Cache both nested and toplevel var handles

mcimadamore · May 10, 2024 · 43eded4 · 43eded4
1 parent 0500824
commit 43eded4
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Showing 2 changed files with 21 additions and 5 deletions.
diff --git a/src/java.base/share/classes/jdk/internal/foreign/Utils.java b/src/java.base/share/classes/jdk/internal/foreign/Utils.java
@@ -37,6 +37,8 @@
 import java.lang.invoke.VarHandle;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.Supplier;
 
 import jdk.internal.access.SharedSecrets;
@@ -88,6 +90,24 @@ public static MemorySegment alignUp(MemorySegment ms, long alignment) {
     }
 
     public static VarHandle makeSegmentViewVarHandle(ValueLayout layout, boolean nested) {
+        final class VarHandleCache {
+            private static final Map<ValueLayout, VarHandle> HANDLE_MAP_TOPLEVEL = new ConcurrentHashMap<>();
+            private static final Map<ValueLayout, VarHandle> HANDLE_MAP_NESTED = new ConcurrentHashMap<>();
+        }
+        return nested ?
+                VarHandleCache.HANDLE_MAP_NESTED.computeIfAbsent(layout.withoutName(), Utils::makeNestedSegmentViewVarHandle) :
+                VarHandleCache.HANDLE_MAP_TOPLEVEL.computeIfAbsent(layout.withoutName(), Utils::makeToplevelSegmentViewVarHandle);
+    }
+
+    private static VarHandle makeToplevelSegmentViewVarHandle(ValueLayout layout) {
+        return makeSegmentViewVarHandleInternal(layout, false);
+    }
+
+    private static VarHandle makeNestedSegmentViewVarHandle(ValueLayout layout) {
+        return makeSegmentViewVarHandleInternal(layout, true);
+    }
+
+    private static VarHandle makeSegmentViewVarHandleInternal(ValueLayout layout, boolean nested) {
         Class<?> baseCarrier = layout.carrier();
         if (layout.carrier() == MemorySegment.class) {
             baseCarrier = switch ((int) ValueLayout.ADDRESS.byteSize()) {

diff --git a/src/java.base/share/classes/jdk/internal/foreign/layout/ValueLayouts.java b/src/java.base/share/classes/jdk/internal/foreign/layout/ValueLayouts.java
@@ -160,13 +160,9 @@ static boolean isValidCarrier(Class<?> carrier) {
 
         @ForceInline
         public final VarHandle varHandle() {
-            final class VarHandleCache {
-                private static final Map<ValueLayout, VarHandle> HANDLE_MAP = new ConcurrentHashMap<>();
-            }
             if (handle == null) {
                 // this store to stable field is safe, because return value of 'makeMemoryAccessVarHandle' has stable identity
-                handle = VarHandleCache.HANDLE_MAP
-                        .computeIfAbsent(withoutName(), l -> Utils.makeSegmentViewVarHandle(l, false));
+                handle = Utils.makeSegmentViewVarHandle((ValueLayout) this, false);
             }
             return handle;
         }