mikemccand commented on code in PR #12872:
URL: https://github.com/apache/lucene/pull/12872#discussion_r1418947126
##########
lucene/core/src/java/org/apache/lucene/index/CheckIndex.java:
##########
@@ -873,13 +876,26 @@ public int compare(String a, String b) {
if (0 == result.numBadSegments) {
result.clean = true;
} else {
- msg(
- infoStream,
- "WARNING: "
- + result.numBadSegments
- + " broken segments (containing "
- + result.totLoseDocCount
- + " documents) detected");
+ if (result.numBadSegmentsWithoutSegmentInfo > 0) {
+ msg(
+ infoStream,
+ "WARNING: "
+ + result.numBadSegments
+ + " broken segments (containing "
Review Comment:
Maybe say `containing at least`?
##########
lucene/core/src/java/org/apache/lucene/index/CheckIndex.java:
##########
@@ -664,7 +667,7 @@ public int compare(String a, String b) {
// failure (fastFail == false). so if we get here, we should // always
have a valid lastCommit:
assert lastCommit != null;
- if (lastCommit == null) {
+ if (lastCommit == null) { // TODO: Remove/move unreachable if statement?
Review Comment:
Hmm this might still happen? E.g. some transient `IOException` or an Access
Denied or so?
##########
lucene/core/src/java/org/apache/lucene/index/CheckIndex.java:
##########
@@ -957,6 +974,9 @@ private Status.SegmentInfoStatus testSegment(
SegmentReader reader = null;
try {
+ if (info.info.maxDoc() == 0) {
+ throw new CheckIndexException(" this segment has missing or corrupt
segment info");
Review Comment:
Remove the extra space before `this`?
Also, can we include specifics about which segment we were unable to read
the `.si` for in the exception message?
##########
lucene/core/src/java/org/apache/lucene/index/SegmentInfos.java:
##########
@@ -389,13 +389,39 @@ private static void parseSegmentInfos(
}
long totalDocs = 0;
+ SegmentInfo info;
for (int seg = 0; seg < numSegments; seg++) {
String segName = input.readString();
byte[] segmentID = new byte[StringHelper.ID_LENGTH];
input.readBytes(segmentID, 0, segmentID.length);
Codec codec = readCodec(input);
- SegmentInfo info =
- codec.segmentInfoFormat().read(directory, segName, segmentID,
IOContext.READ);
+ try {
+ info = codec.segmentInfoFormat().read(directory, segName, segmentID,
IOContext.READ);
+ } catch (FileNotFoundException | NoSuchFileException e) {
Review Comment:
Hmm can we upgrade this to catch any "normal" (not crazy things like OOME)
`Throwable`? E.g. if the `.si` file had some bits scrambled or what not we
will get a more exotic exception or maybe an exception because the checksum is
mismatched.
Can we somehow return the root cause exception here and include it in
`CheckIndexException` that we raise above?
##########
lucene/core/src/java/org/apache/lucene/index/CheckIndex.java:
##########
@@ -957,6 +974,9 @@ private Status.SegmentInfoStatus testSegment(
SegmentReader reader = null;
try {
+ if (info.info.maxDoc() == 0) {
Review Comment:
Ahh I see, you now separately handle the `maxDoc == 0` case, here. But,
what if an index has an illegal 0 doc segment, and an intact `.si`? We will
now (incorrectly) state that it is missing its `SegmentInfo`? Maybe we could
add a separate boolean somewhere to track `segmentInfoMissing` or so?
##########
lucene/core/src/java/org/apache/lucene/index/SegmentInfos.java:
##########
@@ -389,13 +389,39 @@ private static void parseSegmentInfos(
}
long totalDocs = 0;
+ SegmentInfo info;
for (int seg = 0; seg < numSegments; seg++) {
String segName = input.readString();
byte[] segmentID = new byte[StringHelper.ID_LENGTH];
input.readBytes(segmentID, 0, segmentID.length);
Codec codec = readCodec(input);
- SegmentInfo info =
- codec.segmentInfoFormat().read(directory, segName, segmentID,
IOContext.READ);
+ try {
+ info = codec.segmentInfoFormat().read(directory, segName, segmentID,
IOContext.READ);
+ } catch (FileNotFoundException | NoSuchFileException e) {
+ // https://github.com/apache/lucene/issues/7820 - If we throw a
CorruptIndex exception here,
+ // a missing segment info will cause parseSegmentInfos() to
short-circuit and stop reading
+ // the rest of the segments. So, when encountering a segment with a
missing
+ // segment info (.si) file, we initialize an empty segment info
(containing 0 docs)
+ // to keep track of the segment name, so that we can continue reading
other segments, and
+ // the segment with the missing .si file can be later validated or
exorcised by CheckIndex()
+ info =
Review Comment:
Hmm I don't like that this will suppress corruption when `SegmentInfos` is
being loaded NOT from `CheckIndex`? This is the wrong layer to have such
leniency? This method should throw the exception back up to the caller and
caller should handle properly?
Could we instead 1) create a subclass of `CorruptIndexException`, maybe
`CorruptSegmentInfoException` or so, 2) require that caller pass in the segment
name, and root cause exception, when creating it, and 3) catch any `Throwable`
here and re-throw that subclass?
Then we can fix `CheckIndex` to specifically catch that, pull the segment
name out, and do its thing.
##########
lucene/core/src/java/org/apache/lucene/index/CheckIndex.java:
##########
@@ -948,7 +965,7 @@ private Status.SegmentInfoStatus testSegment(
segInfoStat.maxDoc = info.info.maxDoc();
final Version version = info.info.getVersion();
- if (info.info.maxDoc() <= 0) {
+ if (info.info.maxDoc() < 0) {
Review Comment:
Hmm why did you have to remove the `0` case? Lucene considers this
corruption (IW should never flush or merge to a 0 doc segment).
##########
lucene/core/src/java/org/apache/lucene/index/CheckIndex.java:
##########
@@ -4270,11 +4290,21 @@ public int doCheck(Options opts) throws IOException,
InterruptedException {
+ result.totLoseDocCount
+ " documents would be lost, if -exorcise were specified\n");
} else {
- opts.out.println("WARNING: " + result.totLoseDocCount + " documents
will be lost\n");
- opts.out.println(
- "NOTE: will write new segments file in 5 seconds; this will remove
"
- + result.totLoseDocCount
- + " docs from the index. YOU WILL LOSE DATA. THIS IS YOUR LAST
CHANCE TO CTRL+C!");
+ if (result.numBadSegmentsWithoutSegmentInfo > 0) {
+ opts.out.println(
+ "WARNING: " + result.totLoseDocCount + " or more documents will
be lost\n");
Review Comment:
Can we change the wording to `at least ...`? I think that's stronger / more
alarming on casual read than ` or more`.
Or maybe `more than XX documents will be lost`, since we (almost certainly)
know the lost segment(s) have `maxDoc > 0`?
Whichever wording we use, let's be consistent in the thrown exception
message above too.
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