commit 1f9c76b9165e3a5b3c0e6faab810f191c05fd9f4
author Stuart McCulloch <mcculls@gmail.com> Sat Mar 21 17:01:15 2015 +0000
committer Stuart McCulloch <mcculls@gmail.com> Sat Mar 21 17:01:15 2015 +0000
tree 09e98bac0bdf484c95b4b25b46ba68744071f946
parent 156c8cc762fab971efb727c7ab107fa243be2fc9

Improve performance of internal DependencyStack collection

core/src/com/google/inject/internal/InternalContext.java

diff --git a/core/src/com/google/inject/internal/InternalContext.java b/core/src/com/google/inject/internal/InternalContext.java
index 6a6f7ef..834f26d 100644
--- a/core/src/com/google/inject/internal/InternalContext.java
+++ b/core/src/com/google/inject/internal/InternalContext.java
@@ -23,7 +23,7 @@
 import com.google.inject.spi.Dependency;
 import com.google.inject.spi.DependencyAndSource;
 
-import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
 
@@ -68,8 +68,7 @@
   public Dependency<?> pushDependency(Dependency<?> dependency, Object source) {
     Dependency<?> previous = this.dependency;
     this.dependency = dependency;
-    state.add(dependency);
-    state.add(source);
+    state.add(dependency, source);
     return previous;
   }
   
@@ -81,8 +80,7 @@
   
   /** Adds to the state without setting the dependency. */
   public void pushState(Key<?> key, Object source) {
-    state.add(key);
-    state.add(source);
+    state.add(key, source);
   }
   
   /** Pops from the state without setting a dependency. */
@@ -106,10 +104,29 @@
     return builder.build();
   }
 
-  private static final class DependencyStack extends ArrayList<Object> {
-    void pop() {
-      int sz = size();
-      removeRange(sz - 2, sz);
+  private static final class DependencyStack {
+    private Object[] elements = new Object[10];
+    private int size = 0;
+
+    public void add(Object dependencyOrKey, Object source) {
+      if (elements.length < size + 2) {
+        elements = Arrays.copyOf(elements, (elements.length*3)/2 + 2);
+      }
+      elements[size++] = dependencyOrKey;
+      elements[size++] = source;
+    }
+
+    public void pop() {
+      elements[--size] = null;
+      elements[--size] = null;
+    }
+
+    public Object get(int i) {
+      return elements[i];
+    }
+
+    public int size() {
+      return size;
     }
   }
 }