiStatus.Internal
+  public SentryEnvelopeItemHeader(
       final @NotNull SentryItemType type,
-      final @Nullable Callable<Integer> getLength,
+      int length,
       final @Nullable String contentType,
       final @Nullable String fileName,
-      final @Nullable String attachmentType) {
-    this(type, getLength, contentType, fileName, attachmentType, null, null);
+      final @Nullable String attachmentType,
+      final @Nullable String platform,
+      final @Nullable Integer itemCount) {
+    this(type, length, contentType, fileName, attachmentType, platform, itemCount, null);
   }
 
+  /**
+   * Lazy constructor. Both length and metaLength are computed lazily as these depend on
+   * the Item having been evaluated.
+   */
   SentryEnvelopeItemHeader(
       final @NotNull SentryItemType type,
       final @Nullable Callable<Integer> getLength,
       final @Nullable String contentType,
       final @Nullable String fileName,
       final @Nullable String attachmentType,
       final @Nullable String platform,
-      final @Nullable Integer itemCount) {
-    this(
-        type,
-        getLength,
-        contentType,
-        fileName,
-        attachmentType,
-        platform,
-        itemCount,
-        (Integer) null);
+      final @Nullable Integer itemCount,
+      final @Nullable Callable<Integer> calculateMetaLength) {
+    this(type, -1, getLength, contentType, fileName, attachmentType, platform, itemCount, calculateMetaLength);
   }
 
   SentryEnvelopeItemHeader(
@@ -134,39 +136,17 @@ public SentryEnvelopeItemHeader(
       final @Nullable String fileName,
       final @Nullable String attachmentType,
       final @Nullable String platform,
-      final @Nullable Integer itemCount,
-      final @Nullable Integer metaLength) {
-    this.type = Objects.requireNonNull(type, "type is required");
-    this.contentType = contentType;
-    this.length = -1;
-    this.fileName = fileName;
-    this.getLength = getLength;
-    this.attachmentType = attachmentType;
-    this.platform = platform;
-    this.itemCount = itemCount;
-    this.metaLength = metaLength;
-    this.getMetaLength = null;
+      final @Nullable Integer itemCount) {
+    this(type, getLength, contentType, fileName, attachmentType, platform, itemCount, null);
   }
 
   SentryEnvelopeItemHeader(
       final @NotNull SentryItemType type,
       final @Nullable Callable<Integer> getLength,
       final @Nullable String contentType,
       final @Nullable String fileName,
-      final @Nullable String attachmentType,
-      final @Nullable String platform,
-      final @Nullable Integer itemCount,
-      final @Nullable Callable<Integer> getMetaLength) {
-    this.type = Objects.requireNonNull(type, "type is required");
-    this.contentType = contentType;
-    this.length = -1;
-    this.fileName = fileName;
-    this.getLength = getLength;
-    this.attachmentType = attachmentType;
-    this.platform = platform;
-    this.itemCount = itemCount;
-    this.metaLength = null;
-    this.getMetaLength = getMetaLength;
+      final @Nullable String attachmentType) {
+    this(type, getLength, contentType, fileName, attachmentType, null, null);
   }
 
   SentryEnvelopeItemHeader(
@@ -219,8 +199,9 @@ public void serialize(final @NotNull ObjectWriter writer, final @NotNull ILogger
     if (itemCount != null) {
       writer.name(JsonKeys.ITEM_COUNT).value(itemCount);
     }
-    if (metaLength != null) {
-      writer.name(JsonKeys.META_LENGTH).value(metaLength);
+    final @Nullable Integer resolvedMetaLength = getMetaLength();
+    if (resolvedMetaLength != null) {
+      writer.name(JsonKeys.META_LENGTH).value(resolvedMetaLength);
     }
     writer.name(JsonKeys.LENGTH).value(getLength());
     if (unknown != null) {