Guard service_.run() in threadpool::add().

include/bitcoin/network/async/threadpool.hpp

@@ -70,12 +70,16 @@ class BCT_API threadpool final
     // Join the specified thread.
     bool join(std::thread& thread) NOEXCEPT;
 
-    // These are thread safe.
-    thread_priority priority_;
+    // This is thread safe.
+    const thread_priority priority_;
+
+    // This is protected by mutex.
+    // io_context is thread safe but we are isolating service_.poll().
+    std::mutex service_mutex_{};
     asio::io_context service_{};
-    std::mutex mutex_{};
 
-    // These are (partially) protected by mutex.
+    // These are protected by mutex.
+    std::mutex threads_mutex_{};
     std::vector<std::thread> threads_{};
     bool stopped_;
 

src/async/threadpool.cpp

@@ -18,6 +18,7 @@
  */
 #include <bitcoin/network/async/threadpool.hpp>
 
+#include <algorithm>
 #include <mutex>
 #include <thread>
 #include <bitcoin/system.hpp>
@@ -56,28 +57,25 @@ threadpool::~threadpool() NOEXCEPT
 
 size_t threadpool::add() NOEXCEPT
 {
-    std::unique_lock lock(mutex_);
-
+    std::unique_lock lock(threads_mutex_);
     const auto size = threads_.size();
     if (stopped_ || size == limit)
         return size;
 
-    threads_.push_back(std::thread([this]() NOEXCEPT
+    threads_.push_back(std::thread([this]()
     {
         set_priority(priority_);
 
-        // If service.run throws, application will abort at startup.
-        BC_PUSH_WARNING(NO_THROW_IN_NOEXCEPT)
+        std::unique_lock guard(service_mutex_);
         service_.run();
-        BC_POP_WARNING()
     }));
 
     return add1(size);
 }
 
 size_t threadpool::remove() NOEXCEPT
 {
-    std::unique_lock lock(mutex_);
+    std::unique_lock lock(threads_mutex_);
 
     const auto size = threads_.size();
     if (is_zero(size))
@@ -134,7 +132,7 @@ bool threadpool::join(std::thread& thread) NOEXCEPT
 bool threadpool::join() NOEXCEPT
 {
     // This exists due to add/remove.
-    std::unique_lock lock(mutex_);
+    std::unique_lock lock(threads_mutex_);
 
     for (auto& thread: threads_)
         if (!join(thread))