From 9ee448a757f2fa15608fd7397a41feb5f59c0ff2 Mon Sep 17 00:00:00 2001
From: Douglas Q Hawkins <douglas.hawkins@datadoghq.com>
Date: Thu, 16 Jul 2026 15:06:37 -0400
Subject: [PATCH] Deprecate TagMap.create(int) -- size is ignored

create(int) ignores its size (returns new OptimizedTagMap()); TagMap's
storage can't honor a size hint without compromising its other
optimizations. Mark it @Deprecated pointing at create(), and migrate the
two TagMap-internal callers (fromMap, Ledger.build) off it. The external
callers (CoreTracer, DDSpanContext, TagContext) are left -- their
deprecation warnings flag the sites a future dedicated sizing mechanism
will convert (DDSpanContext especially).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 .../src/main/java/datadog/trace/api/TagMap.java        | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/internal-api/src/main/java/datadog/trace/api/TagMap.java b/internal-api/src/main/java/datadog/trace/api/TagMap.java
index 1610cb3a5f2..1c66bef8075 100644
--- a/internal-api/src/main/java/datadog/trace/api/TagMap.java
+++ b/internal-api/src/main/java/datadog/trace/api/TagMap.java
@@ -50,7 +50,7 @@ public interface TagMap extends Map<String, Object>, Iterable<TagMap.EntryReader
 
   /** Creates a new mutable TagMap that contains the contents of <code>map</code> */
   static TagMap fromMap(Map<String, ?> map) {
-    TagMap tagMap = TagMap.create(map.size());
+    TagMap tagMap = TagMap.create();
     tagMap.putAll(map);
     return tagMap;
   }
@@ -68,6 +68,12 @@ static TagMap create() {
     return new OptimizedTagMap();
   }
 
+  /**
+   * @deprecated {@code size} is ignored -- TagMap's storage can't honor a size hint without
+   *     compromising its other optimizations, so this behaves identically to {@link #create()};
+   *     prefer that. A dedicated sizing mechanism may be introduced separately.
+   */
+  @Deprecated
   static TagMap create(int size) {
     return new OptimizedTagMap();
   }
@@ -1114,7 +1120,7 @@ public Iterator<EntryChange> iterator() {
     }
 
     public TagMap build() {
-      TagMap map = TagMap.create(this.estimateSize());
+      TagMap map = TagMap.create();
       fill(map);
       return map;
     }