fix: #177 Infinite loop when saving buffer with transclusions #263
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Fixing a long-lasting (issue open since March 2023, but it had been an known issue before it) issue that was difficult to reproduce. The fix is to stop using the text-properties of the transclusion that hold markers of beginning and ending points of itself, which is meant to remember and indicate its own the location; or the range of "this" transclusion at point. The text-properties are named `org-transclusion-beg-mkr' and `org-transclusion-end-mkr'. They are replaced with use of a new text-property `org-transclusion-id' and function `org-transclusion-at-point'. This new function uses `prop-match' with `org-transclusion-id' to identify the range of "this" transclusion at point only when it is needed, thus eliminating the need for memorizing it as a pair of markers. Stable reproduction was achieved and recorded in a comment to the GitHub issue at #177 (comment). A quick summary of the design hitherto and how the infinite loop occurs is as follows: [Fact / design of org-transclusion] - Each transclusion has text-properties org-transclusion-beg-mkr and org-transclusion-end-mkr. - They hold markers to keep track of where the transclusion begins and ends. [Now what happens] - In some combination of undo and buffer-save with transclusions, the markers can temporarily point to non-existing locations in the buffer. - If the garbage collection happens to run at this moment, it will sweep these pointers. Now they end up pointing to start of the buffer (point 1). docs: Update NEWS
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Fixing a long-lasting (issue open since March 2023, but it had been an known issue before it) issue that was difficult to reproduce.
The fix is to stop using the text-properties of the transclusion that hold markers of beginning and ending points of itself, which is meant to remember and indicate its own the location; or the range of "this" transclusion at point. The text-properties are named
org-transclusion-beg-mkrandorg-transclusion-end-mkr. They are replaced with use of a new text-propertyorg-transclusion-idand functionorg-transclusion-at-point. This new function usestext-property-searchwithorg-transclusion-idto identify the range of "this" transclusion at point only when it is needed, thus eliminating the need for memorizing it as a pair of markers.Stable reproduction was achieved and recorded in a comment to the GitHub issue at #177 (comment).
A quick summary of the design hitherto and how the infinite loop occurs is as follows:
[Fact / design of org-transclusion]
Each transclusion has text-properties
org-transclusion-beg-mkrandorg-transclusion-end-mkr.They hold markers to keep track of where the transclusion begins and ends.
[Now what happens]
In some combination of undo and buffer-save with transclusions, the markers can temporarily point to non-existing locations in the buffer.
If the garbage collection happens to run at this moment, it will sweep these pointers. Now they end up pointing to start of the buffer (point 1).