Expose RepairDB as ldb command

Summary: This will make it easier for admins and devs to use RepairDB.

Test Plan:
Tried deleting the manifest and verified it recovers:

  $ ldb --create_if_missing --db=/tmp/test_db put ok ok
  $ rm -f /tmp/test_db/MANIFEST-000001
  $ ./ldb --db=/tmp/test_db repair
  $ ldb --db=/tmp/test_db get ok
  ok

Reviewers: yhchiang, sdong, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: leveldb, andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D55359

tools/ldb_cmd.cc

@@ -191,6 +191,8 @@ LDBCommand* LDBCommand::SelectCommand(
     return new InternalDumpCommand(cmdParams, option_map, flags);
   } else if (cmd == CheckConsistencyCommand::Name()) {
     return new CheckConsistencyCommand(cmdParams, option_map, flags);
+  } else if (cmd == RepairCommand::Name()) {
+    return new RepairCommand(cmdParams, option_map, flags);
   }
   return nullptr;
 }
@@ -2144,6 +2146,29 @@ void CheckConsistencyCommand::DoCommand() {
 
 // ----------------------------------------------------------------------------
 
+RepairCommand::RepairCommand(const vector<string>& params,
+                             const map<string, string>& options,
+                             const vector<string>& flags)
+    : LDBCommand(options, flags, false, BuildCmdLineOptions({})) {}
+
+void RepairCommand::Help(string& ret) {
+  ret.append("  ");
+  ret.append(RepairCommand::Name());
+  ret.append("\n");
+}
+
+void RepairCommand::DoCommand() {
+  Options options = PrepareOptionsForOpenDB();
+  Status status = RepairDB(db_path_, options);
+  if (status.ok()) {
+    printf("OK\n");
+  } else {
+    exec_state_ = LDBCommandExecuteResult::Failed(status.ToString());
+  }
+}
+
+// ----------------------------------------------------------------------------
+
 namespace {
 
 void DumpSstFile(std::string filename, bool output_hex, bool show_properties) {

tools/ldb_cmd.h

@@ -883,6 +883,21 @@ class CheckConsistencyCommand : public LDBCommand {
   static void Help(string& ret);
 };
 
+class RepairCommand : public LDBCommand {
+ public:
+  static string Name() { return "repair"; }
+
+  RepairCommand(const vector<string>& params,
+                const map<string, string>& options,
+                const vector<string>& flags);
+
+  virtual void DoCommand() override;
+
+  virtual bool NoDBOpen() override { return true; }
+
+  static void Help(string& ret);
+};
+
 } // namespace rocksdb
 
 #endif  // ROCKSDB_LITE

tools/ldb_tool.cc

@@ -77,6 +77,7 @@ class LDBCommandRunner {
     ListColumnFamiliesCommand::Help(ret);
     DBFileDumperCommand::Help(ret);
     InternalDumpCommand::Help(ret);
+    RepairCommand::Help(ret);
 
     fprintf(stderr, "%s\n", ret.c_str());
   }