1 files changed, 53 insertions, 0 deletions
diff --git a/tools/preload/ClassRank.java b/tools/preload/ClassRank.java
new file mode 100644
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+++ b/tools/preload/ClassRank.java
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+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.util.Comparator;
+
+/**
+ * Ranks classes for preloading based on how long their operations took
+ * and how early the operations happened. Higher ranked classes come first.
+ */
+class ClassRank implements Comparator<Operation> {
+
+    /**
+     * Increase this number to add more weight to classes which were loaded
+     * earlier.
+     */
+    static final int SEQUENCE_WEIGHT = 500; // 5 ms
+
+    static final int BUCKET_SIZE = 5;
+
+    public int compare(Operation a, Operation b) {
+        // Higher ranked operations should come first.
+        int result = rankOf(b) - rankOf(a);
+        if (result != 0) {
+            return result;
+        }
+
+        // Make sure we don't drop one of two classes w/ the same rank.
+        // If a load and an initialization have the same rank, it's OK
+        // to treat the operations equally.
+        return a.loadedClass.name.compareTo(b.loadedClass.name);
+    }
+
+    /** Ranks the given operation. */
+    private static int rankOf(Operation o) {
+        return o.medianExclusiveTimeMicros()
+                + SEQUENCE_WEIGHT / (o.index / BUCKET_SIZE + 1);
+    }
+}
+
+