Fix BloscCompression class poisoning when Blosc is unavailable#6
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GeffUtils.DEFAULT_COMPRESSION was a static field initialized at class
load time. When computeFirstDimChunk() was called before N5ZarrWriter
was constructed, loading GeffUtils triggered new BloscCompression(),
which threw UnsatisfiedLinkError and permanently marked the class as
failed. N5ZarrWriter subsequently called Class.forName("BloscCompression")
internally and received NoClassDefFoundError, which it does not catch,
causing a crash.
Replace the static field with a lazy-initialization holder (the
initialization-on-demand holder idiom). DefaultCompressionHolder.INSTANCE
is only initialized the first time a write method calls defaultCompression(),
by which point N5ZarrWriter has already handled the UnsatisfiedLinkError
itself. The subsequent NoClassDefFoundError thrown inside
createDefaultCompression() is caught by the existing Throwable handler and
falls back to RawCompression as intended.
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GeffUtils.DEFAULT_COMPRESSION was a static field initialized at class load time. When computeFirstDimChunk() was called before N5ZarrWriter was constructed, loading GeffUtils triggered new BloscCompression(), which threw UnsatisfiedLinkError and permanently marked the class as failed. N5ZarrWriter subsequently called Class.forName("BloscCompression") internally and received NoClassDefFoundError, which it does not catch, causing a crash.
Replace the static field with a lazy-initialization holder (the initialization-on-demand holder idiom). DefaultCompressionHolder.INSTANCE is only initialized the first time a write method calls defaultCompression(), by which point N5ZarrWriter has already handled the UnsatisfiedLinkError itself. The subsequent NoClassDefFoundError thrown inside createDefaultCompression() is caught by the existing Throwable handler and falls back to RawCompression as intended.