Remove unnecessary inclusion of version_edit.h in env (#6952)

Summary:
In db_options.c, we should avoid including header files in the `db` directory to avoid introducing unnecessary dependency. The reason why `version_edit.h` has been included in `db_options.cc` is because we need two constants, `kUnknownChecksum` and `kUnknownChecksumFuncName`. We can put these two constants as `constexpr` in the public header `file_checksum.h`.

Test plan (devserver):
make check
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6952

Reviewed By: zhichao-cao

Differential Revision: D21925341

Pulled By: riversand963

fbshipit-source-id: 2902f3b74c97f0cf16c58ad24c095c787c3a40e2

db/version_edit.cc

@@ -18,10 +18,6 @@
 #include "util/string_util.h"
 
 namespace ROCKSDB_NAMESPACE {
-// The unknown file checksum.
-const std::string kUnknownFileChecksum("");
-// The unknown sst file checksum function name.
-const std::string kUnknownFileChecksumFuncName("Unknown");
 
 namespace {
 

db/version_edit.h

@@ -29,9 +29,6 @@ constexpr uint64_t kFileNumberMask = 0x3FFFFFFFFFFFFFFF;
 constexpr uint64_t kUnknownOldestAncesterTime = 0;
 constexpr uint64_t kUnknownFileCreationTime = 0;
 
-extern const std::string kUnknownFileChecksum;
-extern const std::string kUnknownFileChecksumFuncName;
-
 extern uint64_t PackFileNumberAndPathId(uint64_t number, uint64_t path_id);
 
 // A copyable structure contains information needed to read data from an SST

file/writable_file_writer.cc

@@ -236,7 +236,7 @@ const char* WritableFileWriter::GetFileChecksumFuncName() const {
   if (checksum_generator_ != nullptr) {
     return checksum_generator_->Name();
   } else {
-    return kUnknownFileChecksumFuncName.c_str();
+    return kUnknownFileChecksumFuncName;
   }
 }
 

include/rocksdb/file_checksum.h

@@ -18,6 +18,11 @@
 
 namespace ROCKSDB_NAMESPACE {
 
+// The unknown file checksum.
+constexpr char kUnknownFileChecksum[] = "";
+// The unknown sst file checksum function name.
+constexpr char kUnknownFileChecksumFuncName[] = "Unknown";
+
 struct FileChecksumGenContext {
   std::string file_name;
 };

options/db_options.cc

@@ -7,7 +7,6 @@
 
 #include <cinttypes>
 
-#include "db/version_edit.h"
 #include "logging/logging.h"
 #include "options/options_helper.h"
 #include "port/port.h"
@@ -616,9 +615,8 @@ void ImmutableDBOptions::Dump(Logger* log) const {
       log, "                Options.log_readahead_size: %" ROCKSDB_PRIszt,
       log_readahead_size);
   ROCKS_LOG_HEADER(log, "                Options.file_checksum_gen_factory: %s",
-                   file_checksum_gen_factory
-                       ? file_checksum_gen_factory->Name()
-                       : kUnknownFileChecksumFuncName.c_str());
+                   file_checksum_gen_factory ? file_checksum_gen_factory->Name()
+                                             : kUnknownFileChecksumFuncName);
   ROCKS_LOG_HEADER(log, "                Options.best_efforts_recovery: %d",
                    static_cast<int>(best_efforts_recovery));
 }

table/block_based/block_based_table_builder.cc

@@ -1781,7 +1781,7 @@ const char* BlockBasedTableBuilder::GetFileChecksumFuncName() const {
   if (rep_->file != nullptr) {
     return rep_->file->GetFileChecksumFuncName();
   } else {
-    return kUnknownFileChecksumFuncName.c_str();
+    return kUnknownFileChecksumFuncName;
   }
 }
 

table/cuckoo/cuckoo_table_builder.cc

@@ -528,7 +528,7 @@ const char* CuckooTableBuilder::GetFileChecksumFuncName() const {
   if (file_ != nullptr) {
     return file_->GetFileChecksumFuncName();
   } else {
-    return kUnknownFileChecksumFuncName.c_str();
+    return kUnknownFileChecksumFuncName;
   }
 }
 

table/mock_table.h

@@ -163,7 +163,7 @@ class MockTableBuilder : public TableBuilder {
   std::string GetFileChecksum() const override { return kUnknownFileChecksum; }
   // Get file checksum function name
   const char* GetFileChecksumFuncName() const override {
-    return kUnknownFileChecksumFuncName.c_str();
+    return kUnknownFileChecksumFuncName;
   }
 
  private:

table/plain/plain_table_builder.cc

@@ -313,7 +313,7 @@ const char* PlainTableBuilder::GetFileChecksumFuncName() const {
   if (file_ != nullptr) {
     return file_->GetFileChecksumFuncName();
   } else {
-    return kUnknownFileChecksumFuncName.c_str();
+    return kUnknownFileChecksumFuncName;
   }
 }
 

table/table_test.cc

@@ -3284,9 +3284,8 @@ TEST_P(BlockBasedTableTest, NoFileChecksum) {
   f.ResetTableBuilder(std::move(builder));
   f.AddKVtoKVMap(1000);
   f.WriteKVAndFlushTable();
-  ASSERT_STREQ(f.GetFileChecksumFuncName(),
-               kUnknownFileChecksumFuncName.c_str());
-  ASSERT_STREQ(f.GetFileChecksum().c_str(), kUnknownFileChecksum.c_str());
+  ASSERT_STREQ(f.GetFileChecksumFuncName(), kUnknownFileChecksumFuncName);
+  ASSERT_STREQ(f.GetFileChecksum().c_str(), kUnknownFileChecksum);
 }
 
 TEST_P(BlockBasedTableTest, Crc32cFileChecksum) {
@@ -3430,9 +3429,8 @@ TEST_F(PlainTableTest, NoFileChecksum) {
   f.ResetTableBuilder(std::move(builder));
   f.AddKVtoKVMap(1000);
   f.WriteKVAndFlushTable();
-  ASSERT_STREQ(f.GetFileChecksumFuncName(),
-               kUnknownFileChecksumFuncName.c_str());
-  EXPECT_EQ(f.GetFileChecksum(), kUnknownFileChecksum.c_str());
+  ASSERT_STREQ(f.GetFileChecksumFuncName(), kUnknownFileChecksumFuncName);
+  EXPECT_EQ(f.GetFileChecksum(), kUnknownFileChecksum);
 }
 
 TEST_F(PlainTableTest, Crc32cFileChecksum) {