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Commit 13e11e83 authored by Christopher Tate's avatar Christopher Tate
Browse files

Add buffer-size parameter to FastXmlSerializer ctor 

Also increase the default internal buffer size from 8kb to 32kb.  We
have evidence that we're incurring a fair bit of "extra" disk write load
in various common circumstances like SharedPreferences, and this should
help eliminate that.

Bug 63432101
Test: bit CtsContentTestCases:.SharedPreferencesTest

Change-Id: Iba4768262142555a279284b2ae70741424ee2184
parent 46307b11

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

+29 −12
Original line number Diff line number Diff line
@@ -49,18 +49,19 @@ public class FastXmlSerializer implements XmlSerializer { 
        null,     null,     null,     null,     "<",   null,     ">",   null,   // 56-63

    };



    private static final int BUFFER_LEN = 8192;

    private static final int DEFAULT_BUFFER_LEN = 32*1024;



    private static String sSpace = "                                                              ";



    private final char[] mText = new char[BUFFER_LEN];

    private final int mBufferLen;

    private final char[] mText;

    private int mPos;



    private Writer mWriter;



    private OutputStream mOutputStream;

    private CharsetEncoder mCharset;

    private ByteBuffer mBytes = ByteBuffer.allocate(BUFFER_LEN);

    private ByteBuffer mBytes;



    private boolean mIndent = false;

    private boolean mInTag;
@@ -68,9 +69,25 @@ public class FastXmlSerializer implements XmlSerializer { 
    private int mNesting = 0;

    private boolean mLineStart = true;



    public FastXmlSerializer() {

        this(DEFAULT_BUFFER_LEN);

    }



    /**

     * Allocate a FastXmlSerializer with the given internal output buffer size.  If the

     * size is zero or negative, then the default buffer size will be used.

     *

     * @param bufferSize Size in bytes of the in-memory output buffer that the writer will use.

     */

    public FastXmlSerializer(int bufferSize) {

        mBufferLen = (bufferSize > 0) ? bufferSize : DEFAULT_BUFFER_LEN;

        mText = new char[mBufferLen];

        mBytes = ByteBuffer.allocate(mBufferLen);

    }



    private void append(char c) throws IOException {

        int pos = mPos;

        if (pos >= (BUFFER_LEN-1)) {

        if (pos >= (mBufferLen-1)) {

            flush();

            pos = mPos;

        }
@@ -79,17 +96,17 @@ public class FastXmlSerializer implements XmlSerializer { 
    }



    private void append(String str, int i, final int length) throws IOException {

        if (length > BUFFER_LEN) {

        if (length > mBufferLen) {

            final int end = i + length;

            while (i < end) {

                int next = i + BUFFER_LEN;

                append(str, i, next<end ? BUFFER_LEN : (end-i));

                int next = i + mBufferLen;

                append(str, i, next<end ? mBufferLen : (end-i));

                i = next;

            }

            return;

        }

        int pos = mPos;

        if ((pos+length) > BUFFER_LEN) {

        if ((pos+length) > mBufferLen) {

            flush();

            pos = mPos;

        }
@@ -98,17 +115,17 @@ public class FastXmlSerializer implements XmlSerializer { 
    }



    private void append(char[] buf, int i, final int length) throws IOException {

        if (length > BUFFER_LEN) {

        if (length > mBufferLen) {

            final int end = i + length;

            while (i < end) {

                int next = i + BUFFER_LEN;

                append(buf, i, next<end ? BUFFER_LEN : (end-i));

                int next = i + mBufferLen;

                append(buf, i, next<end ? mBufferLen : (end-i));

                i = next;

            }

            return;

        }

        int pos = mPos;

        if ((pos+length) > BUFFER_LEN) {

        if ((pos+length) > mBufferLen) {

            flush();

            pos = mPos;

        }