[C++] std::forward fragment handlers to avoid unnecessary copies (#1405)

Co-authored-by: Joan-Roch Sala <[email protected]>

Author: jrsala-auguration

aeron-client/src/main/cpp/Image.h

@@ -404,7 +404,7 @@ class Image
         AtomicBuffer &termBuffer = m_termBuffers[index];
         TermReader::ReadOutcome outcome{};
 
-        TermReader::read(outcome, termBuffer, offset, fragmentHandler, fragmentLimit, m_header, m_exceptionHandler);
+        TermReader::read(outcome, termBuffer, offset, std::forward<F>(fragmentHandler), fragmentLimit, m_header, m_exceptionHandler);
 
         const std::int64_t newPosition = position + (outcome.offset - offset);
         if (newPosition > position)

aeron-client/src/main/cpp/Subscription.h

@@ -221,12 +221,12 @@ class CLIENT_EXPORT Subscription
 
         for (std::size_t i = startingIndex; i < length && fragmentsRead < fragmentLimit; i++)
         {
-            fragmentsRead += imageArray[i]->poll(fragmentHandler, fragmentLimit - fragmentsRead);
+            fragmentsRead += imageArray[i]->poll(std::forward<F>(fragmentHandler), fragmentLimit - fragmentsRead);
         }
 
         for (std::size_t i = 0; i < startingIndex && fragmentsRead < fragmentLimit; i++)
         {
-            fragmentsRead += imageArray[i]->poll(fragmentHandler, fragmentLimit - fragmentsRead);
+            fragmentsRead += imageArray[i]->poll(std::forward<F>(fragmentHandler), fragmentLimit - fragmentsRead);
         }
 
         return fragmentsRead;
@@ -263,12 +263,12 @@ class CLIENT_EXPORT Subscription
 
         for (std::size_t i = startingIndex; i < length && fragmentsRead < fragmentLimit; i++)
         {
-            fragmentsRead += imageArray[i]->controlledPoll(fragmentHandler, fragmentLimit - fragmentsRead);
+            fragmentsRead += imageArray[i]->controlledPoll(std::forward<F>(fragmentHandler), fragmentLimit - fragmentsRead);
         }
 
         for (std::size_t i = 0; i < startingIndex && fragmentsRead < fragmentLimit; i++)
         {
-            fragmentsRead += imageArray[i]->controlledPoll(fragmentHandler, fragmentLimit - fragmentsRead);
+            fragmentsRead += imageArray[i]->controlledPoll(std::forward<F>(fragmentHandler), fragmentLimit - fragmentsRead);
         }
 
         return fragmentsRead;
@@ -291,7 +291,7 @@ class CLIENT_EXPORT Subscription
 
         for (std::size_t i = 0; i < length; i++)
         {
-            bytesConsumed += imageArray[i]->blockPoll(blockHandler, blockLengthLimit);
+            bytesConsumed += imageArray[i]->blockPoll(std::forward<F>(blockHandler), blockLengthLimit);
         }
 
         return bytesConsumed;