feat: building mutex in AllCases

all_cases/CMakeLists.txt

@@ -2,3 +2,4 @@ cmake_minimum_required(VERSION 3.0)
 set(CMAKE_CXX_STANDARD 14)
 
 add_executable(klotski main.cc all_cases.cc)
+target_link_libraries(klotski pthread)

all_cases/all_cases.cc

@@ -1,9 +1,45 @@
 #include "all_cases.h"
 
+#include <iostream>
+#include <thread>
+#include <unistd.h>
+
 std::vector<uint32_t> AllCases::basic_ranges;
 
+bool AllCases::basic_ranges_available = false;
+
+std::mutex AllCases::basic_ranges_building;
+
 void AllCases::build_basic_ranges() {
+
+    std::cout << std::this_thread::get_id() << " enter build function" << std::endl;
+
+    if (AllCases::basic_ranges_available) {
+        std::cout << std::this_thread::get_id() << " data already built -> skip" << std::endl;
+        return; // basic ranges already built
+    }
+
+    if (AllCases::basic_ranges_building.try_lock()) { // lock success -> not building
+
+        std::cout << std::this_thread::get_id() << " try lock success -> start build process" << std::endl;
+
         AllCases::basic_ranges.emplace_back(0);
         AllCases::basic_ranges.emplace_back(1);
         AllCases::basic_ranges.emplace_back(2);
+        sleep(2); // assume using a lot of time
+
+        AllCases::basic_ranges_available = true; // enable available flag
+
+        std::cout << std::this_thread::get_id() << " build complete -> continue" << std::endl;
+
+    } else { // another thread building
+
+        std::cout << std::this_thread::get_id() << " another thread building -> wait" << std::endl;
+        AllCases::basic_ranges_building.lock(); // blocking wait
+
+    }
+    std::cout << std::this_thread::get_id() << " work complete -> unlock" << std::endl;
+    AllCases::basic_ranges_building.unlock();
+
+
 }

all_cases/all_cases.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <mutex>
 #include <vector>
 #include <cstdint>
 
@@ -9,4 +10,8 @@ public:
 
     static void build_basic_ranges();
 
+    static bool basic_ranges_available;
+
+    static std::mutex basic_ranges_building;
+
 };

all_cases/main.cc

@@ -1,10 +1,26 @@
 #include <iostream>
 #include "all_cases.h"
 
+#include <thread>
+#include <unistd.h>
+
 int main() {
 
     std::cout << AllCases::basic_ranges.size() << std::endl;
+
+    std::thread t1(AllCases::build_basic_ranges);
+    usleep(100);
+    std::thread t2(AllCases::build_basic_ranges);
+    usleep(100);
+    std::thread t3(AllCases::build_basic_ranges);
+    usleep(100);
+
+    t1.join();
+    t2.join();
+    t3.join();
+
     AllCases::build_basic_ranges();
+
     std::cout << AllCases::basic_ranges.size() << std::endl;
 
     return 0;