Deflake DBBlockCacheTest1.WarmCacheWithBlocksDuringFlush (#10635)

Summary:
Previously, automatic compaction could be triggered prior to the test invoking CompactRange(). It could lead to the following flaky failure:

```
/root/project/db/db_block_cache_test.cc:753: Failure
Expected equality of these values:
  1 + kNumBlocks
    Which is: 11
  options.statistics->getTickerCount(BLOCK_CACHE_INDEX_ADD)
    Which is: 10
```

A sequence leading to this failure was:

* Automatic compaction
  * files [1] [2] trivially moved
  * files [3] [4] [5] [6] trivially moved
* CompactRange()
  * files [7] [8] [9] trivially moved
  * file [10] trivially moved

In such a case, the index/filter block adds that the test expected did not happen since there were no new files.

This PR just tweaks settings to ensure the `CompactRange()` produces one new file.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10635

Reviewed By: cbi42

Differential Revision: D39250869

Pulled By: ajkr

fbshipit-source-id: a3c94c49069e28c49c40b4b80dae0059739d19fd

db/db_block_cache_test.cc

@@ -678,8 +678,8 @@ INSTANTIATE_TEST_CASE_P(DBBlockCacheTest1, DBBlockCacheTest1,
 TEST_P(DBBlockCacheTest1, WarmCacheWithBlocksDuringFlush) {
   Options options = CurrentOptions();
   options.create_if_missing = true;
+  options.disable_auto_compactions = true;
   options.statistics = ROCKSDB_NAMESPACE::CreateDBStatistics();
-  options.max_compaction_bytes = 2000;
 
   BlockBasedTableOptions table_options;
   table_options.block_cache = NewLRUCache(1 << 25, 0, false);
@@ -737,8 +737,10 @@ TEST_P(DBBlockCacheTest1, WarmCacheWithBlocksDuringFlush) {
   }
 
   // Verify compaction not counted
-  ASSERT_OK(db_->CompactRange(CompactRangeOptions(), /*begin=*/nullptr,
+  CompactRangeOptions cro;
-                              /*end=*/nullptr));
+  // Ensure files are rewritten, not just trivially moved.
+  cro.bottommost_level_compaction = BottommostLevelCompaction::kForceOptimized;
+  ASSERT_OK(db_->CompactRange(cro, /*begin=*/nullptr, /*end=*/nullptr));
   EXPECT_EQ(kNumBlocks,
             options.statistics->getTickerCount(BLOCK_CACHE_DATA_ADD));
   // Index and filter blocks are automatically warmed when the new table file