benchmarks: Add a String benchmark for replace.

Benchmarks have been added for the single char replacements as
well as Charsequence replacements.

bug: 28060800

Change-Id: Ib0fc466b38ff2037a422d5197694605f371a6959
diff --git a/benchmarks/src/benchmarks/regression/StringReplaceBenchmark.java b/benchmarks/src/benchmarks/regression/StringReplaceBenchmark.java
new file mode 100644
index 0000000..a527633
--- /dev/null
+++ b/benchmarks/src/benchmarks/regression/StringReplaceBenchmark.java
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2016 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
+ */
+
+package benchmarks.regression;
+
+import com.google.caliper.Param;
+
+public class StringReplaceBenchmark {
+    static enum StringLengths {
+        EMPTY(""),
+        L_16(makeString(16)),
+        L_64(makeString(64)),
+        L_256(makeString(256)),
+        L_512(makeString(512));
+
+        private final String value;
+
+        private StringLengths(String s) {
+            this.value = s;
+        }
+    }
+
+    private static final String makeString(int length) {
+        final String sequence8 = "abcdefghijklmnop";
+        final int numAppends = (length / 16) - 1;
+        StringBuilder stringBuilder = new StringBuilder(length);
+
+        // (n-1) occurences of "abcdefghijklmnop"
+        for (int i = 0; i < numAppends; ++i) {
+            stringBuilder.append(sequence8);
+        }
+
+        // and one final occurence of qrstuvwx.
+        stringBuilder.append("qrstuvwx");
+
+        return stringBuilder.toString();
+    }
+
+    @Param private StringLengths s;
+
+    public void timeReplaceCharNonExistent(int reps) {
+        for (int i = 0; i < reps; ++i) {
+            s.value.replace('z', '0');
+        }
+    }
+
+    public void timeReplaceCharRepeated(int reps) {
+        for (int i = 0; i < reps; ++i) {
+            s.value.replace('a', '0');
+        }
+    }
+
+    public void timeReplaceSingleChar(int reps) {
+        for (int i = 0; i < reps; ++i) {
+            s.value.replace('q', '0');
+        }
+    }
+
+    public void timeReplaceSequenceNonExistent(int reps) {
+        for (int i = 0; i < reps; ++i) {
+            s.value.replace("fish", "0");
+        }
+    }
+
+    public void timeReplaceSequenceRepeated(int reps) {
+        for (int i = 0; i < reps; ++i) {
+            s.value.replace("jklm", "0");
+        }
+    }
+
+    public void timeReplaceSingleSequence(int reps) {
+        for (int i = 0; i < reps; ++i) {
+            s.value.replace("qrst", "0");
+        }
+    }
+}