Fix calculation of max_total_wal_size in db_options_.max_total_wal_size == 0 case

Summary: This is a regression bug introduced by https://reviews.facebook.net/D24729 . max_total_wal_size would be off the target it should be more and more in the case that the a user holds the current super version after flush or compaction. This patch fixes it

Test Plan: make all check

Reviewers: yhchiang, rven, igor

Reviewed By: igor

Subscribers: ljin, yoshinorim, MarkCallaghan, hermanlee4, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D29961

db/column_family_test.cc

@@ -529,8 +529,28 @@ TEST(ColumnFamilyTest, FlushTest) {
   ASSERT_OK(Put(1, "mirko", "v3"));
   ASSERT_OK(Put(0, "foo", "v2"));
   ASSERT_OK(Put(2, "fodor", "v5"));
+
+  for (int j = 0; j < 2; j++) {
+    ReadOptions ro;
+    std::vector<Iterator*> iterators;
+    // Hold super version.
+    if (j == 0) {
+      ASSERT_OK(db_->NewIterators(ro, handles_, &iterators));
+    }
+
     for (int i = 0; i < 3; ++i) {
+      uint64_t max_total_in_memory_state =
+          dbfull()->TEST_max_total_in_memory_state();
       Flush(i);
+      ASSERT_EQ(dbfull()->TEST_max_total_in_memory_state(),
+                max_total_in_memory_state);
+    }
+    ASSERT_OK(Put(1, "foofoo", "bar"));
+    ASSERT_OK(Put(0, "foofoo", "bar"));
+
+    for (auto* it : iterators) {
+      delete it;
+    }
   }
   Reopen();
 

db/db_impl.cc

@@ -2272,6 +2272,15 @@ SuperVersion* DBImpl::InstallSuperVersion(
     ColumnFamilyData* cfd, SuperVersion* new_sv,
     const MutableCFOptions& mutable_cf_options) {
   mutex_.AssertHeld();
+
+  // Update max_total_in_memory_state_
+  size_t old_memtable_size = 0;
+  auto* old_sv = cfd->GetSuperVersion();
+  if (old_sv) {
+    old_memtable_size = old_sv->mutable_cf_options.write_buffer_size *
+                        old_sv->mutable_cf_options.max_write_buffer_number;
+  }
+
   auto* old = cfd->InstallSuperVersion(
       new_sv ? new_sv : new SuperVersion(), &mutex_, mutable_cf_options);
 
@@ -2281,11 +2290,6 @@ SuperVersion* DBImpl::InstallSuperVersion(
   MaybeScheduleFlushOrCompaction();
 
   // Update max_total_in_memory_state_
-  size_t old_memtable_size = 0;
-  if (old) {
-    old_memtable_size = old->mutable_cf_options.write_buffer_size *
-                        old->mutable_cf_options.max_write_buffer_number;
-  }
   max_total_in_memory_state_ =
       max_total_in_memory_state_ - old_memtable_size +
       mutable_cf_options.write_buffer_size *

db/db_impl.h

@@ -230,6 +230,10 @@ class DBImpl : public DB {
   // REQUIRES: mutex locked
   // pass the pointer that you got from TEST_BeginWrite()
   void TEST_EndWrite(void* w);
+
+  uint64_t TEST_max_total_in_memory_state() {
+    return max_total_in_memory_state_;
+  }
 #endif  // ROCKSDB_LITE
 
   // Returns the list of live files in 'live' and the list

include/rocksdb/options.h

@@ -686,7 +686,7 @@ struct DBOptions {
   // column families whose memtables are backed by the oldest live WAL file
   // (i.e. the ones that are causing all the space amplification). If set to 0
   // (default), we will dynamically choose the WAL size limit to be
-  // [sum of all write_buffer_size * max_write_buffer_number] * 2
+  // [sum of all write_buffer_size * max_write_buffer_number] * 4
   // Default: 0
   uint64_t max_total_wal_size;