Add benchmark for System.getProperty() vs. AccessController/GetPropertyAction.

Comparing the performance of these options is interesting because
libcore carries patches to short-circuit such logic in a few places.

This CL came out of a verbal discussion of http://r.android.com/710427

Benchmark results on a 5.5" Google Pixel device from 2016:
Using the legacy security code costs approx. 500 nanoseconds
per invocation (1136 vs. 1061 ns) when not specifying a default value,
or, or 320 nanoseconds (1041 vs. 710 ns) when specifying a default
value (1061 vs. 740 ns).

Both properties that are accessed (user.language and user.region)
have nonempty values on the device that was tested.

I ran the benchmark a couple of times; here's the output from one run:

Trial Report (1 of 4):
  Experiment {instrument=runtime, benchmarkMethod=timeAccessController_getPropertyAction, vm=default, parameters={}}
  Results:
    runtime(ns): min=1136.75, 1st qu.=1136.75, median=1136.75, mean=1136.75, 3rd qu.=1136.75, max=1136.75
Trial Report (2 of 4):
  Experiment {instrument=runtime, benchmarkMethod=timeAccessController_getPropertyAction_default, vm=default, parameters={}}
  Results:
    runtime(ns): min=1061.38, 1st qu.=1061.38, median=1061.38, mean=1061.38, 3rd qu.=1061.38, max=1061.38
Trial Report (3 of 4):
  Experiment {instrument=runtime, benchmarkMethod=timeSystem_getProperty, vm=default, parameters={}}
  Results:
    runtime(ns): min=634.09, 1st qu.=634.09, median=634.09, mean=634.09, 3rd qu.=634.09, max=634.09
Trial Report (4 of 4):
  Experiment {instrument=runtime, benchmarkMethod=timeSystem_getProperty_default, vm=default, parameters={}}
  Results:
    runtime(ns): min=740.08, 1st qu.=740.08, median=740.08, mean=740.08, 3rd qu.=740.08, max=740.08

Test: vogar --benchmark --verbose benchmarks/GetSystemPropertyBenchmark.java

Change-Id: I77461a5007351b144b2dc09ac7c194240332636d

1 files changed, 60 insertions, 0 deletions

diff --git a/benchmarks/src/benchmarks/GetSystemPropertyBenchmark.java b/benchmarks/src/benchmarks/GetSystemPropertyBenchmark.java
new file mode 100644
index 0000000000..3a93285db3
--- /dev/null
+++ b/benchmarks/src/benchmarks/GetSystemPropertyBenchmark.java
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2018 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;
+
+import java.security.AccessController;
+
+import sun.security.action.GetPropertyAction;
+
+/**
+ * Compares performance of accessing system properties via
+ * legacy security code
+ * {@code AccessController.doPrivileged(new GetPropertyAction(key[, default]))}
+ * vs. direct invocation of {@code System.getProperty(key[, default])}.
+ *
+ * As of 2018-07, libcore carries some patches to perform such short-circuiting,
+ * so it's interesting to know how much better it performs.
+ */
+public class GetSystemPropertyBenchmark {
+
+    public void timeSystem_getProperty_default(int reps) {
+        for (int i = 0; i < reps; i++) {
+            System.getProperty("user.language", "en");
+        }
+    }
+
+    public void timeSystem_getProperty(int reps) {
+        for (int i = 0; i < reps; i++) {
+            System.getProperty("user.region");
+        }
+    }
+
+    public void timeAccessController_getPropertyAction(int reps) {
+        for (int i = 0; i < reps; i++) {
+            AccessController.doPrivileged(
+                    new GetPropertyAction("user.language", "en"));
+        }
+    }
+
+    public void timeAccessController_getPropertyAction_default(int reps) {
+        for (int i = 0; i < reps; i++) {
+            AccessController.doPrivileged(
+                    new GetPropertyAction("user.region"));
+        }
+    }
+
+}