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tdutils/td/utils/port/detail/ThreadIdGuard.cpp

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+/*
+    This file is part of TON Blockchain Library.
+
+    TON Blockchain Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    TON Blockchain Library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with TON Blockchain Library.  If not, see <http://www.gnu.org/licenses/>.
+
+    Copyright 2017-2019 Telegram Systems LLP
+*/
+#include "td/utils/port/detail/ThreadIdGuard.h"
+
+#include "td/utils/common.h"
+#include "td/utils/port/thread_local.h"
+
+#include <mutex>
+#include <set>
+
+namespace td {
+namespace detail {
+class ThreadIdManager {
+ public:
+  int32 register_thread() {
+    std::lock_guard<std::mutex> guard(mutex_);
+    if (unused_thread_ids_.empty()) {
+      return ++max_thread_id_;
+    }
+    auto it = unused_thread_ids_.begin();
+    auto result = *it;
+    unused_thread_ids_.erase(it);
+    return result;
+  }
+  void unregister_thread(int32 thread_id) {
+    std::lock_guard<std::mutex> guard(mutex_);
+    CHECK(0 < thread_id && thread_id <= max_thread_id_);
+    bool is_inserted = unused_thread_ids_.insert(thread_id).second;
+    CHECK(is_inserted);
+  }
+
+ private:
+  std::mutex mutex_;
+  std::set<int32> unused_thread_ids_;
+  int32 max_thread_id_ = 0;
+};
+static ThreadIdManager thread_id_manager;
+
+ThreadIdGuard::ThreadIdGuard() {
+  thread_id_ = thread_id_manager.register_thread();
+  set_thread_id(thread_id_);
+}
+ThreadIdGuard::~ThreadIdGuard() {
+  thread_id_manager.unregister_thread(thread_id_);
+  set_thread_id(0);
+}
+}  // namespace detail
+}  // namespace td