Remove lambda expression to support older compilers

2 files changed, 23 insertions, 20 deletions

diff --git a/src/cpp/server/thread_pool.cc b/src/cpp/server/thread_pool.cc
index d3013b806c..10dceec836 100644
--- a/src/cpp/server/thread_pool.cc
+++ b/src/cpp/server/thread_pool.cc
@@ -35,28 +35,29 @@
 
 namespace grpc {
 
+#ifdef __GNUC__
+#if (__GNUC__ * 100 + __GNUC_MINOR__ < 406)
+#define GRPC_NO_NULLPTR
+#endif
+#endif
+
+#ifdef GRPC_NO_NULLPTR
+#include <memory>
+const class {
+public:
+  template <class T> operator T*() const {return static_cast<T *>(0);}
+  template <class T> operator std::unique_ptr<T>() const {
+    return std::unique_ptr<T>(static_cast<T *>(0));
+  }
+  operator bool() const {return false;}
+private:
+  void operator&() const = delete;
+} nullptr = {};
+#endif
+
 ThreadPool::ThreadPool(int num_threads) : shutdown_(false) {
   for (int i = 0; i < num_threads; i++) {
-    threads_.push_back(std::thread([this]() {
-      for (;;) {
-        // Wait until work is available or we are shutting down.
-        auto have_work = [this]() { return shutdown_ || !callbacks_.empty(); };
-        std::unique_lock<std::mutex> lock(mu_);
-        if (!have_work()) {
-          cv_.wait(lock, have_work);
-        }
-        // Drain callbacks before considering shutdown to ensure all work
-        // gets completed.
-        if (!callbacks_.empty()) {
-          auto cb = callbacks_.front();
-          callbacks_.pop();
-          lock.unlock();
-          cb();
-        } else if (shutdown_) {
-          return;
-        }
-      }
-    }));
+    threads_.push_back(std::thread(&ThreadPool::ThreadFunc, this));
   }
 }
 
diff --git a/src/cpp/server/thread_pool.h b/src/cpp/server/thread_pool.h
index 6225d82a0b..41e2009ff1 100644
--- a/src/cpp/server/thread_pool.h
+++ b/src/cpp/server/thread_pool.h
@@ -58,6 +58,8 @@ class ThreadPool GRPC_FINAL : public ThreadPoolInterface {
   bool shutdown_;
   std::queue<std::function<void()>> callbacks_;
   std::vector<std::thread> threads_;
+
+  void ThreadFunc();
 };
 
 }  // namespace grpc