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desruisseaux pushed a commit to branch geoapi-4.0
in repository https://gitbox.apache.org/repos/asf/sis.git
The following commit(s) were added to refs/heads/geoapi-4.0 by this push:
new b9edb1f Add a note about another failed attempt to optimize.
b9edb1f is described below
commit b9edb1fb3863c20314c6a30b84f0cc2576a9ed3b
Author: Martin Desruisseaux <[email protected]>
AuthorDate: Thu Dec 31 10:56:33 2020 +0100
Add a note about another failed attempt to optimize.
---
.../internal/processing/image/IsolineTracer.java | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git
a/core/sis-feature/src/main/java/org/apache/sis/internal/processing/image/IsolineTracer.java
b/core/sis-feature/src/main/java/org/apache/sis/internal/processing/image/IsolineTracer.java
index 364b186..71af85f 100644
---
a/core/sis-feature/src/main/java/org/apache/sis/internal/processing/image/IsolineTracer.java
+++
b/core/sis-feature/src/main/java/org/apache/sis/internal/processing/image/IsolineTracer.java
@@ -267,6 +267,27 @@ final class IsolineTracer {
*/
@SuppressWarnings("AssertWithSideEffects")
final void interpolate() throws TransformException {
+ /*
+ * Note: `interpolateMissingLeftSide()` and
`interpolateMissingTopSide(…)` should do interpolations
+ * only for cells in the first column and first row respectively.
We could avoid those method calls
+ * for all other cells if we add two flags in the `isDataAbove`
bitmask: FIRST_ROW and FIRST_COLUMN.
+ * The switch cases them become something like below:
+ *
+ * case <bitmask> | FIRST_COLUMN | FIRST_ROW:
+ * case <bitmask> | FIRST_COLUMN: {
+ * interpolateMissingLeftSide();
+ * // Fall through
+ * }
+ * case <bitmask> | FIRST_ROW:
+ * case <bitmask>: {
+ * // Interpolations on other borders.
+ * break;
+ * }
+ *
+ * We tried that approach, but benchmarking on Java 15 suggested a
small performance decrease
+ * instead than an improvement. It may be worth to try again in
the future, after advancement
+ * in compiler technology.
+ */
switch (isDataAbove) {
default: {
throw new AssertionError(isDataAbove); // Should
never happen.
