Wrapping block I/O call in a coroutine

gateway/src/apicast/http_proxy.lua

@@ -170,7 +170,7 @@ local function forward_https_request(proxy_uri, uri, proxy_opts)
                 -- set by openresty based on the size of the buffer. However, when the body is rendered
                 -- to a file, we will need to calculate and manually set the Content-Length header based
                 -- on the file size
-                local contentLength, err = file_size(temp_file_path)
+                local contentLength, err = file_size(temp_file_path)()
                 if err then
                     ngx.log(ngx.ERR, "HTTPS proxy: Failed to set content length, err: ", err)
                     ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR)

gateway/src/resty/file.lua

@@ -1,4 +1,5 @@
 local co_yield = coroutine._yield
+local co_wrap = coroutine._wrap
 local open = io.open
 
 local co_wrap_iter = require("resty.coroutines").co_wrap_iter
@@ -29,19 +30,21 @@ function _M.file_reader(filename)
 end
 
 function _M.file_size(filename)
-  local handle, err = open(filename)
+    return co_wrap(function()
+        local handle, err = open(filename)
 
-  if err then
-    return nil, err
-  end
+        if err then
+          return nil, err
+        end
 
-  local current = handle:seek()
-  local size = handle:seek("end")
+        local current = handle:seek()
+        local size = handle:seek("end")
 
-  handle:seek("set", current)
-  handle:close()
+        handle:seek("set", current)
+        handle:close()
 
-  return size
+        return size
+    end)
 end
 
 return _M