Fix CPPlint errors in channel.h, channel_impl.h and channel_test.cc (#9628)

* Fix cpplint issues

* Fix cpplint issues in channel.h and channel_impl.h

* Fix typo

paddle/fluid/framework/channel.h

@@ -14,8 +14,8 @@ limitations under the License. */
 
 #pragma once
 
-#include <stddef.h>  // for size_t
-#include <condition_variable>
+#include <stddef.h>            // for size_t
+#include <condition_variable>  // NOLINT
 #include <typeindex>
 #include "paddle/fluid/platform/enforce.h"
 
@@ -216,7 +216,8 @@ class ChannelHolder {
 
   template <typename T>
   struct PlaceholderImpl : public Placeholder {
-    PlaceholderImpl(size_t buffer_size) : type_(std::type_index(typeid(T))) {
+    explicit PlaceholderImpl(size_t buffer_size)
+        : type_(std::type_index(typeid(T))) {
       channel_.reset(MakeChannel<T>(buffer_size));
     }
 

paddle/fluid/framework/channel_impl.h

@@ -15,7 +15,7 @@ limitations under the License. */
 #pragma once
 #include <stddef.h>  // for size_t
 #include <atomic>
-#include <condition_variable>
+#include <condition_variable>  // NOLINT
 #include <deque>
 #include "paddle/fluid/framework/channel.h"
 #include "paddle/fluid/platform/enforce.h"
@@ -38,7 +38,7 @@ class ChannelImpl : public paddle::framework::Channel<T> {
   virtual void Unlock();
   virtual bool IsClosed();
   virtual void Close();
-  ChannelImpl(size_t);
+  explicit ChannelImpl(size_t);
   virtual ~ChannelImpl();
 
   virtual void AddToSendQ(const void *referrer, T *data,
@@ -60,7 +60,7 @@ class ChannelImpl : public paddle::framework::Channel<T> {
     const void *referrer;  // TODO(thuan): figure out better way to do this
     std::function<bool(ChannelAction)> callback;
 
-    QueueMessage(T *item)
+    explicit QueueMessage(T *item)
         : data(item), cond(std::make_shared<std::condition_variable_any>()) {}
 
     QueueMessage(T *item, std::shared_ptr<std::condition_variable_any> cond)
@@ -88,15 +88,15 @@ class ChannelImpl : public paddle::framework::Channel<T> {
   }
 
   std::shared_ptr<QueueMessage> get_first_message(
-      std::deque<std::shared_ptr<QueueMessage>> &queue, ChannelAction action) {
-    while (!queue.empty()) {
+      std::deque<std::shared_ptr<QueueMessage>> *queue, ChannelAction action) {
+    while (!queue->empty()) {
       // Check whether this message was added by Select
       // If this was added by Select then execute the callback
       // to check if you can execute this message. The callback
       // can return false if some other case was executed in Select.
       // In that case just discard this QueueMessage and process next.
-      std::shared_ptr<QueueMessage> m = queue.front();
-      queue.pop_front();
+      std::shared_ptr<QueueMessage> m = queue->front();
+      queue->pop_front();
       if (m->callback == nullptr || m->callback(action)) return m;
     }
     return nullptr;
@@ -147,7 +147,7 @@ void ChannelImpl<T>::Send(T *item) {
   // to send to the receiver, bypassing the channel buffer if any
   if (!recvq.empty()) {
     std::shared_ptr<QueueMessage> m =
-        get_first_message(recvq, ChannelAction::SEND);
+        get_first_message(&recvq, ChannelAction::SEND);
 
     if (m != nullptr) {
       *(m->data) = std::move(*item);
@@ -198,7 +198,7 @@ bool ChannelImpl<T>::Receive(T *item) {
   // buffer and move front of send queue to the buffer
   if (!sendq.empty()) {
     std::shared_ptr<QueueMessage> m =
-        get_first_message(sendq, ChannelAction::RECEIVE);
+        get_first_message(&sendq, ChannelAction::RECEIVE);
     if (buf_.size() > 0) {
       // Case 1 : Channel is Buffered
       // Do Data transfer from front of buffer
@@ -219,8 +219,9 @@ bool ChannelImpl<T>::Receive(T *item) {
       if (m != nullptr) {
         *item = std::move(*(m->data));
         m->Notify();
-      } else
+      } else {
         return recv_return(Receive(item));
+      }
     }
     return recv_return(true);
   }