Merge: Use a Buffer in StringWriter

This aims to replace the dirty #2367 and might solve the underlying problem in a better way by using a Buffer instead of an Array[String] in StringWriter.

With the following pseudo-oneliner

~~~nit
import json::string_parser
import json
print args.first.to_path.read_all.parse_json.as(not null).serialize_to_json(pretty=true, plain=true).length
~~~

And the file `nit/benchmarks/json/inputs/magic.json` a 54MB json file.

Before:

* User time (seconds): 18.02
* Elapsed (wall clock) time: 13.43
* Maximum resident set size (GB): 6.09

After:

* User time (seconds): 4.26 (-76%)
* Elapsed (wall clock) time: 3.98 (-70%)
* Maximum resident set size (GB): 1.16 (-80%)

Nevertheless, 1GB of ram to process a 54MB file is still huge.

Pull-Request: #2371
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>

diff --git a/lib/core/stream.nit b/lib/core/stream.nit
index 217e9c8..6fbc63c 100644 (file)
--- a/lib/core/stream.nit
+++ b/lib/core/stream.nit
@@ -668,18 +668,24 @@ end
 class StringWriter
        super Writer
 
-       private var content = new Array[String]
-       redef fun to_s do return content.plain_to_s
+       private var content = new Buffer
+       redef fun to_s do return content.to_s
        redef fun is_writable do return not closed
 
        redef fun write_bytes(b) do
-               content.add(b.to_s)
+               content.append(b.to_s)
        end
 
        redef fun write(str)
        do
                assert not closed
-               content.add(str.to_s)
+               content.append(str)
+       end
+
+       redef fun write_char(c)
+       do
+               assert not closed
+               content.add(c)
        end
 
        # Is the stream closed?

diff --git a/lib/json/serialization_write.nit b/lib/json/serialization_write.nit
index 43987e8..e226e30 100644 (file)
--- a/lib/json/serialization_write.nit
+++ b/lib/json/serialization_write.nit
@@ -161,7 +161,7 @@ redef class Text
                                        v.stream.write char.escape_to_utf16
                                end
                        else
-                               v.stream.write char.to_s
+                               v.stream.write_char char
                        end
                end
                v.stream.write "\""