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unmarshaller performance: use bulk operations instead of charAt() where possible #1873

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unmarshaller performance: use bulk operations instead of charAt() where possible #1873

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22 changes: 20 additions & 2 deletions .../main/java/org/glassfish/jaxb/runtime/v2/runtime/unmarshaller/ValidatingUnmarshaller.java
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@

package org.glassfish.jaxb.runtime.v2.runtime.unmarshaller;

import org.glassfish.jaxb.runtime.v2.runtime.output.Pcdata;
import org.glassfish.jaxb.runtime.v2.util.FatalAdapter;
import org.glassfish.jaxb.core.v2.runtime.unmarshaller.LocatorEx;
import org.xml.sax.SAXException;
Expand Down Expand Up @@ -99,8 +100,25 @@ public void text( CharSequence pcdata ) throws SAXException {
if(buf.length<len) {
buf = new char[len];
}
for( int i=0;i<len; i++ )
buf[i] = pcdata.charAt(i); // isn't this kinda slow?

// performance optimization: use getChars()/writeTo() if possible
// note: this will become just pcdata.getChars() once minimum supported JDK version reaches 25 (cf. JDK-8343110)
if (pcdata instanceof String) {
((String) pcdata).getChars(0, len, buf, 0);
}
else if (pcdata instanceof StringBuilder) {
((StringBuilder) pcdata).getChars(0, len, buf, 0);
}
else if (pcdata instanceof StringBuffer) {
((StringBuffer) pcdata).getChars(0, len, buf, 0);
}
Comment on lines +109 to +114
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@laurentschoelens laurentschoelens Nov 7, 2025

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Could you use instanceof AbstractStringBuilder since it's extented by both StringBuilder and StringBuffer ?

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@winfriedgerlach winfriedgerlach Nov 7, 2025

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would like to but that class is not public...

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@laurentschoelens laurentschoelens Nov 7, 2025

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oups, yes you're right :)

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@jansupol jansupol Nov 8, 2025

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CharSequence is what you need, implemented by String, StringBuilder, StringBuffer...

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@laurentschoelens laurentschoelens Nov 8, 2025

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Yes but

  • it's already method argument and type of pcdata
  • it doesn't bring optimized method getChars

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@jansupol jansupol Nov 9, 2025

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Ah, sorry. getChars is there since JDK 25 only. I did miss that.

else if (pcdata instanceof Pcdata) {
((Pcdata) pcdata).writeTo(buf, 0);
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@winfriedgerlach winfriedgerlach Nov 7, 2025 •
edited
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looking at the implementation, this should give massive gains for Base64Data, but IntArrayData and IntData also benefit

}
else {
for (int i = 0; i < len; i++)
buf[i] = pcdata.charAt(i); // this is slow due to O(n) range checks
}

validator.characters(buf,0,len);
if(predictor.expectText())
Expand Down