remove_internal_filter_policy

Summary:
1. remove class InternalFilterPolicy in db/dbformat.h
2. Transformation from internal key to user key is done in filter_block.cc
3. This is a preparation for patch D20979

Test Plan:
make all check
valgrind ./db_test

Reviewers: igor, yhchiang, ljin, sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D22509

Author: Feng Zhu

db/dbformat.cc

@@ -127,26 +127,6 @@ void InternalKeyComparator::FindShortSuccessor(std::string* key) const {
   }
 }
 
-const char* InternalFilterPolicy::Name() const {
-  return user_policy_->Name();
-}
-
-void InternalFilterPolicy::CreateFilter(const Slice* keys, int n,
-                                        std::string* dst) const {
-  // We rely on the fact that the code in table.cc does not mind us
-  // adjusting keys[].
-  Slice* mkey = const_cast<Slice*>(keys);
-  for (int i = 0; i < n; i++) {
-    mkey[i] = ExtractUserKey(keys[i]);
-    // TODO(sanjay): Suppress dups?
-  }
-  user_policy_->CreateFilter(keys, n, dst);
-}
-
-bool InternalFilterPolicy::KeyMayMatch(const Slice& key, const Slice& f) const {
-  return user_policy_->KeyMayMatch(ExtractUserKey(key), f);
-}
-
 LookupKey::LookupKey(const Slice& user_key, SequenceNumber s) {
   size_t usize = user_key.size();
   size_t needed = usize + 13;  // A conservative estimate

db/dbformat.h

@@ -124,19 +124,6 @@ class InternalKeyComparator : public Comparator {
   int Compare(const ParsedInternalKey& a, const ParsedInternalKey& b) const;
 };
 
-// Filter policy wrapper that converts from internal keys to user keys
-class InternalFilterPolicy : public FilterPolicy {
- private:
-  std::shared_ptr<const FilterPolicy> shared_ptr_;
-  const FilterPolicy* const user_policy_;
- public:
-  explicit InternalFilterPolicy(std::shared_ptr<const FilterPolicy> p)
-    : shared_ptr_(p), user_policy_(p.get()) {}
-  virtual const char* Name() const;
-  virtual void CreateFilter(const Slice* keys, int n, std::string* dst) const;
-  virtual bool KeyMayMatch(const Slice& key, const Slice& filter) const;
-};
-
 // Modules in this directory should keep internal keys wrapped inside
 // the following class instead of plain strings so that we do not
 // incorrectly use string comparisons instead of an InternalKeyComparator.

table/block_based_table_builder.cc

@@ -492,7 +492,7 @@ void BlockBasedTableBuilder::Add(const Slice& key, const Slice& value) {
   }
 
   if (r->filter_block != nullptr) {
-    r->filter_block->AddKey(key);
+    r->filter_block->AddKey(ExtractUserKey(key));
   }
 
   r->last_key.assign(key.data(), key.size());

table/block_based_table_factory.cc

@@ -38,10 +38,6 @@ BlockBasedTableFactory::BlockBasedTableFactory(
       table_options_.block_size_deviation > 100) {
     table_options_.block_size_deviation = 0;
   }
-  if (table_options_.filter_policy) {
-    auto* p = new InternalFilterPolicy(table_options_.filter_policy);
-    table_options_.filter_policy.reset(p);
-  }
 }
 
 Status BlockBasedTableFactory::NewTableReader(

table/block_based_table_reader.cc

@@ -1067,9 +1067,8 @@ bool BlockBasedTable::PrefixMayMatch(const Slice& internal_key) {
     s = handle.DecodeFrom(&handle_value);
     assert(s.ok());
     auto filter_entry = GetFilter(true /* no io */);
-    may_match =
-      filter_entry.value == nullptr ||
-      filter_entry.value->PrefixMayMatch(handle.offset(), internal_prefix);
+    may_match = filter_entry.value == nullptr ||
+                filter_entry.value->PrefixMayMatch(handle.offset(), prefix);
     filter_entry.Release(rep_->table_options.block_cache.get());
   }
 
@@ -1105,9 +1104,8 @@ Status BlockBasedTable::Get(
 
     BlockHandle handle;
     bool may_not_exist_in_filter =
-      filter != nullptr &&
-      handle.DecodeFrom(&handle_value).ok() &&
-      !filter->KeyMayMatch(handle.offset(), key);
+        filter != nullptr && handle.DecodeFrom(&handle_value).ok() &&
+        !filter->KeyMayMatch(handle.offset(), ExtractUserKey(key));
 
     if (may_not_exist_in_filter) {
       // Not found

table/filter_block.cc

@@ -71,20 +71,14 @@ void FilterBlockBuilder::AddKey(const Slice& key) {
   }
 
   // add prefix to filter if needed
-  if (prefix_extractor_ && prefix_extractor_->InDomain(ExtractUserKey(key))) {
-    // If prefix_extractor_, this filter_block layer assumes we only
-    // operate on internal keys.
-    Slice user_key = ExtractUserKey(key);
+  if (prefix_extractor_ && prefix_extractor_->InDomain(key)) {
     // this assumes prefix(prefix(key)) == prefix(key), as the last
     // entry in entries_ may be either a key or prefix, and we use
     // prefix(last entry) to get the prefix of the last key.
-    if (prev.size() == 0 ||
-        !SamePrefix(user_key, ExtractUserKey(prev))) {
-      Slice prefix = prefix_extractor_->Transform(user_key);
-      InternalKey internal_prefix_tmp(prefix, 0, kTypeValue);
-      Slice internal_prefix = internal_prefix_tmp.Encode();
+    if (prev.size() == 0 || !SamePrefix(key, prev)) {
+      Slice prefix = prefix_extractor_->Transform(key);
       start_.push_back(entries_.size());
-      entries_.append(internal_prefix.data(), internal_prefix.size());
+      entries_.append(prefix.data(), prefix.size());
     }
   }
 }