leerho commented on code in PR #669:
URL: https://github.com/apache/datasketches-java/pull/669#discussion_r2187798899
##########
src/main/java/org/apache/datasketches/common/MemorySegmentStatus.java:
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@@ -51,8 +51,41 @@ public interface MemorySegmentStatus {
* <p>Returns false if either argument is null;</p>
*
* @param that The given MemorySegment.
- * @return true if the backing MemorySegment of this object hierarchy refers
to the same MemorySegment of <i>that</i>.
+ * @return true if an internally referenced MemorySegment refers to the same
MemorySegment as <i>that</i>.
*/
boolean isSameResource(final MemorySegment that);
+ /**
+ * Returns true if the two given MemorySegments refer to the same backing
resource,
+ * which is either an off-heap memory address and size, or the same on-heap
array object.
+ *
+ * <p>If both segment are off-heap, they both must have the same starting
address and the same size.</p>
+ *
+ * <p>For on-heap segments, both segments must be based on or derived from
the same array object and neither segment
+ * can be read-only.</p>
+ *
+ * <p>Returns false if either argument is null;</p>
+ *
+ * @param seg1 The first given MemorySegment
+ * @param seg2 The second given MemorySegment
+ * @return true if both MemorySegments are determined to be the same backing
memory.
+ */
+ static boolean isSameResource(final MemorySegment seg1, final MemorySegment
seg2) {
+ if ((seg1 == null) || (seg2 == null)) { return false; }
+ if (!seg1.scope().isAlive() || !seg2.scope().isAlive()) {
+ throw new IllegalArgumentException("Both arguments must be alive.");
+ }
+ final boolean seg1Native = seg1.isNative();
+ final boolean seg2Native = seg2.isNative();
+ if (seg1Native ^ seg2Native) { return false; }
+ if (seg1Native && seg2Native) { //both off heap
+ return (seg1.address() == seg2.address()) && (seg1.byteSize() ==
seg2.byteSize());
+ }
+ //both on heap
+ if (seg1.isReadOnly() || seg2.isReadOnly()) {
+ throw new IllegalArgumentException("Cannot determine
'isSameBackingMemory(..)' on heap if either MemorySegment is Read-only.");
Review Comment:
Yes. How dumb! My mistake! If they are both on heap I can just compare with
"==".
Fixed.
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