Use copy-on-write IntHashMaps to avoid sync cost on lookup.

Part of fixes for #3394.
jruby · Oct 14, 2015 · f28fd8b · f28fd8b
1 parent b52e483
commit f28fd8b
Showing 2 changed files with 25 additions and 9 deletions.
diff --git a/core/src/main/java/org/jruby/java/invokers/RubyToJavaInvoker.java b/core/src/main/java/org/jruby/java/invokers/RubyToJavaInvoker.java
@@ -35,7 +35,8 @@ public abstract class RubyToJavaInvoker<T extends JavaCallable> extends JavaMeth
 
     // in case multiple callables (overloaded Java method - same name different args)
     // for the invoker exists  CallableSelector caches resolution based on args here
-    final IntHashMap<T> cache;
+    final IntHashMap<T> writeCache;
+    volatile IntHashMap<T> readCache;
 
     private final Ruby runtime;
 
@@ -54,7 +55,8 @@ public abstract class RubyToJavaInvoker<T extends JavaCallable> extends JavaMeth
             minVarArgsArity = getMemberArity(member) - 1;
         }
 
-        cache = NULL_CACHE; // if there's a single callable - matching (and thus the cache) won't be used
+        writeCache = NULL_CACHE; // if there's a single callable - matching (and thus the cache) won't be used
+        readCache = writeCache;
 
         this.javaCallable = callable;
         this.javaCallables = null;
@@ -84,7 +86,8 @@ public abstract class RubyToJavaInvoker<T extends JavaCallable> extends JavaMeth
             }
             callables = null;
 
-            cache = NULL_CACHE; // if there's a single callable - matching (and thus the cache) won't be used
+            writeCache = NULL_CACHE; // if there's a single callable - matching (and thus the cache) won't be used
+            readCache = writeCache;
         }
         else {
             callable = null; maxArity = -1; minArity = Integer.MAX_VALUE;
@@ -139,7 +142,8 @@ public abstract class RubyToJavaInvoker<T extends JavaCallable> extends JavaMeth
                 varargsCallables = varArgs.toArray( createCallableArray(varArgs.size()) );
             }
 
-            cache = newCallableCache();
+            writeCache = newCallableCache();
+            readCache = (IntHashMap<T>)writeCache.clone();
         }
 
         this.javaCallable = callable;
@@ -192,14 +196,13 @@ private boolean setNativeCallIfPublic(final Method method) {
     }
 
     public T getSignature(int signatureCode) {
-        synchronized (cache) {
-            return cache.get(signatureCode);
-        }
+        return readCache.get(signatureCode);
     }
 
     public void putSignature(int signatureCode, T callable) {
-        synchronized (cache) {
-            cache.put(signatureCode, callable);
+        synchronized (writeCache) {
+            writeCache.put(signatureCode, callable);
+            readCache = (IntHashMap<T>)writeCache.clone();
         }
     }
 

diff --git a/core/src/main/java/org/jruby/util/collections/IntHashMap.java b/core/src/main/java/org/jruby/util/collections/IntHashMap.java
@@ -397,6 +397,19 @@ public String toString() {
 	    }
     }
 
+    @Override
+    public Object clone() {
+        IntHashMap<V> newMap = new IntHashMap<>(table.length, loadFactor);
+        for (int i = 0; i < table.length; i++) {
+            Entry<V> entry = table[i];
+            while (entry != null) {
+                newMap.put(entry.getKey(), entry.getValue());
+                entry = entry.next;
+            }
+        }
+        return newMap;
+    }
+
     @SuppressWarnings("unchecked")
     public static <U> IntHashMap<U> nullMap() { return NullMap.INSTANCE; }