SocketRecvBuffer: Eliminate memmove

Since we don't try to read into buffer if buffer is not empty, we
don't have to memmove things.  This commit mostly rewrites
SocketRecvBuffer.

1 files changed, 13 insertions, 17 deletions

diff --git a/src/SocketRecvBuffer.h b/src/SocketRecvBuffer.h
index 00d04bb7..ceee253e 100644
--- a/src/SocketRecvBuffer.h
+++ b/src/SocketRecvBuffer.h
@@ -38,6 +38,7 @@
 #include "common.h"
 
 #include <memory>
+#include <array>
 
 namespace aria2 {
 
@@ -45,21 +46,17 @@ class SocketCore;
 
 class SocketRecvBuffer {
 public:
-  SocketRecvBuffer
-  (std::shared_ptr<SocketCore> socket,
-   size_t capacity = 16*1024);
+  SocketRecvBuffer(std::shared_ptr<SocketCore> socket);
   ~SocketRecvBuffer();
   // Reads data from socket as much as capacity allows. Returns the
   // number of bytes read.
   ssize_t recv();
-  // Shifts buffer by offset bytes. offset must satisfy offset <=
-  // getBufferLength().
-  void shiftBuffer(size_t offset);
   // Truncates the contents of buffer to 0.
-  void clearBuffer()
-  {
-    bufLen_ = 0;
-  }
+  void truncateBuffer();
+  // Drains first n bytes of data from buffer.  It is an programmer's
+  // responsibility to ensure that n is smaller or equal to the
+  // buffered data.
+  void drain(size_t n);
 
   const std::shared_ptr<SocketCore>& getSocket() const
   {
@@ -68,25 +65,24 @@ public:
 
   const unsigned char* getBuffer() const
   {
-    return buf_.get();
+    return pos_;
   }
 
   size_t getBufferLength() const
   {
-    return bufLen_;
+    return last_ - pos_;
   }
 
   bool bufferEmpty() const
   {
-    return bufLen_ == 0;
+    return pos_ == last_;
   }
 
-  void pushBuffer(const unsigned char* data, size_t len);
 private:
+  std::array<unsigned char, 16384> buf_;
   std::shared_ptr<SocketCore> socket_;
-  size_t capacity_;
-  std::unique_ptr<unsigned char[]> buf_;
-  size_t bufLen_;
+  unsigned char *pos_;
+  unsigned char *last_;
 };
 
 } // namespace aria2