[Qemu-devel] [PATCH 1/4] qjson: replace QString in JSONLexer with GString

[Paolo Bonzini <pbonzini@redhat.com>]

JSONLexer only needs a simple resizable buffer.  json-streamer.c
can allocate memory for each token instead of relying on reference
counting of QStrings.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 include/qapi/qmp/json-lexer.h    |  7 +++----
 include/qapi/qmp/json-streamer.h |  1 +
 qobject/json-lexer.c             | 22 ++++++++--------------
 qobject/json-streamer.c          | 10 +++++-----
 4 files changed, 17 insertions(+), 23 deletions(-)

diff --git a/include/qapi/qmp/json-lexer.h b/include/qapi/qmp/json-lexer.h
index cdff046..584b27d 100644
--- a/include/qapi/qmp/json-lexer.h
+++ b/include/qapi/qmp/json-lexer.h
@@ -14,8 +14,7 @@
 #ifndef QEMU_JSON_LEXER_H
 #define QEMU_JSON_LEXER_H
 
-#include "qapi/qmp/qstring.h"
-#include "qapi/qmp/qlist.h"
+#include "glib-compat.h"
 
 typedef enum json_token_type {
     JSON_OPERATOR = 100,
@@ -30,13 +29,13 @@ typedef enum json_token_type {
 
 typedef struct JSONLexer JSONLexer;
 
-typedef void (JSONLexerEmitter)(JSONLexer *, QString *, JSONTokenType, int x, int y);
+typedef void (JSONLexerEmitter)(JSONLexer *, GString *, JSONTokenType, int x, int y);
 
 struct JSONLexer
 {
     JSONLexerEmitter *emit;
     int state;
-    QString *token;
+    GString *token;
     int x, y;
 };
 
diff --git a/include/qapi/qmp/json-streamer.h b/include/qapi/qmp/json-streamer.h
index 823f7d7..e901144 100644
--- a/include/qapi/qmp/json-streamer.h
+++ b/include/qapi/qmp/json-streamer.h
@@ -14,6 +14,7 @@
 #ifndef QEMU_JSON_STREAMER_H
 #define QEMU_JSON_STREAMER_H
 
+#include <stdint.h>
 #include "qapi/qmp/qlist.h"
 #include "qapi/qmp/json-lexer.h"
 
diff --git a/qobject/json-lexer.c b/qobject/json-lexer.c
index b19623e..c2060f8 100644
--- a/qobject/json-lexer.c
+++ b/qobject/json-lexer.c
@@ -11,12 +11,9 @@
  *
  */
 
-#include "qapi/qmp/qstring.h"
-#include "qapi/qmp/qlist.h"
-#include "qapi/qmp/qdict.h"
-#include "qapi/qmp/qint.h"
 #include "qemu-common.h"
 #include "qapi/qmp/json-lexer.h"
+#include <stdint.h>
 
 #define MAX_TOKEN_SIZE (64ULL << 20)
 
@@ -272,7 +269,7 @@ void json_lexer_init(JSONLexer *lexer, JSONLexerEmitter func)
 {
     lexer->emit = func;
     lexer->state = IN_START;
-    lexer->token = qstring_new();
+    lexer->token = g_string_sized_new(3);
     lexer->x = lexer->y = 0;
 }
 
@@ -290,7 +287,7 @@ static int json_lexer_feed_char(JSONLexer *lexer, char ch, bool flush)
         new_state = json_lexer[lexer->state][(uint8_t)ch];
         char_consumed = !TERMINAL_NEEDED_LOOKAHEAD(lexer->state, new_state);
         if (char_consumed) {
-            qstring_append_chr(lexer->token, ch);
+            g_string_append_c(lexer->token, ch);
         }
 
         switch (new_state) {
@@ -303,8 +300,7 @@ static int json_lexer_feed_char(JSONLexer *lexer, char ch, bool flush)
             lexer->emit(lexer, lexer->token, new_state, lexer->x, lexer->y);
             /* fall through */
         case JSON_SKIP:
-            QDECREF(lexer->token);
-            lexer->token = qstring_new();
+            g_string_truncate(lexer->token, 0);
             new_state = IN_START;
             break;
         case IN_ERROR:
@@ -322,8 +318,7 @@ static int json_lexer_feed_char(JSONLexer *lexer, char ch, bool flush)
              * induce an error/flush state.
              */
             lexer->emit(lexer, lexer->token, JSON_ERROR, lexer->x, lexer->y);
-            QDECREF(lexer->token);
-            lexer->token = qstring_new();
+            g_string_truncate(lexer->token, 0);
             new_state = IN_START;
             lexer->state = new_state;
             return 0;
@@ -336,10 +331,9 @@ static int json_lexer_feed_char(JSONLexer *lexer, char ch, bool flush)
     /* Do not let a single token grow to an arbitrarily large size,
      * this is a security consideration.
      */
-    if (lexer->token->length > MAX_TOKEN_SIZE) {
+    if (lexer->token->len > MAX_TOKEN_SIZE) {
         lexer->emit(lexer, lexer->token, lexer->state, lexer->x, lexer->y);
-        QDECREF(lexer->token);
-        lexer->token = qstring_new();
+        g_string_truncate(lexer->token, 0);
         lexer->state = IN_START;
     }
 
@@ -369,5 +363,5 @@ int json_lexer_flush(JSONLexer *lexer)
 
 void json_lexer_destroy(JSONLexer *lexer)
 {
-    QDECREF(lexer->token);
+    g_string_free(lexer->token, true);
 }
diff --git a/qobject/json-streamer.c b/qobject/json-streamer.c
index 1b2f9b1..f240501 100644
--- a/qobject/json-streamer.c
+++ b/qobject/json-streamer.c
@@ -12,6 +12,7 @@
  */
 
 #include "qapi/qmp/qlist.h"
+#include "qapi/qmp/qstring.h"
 #include "qapi/qmp/qint.h"
 #include "qapi/qmp/qdict.h"
 #include "qemu-common.h"
@@ -21,13 +22,13 @@
 #define MAX_TOKEN_SIZE (64ULL << 20)
 #define MAX_NESTING (1ULL << 10)
 
-static void json_message_process_token(JSONLexer *lexer, QString *token, JSONTokenType type, int x, int y)
+static void json_message_process_token(JSONLexer *lexer, GString *input, JSONTokenType type, int x, int y)
 {
     JSONMessageParser *parser = container_of(lexer, JSONMessageParser, lexer);
     QDict *dict;
 
     if (type == JSON_OPERATOR) {
-        switch (qstring_get_str(token)[0]) {
+        switch (input->str[0]) {
         case '{':
             parser->brace_count++;
             break;
@@ -47,12 +48,11 @@ static void json_message_process_token(JSONLexer *lexer, QString *token, JSONTok
 
     dict = qdict_new();
     qdict_put(dict, "type", qint_from_int(type));
-    QINCREF(token);
-    qdict_put(dict, "token", token);
+    qdict_put(dict, "token", qstring_from_str(input->str));
     qdict_put(dict, "x", qint_from_int(x));
     qdict_put(dict, "y", qint_from_int(y));
 
-    parser->token_size += token->length;
+    parser->token_size += input->len;
 
     qlist_append(parser->tokens, dict);
 
-- 
2.5.0