regression for trigger compaction logic

Summary: as subject

Test Plan: manually run db_bench confirmed

Reviewers: dhruba

Differential Revision: https://reviews.facebook.net/D4809

db/db_bench.cc

@@ -146,8 +146,8 @@ static int FLAGS_max_bytes_for_level_multiplier = 10;
 // Number of files in level-0 that will trigger put stop.
 static int FLAGS_level0_stop_writes_trigger = 12;
 
-// Nulber of files in level-0 that will slow down writes.
-static int FLAGS_level0_slowdown_writes_trigger = 4;
+// Number of files in level-0 that will slow down writes.
+static int FLAGS_level0_slowdown_writes_trigger = 8;
 
 // posix or hdfs environment
 static leveldb::Env* FLAGS_env = leveldb::Env::Default();

db/version_set.cc

@@ -702,15 +702,16 @@ VersionSet::VersionSet(const std::string& dbname,
 	compact_pointer_ = new std::string[options_->num_levels];
 	max_file_size_ = new uint64_t[options_->num_levels];
 	level_max_bytes_ = new uint64_t[options->num_levels];
-	max_file_size_[0] = options_->target_file_size_base;
-	level_max_bytes_[0] = options_->max_bytes_for_level_base;
 	int target_file_size_multiplier = options_->target_file_size_multiplier;
 	int max_bytes_multiplier = options_->max_bytes_for_level_multiplier;
-	int i = 1;
-	while (i < options_->num_levels) {
+	for (int i = 0; i < options_->num_levels; i++) {
+	  if (i > 1) {
 	    max_file_size_[i] = max_file_size_[i-1] * target_file_size_multiplier;
 	    level_max_bytes_[i] = level_max_bytes_[i-1] * max_bytes_multiplier;
-		i++;
+	  } else {
+	    max_file_size_[i] = options_->target_file_size_base;
+	    level_max_bytes_[i] = options_->max_bytes_for_level_base;
+	  }
 	}
   AppendVersion(new Version(this));
 }

util/options.cc

@@ -28,7 +28,7 @@ Options::Options()
       level0_stop_writes_trigger(12),
       max_mem_compaction_level(2),
       target_file_size_base(2 * 1048576),
-      target_file_size_multiplier(10),
+      target_file_size_multiplier(1),
       max_bytes_for_level_base(10 * 1048576),
       max_bytes_for_level_multiplier(10),
       expanded_compaction_factor(25),