From 2be5b4c118a77cf15544ce9f8d0464f2d416125c Mon Sep 17 00:00:00 2001
From: Alex Buynytskyy <alexbuy@google.com>
Date: Tue, 10 Aug 2021 11:20:56 -0700
Subject: [PATCH] Cache least recently used output buffer.
- reduce memory allocations especially when Xml is serialized inside a
tight inner loop,
- performance slightly improved.
BEFORE:
100 packages:
[2/4] android.util.XmlPerfTest#timeWrite_Binary: PASSED (10.516s)
timeWrite_Binary_mean: 674979
threadAllocCount_mean: 59
timeWrite_Binary_min: 671194
timeWrite_Binary_median: 674798
timeWrite_Binary_standardDeviation: 3658
threadAllocSize_mean: 530176
10 packages:
[2/4] android.util.XmlPerfTest#timeWrite_Binary: PASSED (10.542s)
timeWrite_Binary_mean: 71113
threadAllocCount_mean: 56
timeWrite_Binary_min: 70201
timeWrite_Binary_median: 71237
timeWrite_Binary_standardDeviation: 692
threadAllocSize_mean: 59136
1 package:
[2/4] android.util.XmlPerfTest#timeWrite_Binary: PASSED (10.091s)
timeWrite_Binary_mean: 15698
threadAllocCount_mean: 56
timeWrite_Binary_min: 15072
timeWrite_Binary_median: 15677
timeWrite_Binary_standardDeviation: 410
threadAllocSize_mean: 6439
AFTER:
100 packages:
[1/1] android.util.XmlPerfTest#timeWrite_Binary: PASSED (10.221s)
timeWrite_Binary_mean: 605862
threadAllocCount_mean: 53
timeWrite_Binary_min: 602353
timeWrite_Binary_median: 604424
timeWrite_Binary_standardDeviation: 4972
threadAllocSize_mean: 492748
10 packages:
[1/1] android.util.XmlPerfTest#timeWrite_Binary: PASSED (10.575s)
timeWrite_Binary_mean: 58710
threadAllocCount_mean: 50
timeWrite_Binary_min: 57551
timeWrite_Binary_median: 57798
timeWrite_Binary_standardDeviation: 2129
threadAllocSize_mean: 21696
1 package:
[1/1] android.util.XmlPerfTest#timeWrite_Binary: PASSED (10.151s)
timeWrite_Binary_mean: 11576
threadAllocCount_mean: 50
timeWrite_Binary_min: 11315
timeWrite_Binary_median: 11381
timeWrite_Binary_standardDeviation: 431
threadAllocSize_mean: 4336
Test: atest FastDataPerfTest XmlPerfTest
Bug: 195994150
Fixes: 195994150
Merged-In: Ieedd27a676d718967c2fac30bc48a68ae636a180
Change-Id: Ieedd27a676d718967c2fac30bc48a68ae636a180
---
.../internal/util/FastDataPerfTest.java | 10 ++--
.../internal/util/BinaryXmlSerializer.java | 9 +++-
.../android/internal/util/FastDataOutput.java | 53 +++++++++++++++++--
3 files changed, 64 insertions(+), 8 deletions(-)
diff --git a/apct-tests/perftests/core/src/com/android/internal/util/FastDataPerfTest.java b/apct-tests/perftests/core/src/com/android/internal/util/FastDataPerfTest.java
index 2700fff4cba1..e3691a783bd6 100644
--- a/apct-tests/perftests/core/src/com/android/internal/util/FastDataPerfTest.java
+++ b/apct-tests/perftests/core/src/com/android/internal/util/FastDataPerfTest.java
@@ -64,9 +64,13 @@ public class FastDataPerfTest {
final BenchmarkState state = mPerfStatusReporter.getBenchmarkState();
while (state.keepRunning()) {
os.reset();
- final FastDataOutput out = new FastDataOutput(os, BUFFER_SIZE);
- doWrite(out);
- out.flush();
+ final FastDataOutput out = FastDataOutput.obtain(os);
+ try {
+ doWrite(out);
+ out.flush();
+ } finally {
+ out.release();
+ }
}
}
diff --git a/core/java/com/android/internal/util/BinaryXmlSerializer.java b/core/java/com/android/internal/util/BinaryXmlSerializer.java
index 9df4bdb157c8..f0ca1edb0b90 100644
--- a/core/java/com/android/internal/util/BinaryXmlSerializer.java
+++ b/core/java/com/android/internal/util/BinaryXmlSerializer.java
@@ -124,7 +124,7 @@ public final class BinaryXmlSerializer implements TypedXmlSerializer {
throw new UnsupportedOperationException();
}
- mOut = new FastDataOutput(os, BUFFER_SIZE);
+ mOut = FastDataOutput.obtain(os);
mOut.write(PROTOCOL_MAGIC_VERSION_0);
mTagCount = 0;
@@ -138,7 +138,9 @@ public final class BinaryXmlSerializer implements TypedXmlSerializer {
@Override
public void flush() throws IOException {
- mOut.flush();
+ if (mOut != null) {
+ mOut.flush();
+ }
}
@Override
@@ -157,6 +159,9 @@ public final class BinaryXmlSerializer implements TypedXmlSerializer {
public void endDocument() throws IOException {
mOut.writeByte(END_DOCUMENT | TYPE_NULL);
flush();
+
+ mOut.release();
+ mOut = null;
}
@Override
diff --git a/core/java/com/android/internal/util/FastDataOutput.java b/core/java/com/android/internal/util/FastDataOutput.java
index cf5b2966d889..bc8496b3bdd3 100644
--- a/core/java/com/android/internal/util/FastDataOutput.java
+++ b/core/java/com/android/internal/util/FastDataOutput.java
@@ -30,6 +30,7 @@ import java.io.IOException;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.Objects;
+import java.util.concurrent.atomic.AtomicReference;
/**
* Optimized implementation of {@link DataOutput} which buffers data in memory
@@ -41,23 +42,26 @@ import java.util.Objects;
public class FastDataOutput implements DataOutput, Flushable, Closeable {
private static final int MAX_UNSIGNED_SHORT = 65_535;
+ private static final int BUFFER_SIZE = 32_768;
+
+ private static AtomicReference<FastDataOutput> sOutCache = new AtomicReference<>();
+
private final VMRuntime mRuntime;
- private final OutputStream mOut;
private final byte[] mBuffer;
private final long mBufferPtr;
private final int mBufferCap;
+ private OutputStream mOut;
private int mBufferPos;
/**
* Values that have been "interned" by {@link #writeInternedUTF(String)}.
*/
- private HashMap<String, Short> mStringRefs = new HashMap<>();
+ private final HashMap<String, Short> mStringRefs = new HashMap<>();
public FastDataOutput(@NonNull OutputStream out, int bufferSize) {
mRuntime = VMRuntime.getRuntime();
- mOut = Objects.requireNonNull(out);
if (bufferSize < 8) {
throw new IllegalArgumentException();
}
@@ -65,6 +69,48 @@ public class FastDataOutput implements DataOutput, Flushable, Closeable {
mBuffer = (byte[]) mRuntime.newNonMovableArray(byte.class, bufferSize);
mBufferPtr = mRuntime.addressOf(mBuffer);
mBufferCap = mBuffer.length;
+
+ setOutput(out);
+ }
+
+ /**
+ * Create a new FastDataOutput object or retrieve one from cache.
+ */
+ public static FastDataOutput obtain(@NonNull OutputStream out) {
+ FastDataOutput instance = sOutCache.getAndSet(null);
+ if (instance != null) {
+ instance.setOutput(out);
+ return instance;
+ }
+ return new FastDataOutput(out, BUFFER_SIZE);
+ }
+
+ /**
+ * Put a FastDataOutput object back into the cache.
+ * You must not touch the object after this call.
+ */
+ public void release() {
+ if (mBufferPos > 0) {
+ throw new IllegalStateException("Lingering data, call flush() before releasing.");
+ }
+
+ mOut = null;
+ mBufferPos = 0;
+ mStringRefs.clear();
+
+ if (mBufferCap == BUFFER_SIZE) {
+ // Try to return to the cache.
+ sOutCache.compareAndSet(null, this);
+ }
+ }
+
+ /**
+ * Re-initializes the object for the new output.
+ */
+ private void setOutput(@NonNull OutputStream out) {
+ mOut = Objects.requireNonNull(out);
+ mBufferPos = 0;
+ mStringRefs.clear();
}
private void drain() throws IOException {
@@ -83,6 +129,7 @@ public class FastDataOutput implements DataOutput, Flushable, Closeable {
@Override
public void close() throws IOException {
mOut.close();
+ release();
}
@Override
--
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