Avoid redundant content reads when opening a compare editor#2804
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Avoid redundant content reads when opening a compare editor#2804vogella wants to merge 1 commit into
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Opening a compare editor read each side's contents up to 15 times: the content and structure switching panes looked the viewer descriptors up twice per pane, and every lookup re-ran content-type sniffing and the text heuristic against a fresh stream. The panes now cache the descriptor array computed while creating the viewer, and the sniffing results are memoized per element for the duration of one open, keyed by element identity and reset whenever a different input is examined. Each side is now read at most three times: once for content-type detection, once for the text heuristic, and once for the document shown in the viewer. Viewer selection is unchanged. Contributes to eclipse-platform#2795
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Test Results 54 files ±0 54 suites ±0 58m 21s ⏱️ -37s For more details on these failures, see this check. Results for commit b13fb21. ± Comparison against base commit 32aa15c. |
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Opening a compare editor read each side's contents up to 15 times: the content and structure switching panes looked the viewer descriptors up twice per pane, and every lookup re-ran content-type sniffing and the text heuristic against a fresh stream. The panes now cache the descriptor array computed while creating the viewer, and the sniffing results are memoized per element for the duration of one open, reset whenever a different input is examined. Each side is now read at most three times: once for content-type detection, once for the text heuristic, and once for the actual document; CompareOpenEfficiencyTest's bound tightens from 15 to 3 to lock the improvement in. Viewer selection is unchanged. For inputs whose streams are expensive to produce, such as EGit revisions that re-inflate the blob and re-run smudge filters on every read, this removes most of the I/O on the open path.
Contributes to #2795