Bug #3584
closed
Streaming fallback for template rules should affect the whole mode or possibly the whole stylesheet
Applies to branch:
9.8, trunk
Fix Committed on Branch:
9.8, trunk
Fixed in Maintenance Release:
Description
When one template rule in a mode is found to be not streamable, and the STREAMING_FALLBACK configuration option is enabled, we are marking that particular template rule as non-streamable. This isn't going to work: once we've started streaming a document, we can't suddenly pass a streamed node to a template rule that does (say) preceding-sibling::node on it.
Test case: run Transform with options
-xsl:si-value-of-101.xsl -t -s:si-value-of-100.xml --streamingFallback:on
in XSLT30 test suite directory tests/strm/si-value-of
With -jit:off we get a hard XTSE3430 failure (after a fallback warning). With -jit:on we get a fallback warning and then a run-time NPE.
- Description updated (diff)
- Category set to Streaming
- Applies to branch 9.8, trunk added
The options streamingFallback and jit are basically incompatible. If we use JIT compilation then we might not discover that a template rule is non-streamable until we're half way through processing the source document, and at this point we have streamable nodes (we haven't built a tree) so it's too late to switch to non-streaming. I think the simplest way to tackle this is that if streamingFallback has been requested, we ignore the request (and fail anyway) if a non-streamable template is found during JIT processing.
In the case of xsl:source-document we need to change the strategy. Currently this compiles into different code depending on the value of the streamable attribute. If fallback to non-streaming is necessitated because some template rule is non-streamable, it may be too late to recompile the xsl;source-document instruction. It therefore needs to be able to make a run-time switch into non-streamed execution - which is probably a good thing anyway, because it means we can give better diagnostics.
The changes here are starting to become sufficiently extensive that I think patching 9.8 to make this work is probably not a good idea. Instead I propose to fix the bug by dropping the feature (streaming fallback) on the 9.8 branch, and implementing it afresh on the development branch.
- Status changed from New to Resolved
- Fix Committed on Branch 9.8, trunk added
For 9.9 I've implemented this and tested for a number of non-streamability conditions in the new test set streaming-fallback.
For 9.8 I've made cases that won't readily work (especially non-streamable template rules) no longer attempt fallback, with an explanation.
- Status changed from Resolved to Closed
- % Done changed from 0 to 100
- Fixed in Maintenance Release 9.8.0.8 added
Bug fix applied in the Saxon 9.8.0.8 maintenance release.
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