account for L0 size in estimated compaction bytes

Summary:
also changed the `>` in the comparison against `level0_file_num_compaction_trigger` into a `>=` since exactly `level0_file_num_compaction_trigger` can trigger a compaction from L0.
Closes https://github.com/facebook/rocksdb/pull/2179

Differential Revision: D4915772

Pulled By: ajkr

fbshipit-source-id: e38fec6253de6f9a40e61734615c6670d84038aa

db/compaction_picker_test.cc

@@ -952,7 +952,7 @@ TEST_F(CompactionPickerTest, NotScheduleL1IfL0WithHigherPri3) {
 TEST_F(CompactionPickerTest, EstimateCompactionBytesNeeded1) {
   int num_levels = ioptions_.num_levels;
   ioptions_.level_compaction_dynamic_level_bytes = false;
-  mutable_cf_options_.level0_file_num_compaction_trigger = 3;
+  mutable_cf_options_.level0_file_num_compaction_trigger = 4;
   mutable_cf_options_.max_bytes_for_level_base = 1000;
   mutable_cf_options_.max_bytes_for_level_multiplier = 10;
   NewVersionStorage(num_levels, kCompactionStyleLevel);

db/db_properties_test.cc

@@ -913,7 +913,7 @@ TEST_F(DBPropertiesTest, EstimatePendingCompBytes) {
   Flush();
   ASSERT_TRUE(dbfull()->GetIntProperty(
       "rocksdb.estimate-pending-compaction-bytes", &int_num));
-  ASSERT_EQ(int_num, 0U);
+  ASSERT_GT(int_num, 0U);
 
   ASSERT_OK(dbfull()->Put(writeOpt, "k3", big_value));
   Flush();

db/version_set.cc

@@ -1230,15 +1230,18 @@ void VersionStorageInfo::EstimateCompactionBytesNeeded(
   // accumulated bytes.
 
   uint64_t bytes_compact_to_next_level = 0;
+  uint64_t level_size = 0;
+  for (auto* f : files_[0]) {
+    level_size += f->fd.GetFileSize();
+  }
   // Level 0
   bool level0_compact_triggered = false;
-  if (static_cast<int>(files_[0].size()) >
+  if (static_cast<int>(files_[0].size()) >=
-      mutable_cf_options.level0_file_num_compaction_trigger) {
+          mutable_cf_options.level0_file_num_compaction_trigger ||
+      level_size >= mutable_cf_options.max_bytes_for_level_base) {
     level0_compact_triggered = true;
-    for (auto* f : files_[0]) {
+    estimated_compaction_needed_bytes_ = level_size;
-      bytes_compact_to_next_level += f->fd.GetFileSize();
+    bytes_compact_to_next_level = level_size;
-    }
-    estimated_compaction_needed_bytes_ = bytes_compact_to_next_level;
   } else {
     estimated_compaction_needed_bytes_ = 0;
   }
@@ -1246,7 +1249,7 @@ void VersionStorageInfo::EstimateCompactionBytesNeeded(
   // Level 1 and up.
   uint64_t bytes_next_level = 0;
   for (int level = base_level(); level <= MaxInputLevel(); level++) {
-    uint64_t level_size = 0;
+    level_size = 0;
     if (bytes_next_level > 0) {
 #ifndef NDEBUG
       uint64_t level_size2 = 0;