Simplify DBWithMaxSpaceAllowedRandomized (#4235)

Summary:
The test has become complicated over the years and hard to reason about the corner cases that makes the test flaky. The patch simplifies the test and also fixes some probable synchronization issues.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4235

Differential Revision: D9187995

Pulled By: maysamyabandeh

fbshipit-source-id: 53c7b060f14367e5a9e361014578c26debfe3d27

db/db_sst_test.cc

@@ -703,26 +703,19 @@ TEST_F(DBSSTTest, DBWithMaxSpaceAllowedRandomized) {
   // When bg_error_ is set we will verify that the DB size is greater
   // than the limit.
 
-  std::vector<int> max_space_limits_mbs = {1, 2, 4, 8, 10};
-  decltype(max_space_limits_mbs)::value_type limit_mb_cb;
-  bool bg_error_set = false;
-  uint64_t total_sst_files_size = 0;
+  std::vector<int> max_space_limits_mbs = {1, 10};
+  std::atomic<bool> bg_error_set(false);
 
-  std::atomic<int> estimate_multiplier(1);
-  int reached_max_space_on_flush = 0;
-  int reached_max_space_on_compaction = 0;
+  std::atomic<int> reached_max_space_on_flush(0);
+  std::atomic<int> reached_max_space_on_compaction(0);
   rocksdb::SyncPoint::GetInstance()->SetCallBack(
       "DBImpl::FlushMemTableToOutputFile:MaxAllowedSpaceReached",
       [&](void* arg) {
         Status* bg_error = static_cast<Status*>(arg);
         bg_error_set = true;
-        GetAllSSTFiles(&total_sst_files_size);
         reached_max_space_on_flush++;
-        // low limit for size calculated using sst files
-        ASSERT_GE(total_sst_files_size, limit_mb_cb * 1024 * 1024);
         // clear error to ensure compaction callback is called
         *bg_error = Status::OK();
-        estimate_multiplier++;  // used in the main loop assert
       });
 
   rocksdb::SyncPoint::GetInstance()->SetCallBack(
@@ -735,15 +728,11 @@ TEST_F(DBSSTTest, DBWithMaxSpaceAllowedRandomized) {
       "CompactionJob::FinishCompactionOutputFile:MaxAllowedSpaceReached",
       [&](void* /*arg*/) {
         bg_error_set = true;
-        GetAllSSTFiles(&total_sst_files_size);
         reached_max_space_on_compaction++;
       });
 
   for (auto limit_mb : max_space_limits_mbs) {
     bg_error_set = false;
-    total_sst_files_size = 0;
-    estimate_multiplier = 1;
-    limit_mb_cb = limit_mb;
     rocksdb::SyncPoint::GetInstance()->ClearTrace();
     rocksdb::SyncPoint::GetInstance()->EnableProcessing();
     std::shared_ptr<SstFileManager> sst_file_manager(NewSstFileManager(env_));
@@ -757,21 +746,17 @@ TEST_F(DBSSTTest, DBWithMaxSpaceAllowedRandomized) {
 
     sfm->SetMaxAllowedSpaceUsage(limit_mb * 1024 * 1024);
 
-    int keys_written = 0;
-    uint64_t estimated_db_size = 0;
+    // It is easy to detect if the test is stuck in a loop. No need for
+    // complex termination logic.
     while (true) {
       auto s = Put(RandomString(&rnd, 10), RandomString(&rnd, 50));
       if (!s.ok()) {
         break;
       }
-      keys_written++;
-      // Check the estimated db size vs the db limit just to make sure we
-      // dont run into an infinite loop
-      estimated_db_size = keys_written * 60;  // ~60 bytes per key
-      ASSERT_LT(estimated_db_size,
-                estimate_multiplier * limit_mb * 1024 * 1024 * 2);
     }
     ASSERT_TRUE(bg_error_set);
+    uint64_t total_sst_files_size = 0;
+    GetAllSSTFiles(&total_sst_files_size);
     ASSERT_GE(total_sst_files_size, limit_mb * 1024 * 1024);
     rocksdb::SyncPoint::GetInstance()->DisableProcessing();
   }