Update DBTestUniversalCompaction.UniversalCompactionSingleSortedRun to use max_size_amplification_percent = 0

Summary: With max_size_amplification_percent = 0 to make sure that DBTestUniversalCompaction.UniversalCompactionSingleSortedRun tests the configuration to compact to one single sorted run.

Test Plan: Run all existing tests

Reviewers: yhchiang, andrewkr, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: leveldb, andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D60021

db/compaction_picker.cc

@@ -1708,14 +1708,14 @@ Compaction* UniversalCompactionPicker::PickCompactionUniversalSizeAmp(
     LogToBuffer(
         log_buffer,
         "[%s] Universal: size amp not needed. newer-files-total-size %" PRIu64
-        "earliest-file-size %" PRIu64,
+        " earliest-file-size %" PRIu64,
         cf_name.c_str(), candidate_size, earliest_file_size);
     return nullptr;
   } else {
     LogToBuffer(
         log_buffer,
         "[%s] Universal: size amp needed. newer-files-total-size %" PRIu64
-        "earliest-file-size %" PRIu64,
+        " earliest-file-size %" PRIu64,
         cf_name.c_str(), candidate_size, earliest_file_size);
   }
   assert(start_index < sorted_runs.size() - 1);

db/db_universal_compaction_test.cc

@@ -127,7 +127,7 @@ TEST_P(DBTestUniversalCompaction, UniversalCompactionSingleSortedRun) {
   options.level0_file_num_compaction_trigger = 0;
   options.compaction_options_universal.size_ratio = 10;
   options.compaction_options_universal.min_merge_width = 2;
-  options.compaction_options_universal.max_size_amplification_percent = 1;
+  options.compaction_options_universal.max_size_amplification_percent = 0;
 
   options.write_buffer_size = 105 << 10;  // 105KB
   options.arena_block_size = 4 << 10;
@@ -151,6 +151,9 @@ TEST_P(DBTestUniversalCompaction, UniversalCompactionSingleSortedRun) {
     dbfull()->TEST_WaitForCompact();
     ASSERT_EQ(NumSortedRuns(0), 1);
   }
+  ASSERT_OK(Put(Key(key_idx), ""));
+  dbfull()->TEST_WaitForCompact();
+  ASSERT_EQ(NumSortedRuns(0), 1);
 }
 
 TEST_P(DBTestUniversalCompaction, OptimizeFiltersForHits) {