Blob DB: Fix flaky BlobDBTest::GCExpiredKeyWhileOverwriting test

Summary:
The test intent to wait until key being overwritten until proceed with garbage collection. It failed to wait for `PutUntil` finally finish. Fixing it.
Closes https://github.com/facebook/rocksdb/pull/3116

Differential Revision: D6222833

Pulled By: yiwu-arbug

fbshipit-source-id: fa9b57a772b92a66cf250b44e7975c43f62f45c5

utilities/blob_db/blob_db_impl.cc

@@ -838,6 +838,7 @@ Status BlobDBImpl::PutWithTTL(const WriteOptions& options,
 
 Status BlobDBImpl::PutUntil(const WriteOptions& options, const Slice& key,
                             const Slice& value, uint64_t expiration) {
+  TEST_SYNC_POINT("BlobDBImpl::PutUntil:Start");
   MutexLock l(&write_mutex_);
   SequenceNumber sequence = GetLatestSequenceNumber() + 1;
   WriteBatch batch;
@@ -845,13 +846,13 @@ Status BlobDBImpl::PutUntil(const WriteOptions& options, const Slice& key,
   if (s.ok()) {
     s = db_->Write(options, &batch);
   }
+  TEST_SYNC_POINT("BlobDBImpl::PutUntil:Finish");
   return s;
 }
 
 Status BlobDBImpl::PutBlobValue(const WriteOptions& options, const Slice& key,
                                 const Slice& value, uint64_t expiration,
                                 SequenceNumber sequence, WriteBatch* batch) {
-  TEST_SYNC_POINT("BlobDBImpl::PutBlobValue:Start");
   Status s;
   std::string index_entry;
   uint32_t column_family_id =
@@ -903,7 +904,6 @@ Status BlobDBImpl::PutBlobValue(const WriteOptions& options, const Slice& key,
     }
   }
 
-  TEST_SYNC_POINT("BlobDBImpl::PutBlobValue:Finish");
   return s;
 }
 

utilities/blob_db/blob_db_test.cc

@@ -642,8 +642,8 @@ TEST_F(BlobDBTest, GCRelocateKeyWhileOverwriting) {
 
   SyncPoint::GetInstance()->LoadDependency(
       {{"BlobDBImpl::GCFileAndUpdateLSM:AfterGetFromBaseDB",
-        "BlobDBImpl::PutBlobValue:Start"},
+        "BlobDBImpl::PutUntil:Start"},
-       {"BlobDBImpl::PutBlobValue:Finish",
+       {"BlobDBImpl::PutUntil:Finish",
         "BlobDBImpl::GCFileAndUpdateLSM:BeforeRelocate"}});
   SyncPoint::GetInstance()->EnableProcessing();
 
@@ -680,8 +680,8 @@ TEST_F(BlobDBTest, GCExpiredKeyWhileOverwriting) {
 
   SyncPoint::GetInstance()->LoadDependency(
       {{"BlobDBImpl::GCFileAndUpdateLSM:AfterGetFromBaseDB",
-        "BlobDBImpl::PutBlobValue:Start"},
+        "BlobDBImpl::PutUntil:Start"},
-       {"BlobDBImpl::PutBlobValue:Finish",
+       {"BlobDBImpl::PutUntil:Finish",
         "BlobDBImpl::GCFileAndUpdateLSM:BeforeDelete"}});
   SyncPoint::GetInstance()->EnableProcessing();