libs/core: optimize strip_bytecode() memory usage by avoiding string concatenation

diff --git a/libs/core/luasrc/util.lua b/libs/core/luasrc/util.lua
index 79f01a6..adeb99f 100644 (file)
--- a/libs/core/luasrc/util.lua
+++ b/libs/core/luasrc/util.lua
@@ -554,10 +554,10 @@ function strip_bytecode(code)
                end
        end
 
                end
        end
 

-       local strip_function
-       strip_function = function(code)
+       local function strip_function(code)

                local count, offset = subint(code, 1, size)
                local count, offset = subint(code, 1, size)

-               local stripped, dirty = string.rep("\0", size), offset + count
+               local stripped = { string.rep("\0", size) }
+               local dirty = offset + count

                offset = offset + count + int * 2 + 4
                offset = offset + int + subint(code, offset, int) * ins
                count, offset = subint(code, offset, int)
                offset = offset + count + int * 2 + 4
                offset = offset + int + subint(code, offset, int) * ins
                count, offset = subint(code, offset, int)


@@ -575,10 +575,11 @@ function strip_bytecode(code)
                        end
                end
                count, offset = subint(code, offset, int)
                        end
                end
                count, offset = subint(code, offset, int)

-               stripped = stripped .. code:sub(dirty, offset - 1)
+               stripped[#stripped+1] = code:sub(dirty, offset - 1)

                for n = 1, count do
                        local proto, off = strip_function(code:sub(offset, -1))
                for n = 1, count do
                        local proto, off = strip_function(code:sub(offset, -1))

-                       stripped, offset = stripped .. proto, offset + off - 1
+                       stripped[#stripped+1] = proto
+                       offset = offset + off - 1

                end
                offset = offset + subint(code, offset, int) * int + int
                count, offset = subint(code, offset, int)
                end
                offset = offset + subint(code, offset, int) * int + int
                count, offset = subint(code, offset, int)


@@ -589,8 +590,8 @@ function strip_bytecode(code)
                for n = 1, count do
                        offset = offset + subint(code, offset, size) + size
                end
                for n = 1, count do
                        offset = offset + subint(code, offset, size) + size
                end

-               stripped = stripped .. string.rep("\0", int * 3)
-               return stripped, offset
+               stripped[#stripped+1] = string.rep("\0", int * 3)
+               return table.concat(stripped), offset

        end
 
        return code:sub(1,12) .. strip_function(code:sub(13,-1))
        end
 
        return code:sub(1,12) .. strip_function(code:sub(13,-1))