util/PeakBuffer: return ConstBuffer<void>

src/event/FullyBufferedSocket.cxx

@@ -60,15 +60,14 @@ FullyBufferedSocket::Flush()
 {
 	assert(IsDefined());
 
-	size_t length;
-	const void *data = output.Read(&length);
-	if (data == nullptr) {
+	const auto data = output.Read();
+	if (data.IsNull()) {
 		IdleMonitor::Cancel();
 		CancelWrite();
 		return true;
 	}
 
-	auto nbytes = DirectWrite(data, length);
+	auto nbytes = DirectWrite(data.data, data.size);
 	if (gcc_unlikely(nbytes <= 0))
 		return nbytes == 0;
 

src/util/PeakBuffer.cxx

@@ -45,19 +45,21 @@ PeakBuffer::IsEmpty() const
 		 fifo_buffer_is_empty(peak_buffer));
 }
 
-const void *
-PeakBuffer::Read(size_t *length_r) const
+ConstBuffer<void>
+PeakBuffer::Read() const
 {
 	if (normal_buffer != nullptr) {
-		const void *p = fifo_buffer_read(normal_buffer, length_r);
+		size_t size;
+		const void *p = fifo_buffer_read(normal_buffer, &size);
 		if (p != nullptr)
-			return p;
+			return { p, size };
 	}
 
 	if (peak_buffer != nullptr) {
-		const void *p = fifo_buffer_read(peak_buffer, length_r);
+		size_t size;
+		const void *p = fifo_buffer_read(peak_buffer, &size);
 		if (p != nullptr)
-			return p;
+			return { p, size };
 	}
 
 	return nullptr;

src/util/PeakBuffer.hxx

@@ -20,11 +20,13 @@
 #ifndef MPD_PEAK_BUFFER_HXX
 #define MPD_PEAK_BUFFER_HXX
 
+#include "ConstBuffer.hxx"
 #include "Compiler.h"
 
 #include <stddef.h>
 
 struct fifo_buffer;
+template<typename T> struct ConstBuffer;
 
 /**
  * A FIFO-like buffer that will allocate more memory on demand to
@@ -57,7 +59,9 @@ public:
 	gcc_pure
 	bool IsEmpty() const;
 
-	const void *Read(size_t *length_r) const;
+	gcc_pure
+	ConstBuffer<void> Read() const;
+
 	void Consume(size_t length);
 
 	bool Append(const void *data, size_t length);