Double speed of Parcel.writeString().
Previous logic was using GetStringUTFChars() and GetStringCritical(),
which resulted in making a new temporary heap allocation and an extra
memcpy(). The new approach in this CL bypasses those operations by
asking the JNI helpers to copy directly into the Parcel buffer.
This does mean that the contract for writing strings (prefixed with
length) is now duplicated in Parcel.cpp and android_os_Parcel.cpp,
so we leave docs to ensure future maintainers keep them in sync.
Benchmarking shows that this change improves performance by ~36%
for UTF-8 strings and ~52% for UTF-16 strings:
Before:
timeWriteString8[simple]_mean: 1323
timeWriteString8[complex]_mean: 2103
timeWriteString16[simple]_mean: 1427
timeWriteString16[complex]_mean: 1368
After:
timeWriteString8[simple]_mean: 846
timeWriteString8[complex]_mean: 1671
timeWriteString16[simple]_mean: 685
timeWriteString16[complex]_mean: 748
Bug: 172562452
Test: atest CorePerfTests:android.os.ParcelStringPerfTest
Change-Id: Ibacce2547ecc7a050b698cee8aa5b4e3bc45956f
diff --git a/apct-tests/perftests/core/src/android/os/ParcelStringPerfTest.java b/apct-tests/perftests/core/src/android/os/ParcelStringPerfTest.java
new file mode 100644
index 0000000..2b861cb
--- /dev/null
+++ b/apct-tests/perftests/core/src/android/os/ParcelStringPerfTest.java
@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2020 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 android.os;
+
+import android.perftests.utils.BenchmarkState;
+import android.perftests.utils.PerfStatusReporter;
+
+import androidx.test.filters.LargeTest;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+import java.util.Arrays;
+import java.util.Collection;
+
+@LargeTest
+@RunWith(Parameterized.class)
+public class ParcelStringPerfTest {
+ @Rule
+ public PerfStatusReporter mPerfStatusReporter = new PerfStatusReporter();
+
+ @Parameterized.Parameter(0)
+ public String mName;
+ @Parameterized.Parameter(1)
+ public String mValue;
+
+ @Parameterized.Parameters(name = "{0}")
+ public static Collection<Object[]> getParameters() {
+ return Arrays.asList(new Object[][] {
+ { "simple", "com.example.typical_package_name" },
+ { "complex", "從不喜歡孤單一個 - 蘇永康／吳雨霏" },
+ });
+ }
+
+ @Test
+ public void timeWriteString8() {
+ final Parcel parcel = Parcel.obtain();
+ final BenchmarkState state = mPerfStatusReporter.getBenchmarkState();
+ while (state.keepRunning()) {
+ parcel.setDataPosition(0);
+ parcel.writeString8(mValue);
+ }
+ }
+
+ @Test
+ public void timeWriteString16() {
+ final Parcel parcel = Parcel.obtain();
+ final BenchmarkState state = mPerfStatusReporter.getBenchmarkState();
+ while (state.keepRunning()) {
+ parcel.setDataPosition(0);
+ parcel.writeString16(mValue);
+ }
+ }
+}
diff --git a/core/jni/android_os_Parcel.cpp b/core/jni/android_os_Parcel.cpp
index 355ef0c..f05c6a4 100644
--- a/core/jni/android_os_Parcel.cpp
+++ b/core/jni/android_os_Parcel.cpp
@@ -252,20 +252,25 @@
signalExceptionForError(env, clazz, err);
}
-static void android_os_Parcel_writeString8(JNIEnv* env, jclass clazz, jlong nativePtr, jstring val)
-{
+static void android_os_Parcel_writeString8(JNIEnv *env, jclass clazz, jlong nativePtr,
+ jstring val) {
Parcel* parcel = reinterpret_cast<Parcel*>(nativePtr);
- if (parcel != NULL) {
- status_t err = NO_MEMORY;
+ if (parcel != nullptr) {
+ status_t err = NO_ERROR;
if (val) {
- const size_t len = env->GetStringUTFLength(val);
- const char* str = env->GetStringUTFChars(val, 0);
- if (str) {
- err = parcel->writeString8(str, len);
- env->ReleaseStringUTFChars(val, str);
+ // NOTE: Keep this logic in sync with Parcel.cpp
+ const size_t len = env->GetStringLength(val);
+ const size_t allocLen = env->GetStringUTFLength(val);
+ err = parcel->writeInt32(allocLen);
+ char *data = reinterpret_cast<char*>(parcel->writeInplace(allocLen + sizeof(char)));
+ if (data != nullptr) {
+ env->GetStringUTFRegion(val, 0, len, data);
+ *(data + allocLen) = 0;
+ } else {
+ err = NO_MEMORY;
}
} else {
- err = parcel->writeString8(NULL, 0);
+ err = parcel->writeString8(nullptr, 0);
}
if (err != NO_ERROR) {
signalExceptionForError(env, clazz, err);
@@ -273,21 +278,25 @@
}
}
-static void android_os_Parcel_writeString16(JNIEnv* env, jclass clazz, jlong nativePtr, jstring val)
-{
+static void android_os_Parcel_writeString16(JNIEnv *env, jclass clazz, jlong nativePtr,
+ jstring val) {
Parcel* parcel = reinterpret_cast<Parcel*>(nativePtr);
- if (parcel != NULL) {
- status_t err = NO_MEMORY;
+ if (parcel != nullptr) {
+ status_t err = NO_ERROR;
if (val) {
- const jchar* str = env->GetStringCritical(val, 0);
- if (str) {
- err = parcel->writeString16(
- reinterpret_cast<const char16_t*>(str),
- env->GetStringLength(val));
- env->ReleaseStringCritical(val, str);
+ // NOTE: Keep this logic in sync with Parcel.cpp
+ const size_t len = env->GetStringLength(val);
+ const size_t allocLen = len * sizeof(char16_t);
+ err = parcel->writeInt32(len);
+ char *data = reinterpret_cast<char*>(parcel->writeInplace(allocLen + sizeof(char16_t)));
+ if (data != nullptr) {
+ env->GetStringRegion(val, 0, len, reinterpret_cast<jchar*>(data));
+ *reinterpret_cast<char16_t*>(data + allocLen) = 0;
+ } else {
+ err = NO_MEMORY;
}
} else {
- err = parcel->writeString16(NULL, 0);
+ err = parcel->writeString16(nullptr, 0);
}
if (err != NO_ERROR) {
signalExceptionForError(env, clazz, err);