jbewing commented on code in PR #5373:
URL: https://github.com/apache/hbase/pull/5373#discussion_r1385442557
##########
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StoreFileScanner.java:
##########
@@ -486,52 +500,171 @@ public boolean shouldUseScanner(Scan scan, HStore store,
long oldestUnexpiredTS)
@Override
public boolean seekToPreviousRow(Cell originalKey) throws IOException {
try {
- try {
- boolean keepSeeking = false;
- Cell key = originalKey;
- do {
- Cell seekKey = PrivateCellUtil.createFirstOnRow(key);
- if (seekCount != null) seekCount.increment();
- if (!hfs.seekBefore(seekKey)) {
- this.cur = null;
- return false;
- }
- Cell curCell = hfs.getCell();
- Cell firstKeyOfPreviousRow =
PrivateCellUtil.createFirstOnRow(curCell);
-
- if (seekCount != null) seekCount.increment();
- if (!seekAtOrAfter(hfs, firstKeyOfPreviousRow)) {
- this.cur = null;
- return false;
- }
-
- setCurrentCell(hfs.getCell());
- this.stopSkippingKVsIfNextRow = true;
- boolean resultOfSkipKVs;
- try {
- resultOfSkipKVs = skipKVsNewerThanReadpoint();
- } finally {
- this.stopSkippingKVsIfNextRow = false;
- }
- if (!resultOfSkipKVs || getComparator().compareRows(cur,
firstKeyOfPreviousRow) > 0) {
- keepSeeking = true;
- key = firstKeyOfPreviousRow;
- continue;
- } else {
- keepSeeking = false;
- }
- } while (keepSeeking);
- return true;
- } finally {
- realSeekDone = true;
+ if (isFastSeekingEncoding) {
+ return seekToPreviousRowStateless(originalKey);
+ } else if (previousRow == null ||
getComparator().compareRows(previousRow, originalKey) > 0) {
+ return seekToPreviousRowWithoutHint(originalKey);
+ } else {
+ return seekToPreviousRowWithHint(originalKey);
}
} catch (FileNotFoundException e) {
throw e;
} catch (IOException ioe) {
throw new IOException("Could not seekToPreviousRow " + this + " to key "
+ originalKey, ioe);
+ } finally {
+ this.realSeekDone = true;
}
}
+ private boolean seekToPreviousRowWithHint(Cell originalKey) throws
IOException {
+ do {
+ if (previousRow == null) {
+ return seekToPreviousRowWithoutHint(originalKey);
+ }
+
+ Cell firstKeyOfPreviousRow =
PrivateCellUtil.createFirstOnRow(previousRow);
+ if (!seekBeforeAndSaveKeyToPreviousRow(firstKeyOfPreviousRow)) {
+ return false;
+ }
+
+ if (!reseekAtOrAfter(firstKeyOfPreviousRow)) {
+ return false;
+ }
+
+ if (
+ setReadpointAndSkipNewerKvs()
+ && getComparator().compareRows(cur, firstKeyOfPreviousRow) <= 0
+ ) {
+ return true;
+ }
+ } while (true);
+ }
+
+ private boolean seekToPreviousRowWithoutHint(Cell originalKey) throws
IOException {
+ boolean keepSeeking;
+ Cell key = originalKey;
+ do {
+ // Rewind to the cell before the beginning of this row
+ Cell keyAtBeginningOfRow = PrivateCellUtil.createFirstOnRow(key);
+ if (!seekBefore(keyAtBeginningOfRow)) {
+ return false;
+ }
+
+ // Rewind before this row and save what we find as a seek hint
+ Cell firstKeyOfPreviousRow =
PrivateCellUtil.createFirstOnRow(hfs.getCell());
+ if (!seekBeforeAndSaveKeyToPreviousRow(firstKeyOfPreviousRow)) {
+ return false;
+ }
+
+ // Seek back to the start of the previous row
+ if (!reseekAtOrAfter(firstKeyOfPreviousRow)) {
+ return false;
+ }
+
+ if (
+ !setReadpointAndSkipNewerKvs()
+ || getComparator().compareRows(cur, firstKeyOfPreviousRow) > 0
+ ) {
+ keepSeeking = true;
+ key = firstKeyOfPreviousRow;
+ } else {
+ keepSeeking = false;
Review Comment:
Incorporated this by introducing a new helper method
```java
private boolean isStillAtSeekTargetAfterSkippingNewerKvs(Cell seekKey)
throws IOException {
setCurrentCell(hfs.getCell());
return skipNewerKvsNewerThanReadpointReversed() &&
getComparator().compareRows(cur, seekKey) <= 0;
}
private boolean skipNewerKvsNewerThanReadpointReversed() throws IOException {
this.stopSkippingKVsIfNextRow = true;
boolean resultOfSkipKVs;
try {
resultOfSkipKVs = skipKVsNewerThanReadpoint();
} finally {
this.stopSkippingKVsIfNextRow = false;
}
return resultOfSkipKVs;
}
```
that are then utilized like this:
```java
if (isStillAtSeekTargetAfterSkippingNewerKvs(firstKeyOfPreviousRow)) {
return true;
}
key = firstKeyOfPreviousRow;
```
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