From 2a7b100bdaae8daf42d71425b9d9a4fbfab6a908 Mon Sep 17 00:00:00 2001
From: Maciej Szeszko <mszeszko@meta.com>
Date: Wed, 29 Jan 2025 13:39:49 -0800
Subject: [PATCH] Get rid of keys reshuffling

---
 db/db_test.cc     | 21 ++++++++++++++++++++-
 db/db_test_util.h |  4 ++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/db/db_test.cc b/db/db_test.cc
index 6bb900bc811..80c773b0aac 100644
--- a/db/db_test.cc
+++ b/db/db_test.cc
@@ -5290,7 +5290,6 @@ TEST_F(DBTest, DynamicLevelCompressionPerLevel) {
   for (int i = 0; i < kNKeys; i++) {
     keys[i] = i;
   }
-  RandomShuffle(std::begin(keys), std::end(keys));
 
   Random rnd(301);
   Options options;
@@ -5367,10 +5366,30 @@ TEST_F(DBTest, DynamicLevelCompressionPerLevel) {
   }));
   ColumnFamilyMetaData cf_meta;
   db_->GetColumnFamilyMetaData(&cf_meta);
+
+  // Ensure that files are non-overlapping and encompass full key range
+  // between 'smallestkey' and 'largestkey' recorded in CF file metadata.
+  std::vector<std::pair<std::string, std::string>> no_overlap_intervals;
+  for (size_t i = 0; i < cf_meta.levels.size(); i++) {
+    for (const auto& file : cf_meta.levels[i].files) {
+      auto smallest_int_key = IdFromKey(file.smallestkey);
+      auto largest_int_key = IdFromKey(file.largestkey);
+      ASSERT_EQ(file.num_entries, largest_int_key - smallest_int_key + 1);
+
+      for (const auto& interval: no_overlap_intervals) {
+        ASSERT_FALSE(file.smallestkey <= interval.second && file.largestkey >= interval.first);
+      }
+      no_overlap_intervals.emplace_back(std::make_pair(file.smallestkey, file.largestkey));
+    }
+  }
+
   for (const auto& file : cf_meta.levels[4].files) {
     listener->SetExpectedFileName(dbname_ + file.name);
     Slice start(file.smallestkey), limit(file.largestkey);
     const RangePtr ranges(&start, &limit);
+    // Given verification from above, we're guaranteed that by deleting all the
+    // files in [<smallestkey>, <largestkey>] range, we're effectively deleting
+    // that very single file and nothing more.
     EXPECT_OK(dbfull()->DeleteFilesInRanges(dbfull()->DefaultColumnFamily(),
                                             &ranges, true /* include_end */));
   }
diff --git a/db/db_test_util.h b/db/db_test_util.h
index 4b5bc48450d..8be174fac68 100644
--- a/db/db_test_util.h
+++ b/db/db_test_util.h
@@ -1106,6 +1106,10 @@ class DBTestBase : public testing::Test {
     return std::string(buf);
   }
 
+  static int IdFromKey(const std::string& key) {
+    return std::stoi(key.substr(3));
+  }
+
   static bool ShouldSkipOptions(int option_config, int skip_mask = kNoSkip);
 
   // Switch to a fresh database with the next option configuration to