partial read or recv for openresty stream-lua-nginx-module, receive('*p') introduced.

ngxstream_readpartial.patch

diff --git a/src/ngx_stream_lua_socket_tcp.c b/src/ngx_stream_lua_socket_tcp.c
index 4680811..4da1ac6 100644
--- a/src/ngx_stream_lua_socket_tcp.c
+++ b/src/ngx_stream_lua_socket_tcp.c
@@ -88,6 +88,7 @@ static int ngx_stream_lua_socket_write_error_retval_handler(
     ngx_stream_session_t *s, ngx_stream_lua_socket_tcp_upstream_t *u,
     lua_State *L);
 static ngx_int_t ngx_stream_lua_socket_read_all(void *data, ssize_t bytes);
+static ngx_int_t ngx_stream_lua_socket_read_partial(void *data, ssize_t bytes);
 static ngx_int_t ngx_stream_lua_socket_read_until(void *data, ssize_t bytes);
 static ngx_int_t ngx_stream_lua_socket_read_chunk(void *data, ssize_t bytes);
 static int ngx_stream_lua_socket_tcp_receiveuntil(lua_State *L);
@@ -1736,6 +1737,10 @@ ngx_stream_lua_socket_tcp_receive(lua_State *L)
                 u->input_filter = ngx_stream_lua_socket_read_all;
                 break;
 
+            case 'p':
+                u->input_filter = ngx_stream_lua_socket_read_partial;
+                break;
+
             default:
                 return luaL_argerror(L, 2, "bad pattern argument");
                 break;
@@ -1918,6 +1923,35 @@ ngx_stream_lua_socket_read_all(void *data, ssize_t bytes)
 
 
 static ngx_int_t
+ngx_stream_lua_socket_read_partial(void *data, ssize_t bytes)
+{
+    ngx_stream_lua_socket_tcp_upstream_t      *u = data;
+
+    ngx_buf_t                   *b;
+#if (NGX_DEBUG)
+    ngx_stream_session_t          *s;
+
+    s = u->request;
+#endif
+
+    ngx_log_debug0(NGX_LOG_DEBUG_STREAM, s->connection->log, 0,
+                   "stream lua tcp socket read partial");
+
+    if (bytes == 0) {
+        u->ft_type |= NGX_STREAM_LUA_SOCKET_FT_CLOSED;
+        return NGX_ERROR;
+    }
+
+    b = &u->buffer;
+
+    u->buf_in->buf->last += bytes;
+    b->pos += bytes;
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
 ngx_stream_lua_socket_read_line(void *data, ssize_t bytes)
 {
     ngx_stream_lua_socket_tcp_upstream_t      *u = data;