Add socket buffer to improve TCP socket read performance

Author: sandeepmistry

src/GSMClient.cpp

@@ -17,6 +17,8 @@
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */
 
+#include "utility/GSMSocketBuffer.h"
+
 #include "GSMClient.h"
 
 enum {
@@ -44,9 +46,7 @@ GSMClient::GSMClient(int socket, bool synch) :
   _host(NULL),
   _port(0),
   _ssl(false),
-  _writeSync(true),
-  _peek(-1),
-  _available(0)
+  _writeSync(true)
 {
   MODEM.addUrcHandler(this);
 }
@@ -199,6 +199,10 @@ int GSMClient::connectSSL(const char *host, uint16_t port)
 
 int GSMClient::connect()
 {
+  if (_socket != -1) {
+    stop();
+  }
+
   if (_synch) {
     while (ready() == 0);
   } else if (ready() == 0) {
@@ -323,63 +327,19 @@ int GSMClient::read(uint8_t *buf, size_t size)
     return 0;
   }
 
-  if (size > 512) {
-    size = 512;
-  }
-
-  String response;
-
-  MODEM.sendf("AT+USORD=%d,%d", _socket, size);
-  if (MODEM.waitForResponse(10000, &response) != 1) {
-    return 0;
-  }
+  int avail = available();
 
-  if (!response.startsWith("+USORD: ")) {
+  if (avail == 0) {
     return 0;
   }
 
-  int firstQuoteIndex = response.indexOf("\"");
-
-  response.remove(0, firstQuoteIndex + 1);
-  response.remove(response.length() - 1);
-
-  size = response.length() / 2;
-
-  for (size_t i = 0; i < size; i++) {
-    byte n1 = response[i * 2];
-    byte n2 = response[i * 2 + 1];
-
-    if (n1 > '9') {
-      n1 = (n1 - 'A') + 10;
-    } else {
-      n1 = (n1 - '0');
-    }
-
-    if (n2 > '9') {
-      n2 = (n2 - 'A') + 10;
-    } else {
-      n2 = (n2 - '0');
-    }
-
-    buf[i] = (n1 << 4) | n2;
-  }
-
-  _available = 0;
-  MODEM.poll();
-
-  return size;
+  return GSMSocketBuffer.read(_socket, buf, size);
 }
 
 int GSMClient::read()
 {
   byte b;
 
-  if (_peek != -1) {
-    b = _peek;
-    _peek = -1;
-    return b;
-  }
-
   if (read(&b, 1) == 1) {
     return b;
   }
@@ -399,18 +359,24 @@ int GSMClient::available()
     return 0;
   }
 
-  MODEM.poll();
+  int avail = GSMSocketBuffer.available(_socket);
 
-  return _available;
+  if (avail < 0) {
+    stop();
+
+    return 0;
+  }
+
+  return avail;
 }
 
 int GSMClient::peek()
 {
-  if (_peek == -1) {
-    _peek = read();
+  if (available() > 0) {
+    return GSMSocketBuffer.peek(_socket);
   }
 
-  return _peek;
+  return -1;
 }
 
 void GSMClient::flush()
@@ -426,6 +392,7 @@ void GSMClient::stop()
   MODEM.sendf("AT+USOCL=%d", _socket);
   MODEM.waitForResponse(10000);
 
+  GSMSocketBuffer.close(_socket);
   _socket = -1;
 }
 
@@ -436,8 +403,8 @@ void GSMClient::handleUrc(const String& urc)
 
     if (socket == _socket) {
       // this socket closed
+      GSMSocketBuffer.close(_socket);
       _socket = -1;
-      _available = 0;
     }
   } else if (urc.startsWith("+UUSORD: ")) {
     int socket = urc.charAt(9) - '0';
@@ -446,13 +413,8 @@ void GSMClient::handleUrc(const String& urc)
       if (urc.endsWith(",4294967295")) {
         // SSL disconnect
         // this socket closed
+        GSMSocketBuffer.close(_socket);
         _socket = -1;
-        _available = 0;
-      } else {
-        int commaIndex = urc.indexOf(',');
-        if (commaIndex != -1) {
-          _available = urc.substring(commaIndex + 1).toInt();
-        }
       }
     }
   }

src/GSMClient.h

@@ -144,8 +144,6 @@ class GSMClient : public Client, public ModemUrcHandler {
 
   bool _writeSync;
   String _response;
-  int _peek;
-  int _available;
 };
 
 #endif

src/utility/GSMSocketBuffer.cpp

@@ -0,0 +1,133 @@
+/*
+  This file is part of the MKR GSM library.
+  Copyright (C) 2018  Arduino AG (http://www.arduino.cc/)
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "Modem.h"
+
+#include "GSMSocketBuffer.h"
+
+#define GSM_SOCKET_NUM_BUFFERS (sizeof(_buffers) / sizeof(_buffers[0]))
+
+#define GSM_SOCKET_BUFFER_SIZE 512
+
+GSMSocketBufferClass::GSMSocketBufferClass()
+{
+  memset(&_buffers, 0x00, sizeof(_buffers));
+}
+
+GSMSocketBufferClass::~GSMSocketBufferClass()
+{
+  for (unsigned int i = 0; i < GSM_SOCKET_NUM_BUFFERS; i++) {
+    close(i);
+  }
+}
+
+void GSMSocketBufferClass::close(int socket)
+{
+  if (_buffers[socket].data) {
+    free(_buffers[socket].data);
+    _buffers[socket].data = _buffers[socket].head = NULL;
+    _buffers[socket].length = 0;
+  }
+}
+
+int GSMSocketBufferClass::available(int socket)
+{
+  if (_buffers[socket].length == 0) {
+    if (_buffers[socket].data == NULL) {
+      _buffers[socket].data = _buffers[socket].head = (uint8_t*)malloc(GSM_SOCKET_BUFFER_SIZE);
+      _buffers[socket].length = 0;
+    }
+
+    String response;
+
+    MODEM.sendf("AT+USORD=%d,%d", socket, GSM_SOCKET_BUFFER_SIZE);
+    int status = MODEM.waitForResponse(10000, &response);
+    if (status != 1) {
+      return -1;
+    }
+
+    if (!response.startsWith("+USORD: ")) {
+      return 0;
+    }
+
+    int firstQuoteIndex = response.indexOf("\"");
+
+    response.remove(0, firstQuoteIndex + 1);
+    response.remove(response.length() - 1);
+
+    size_t size = response.length() / 2;
+
+    for (size_t i = 0; i < size; i++) {
+      byte n1 = response[i * 2];
+      byte n2 = response[i * 2 + 1];
+
+      if (n1 > '9') {
+        n1 = (n1 - 'A') + 10;
+      } else {
+        n1 = (n1 - '0');
+      }
+
+      if (n2 > '9') {
+        n2 = (n2 - 'A') + 10;
+      } else {
+        n2 = (n2 - '0');
+      }
+
+      _buffers[socket].data[i] = (n1 << 4) | n2;
+    }
+
+    _buffers[socket].head = _buffers[socket].data;
+    _buffers[socket].length = size;
+  }
+
+  return _buffers[socket].length;
+}
+
+int GSMSocketBufferClass::peek(int socket)
+{
+  if (!available(socket)) {
+    return -1;
+  }
+
+  return *_buffers[socket].head;
+}
+
+int GSMSocketBufferClass::read(int socket, uint8_t* data, size_t length)
+{
+  int avail = available(socket);
+
+  if (!avail) {
+    return 0;
+  }
+
+  if (avail < (int)length) {
+    length = avail;
+  }
+
+  memcpy(data, _buffers[socket].head, length);
+  _buffers[socket].head += length;
+  _buffers[socket].length -= length;
+
+  return length;
+}
+
+GSMSocketBufferClass GSMSocketBuffer;

src/utility/GSMSocketBuffer.h

@@ -0,0 +1,49 @@
+/*
+  This file is part of the MKR GSM library.
+  Copyright (C) 2018  Arduino AG (http://www.arduino.cc/)
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#ifndef _GSMSOCKET_BUFFER_H_INCLUDED
+#define _GSMSOCKET_BUFFER_H_INCLUDED
+
+#include <stddef.h>
+#include <stdint.h>
+
+class GSMSocketBufferClass {
+
+public:
+public:
+  GSMSocketBufferClass();
+  virtual ~GSMSocketBufferClass();
+
+  void close(int socket);
+
+  int available(int socket);
+  int peek(int socket);
+  int read(int socket, uint8_t* data, size_t length);
+
+private:
+  struct {
+    uint8_t* data;
+    uint8_t* head;
+    int length;
+  } _buffers[7];
+};
+
+extern GSMSocketBufferClass GSMSocketBuffer;
+
+#endif