Add utility functions for interpreting ThreadStatus

Summary:
Add ThreadStatus::GetOperationName() and ThreadStatus::GetStateName(),
two utility functions that help interpreting ThreadStatus.

Test Plan: ./thread_list_test

Reviewers: sdong, rven, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D32793

include/rocksdb/thread_status.h

@@ -89,6 +89,16 @@ struct ThreadStatus {
 
   // The state (lower-level action) that the current thread is involved.
   const StateType state_type;
+
+  // The followings are a set of utility functions for interpreting
+  // the information of ThreadStatus
+
+  // Obtain the name of an operation given its type.
+  static const std::string& GetOperationName(OperationType op_type);
+
+  // Obtain the name of a state given its type.
+  static const std::string& GetStateName(StateType state_type);
 };
 
+
 }  // namespace rocksdb

util/thread_list_test.cc

@@ -98,10 +98,16 @@ TEST(ThreadListTest, EventTables) {
   // verify the global tables for operations and states are properly indexed.
   for (int type = 0; type != ThreadStatus::NUM_OP_TYPES; ++type) {
     ASSERT_EQ(global_operation_table[type].type, type);
+    ASSERT_EQ(global_operation_table[type].name,
+              ThreadStatus::GetOperationName(
+                  ThreadStatus::OperationType(type)));
   }
 
   for (int type = 0; type != ThreadStatus::NUM_STATE_TYPES; ++type) {
     ASSERT_EQ(global_state_table[type].type, type);
+    ASSERT_EQ(global_state_table[type].name,
+              ThreadStatus::GetStateName(
+                  ThreadStatus::StateType(type)));
   }
 }
 

util/thread_status_impl.cc

@@ -0,0 +1,38 @@
+// Copyright (c) 2013, Facebook, Inc.  All rights reserved.
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree. An additional grant
+// of patent rights can be found in the PATENTS file in the same directory.
+//
+
+#include "rocksdb/thread_status.h"
+#include "util/thread_operation.h"
+
+namespace rocksdb {
+
+#if ROCKSDB_USING_THREAD_STATUS
+const std::string& ThreadStatus::GetOperationName(
+    ThreadStatus::OperationType op_type) {
+  return global_operation_table[op_type].name;
+}
+
+const std::string& ThreadStatus::GetStateName(
+    ThreadStatus::StateType state_type) {
+  return global_state_table[state_type].name;
+}
+
+#else
+
+const std::string& ThreadStatus::GetOperationName(
+    ThreadStatus::OperationType op_type) {
+  static std::string dummy_str = "";
+  return dummy_str;
+}
+
+const std::string& ThreadStatus::GetStateName(
+    ThreadStatus::StateType state_type) {
+  static std::string dummy_str = "";
+  return dummy_str;
+}
+
+#endif  // ROCKSDB_USING_THREAD_STATUS
+}  // namespace rocksdb