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Commit 19f8adfb authored by Alex Buynytskyy's avatar Alex Buynytskyy
Browse files

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

Change-Id: Ieedd27a676d718967c2fac30bc48a68ae636a180
parent 5cef861a

apct-tests/perftests/core/src/com/android/internal/util/FastDataPerfTest.java

+7 −3
Original line number Diff line number Diff line
@@ -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);

            final FastDataOutput out = FastDataOutput.obtain(os);

            try {

                doWrite(out);

                out.flush();

            } finally {

                out.release();

            }

        }

    }

core/java/com/android/internal/util/BinaryXmlSerializer.java

+7 −2
Original line number Diff line number Diff line
@@ -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;
@@ -138,8 +138,10 @@ public final class BinaryXmlSerializer implements TypedXmlSerializer { 


    @Override

    public void flush() throws IOException {

        if (mOut != null) {

            mOut.flush();

        }

    }



    @Override

    public void startDocument(@Nullable String encoding, @Nullable Boolean standalone)
@@ -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

core/java/com/android/internal/util/FastDataOutput.java

+50 −3
Original line number Diff line number Diff line
@@ -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