Revert "WIP ADAM fix to DOMFile - regressions introduced by '[optimis…

…e] Optimize start position of DOMPage findRecord()' and '[optimise] Switch 'Optimize start position of DOMPage findRecord()' to use ThreadLocal so there is an offset per-thread'" This reverts commit 9b28b88.
evolvedbinary · Dec 13, 2024 · 9b8c98f · 9b8c98f
1 parent 9b28b88
commit 9b8c98f
Showing 1 changed file with 26 additions and 64 deletions.
diff --git a/exist-core/src/main/java/org/exist/storage/dom/DOMFile.java b/exist-core/src/main/java/org/exist/storage/dom/DOMFile.java
@@ -3058,7 +3058,7 @@ protected final class DOMPage implements Cacheable {
         // set to true if the page has been removed from the cache
         boolean invalidated = false;
 
-//        private final ThreadLocal<Integer> lastFound = ThreadLocal.withInitial(() -> 0);
+        private final ThreadLocal<Integer> lastFound = ThreadLocal.withInitial(() -> 0);
 
         DOMPage() {
             this.page = createNewPage();
@@ -3105,10 +3105,33 @@ Page createNewPage() {
             }
         }
 
+        /**
+         * Optimize scanning for records in a page
+         * Based on the fact that we are looking for the same thing again,
+         * Or we are looking for something after the last thing.
+         *
+         * So, start the scan where we left off before.
+         *
+         * @param targetId the tuple id we are looking for in the page
+         *
+         * @return a record describing the tuple, if we found it, otherwise null
+         */
         RecordPos findRecord(final short targetId) {
-            final int dlen = pageHeader.getDataLength();
+            final int startScan = lastFound.get();
+            RecordPos rec = findRecordInRange(targetId, startScan, pageHeader.getDataLength());
+            if (rec == null) {
+                rec = findRecordInRange(targetId, 0, startScan);
+            }
+            if (rec != null) {
+                // start from here again next time; step back over the tuple id
+                lastFound.set(rec.offset - LENGTH_TID);
+            }
+            return rec;
+        }
+
+        RecordPos findRecordInRange(final short targetId, final int from, final int to) {
             RecordPos rec = null;
-            for (int pos = 0; pos < dlen;) {
+            for (int pos = from; pos < to;) {
                 final short tupleID = ByteConversion.byteToShort(data, pos);
                 pos += LENGTH_TID;
                 if (ItemId.matches(tupleID, targetId)) {
@@ -3139,67 +3162,6 @@ RecordPos findRecord(final short targetId) {
             return rec;
         }
 
-//        /**
-//         * Optimize scanning for records in a page
-//         * Based on the fact that we are looking for the same thing again,
-//         * Or we are looking for something after the last thing.
-//         *
-//         * So, start the scan where we left off before.
-//         *
-//         * @param targetId the tuple id we are looking for in the page
-//         *
-//         * @return a record describing the tuple, if we found it, otherwise null
-//         */
-//        RecordPos findRecord(final short targetId) {
-//            final int startScan = lastFound.get();
-//            try {
-//                RecordPos rec = findRecordInRange(targetId, startScan, pageHeader.getDataLength());
-//                if (rec == null) {
-//                    rec = findRecordInRange(targetId, 0, startScan);
-//                }
-//                if (rec != null) {
-//                    // start from here again next time; step back over the tuple id
-//                    lastFound.set(rec.offset - LENGTH_TID);
-//                }
-//                return rec;
-//            } catch (ArrayIndexOutOfBoundsException e) {
-//                throw e;
-//            }
-//        }
-//
-//        RecordPos findRecordInRange(final short targetId, final int from, final int to) {
-//            RecordPos rec = null;
-//            for (int pos = from; pos < to;) {
-//                final short tupleID = ByteConversion.byteToShort(data, pos);
-//                pos += LENGTH_TID;
-//                if (ItemId.matches(tupleID, targetId)) {
-//                    if (ItemId.isLink(tupleID)) {
-//                        rec = new RecordPos(pos, this, tupleID, true);
-//                    } else {
-//                        rec = new RecordPos(pos, this, tupleID);
-//                    }
-//                    break;
-//                } else if (ItemId.isLink(tupleID)) {
-//                    pos += LENGTH_FORWARD_LOCATION;
-//                } else {
-//                    final short vlen = ByteConversion.byteToShort(data, pos);
-//                    pos += LENGTH_DATA_LENGTH;
-//                    if (vlen < 0) {
-//                        LOG.error("page = {}; pos = {}; vlen = {}; tupleID = {}; target = {}", page.getPageNum(), pos, vlen, tupleID, targetId);
-//                    }
-//                    if (ItemId.isRelocated(tupleID)) {
-//                        pos += LENGTH_ORIGINAL_LOCATION + vlen;
-//                    } else {
-//                        pos += vlen;
-//                    }
-//                    if (vlen == OVERFLOW) {
-//                        pos += LENGTH_OVERFLOW_LOCATION;
-//                    }
-//                }
-//            }
-//            return rec;
-//        }
-
         @Override
         public long getKey() {
             return page.getPageNum();