ClientConnection uses too much heap when streaming files esp8266#2871 (esp8266#2874)

* ClientConnection uses too much heap when streaming files esp8266#2871

* make write_chunk_size a member variable

* untabify

Author: joelucid

libraries/ESP8266WiFi/src/include/ClientContext.h

@@ -333,7 +333,6 @@ class ClientContext
         return _written;
     }
 
-
     void _write_some()
     {
         if (!_datasource || !_pcb) {
@@ -346,15 +345,20 @@ class ClientContext
             can_send = 0;
         }
         size_t will_send = (can_send < left) ? can_send : left;
-        if (will_send) {
-            const uint8_t* buf = _datasource->get_buffer(will_send);
-            err_t err = tcp_write(_pcb, buf, will_send, TCP_WRITE_FLAG_COPY);
-            _datasource->release_buffer(buf, will_send);
+        bool did_write = false;
+        while( will_send ) {
+            size_t next_chunk =
+                will_send > _write_chunk_size ? _write_chunk_size : will_send;
+            const uint8_t* buf = _datasource->get_buffer(next_chunk);
+            err_t err = tcp_write(_pcb, buf, next_chunk, TCP_WRITE_FLAG_COPY);
+            _datasource->release_buffer(buf, next_chunk);
             if (err == ERR_OK) {
-                _written += will_send;
-                tcp_output(_pcb);
+                _written += next_chunk;
+                did_write = true;
             }
+            will_send -= next_chunk;
         }
+        if( did_write ) tcp_output(_pcb);
 
         if (!_datasource->available() || _noblock) {
             delete _datasource;
@@ -479,6 +483,7 @@ class ClientContext
 
     DataSource* _datasource = nullptr;
     size_t _written = 0;
+    size_t _write_chunk_size = 256;
     bool _noblock = false;
     bool _send_waiting = false;
 };