Revert "Revert "Matcher: Avoid excessive String copies.""

This reverts commit 53e4e15bb0fc2f789274998f3ce62c4fc021fbe8.

Fixes a memory leak introduced in 53e4e15bb0f. Also :
- switches to using ScopedStringChars to simplify the code further.
- better ICU error checking.

Bug: 36366255
Bug: 36818684

Test: cts -m CtsLibcoreTestCases
Test: ScannerTest on host/x86
Change-Id: I3f108931cd5236be4ff9c0bd608a87701370dbf1

1 files changed, 76 insertions, 0 deletions

diff --git a/benchmarks/src/benchmarks/regression/StringReplaceAllBenchmark.java b/benchmarks/src/benchmarks/regression/StringReplaceAllBenchmark.java
new file mode 100644
index 0000000000..73e797996f
--- /dev/null
+++ b/benchmarks/src/benchmarks/regression/StringReplaceAllBenchmark.java
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2017 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 StringReplaceAllBenchmark {
+    // NOTE: These estimates of MOVEABLE / NON_MOVEABLE are based on a knowledge of
+    // ART implementation details. They make a difference here because JNI calls related
+    // to strings took different paths depending on whether the String in question was
+    // moveable or not.
+    enum StringLengths {
+        EMPTY(""),
+        MOVEABLE_16(makeString(16)),
+        MOVEABLE_256(makeString(256)),
+        MOVEABLE_1024(makeString(1024)),
+        NON_MOVEABLE(makeString(64 * 1024)),
+        BOOT_IMAGE(java.util.jar.JarFile.MANIFEST_NAME);
+
+        private final String value;
+
+        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 timeReplaceAllTrivialPatternNonExistent(int reps) {
+        for (int i = 0; i < reps; ++i) {
+            s.value.replaceAll("fish", "0");
+        }
+    }
+
+    public void timeReplaceTrivialPatternAllRepeated(int reps) {
+        for (int i = 0; i < reps; ++i) {
+            s.value.replaceAll("jklm", "0");
+        }
+    }
+
+    public void timeReplaceAllTrivialPatternSingleOccurence(int reps) {
+        for (int i = 0; i < reps; ++i) {
+            s.value.replaceAll("qrst", "0");
+        }
+    }
+}