reset refitting_level_ flag to false in error paths (#7403)

Summary:
Reset refitting_level_ flag to false in error paths in DBImpl::ReFitLevel()

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7403

Reviewed By: ajkr

Differential Revision: D23909028

Pulled By: ramvadiv

fbshipit-source-id: 521ad9aadc1b734bef9ef9119d1e1ee1fa8126e9

HISTORY.md

 # Rocksdb Change Log
 ## Unreleased
+### Bug fixes
+* Fixed a bug after a `CompactRange()` with `CompactRangeOptions::change_level` set fails due to a conflict in the level change step, which caused all subsequent calls to `CompactRange()` with `CompactRangeOptions::change_level` set to incorrectly fail with a `Status::NotSupported("another thread is refitting")` error.
 ### Public API Change
 * The methods to create and manage EncrypedEnv have been changed.  The EncryptionProvider is now passed to NewEncryptedEnv as a shared pointer, rather than a raw pointer.  Comparably, the CTREncryptedProvider now takes a shared pointer, rather than a reference, to a BlockCipher.  CreateFromString methods have been added to BlockCipher and EncryptionProvider to provide a single API by which different ciphers and providers can be created, respectively.
 * The internal classes (CTREncryptionProvider, ROT13BlockCipher, CTRCipherStream) associated with the EncryptedEnv have been moved out of the public API.  To create a CTREncryptionProvider, one can either use EncryptionProvider::NewCTRProvider, or EncryptionProvider::CreateFromString("CTR").  To create a new ROT13BlockCipher, one can either use BlockCipher::NewROT13Cipher or BlockCipher::CreateFromString("ROT13").

db/db_compaction_test.cc

@@ -5655,7 +5655,6 @@ TEST_F(DBCompactionTest, ChangeLevelCompactRangeConflictsWithManual) {
 
   GenerateNewFile(&rnd, &key_idx);
   GenerateNewFile(&rnd, &key_idx);
-  ASSERT_OK(dbfull()->TEST_WaitForCompact());
   ASSERT_EQ("1,1,2", FilesPerLevel(0));
 
   // The background thread will refit L2->L1 while the
@@ -5719,6 +5718,81 @@ TEST_F(DBCompactionTest, ChangeLevelCompactRangeConflictsWithManual) {
   refit_level_thread.join();
 }
 
+TEST_F(DBCompactionTest, ChangeLevelErrorPathTest) {
+  // This test is added to ensure that RefitLevel() error paths are clearing
+  // internal flags and to test that subsequent valid RefitLevel() calls
+  // succeeds
+  Options options = CurrentOptions();
+  options.memtable_factory.reset(
+      new SpecialSkipListFactory(KNumKeysByGenerateNewFile - 1));
+  options.level0_file_num_compaction_trigger = 2;
+  options.num_levels = 3;
+  Reopen(options);
+
+  ASSERT_EQ("", FilesPerLevel(0));
+
+  // Setup an LSM with three levels populated.
+  Random rnd(301);
+  int key_idx = 0;
+  GenerateNewFile(&rnd, &key_idx);
+  ASSERT_EQ("1", FilesPerLevel(0));
+  {
+    CompactRangeOptions cro;
+    cro.change_level = true;
+    cro.target_level = 2;
+    ASSERT_OK(dbfull()->CompactRange(cro, nullptr, nullptr));
+  }
+  ASSERT_EQ("0,0,2", FilesPerLevel(0));
+
+  auto start_idx = key_idx;
+  GenerateNewFile(&rnd, &key_idx);
+  GenerateNewFile(&rnd, &key_idx);
+  auto end_idx = key_idx - 1;
+  ASSERT_EQ("1,1,2", FilesPerLevel(0));
+
+  // Next two CompactRange() calls are used to test exercise error paths within
+  // RefitLevel() before triggering a valid RefitLevel() call
+
+  // Trigger a refit to L1 first
+  {
+    std::string begin_string = Key(start_idx);
+    std::string end_string = Key(end_idx);
+    Slice begin(begin_string);
+    Slice end(end_string);
+
+    CompactRangeOptions cro;
+    cro.change_level = true;
+    cro.target_level = 1;
+    ASSERT_OK(dbfull()->CompactRange(cro, &begin, &end));
+  }
+  ASSERT_EQ("0,3,2", FilesPerLevel(0));
+
+  // Try a refit from L2->L1 - this should fail and exercise error paths in
+  // RefitLevel()
+  {
+    // Select key range that matches the bottom most level (L2)
+    std::string begin_string = Key(0);
+    std::string end_string = Key(start_idx - 1);
+    Slice begin(begin_string);
+    Slice end(end_string);
+
+    CompactRangeOptions cro;
+    cro.change_level = true;
+    cro.target_level = 1;
+    ASSERT_NOK(dbfull()->CompactRange(cro, &begin, &end));
+  }
+  ASSERT_EQ("0,3,2", FilesPerLevel(0));
+
+  // Try a valid Refit request to ensure, the path is still working
+  {
+    CompactRangeOptions cro;
+    cro.change_level = true;
+    cro.target_level = 1;
+    ASSERT_OK(dbfull()->CompactRange(cro, nullptr, nullptr));
+  }
+  ASSERT_EQ("0,5", FilesPerLevel(0));
+}
+
 #endif  // !defined(ROCKSDB_LITE)
 
 }  // namespace ROCKSDB_NAMESPACE

db/db_impl/db_impl_compaction_flush.cc

@@ -1348,12 +1348,14 @@ Status DBImpl::ReFitLevel(ColumnFamilyData* cfd, int level, int target_level) {
   if (to_level != level) {
     if (to_level > level) {
       if (level == 0) {
+        refitting_level_ = false;
         return Status::NotSupported(
             "Cannot change from level 0 to other levels.");
       }
       // Check levels are empty for a trivial move
       for (int l = level + 1; l <= to_level; l++) {
         if (vstorage->NumLevelFiles(l) > 0) {
+          refitting_level_ = false;
           return Status::NotSupported(
               "Levels between source and target are not empty for a move.");
         }
@@ -1363,6 +1365,7 @@ Status DBImpl::ReFitLevel(ColumnFamilyData* cfd, int level, int target_level) {
       // Check levels are empty for a trivial move
       for (int l = to_level; l < level; l++) {
         if (vstorage->NumLevelFiles(l) > 0) {
+          refitting_level_ = false;
           return Status::NotSupported(
               "Levels between source and target are not empty for a move.");
         }