From 3be4a2ac0bad82ad60657701b9f17731f1f03d3d Mon Sep 17 00:00:00 2001
From: Razvan Becheriu <razvan@isc.org>
Date: Tue, 17 Sep 2019 17:08:23 +0300
Subject: [PATCH] [#883, !506] use references instead of objects whenever
 possible

---
 src/lib/dhcpsrv/thread_pool.cc | 23 +++++++++++++----------
 src/lib/dhcpsrv/thread_pool.h  |  2 +-
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/src/lib/dhcpsrv/thread_pool.cc b/src/lib/dhcpsrv/thread_pool.cc
index b7da07f2ac..2b2c7db484 100644
--- a/src/lib/dhcpsrv/thread_pool.cc
+++ b/src/lib/dhcpsrv/thread_pool.cc
@@ -31,8 +31,8 @@ namespace dhcp {
 ///
 /// The main purpose is to safely manage thread pool tasks.
 /// The thread pool queue can be 'disabled', which means that no items can be
-/// added or removed from the queue, or 'enabled', which guarantees that
-/// inserting or removing items are thread safe.
+/// removed from the queue, or 'enabled', which guarantees that inserting or
+/// removing items are thread safe.
 /// In 'disabled' state, all threads waiting on the queue are unlocked and all
 /// operations are non blocking.
 template <typename WorkItem>
@@ -57,7 +57,7 @@ struct ThreadPoolQueue {
     /// waiting on the queue.
     ///
     /// @param item the new item to be added to the queue
-    void push(WorkItem item) {
+    void push(WorkItem& item) {
         std::lock_guard<std::mutex> lock(mutex_);
         queue_.push(item);
         // Notify pop function so that it can effectively remove a work item.
@@ -77,7 +77,7 @@ struct ThreadPoolQueue {
     ///
     /// @return true if there was a work item removed from the queue, false
     /// otherwise
-    bool pop(WorkItem& item) {
+    WorkItem pop(bool& found) {
         std::unique_lock<std::mutex> lock(mutex_);
         while (!exit_) {
             if (queue_.empty()) {
@@ -86,12 +86,14 @@ struct ThreadPoolQueue {
                 continue;
             }
 
-            item = queue_.front();
+            WorkItem item = queue_.front();
             queue_.pop();
-            return true;
+            found = true;
+            return item;
         }
 
-        return false;
+        found = false;
+        return WorkItem();
     }
 
     /// @brief count number of work items in the queue
@@ -213,7 +215,7 @@ void ThreadPool::stop(bool clear) {
     LOG_INFO(dhcpsrv_logger, "Thread pool stopped");
 }
 
-void ThreadPool::add(WorkItemCallBack call_back) {
+void ThreadPool::add(WorkItemCallBack& call_back) {
     queue_->push(call_back);
 }
 
@@ -230,8 +232,9 @@ void ThreadPool::run() {
     LOG_INFO(dhcpsrv_logger, "Thread pool thread started. id: %1").arg(th_id);
 
     while (!exit_) {
-        WorkItemCallBack item;
-        if (queue_->pop(item)) {
+        bool found = false;
+        WorkItemCallBack item = queue_->pop(found);
+        if (found) {
             item();
         }
     }
diff --git a/src/lib/dhcpsrv/thread_pool.h b/src/lib/dhcpsrv/thread_pool.h
index 4883da19db..0510633a3b 100644
--- a/src/lib/dhcpsrv/thread_pool.h
+++ b/src/lib/dhcpsrv/thread_pool.h
@@ -70,7 +70,7 @@ struct ThreadPool {
     /// @brief add a working item to the thread pool
     ///
     /// @param call_back the 'function' object to be added to the queue
-    void add(WorkItemCallBack call_back);
+    void add(WorkItemCallBack& call_back);
 
     /// @brief count number of work items in the queue
     ///
-- 
2.47.2