Remove xgboost's thread_local and switch to dmlc::ThreadLocalStore (#2121)

* Remove xgboost's own version of thread_local and switch to dmlc::ThreadLocalStore (#2109)

* Update dmlc-core

dmlc-core

@@ -1 +1 @@
-Subproject commit 2b75a0ce6f191ad0fcb5319039b41e990968542a
+Subproject commit b5bec5481df86e8e6728d8bd80a61d87ef3b2cd5

src/c_api/c_api.cc

@@ -4,6 +4,7 @@
 #include <xgboost/learner.h>
 #include <xgboost/c_api.h>
 #include <xgboost/logging.h>
+#include <dmlc/thread_local.h>
 #include <rabit/rabit.h>
 #include <cstdio>
 #include <vector>
@@ -13,7 +14,6 @@
 
 #include "./c_api_error.h"
 #include "../data/simple_csr_source.h"
-#include "../common/thread_local.h"
 #include "../common/math.h"
 #include "../common/io.h"
 #include "../common/group_data.h"
@@ -197,7 +197,7 @@ struct XGBAPIThreadLocalEntry {
 };
 
 // define the threadlocal store.
-typedef xgboost::common::ThreadLocalStore<XGBAPIThreadLocalEntry> XGBAPIThreadLocalStore;
+typedef dmlc::ThreadLocalStore<XGBAPIThreadLocalEntry> XGBAPIThreadLocalStore;
 
 int XGDMatrixCreateFromFile(const char *fname,
                             int silent,

src/c_api/c_api_error.cc

@@ -3,14 +3,14 @@
  * \file c_api_error.cc
  * \brief C error handling
  */
+#include <dmlc/thread_local.h>
 #include "./c_api_error.h"
-#include "../common/thread_local.h"
 
 struct XGBAPIErrorEntry {
   std::string last_error;
 };
 
-typedef xgboost::common::ThreadLocalStore<XGBAPIErrorEntry> XGBAPIErrorStore;
+typedef dmlc::ThreadLocalStore<XGBAPIErrorEntry> XGBAPIErrorStore;
 
 const char *XGBGetLastError() {
   return XGBAPIErrorStore::Get()->last_error.c_str();

src/common/common.cc

@@ -3,8 +3,8 @@
  * \file common.cc
  * \brief Enable all kinds of global variables in common.
  */
+#include <dmlc/thread_local.h>
 #include "./random.h"
-#include "./thread_local.h"
 
 namespace xgboost {
 namespace common {
@@ -14,7 +14,7 @@ struct RandomThreadLocalEntry {
   GlobalRandomEngine engine;
 };
 
-typedef ThreadLocalStore<RandomThreadLocalEntry> RandomThreadLocalStore;
+typedef dmlc::ThreadLocalStore<RandomThreadLocalEntry> RandomThreadLocalStore;
 
 GlobalRandomEngine& GlobalRandom() {
   return RandomThreadLocalStore::Get()->engine;

src/common/thread_local.h

@@ -1,91 +0,0 @@
-/*!
- *  Copyright (c) 2015 by Contributors
- * \file thread_local.h
- * \brief Common utility for thread local storage.
- */
-#ifndef XGBOOST_COMMON_THREAD_LOCAL_H_
-#define XGBOOST_COMMON_THREAD_LOCAL_H_
-
-#include <dmlc/base.h>
-
-#if DMLC_ENABLE_STD_THREAD
-#include <mutex>
-#endif
-
-#include <memory>
-#include <vector>
-
-namespace xgboost {
-namespace common {
-
-// macro hanlding for threadlocal variables
-#ifdef __sun
-  #define MX_TREAD_LOCAL
-#elif defined(__GNUC__)
-  #define MX_TREAD_LOCAL __thread
-#elif __STDC_VERSION__ >= 201112L
-  #define  MX_TREAD_LOCAL _Thread_local
-#elif defined(_MSC_VER)
-  #define MX_TREAD_LOCAL __declspec(thread)
-#endif
-
-#ifndef MX_TREAD_LOCAL
-#message("Warning: Threadlocal is not enabled");
-#endif
-
-/*!
- * \brief A threadlocal store to store threadlocal variables.
- *  Will return a thread local singleton of type T
- * \tparam T the type we like to store
- */
-template<typename T>
-class ThreadLocalStore {
- public:
-  /*! \return get a thread local singleton */
-  static T* Get() {
-    static MX_TREAD_LOCAL T* ptr = nullptr;
-    if (ptr == nullptr) {
-      ptr = new T();
-      Singleton()->RegisterDelete(ptr);
-    }
-    return ptr;
-  }
-
- private:
-  /*! \brief constructor */
-  ThreadLocalStore() {}
-  /*! \brief destructor */
-  ~ThreadLocalStore() {
-    for (size_t i = 0; i < data_.size(); ++i) {
-      delete data_[i];
-    }
-  }
-  /*! \return singleton of the store */
-  static ThreadLocalStore<T> *Singleton() {
-    static ThreadLocalStore<T> inst;
-    return &inst;
-  }
-  /*!
-   * \brief register str for internal deletion
-   * \param str the string pointer
-   */
-  void RegisterDelete(T *str) {
-#if DMLC_ENABLE_STD_THREAD
-    std::unique_lock<std::mutex> lock(mutex_);
-    data_.push_back(str);
-    lock.unlock();
-#else
-    data_.push_back(str);
-#endif
-  }
-
-#if DMLC_ENABLE_STD_THREAD
-  /*! \brief internal mutex */
-  std::mutex mutex_;
-#endif
-  /*!\brief internal data */
-  std::vector<T*> data_;
-};
-}  // namespace common
-}  // namespace xgboost
-#endif  // XGBOOST_COMMON_THREAD_LOCAL_H_