chore: import upstream snapshot with attribution

runtime/http/bin/io_context_pool.cpp

@@ -0,0 +1,66 @@
+/**
+ * Copyright FunASR (https://github.com/alibaba-damo-academy/FunASR). All Rights
+ * Reserved. MIT License  (https://opensource.org/licenses/MIT)
+ */
+/* 2023-2024 by zhaomingwork@qq.com */
+//
+// io_context_pool.cpp
+// ~~~~~~~~~~~~~~~~~~~
+// copy some codes from  http://www.boost.org/
+
+#include "io_context_pool.hpp"
+#include <stdexcept>
+#include <thread>
+
+namespace http {
+namespace server2 {
+
+io_context_pool::io_context_pool(std::size_t pool_size)
+  : next_io_context_(0)
+{
+  if (pool_size == 0)
+    throw std::runtime_error("io_context_pool size is 0");
+
+  // Give all the io_contexts work to do so that their run() functions will not
+  // exit until they are explicitly stopped.
+  for (std::size_t i = 0; i < pool_size; ++i)
+  {
+    io_context_ptr io_context(new asio::io_context);
+    io_contexts_.push_back(io_context);
+    work_.push_back(asio::make_work_guard(*io_context));
+  }
+}
+
+void io_context_pool::run()
+{
+  // Create a pool of threads to run all of the io_contexts.
+  std::vector<std::thread> threads;
+  for (std::size_t i = 0; i < io_contexts_.size(); ++i)
+    threads.emplace_back([this, i]{ io_contexts_[i]->run(); });
+
+  // Wait for all threads in the pool to exit.
+  for (std::size_t i = 0; i < threads.size(); ++i)
+    threads[i].join();
+}
+
+void io_context_pool::stop()
+{
+  // Explicitly stop all io_contexts.
+  for (std::size_t i = 0; i < io_contexts_.size(); ++i)
+    io_contexts_[i]->stop();
+}
+
+asio::io_context& io_context_pool::get_io_context()
+{
+  // Use a round-robin scheme to choose the next io_context to use.
+  
+  asio::io_context& io_context = *io_contexts_[next_io_context_];
+ 
+  ++next_io_context_;
+  if (next_io_context_ == io_contexts_.size())
+    next_io_context_ = 0;
+  return io_context;
+}
+
+} // namespace server2
+} // namespace http