Follow-up Cleaning-up After D13521

Summary:
This patch is to address @haobo's comments on D13521:
1. rename Table to be TableReader and make its factory function to be GetTableReader
2. move the compression type selection logic out of TableBuilder but to compaction logic
3. more accurate comments
4. Move stat name constants into BlockBasedTable implementation.
5. remove some uncleaned codes in simple_table_db_test

Test Plan: pass test suites.

Reviewers: haobo, dhruba, kailiu

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D13785

table/table_test.cc

@@ -22,7 +22,7 @@
 #include "table/block.h"
 #include "table/block_builder.h"
 #include "table/format.h"
-#include "table/block_based_table.h"
+#include "table/block_based_table_reader.h"
 #include "table/block_based_table_builder.h"
 #include "util/random.h"
 #include "util/testharness.h"
@@ -250,7 +250,7 @@ class BlockBasedTableConstructor: public Constructor {
   virtual Status FinishImpl(const Options& options, const KVMap& data) {
     Reset();
     sink_.reset(new StringSink());
-    BlockBasedTableBuilder builder(options, sink_.get());
+    BlockBasedTableBuilder builder(options, sink_.get(), options.compression);
 
     for (KVMap::const_iterator it = data.begin();
          it != data.end();
@@ -267,36 +267,36 @@ class BlockBasedTableConstructor: public Constructor {
     uniq_id_ = cur_uniq_id_++;
     source_.reset(new StringSource(sink_->contents(), uniq_id_));
     unique_ptr<TableFactory> table_factory;
-    return options.table_factory->OpenTable(options, soptions,
-                                            std::move(source_),
-                                            sink_->contents().size(),
-                                            &table_);
+    return options.table_factory->GetTableReader(options, soptions,
+                                                 std::move(source_),
+                                                 sink_->contents().size(),
+                                                 &table_reader_);
   }
 
   virtual Iterator* NewIterator() const {
-    return table_->NewIterator(ReadOptions());
+    return table_reader_->NewIterator(ReadOptions());
   }
 
   uint64_t ApproximateOffsetOf(const Slice& key) const {
-    return table_->ApproximateOffsetOf(key);
+    return table_reader_->ApproximateOffsetOf(key);
   }
 
   virtual Status Reopen(const Options& options) {
     source_.reset(new StringSource(sink_->contents(), uniq_id_));
-    return options.table_factory->OpenTable(options, soptions,
-                                            std::move(source_),
-                                            sink_->contents().size(),
-                                            &table_);
+    return options.table_factory->GetTableReader(options, soptions,
+                                                 std::move(source_),
+                                                 sink_->contents().size(),
+                                                 &table_reader_);
   }
 
-  virtual Table* table() {
-    return table_.get();
+  virtual TableReader* table_reader() {
+    return table_reader_.get();
   }
 
  private:
   void Reset() {
     uniq_id_ = 0;
-    table_.reset();
+    table_reader_.reset();
     sink_.reset();
     source_.reset();
   }
@@ -304,7 +304,7 @@ class BlockBasedTableConstructor: public Constructor {
   uint64_t uniq_id_;
   unique_ptr<StringSink> sink_;
   unique_ptr<StringSource> source_;
-  unique_ptr<Table> table_;
+  unique_ptr<TableReader> table_reader_;
 
   BlockBasedTableConstructor();
 
@@ -883,7 +883,7 @@ TEST(TableTest, BasicTableStats) {
 
   c.Finish(options, &keys, &kvmap);
 
-  auto& stats = c.table()->GetTableStats();
+  auto& stats = c.table_reader()->GetTableStats();
   ASSERT_EQ(kvmap.size(), stats.num_entries);
 
   auto raw_key_size = kvmap.size() * 2ul;
@@ -918,7 +918,7 @@ TEST(TableTest, FilterPolicyNameStats) {
   options.filter_policy = filter_policy.get();
 
   c.Finish(options, &keys, &kvmap);
-  auto& stats = c.table()->GetTableStats();
+  auto& stats = c.table_reader()->GetTableStats();
   ASSERT_EQ("rocksdb.BuiltinBloomFilter", stats.filter_policy_name);
 }
 
@@ -960,7 +960,7 @@ TEST(TableTest, IndexSizeStat) {
 
     c.Finish(options, &ks, &kvmap);
     auto index_size =
-      c.table()->GetTableStats().index_size;
+      c.table_reader()->GetTableStats().index_size;
     ASSERT_GT(index_size, last_index_size);
     last_index_size = index_size;
   }
@@ -985,7 +985,7 @@ TEST(TableTest, NumBlockStat) {
   c.Finish(options, &ks, &kvmap);
   ASSERT_EQ(
       kvmap.size(),
-      c.table()->GetTableStats().num_data_blocks
+      c.table_reader()->GetTableStats().num_data_blocks
   );
 }
 
@@ -1100,7 +1100,7 @@ TEST(TableTest, BlockCacheLeak) {
 
   ASSERT_OK(c.Reopen(opt));
   for (const std::string& key: keys) {
-    ASSERT_TRUE(c.table()->TEST_KeyInCache(ReadOptions(), key));
+    ASSERT_TRUE(c.table_reader()->TEST_KeyInCache(ReadOptions(), key));
   }
 }