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Memoizer: ask any ImageReader instances to remove all but the current reader #4254

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Memoizer: ask any ImageReader instances to remove all but the current reader #4254

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18 changes: 18 additions & 0 deletions components/formats-api/src/loci/formats/ImageReader.java
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Original file line number Diff line number Diff line change
Expand Up @@ -150,6 +150,24 @@ public ImageReader(ClassList<IFormatReader> classList) {

// -- ImageReader API methods --

/**
* Intended for use prior to caching an initialized reader.
* This removes everything except the current reader from the
* list of possible readers to use. Be very careful, and do
* not call this method on an ImageReader that may be reused
* for multiple different files.
*
* If the current reader index is less than 0 (i.e. not initialized),
* this does nothing.
*/
protected void cleanupReaderList() {
if (current >= 0) {
IFormatReader currentReader = readers[current];
current = 0;
readers = new IFormatReader[] {currentReader};
}
}

/**
* Toggles whether or not file system access is allowed when doing type
* detection. By default, file system access is allowed.
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11 changes: 11 additions & 0 deletions components/formats-bsd/src/loci/formats/Memoizer.java
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Expand Up @@ -208,6 +208,17 @@ public void saveRevision(String revision) {

@Override
public void saveReader(IFormatReader reader) {
// clean up reader list in any instances of ImageReader
IFormatReader r = reader;
while (r instanceof ReaderWrapper || r instanceof ImageReader) {
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@gerring gerring Oct 7, 2025

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Suggest it would be cleaner to have ReaderWrapper and ImageReader both implement an interface 'ReaderContainer' (or use existing interface) for the method:
IFormatReader getReader();
Then test r for being an instance of that. Slightly bigger change so understand why not done :)

Since ImageReader requires the clean method the interface could have something like:
IFormatReader getCleanReader();

Which is implemented in ImageReader as cleanupReaderList(); return getReader(); and in ReaderWrapper to just return getReader().

Not a major point though.

if (r instanceof ImageReader) {
ImageReader ir = (ImageReader) r;
ir.cleanupReaderList();
r = ir.getReader();
}
else r = ((ReaderWrapper) r).getReader();
}

kryo.writeObject(output, reader.getClass());
kryo.writeObject(output, reader);
}
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