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       1                 :             : // Copyright (c) The Bitcoin Core developers
       2                 :             : // Distributed under the MIT software license, see the accompanying
       3                 :             : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       4                 :             : 
       5                 :             : #include <logging.h>
       6                 :             : #include <util/threadpool.h>
       7                 :             : 
       8                 :             : #include <test/fuzz/FuzzedDataProvider.h>
       9                 :             : #include <test/fuzz/fuzz.h>
      10                 :             : 
      11                 :             : #include <atomic>
      12                 :             : #include <future>
      13                 :             : #include <queue>
      14                 :             : 
      15                 :             : struct ExpectedException : std::runtime_error {
      16         [ +  - ]:        5827 :     explicit ExpectedException(const std::string& msg) : std::runtime_error(msg) {}
      17                 :             : };
      18                 :             : 
      19                 :             : struct ThrowTask {
      20         [ +  - ]:       11654 :     void operator()() const { throw ExpectedException("fail"); }
      21                 :             : };
      22                 :             : 
      23                 :             : struct CounterTask {
      24                 :             :     std::atomic_uint32_t& m_counter;
      25                 :       35547 :     explicit CounterTask(std::atomic_uint32_t& counter) : m_counter{counter} {}
      26                 :       35547 :     void operator()() const { m_counter.fetch_add(1, std::memory_order_relaxed); }
      27                 :             : };
      28                 :             : 
      29                 :             : // Waits for a future to complete. Increments 'fail_counter' if the expected exception is thrown.
      30                 :       41374 : static void GetFuture(std::future<void>& future, uint32_t& fail_counter)
      31                 :             : {
      32                 :       41374 :     try {
      33         [ +  + ]:       41374 :         future.get();
      34         [ +  - ]:        5827 :     } catch (const ExpectedException&) {
      35                 :        5827 :         fail_counter++;
      36                 :        5827 :     } catch (...) {
      37                 :           0 :         assert(false && "Unexpected exception type");
      38                 :             :     }
      39                 :       41374 : }
      40                 :             : 
      41                 :             : // Global thread pool for fuzzing. Persisting it across iterations prevents
      42                 :             : // the excessive thread creation/destruction overhead that can lead to
      43                 :             : // instability in the fuzzing environment.
      44                 :             : // This is also how we use it in the app's lifecycle.
      45                 :             : ThreadPool g_pool{"fuzz"};
      46                 :             : // Global to verify we always have the same number of threads.
      47                 :             : size_t g_num_workers = 3;
      48                 :             : 
      49                 :          75 : static void StartPoolIfNeeded()
      50                 :             : {
      51         [ +  + ]:          75 :     if (g_pool.WorkersCount() == g_num_workers) return;
      52                 :           1 :     g_pool.Start(g_num_workers);
      53                 :             : }
      54                 :             : 
      55                 :           1 : static void setup_threadpool_test()
      56                 :             : {
      57                 :             :     // Disable logging entirely. It seems to cause memory leaks.
      58                 :           1 :     LogInstance().DisableLogging();
      59                 :           1 : }
      60                 :             : 
      61         [ +  - ]:         541 : FUZZ_TARGET(threadpool, .init = setup_threadpool_test)
      62                 :             : {
      63                 :             :     // Because LibAFL calls fork() after calling the init setup function,
      64                 :             :     // the child processes end up having one thread active and no workers.
      65                 :             :     // To work around this limitation, start thread pool inside the first runner.
      66                 :          75 :     StartPoolIfNeeded();
      67                 :             : 
      68                 :          75 :     FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
      69                 :             : 
      70                 :          75 :     const uint32_t num_tasks = fuzzed_data_provider.ConsumeIntegralInRange<uint32_t>(0, 1024);
      71         [ -  + ]:          75 :     assert(g_pool.WorkersCount() == g_num_workers);
      72         [ -  + ]:          75 :     assert(g_pool.WorkQueueSize() == 0);
      73                 :             : 
      74                 :             :     // Counters
      75                 :          75 :     std::atomic_uint32_t task_counter{0};
      76                 :          75 :     uint32_t fail_counter{0};
      77                 :          75 :     uint32_t expected_task_counter{0};
      78                 :          75 :     uint32_t expected_fail_tasks{0};
      79                 :             : 
      80                 :          75 :     std::queue<std::future<void>> futures;
      81         [ +  + ]:       41449 :     for (uint32_t i = 0; i < num_tasks; ++i) {
      82                 :       41374 :         const bool will_throw = fuzzed_data_provider.ConsumeBool();
      83                 :       41374 :         const bool wait_immediately = fuzzed_data_provider.ConsumeBool();
      84                 :             : 
      85                 :       41374 :         std::future<void> fut;
      86         [ +  + ]:       41374 :         if (will_throw) {
      87                 :        5827 :             expected_fail_tasks++;
      88         [ -  + ]:        5827 :             fut = *Assert(g_pool.Submit(ThrowTask{}));
      89                 :             :         } else {
      90                 :       35547 :             expected_task_counter++;
      91         [ -  + ]:       35547 :             fut = *Assert(g_pool.Submit(CounterTask{task_counter}));
      92                 :             :         }
      93                 :             : 
      94                 :             :         // If caller wants to wait immediately, consume the future here (safe).
      95         [ +  + ]:       41374 :         if (wait_immediately) {
      96                 :             :             // Waits for this task to complete immediately; prior queued tasks may also complete
      97                 :             :             // as they were queued earlier.
      98                 :        5927 :             GetFuture(fut, fail_counter);
      99                 :             :         } else {
     100                 :             :             // Store task for a posterior check
     101   [ +  -  -  + ]:       41374 :             futures.emplace(std::move(fut));
     102                 :             :         }
     103                 :       41374 :     }
     104                 :             : 
     105                 :             :     // Drain remaining futures
     106         [ +  + ]:       35522 :     while (!futures.empty()) {
     107                 :       35447 :         auto fut = std::move(futures.front());
     108                 :       35447 :         futures.pop();
     109         [ -  + ]:       35447 :         GetFuture(fut, fail_counter);
     110                 :       35447 :     }
     111                 :             : 
     112   [ +  -  -  + ]:          75 :     assert(g_pool.WorkQueueSize() == 0);
     113         [ -  + ]:          75 :     assert(task_counter.load() == expected_task_counter);
     114         [ -  + ]:          75 :     assert(fail_counter == expected_fail_tasks);
     115                 :          75 : }