From 331535530240cb91e44002fca36ec9927548ada9 Mon Sep 17 00:00:00 2001
From: Evgeni Dobranov <evgeni.dobranov@mongodb.com>
Date: Tue, 8 Oct 2019 22:35:35 +0000
Subject: SERVER-38020 Log progress for record store and index traversal during
 collection validation

---
 src/mongo/db/catalog/validate_adaptor.cpp | 29 +++++++++++++++++++++++++++++
 src/mongo/db/catalog/validate_adaptor.h   |  8 ++++++++
 2 files changed, 37 insertions(+)

diff --git a/src/mongo/db/catalog/validate_adaptor.cpp b/src/mongo/db/catalog/validate_adaptor.cpp
index 524719dd5c4..bdb81c33faf 100644
--- a/src/mongo/db/catalog/validate_adaptor.cpp
+++ b/src/mongo/db/catalog/validate_adaptor.cpp
@@ -38,6 +38,7 @@
 #include "mongo/db/catalog/index_catalog.h"
 #include "mongo/db/catalog/index_consistency.h"
 #include "mongo/db/catalog/throttle_cursor.h"
+#include "mongo/db/curop.h"
 #include "mongo/db/index/index_access_method.h"
 #include "mongo/db/index/index_descriptor.h"
 #include "mongo/db/index/wildcard_access_method.h"
@@ -126,6 +127,7 @@ Status ValidateAdaptor::validateRecord(OperationContext* opCtx,
 
         for (const auto& keyString : documentKeySet) {
             try {
+                _totalIndexKeys++;
                 _indexConsistency->addDocKey(opCtx, keyString, &indexInfo, recordId);
             } catch (...) {
                 return exceptionToStatus();
@@ -146,6 +148,14 @@ void ValidateAdaptor::traverseIndex(OperationContext* opCtx,
 
     bool isFirstEntry = true;
 
+    // The progress meter will be inactive after traversing the record store to allow the message
+    // and the total to be set to different values.
+    if (!_progress->isActive()) {
+        const char* curopMessage = "Validate: scanning index entries";
+        stdx::unique_lock<Client> lk(*opCtx->getClient());
+        _progress.set(CurOp::get(opCtx)->setProgress_inlock(curopMessage, _totalIndexKeys));
+    }
+
     const KeyString::Version version =
         index->accessMethod()->getSortedDataInterface()->getKeyStringVersion();
     KeyString::Builder firstKeyString(
@@ -187,11 +197,13 @@ void ValidateAdaptor::traverseIndex(OperationContext* opCtx,
         if (descriptor->getIndexType() == IndexType::INDEX_WILDCARD &&
             indexEntry->loc == kWildcardMultikeyMetadataRecordId) {
             _indexConsistency->removeMultikeyMetadataPath(indexEntry->keyString, &indexInfo);
+            _progress->hit();
             numKeys++;
             continue;
         }
 
         _indexConsistency->addIndexKey(indexEntry->keyString, &indexInfo, indexEntry->loc);
+        _progress->hit();
         numKeys++;
         isFirstEntry = false;
         prevIndexKeyStringValue = indexEntry->keyString;
@@ -220,12 +232,27 @@ void ValidateAdaptor::traverseRecordStore(OperationContext* opCtx,
     results->valid = true;
     RecordId prevRecordId;
 
+    // In case validation occurs twice and the progress meter persists after index traversal
+    if (_progress.get() && _progress->isActive()) {
+        _progress->finished();
+    }
+
+    // Because the progress meter is intended as an approximation, it's sufficient to get the number
+    // of records when we begin traversing, even if this number may deviate from the final number.
+    const char* curopMessage = "Validate: scanning documents";
+    const auto totalRecords = _validateState->getCollection()->getRecordStore()->numRecords(opCtx);
+    {
+        stdx::unique_lock<Client> lk(*opCtx->getClient());
+        _progress.set(CurOp::get(opCtx)->setProgress_inlock(curopMessage, totalRecords));
+    }
+
     const std::unique_ptr<SeekableRecordThrottleCursor>& traverseRecordStoreCursor =
         _validateState->getTraverseRecordStoreCursor();
     for (auto record =
              traverseRecordStoreCursor->seekExact(opCtx, _validateState->getFirstRecordId());
          record;
          record = traverseRecordStoreCursor->next(opCtx)) {
+        _progress->hit();
         ++_numRecords;
         interruptIntervalNumBytes += record->data.size();
         if (_numRecords % kInterruptIntervalNumRecords == 0 ||
@@ -286,6 +313,8 @@ void ValidateAdaptor::traverseRecordStore(OperationContext* opCtx,
             opCtx, _numRecords, dataSizeTotal);
     }
 
+    _progress->finished();
+
     output->appendNumber("nInvalidDocuments", nInvalid);
     output->appendNumber("nrecords", _numRecords);
 }
diff --git a/src/mongo/db/catalog/validate_adaptor.h b/src/mongo/db/catalog/validate_adaptor.h
index c035cb167e0..87f843db129 100644
--- a/src/mongo/db/catalog/validate_adaptor.h
+++ b/src/mongo/db/catalog/validate_adaptor.h
@@ -30,6 +30,7 @@
 #pragma once
 
 #include "mongo/db/catalog/validate_state.h"
+#include "mongo/util/progress_meter.h"
 
 namespace mongo {
 
@@ -93,5 +94,12 @@ private:
     // Saves the record count from the record store traversal to be used later to validate the index
     // entries count. Reset every time traverseRecordStore() is called.
     long long _numRecords = 0;
+
+    // For reporting progress during record store and index traversal.
+    ProgressMeterHolder _progress;
+
+    // The total number of index keys is stored during the first validation phase, since this
+    // count may change during a second phase.
+    uint64_t _totalIndexKeys = 0;
 };
 }  // namespace mongo
-- 
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