perf(markdown): reuse Android measurements across view mounts

2026-10-25 10:42:45 +00:00 · 2026-10-16 12:56:03 +02:00
parent 53d614b8f7
commit 9747307d9f
2 changed files with 226 additions and 0 deletions
@@ -22,6 +22,8 @@ Native code blocks use the library's copy control and compiled grammars. Web cod

 The package patch also keeps overflowing native horizontal blocks in control of their drags: Android claims parent interception at touch-down and releases it for vertical drags so the chat list can scroll; iOS keeps its scroll recognizer active for outward drags at the leading edge. This prevents compact sidebar pans from taking block scrolling without changing sidebar swipes on prose or non-overflowing blocks. Native changes require a client rebuild.

+Android measurements use a size-only, 512-entry LRU across view unmounts, matching the library’s existing iOS cache. Scrolling back through history can reuse layout sizes without parsing those rows again. Content, layout props and width identify each entry; font-scale changes and native layout invalidation discard affected sizes. The cache retains no views or spans.
+
 The library determines how incomplete Markdown appears during streaming. Completed text uses the same component and engine as history. Find and scroll-to-message address source message ids; selection-copy understands semantic HTML and the web code component's copy metadata.

 ## Verification
@@ -2601,3 +2601,227 @@ index b98d10c..b645629 100644
 -#endif
 -
 @end
+diff --git a/node_modules/react-native-enriched-markdown/android/src/main/java/com/swmansion/enriched/markdown/MeasurementSizeCache.kt b/node_modules/react-native-enriched-markdown/android/src/main/java/com/swmansion/enriched/markdown/MeasurementSizeCache.kt
+new file mode 100644
+index 0000000..11911c8
+--- /dev/null
+++ b/node_modules/react-native-enriched-markdown/android/src/main/java/com/swmansion/enriched/markdown/MeasurementSizeCache.kt
+@@ -0,0 +1,31 @@
+package com.swmansion.enriched.markdown
+
+/** Size-only cache: no views, spans, Contexts or callbacks survive unmount. */
+internal class MeasurementSizeCache(private val capacity: Int = 512) {
+  data class Key(val markdown: String, val propsHash: Int, val width: Float, val splitTableSegments: Boolean)
+
+  private val sizes = LinkedHashMap<Key, Long>(16, 0.75f, true)
+
+  @Synchronized
+  fun get(key: Key): Long? = sizes[key]
+
+  @Synchronized
+  fun put(key: Key, size: Long) {
+    sizes[key] = size
+    if (sizes.size > capacity) {
+      val oldest = sizes.entries.iterator()
+      oldest.next()
+      oldest.remove()
+    }
+  }
+
+  @Synchronized
+  fun removeMatchingMarkdown(markdown: String) {
+    sizes.keys.removeAll { it.markdown == markdown }
+  }
+
+  @Synchronized
+  fun clear() {
+    sizes.clear()
+  }
+}
+diff --git a/node_modules/react-native-enriched-markdown/android/src/main/java/com/swmansion/enriched/markdown/MeasurementStore.kt b/node_modules/react-native-enriched-markdown/android/src/main/java/com/swmansion/enriched/markdown/MeasurementStore.kt
+index f4840e4..e36b444 100644
+--- a/node_modules/react-native-enriched-markdown/android/src/main/java/com/swmansion/enriched/markdown/MeasurementStore.kt
+++ b/node_modules/react-native-enriched-markdown/android/src/main/java/com/swmansion/enriched/markdown/MeasurementStore.kt
+@@ -66,9 +66,11 @@ object MeasurementStore {
+     val spannable: CharSequence?,
+     val paintParams: PaintParams,
+     val markdownHash: Int,
+    val sizeKey: MeasurementSizeCache.Key? = null,
+   )
+ 
+   private val data = ConcurrentHashMap<Int, MeasurementParams>()
+  private val sizes = MeasurementSizeCache()
+ 
+   // Store font scaling settings per view ID
+   private data class FontScalingSettings(
+@@ -133,7 +135,10 @@ object MeasurementStore {
+           YogaMeasureOutput.getHeight(newSize) + PixelUtil.toDIPFromPixel(trailingMarginBottomPx),
+         )
+     }
+-    data[id] = MeasurementParams(width, newSize, spannable, paintParams, existingHash)
+    if (oldSize != newSize) {
+      cached?.sizeKey?.let { sizes.removeMatchingMarkdown(it.markdown) }
+    }
+    data[id] = MeasurementParams(width, newSize, spannable, paintParams, existingHash, cached?.sizeKey)
+     return oldSize != newSize
+   }
+ 
+@@ -144,7 +149,7 @@ object MeasurementStore {
+   }
+ 
+   fun invalidate(id: Int) {
+-    data.remove(id)
+    data.remove(id)?.sizeKey?.let { sizes.removeMatchingMarkdown(it.markdown) }
+   }
+ 
+   // Content-box width (px) the measure pass last wrapped at; the display view insets to match (#805).
+@@ -212,7 +217,7 @@ object MeasurementStore {
+     val previous = fontScalingSettings[viewId]
+     fontScalingSettings[viewId] = FontScalingSettings(allowFontScaling, maxFontSizeMultiplier)
+     if (previous != null && (previous.allowFontScaling != allowFontScaling || previous.maxFontSizeMultiplier != maxFontSizeMultiplier)) {
+-      data.remove(viewId)
+      invalidate(viewId)
+     }
+   }
+ 
+@@ -285,7 +290,43 @@ object MeasurementStore {
+ 
+     val fontScale = checkAndUpdateFontScale(context, allowFontScaling, maxFontSizeMultiplier)
+ 
+-    // Split measurement always goes through the full measure path (no spannable caching)
+    // Use resolved layout settings, including values supplied by native setters.
+    var layoutHash = computePropsHash(props, allowFontScaling, fontScale, maxFontSizeMultiplier)
+    layoutHash = 31 * layoutHash + resolveBreakStrategy(id)
+    layoutHash = 31 * layoutHash + resolveMaxLines(id)
+    layoutHash = 31 * layoutHash + (resolveEllipsize(id)?.hashCode() ?: 0)
+    layoutHash = 31 * layoutHash + props.getBooleanOrDefault("streamingAnimation", false).hashCode()
+    layoutHash = 31 * layoutHash + (id?.let { streamingTableModes[it] } ?: TableStreamingMode.PROGRESSIVE).hashCode()
+    layoutHash = 31 * layoutHash + (id?.let { streamingCodeBlockModes[it] } ?: CodeBlockStreamingMode.PROGRESSIVE).hashCode()
+    layoutHash = 31 * layoutHash + context.resources.displayMetrics.density.toBits()
+    val key = MeasurementSizeCache.Key(props.getStringOrDefault("markdown", ""), layoutHash, width, splitTableSegments)
+    val cached = id?.let { data[it] }
+    if (cached?.sizeKey == key) return cached.cachedSize
+    sizes.get(key)?.let { size ->
+      if (id != null) {
+        data[id] = MeasurementParams(width, size, null, PaintParams(Typeface.DEFAULT, 0f), 0, key)
+      }
+      return size
+    }
+
+    val size = measureUncached(context, id, width, props, splitTableSegments, allowFontScaling, fontScale, maxFontSizeMultiplier)
+    sizes.put(key, size)
+    if (id != null) {
+      data.computeIfPresent(id) { _, measured -> measured.copy(sizeKey = key) }
+    }
+    return size
+  }
+
+  private fun measureUncached(
+    context: Context,
+    id: Int?,
+    width: Float,
+    props: ReadableMap?,
+    splitTableSegments: Boolean,
+    allowFontScaling: Boolean,
+    fontScale: Float,
+    maxFontSizeMultiplier: Float,
+  ): Long {
+     if (splitTableSegments) {
+       return measureAndCacheSplit(context, id, width, props, allowFontScaling, fontScale, maxFontSizeMultiplier)
+     }
+@@ -295,7 +336,7 @@ object MeasurementStore {
+ 
+     val currentHash = computePropsHash(props, allowFontScaling, fontScale, maxFontSizeMultiplier)
+ 
+-    if (cached.markdownHash != currentHash) {
+    if (cached.markdownHash != currentHash || cached.spannable == null) {
+       return measureAndCache(context, safeId, width, props, allowFontScaling, fontScale, maxFontSizeMultiplier)
+     }
+ 
+@@ -332,8 +373,11 @@ object MeasurementStore {
+     val imageRequestHeaders = parseImageRequestHeaders(props.getArrayOrNull("imageRequestHeaders"))
+     val linkPillContent = parseLinkPillContent(props.getArrayOrNull("linkPillContent"))
+     var result = markdown.hashCode()
+-    result = 31 * result + (styleMap?.hashCode() ?: 0)
+-    result = 31 * result + (md4cFlagsMap?.hashCode() ?: 0)
+    // ReadableNativeArray hashes its backing array identity, not its values.
+    result = 31 * result + (styleMap?.toHashMap()?.hashCode() ?: 0)
+    result = 31 * result + (md4cFlagsMap?.toHashMap()?.hashCode() ?: 0)
+    result = 31 * result + props.getBooleanOrDefault("isGFM", false).hashCode()
+    result = 31 * result + props.getStringOrDefault("textBreakStrategy", BreakStrategyUtils.DEFAULT_STRATEGY).hashCode()
+     result = 31 * result + parseLinkRecognition(props.getMapOrNull("linkRecognition")).hashCode()
+     result = 31 * result + fontScale.toBits()
+     result = 31 * result + allowFontScaling.hashCode()
+@@ -356,6 +400,7 @@ object MeasurementStore {
+       if (lastKnownFontScale != 1.0f) {
+         lastKnownFontScale = 1.0f
+         data.clear()
+        sizes.clear()
+       }
+       return 1.0f
+     }
+@@ -368,6 +413,7 @@ object MeasurementStore {
+     if (currentFontScale != lastKnownFontScale) {
+       lastKnownFontScale = currentFontScale
+       data.clear()
+      sizes.clear()
+     }
+     return currentFontScale
+   }
+diff --git a/node_modules/react-native-enriched-markdown/android/src/test/java/com/swmansion/enriched/markdown/MeasurementSizeCacheTest.kt b/node_modules/react-native-enriched-markdown/android/src/test/java/com/swmansion/enriched/markdown/MeasurementSizeCacheTest.kt
+new file mode 100644
+index 0000000..b3394c4
+--- /dev/null
+++ b/node_modules/react-native-enriched-markdown/android/src/test/java/com/swmansion/enriched/markdown/MeasurementSizeCacheTest.kt
+@@ -0,0 +1,51 @@
+package com.swmansion.enriched.markdown
+
+import org.junit.Assert.*
+import org.junit.Test
+
+class MeasurementSizeCacheTest {
+  private fun key(markdown: String = "hello", propsHash: Int = 1, width: Float = 320f) =
+    MeasurementSizeCache.Key(markdown, propsHash, width, true)
+
+  @Test fun reusesSizeAcrossIndependentEqualKeys() {
+    val cache = MeasurementSizeCache(2)
+    cache.put(key(), 42L)
+    assertEquals(42L, cache.get(key()))
+    assertNull(cache.get(key(propsHash = 2)))
+    assertNull(cache.get(key(width = 321f)))
+    assertNull(cache.get(key().copy(splitTableSegments = false)))
+  }
+
+  @Test fun comparesMarkdownEvenWhenItsHashCollides() {
+    val cache = MeasurementSizeCache(2)
+    assertEquals("Aa".hashCode(), "BB".hashCode())
+    cache.put(key("Aa"), 42L)
+    assertNull(cache.get(key("BB")))
+  }
+
+  @Test fun evictsLeastRecentlyUsedSize() {
+    val cache = MeasurementSizeCache(2)
+    cache.put(key("one"), 1L)
+    cache.put(key("two"), 2L)
+    assertEquals(1L, cache.get(key("one")))
+    cache.put(key("three"), 3L)
+    assertNull(cache.get(key("two")))
+    assertEquals(1L, cache.get(key("one")))
+    assertEquals(3L, cache.get(key("three")))
+  }
+
+  @Test fun invalidatesAllWidthsAndPropsForChangedContent() {
+    val cache = MeasurementSizeCache(4)
+    cache.put(key(), 1L)
+    cache.put(key(width = 640f), 2L)
+    cache.put(key(propsHash = 2), 3L)
+    cache.put(key("other"), 4L)
+    cache.removeMatchingMarkdown("hello")
+    assertNull(cache.get(key()))
+    assertNull(cache.get(key(width = 640f)))
+    assertNull(cache.get(key(propsHash = 2)))
+    assertEquals(4L, cache.get(key("other")))
+    cache.clear()
+    assertNull(cache.get(key("other")))
+  }
+}