qjson: store tokens in a GQueue

Even though we still have the "streamer" concept, the tokens can now
be deleted as they are read.  While doing so convert from QList to
GQueue, since the next step will make tokens not a QObject and we
will have to do the conversion anyway.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1448300659-23559-4-git-send-email-pbonzini@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

8 files changed, 45 insertions, 65 deletions

diff --git a/include/qapi/qmp/json-parser.h b/include/qapi/qmp/json-parser.h
index 44d88f3468..fea89f873a 100644
--- a/include/qapi/qmp/json-parser.h
+++ b/include/qapi/qmp/json-parser.h
@@ -18,7 +18,7 @@
 #include "qapi/qmp/qlist.h"
 #include "qapi/error.h"
 
-QObject *json_parser_parse(QList *tokens, va_list *ap);
-QObject *json_parser_parse_err(QList *tokens, va_list *ap, Error **errp);
+QObject *json_parser_parse(GQueue *tokens, va_list *ap);
+QObject *json_parser_parse_err(GQueue *tokens, va_list *ap, Error **errp);
 
 #endif
diff --git a/include/qapi/qmp/json-streamer.h b/include/qapi/qmp/json-streamer.h
index e90114476a..e9f2937b54 100644
--- a/include/qapi/qmp/json-streamer.h
+++ b/include/qapi/qmp/json-streamer.h
@@ -15,21 +15,21 @@
 #define QEMU_JSON_STREAMER_H
 
 #include <stdint.h>
-#include "qapi/qmp/qlist.h"
+#include "glib-compat.h"
 #include "qapi/qmp/json-lexer.h"
 
 typedef struct JSONMessageParser
 {
-    void (*emit)(struct JSONMessageParser *parser, QList *tokens);
+    void (*emit)(struct JSONMessageParser *parser, GQueue *tokens);
     JSONLexer lexer;
     int brace_count;
     int bracket_count;
-    QList *tokens;
+    GQueue *tokens;
     uint64_t token_size;
 } JSONMessageParser;
 
 void json_message_parser_init(JSONMessageParser *parser,
-                              void (*func)(JSONMessageParser *, QList *));
+                              void (*func)(JSONMessageParser *, GQueue *));
 
 int json_message_parser_feed(JSONMessageParser *parser,
                              const char *buffer, size_t size);
diff --git a/monitor.c b/monitor.c
index 49073ac195..9a35d7265f 100644
--- a/monitor.c
+++ b/monitor.c
@@ -3849,7 +3849,7 @@ static QDict *qmp_check_input_obj(QObject *input_obj, Error **errp)
     return input_dict;
 }
 
-static void handle_qmp_command(JSONMessageParser *parser, QList *tokens)
+static void handle_qmp_command(JSONMessageParser *parser, GQueue *tokens)
 {
     Error *local_err = NULL;
     QObject *obj, *data;
diff --git a/qga/main.c b/qga/main.c
index d2a0ffc807..f83a97d245 100644
--- a/qga/main.c
+++ b/qga/main.c
@@ -570,7 +570,7 @@ static void process_command(GAState *s, QDict *req)
 }
 
 /* handle requests/control events coming in over the channel */
-static void process_event(JSONMessageParser *parser, QList *tokens)
+static void process_event(JSONMessageParser *parser, GQueue *tokens)
 {
     GAState *s = container_of(parser, GAState, parser);
     QDict *qdict;
diff --git a/qobject/json-parser.c b/qobject/json-parser.c
index 60dd6243a6..5a84951e37 100644
--- a/qobject/json-parser.c
+++ b/qobject/json-parser.c
@@ -26,11 +26,8 @@
 typedef struct JSONParserContext
 {
     Error *err;
-    struct {
-        QObject **buf;
-        size_t pos;
-        size_t count;
-    } tokens;
+    QObject *current;
+    GQueue *buf;
 } JSONParserContext;
 
 #define BUG_ON(cond) assert(!(cond))
@@ -243,56 +240,34 @@ out:
     return NULL;
 }
 
+/* Note: unless the token object returned by parser_context_peek_token
+ * or parser_context_pop_token is explicitly incref'd, it will be
+ * deleted as soon as parser_context_pop_token is called again.
+ */
 static QObject *parser_context_pop_token(JSONParserContext *ctxt)
 {
-    QObject *token;
-    g_assert(ctxt->tokens.pos < ctxt->tokens.count);
-    token = ctxt->tokens.buf[ctxt->tokens.pos];
-    ctxt->tokens.pos++;
-    return token;
+    qobject_decref(ctxt->current);
+    assert(!g_queue_is_empty(ctxt->buf));
+    ctxt->current = g_queue_pop_head(ctxt->buf);
+    return ctxt->current;
 }
 
-/* Note: parser_context_{peek|pop}_token do not increment the
- * token object's refcount. In both cases the references will continue
- * to be tracked and cleaned up in parser_context_free(), so do not
- * attempt to free the token object.
- */
 static QObject *parser_context_peek_token(JSONParserContext *ctxt)
 {
-    QObject *token;
-    g_assert(ctxt->tokens.pos < ctxt->tokens.count);
-    token = ctxt->tokens.buf[ctxt->tokens.pos];
-    return token;
-}
-
-static void tokens_append_from_iter(QObject *obj, void *opaque)
-{
-    JSONParserContext *ctxt = opaque;
-    g_assert(ctxt->tokens.pos < ctxt->tokens.count);
-    ctxt->tokens.buf[ctxt->tokens.pos++] = obj;
-    qobject_incref(obj);
+    assert(!g_queue_is_empty(ctxt->buf));
+    return g_queue_peek_head(ctxt->buf);
 }
 
-static JSONParserContext *parser_context_new(QList *tokens)
+static JSONParserContext *parser_context_new(GQueue *tokens)
 {
     JSONParserContext *ctxt;
-    size_t count;
 
     if (!tokens) {
         return NULL;
     }
 
-    count = qlist_size(tokens);
-    if (count == 0) {
-        return NULL;
-    }
-
     ctxt = g_malloc0(sizeof(JSONParserContext));
-    ctxt->tokens.pos = 0;
-    ctxt->tokens.count = count;
-    ctxt->tokens.buf = g_malloc(count * sizeof(QObject *));
-    qlist_iter(tokens, tokens_append_from_iter, ctxt);
-    ctxt->tokens.pos = 0;
+    ctxt->buf = tokens;
 
     return ctxt;
 }
@@ -300,12 +275,12 @@ static JSONParserContext *parser_context_new(QList *tokens)
 /* to support error propagation, ctxt->err must be freed separately */
 static void parser_context_free(JSONParserContext *ctxt)
 {
-    int i;
     if (ctxt) {
-        for (i = 0; i < ctxt->tokens.count; i++) {
-            qobject_decref(ctxt->tokens.buf[i]);
+        while (!g_queue_is_empty(ctxt->buf)) {
+            parser_context_pop_token(ctxt);
         }
-        g_free(ctxt->tokens.buf);
+        qobject_decref(ctxt->current);
+        g_queue_free(ctxt->buf);
         g_free(ctxt);
     }
 }
@@ -598,12 +573,12 @@ static QObject *parse_value(JSONParserContext *ctxt, va_list *ap)
     }
 }
 
-QObject *json_parser_parse(QList *tokens, va_list *ap)
+QObject *json_parser_parse(GQueue *tokens, va_list *ap)
 {
     return json_parser_parse_err(tokens, ap, NULL);
 }
 
-QObject *json_parser_parse_err(QList *tokens, va_list *ap, Error **errp)
+QObject *json_parser_parse_err(GQueue *tokens, va_list *ap, Error **errp)
 {
     JSONParserContext *ctxt = parser_context_new(tokens);
     QObject *result;
diff --git a/qobject/json-streamer.c b/qobject/json-streamer.c
index 7292f3a38f..f7a3e782bd 100644
--- a/qobject/json-streamer.c
+++ b/qobject/json-streamer.c
@@ -22,6 +22,14 @@
 #define MAX_TOKEN_SIZE (64ULL << 20)
 #define MAX_NESTING (1ULL << 10)
 
+static void json_message_free_tokens(JSONMessageParser *parser)
+{
+    if (parser->tokens) {
+        g_queue_free(parser->tokens);
+        parser->tokens = NULL;
+    }
+}
+
 static void json_message_process_token(JSONLexer *lexer, GString *input,
                                        JSONTokenType type, int x, int y)
 {
@@ -53,7 +61,7 @@ static void json_message_process_token(JSONLexer *lexer, GString *input,
 
     parser->token_size += input->len;
 
-    qlist_append(parser->tokens, dict);
+    g_queue_push_tail(parser->tokens, dict);
 
     if (type == JSON_ERROR) {
         goto out_emit_bad;
@@ -77,27 +85,24 @@ out_emit_bad:
      * Clear out token list and tell the parser to emit an error
      * indication by passing it a NULL list
      */
-    QDECREF(parser->tokens);
-    parser->tokens = NULL;
+    json_message_free_tokens(parser);
 out_emit:
     /* send current list of tokens to parser and reset tokenizer */
     parser->brace_count = 0;
     parser->bracket_count = 0;
+    /* parser->emit takes ownership of parser->tokens.  */
     parser->emit(parser, parser->tokens);
-    if (parser->tokens) {
-        QDECREF(parser->tokens);
-    }
-    parser->tokens = qlist_new();
+    parser->tokens = g_queue_new();
     parser->token_size = 0;
 }
 
 void json_message_parser_init(JSONMessageParser *parser,
-                              void (*func)(JSONMessageParser *, QList *))
+                              void (*func)(JSONMessageParser *, GQueue *))
 {
     parser->emit = func;
     parser->brace_count = 0;
     parser->bracket_count = 0;
-    parser->tokens = qlist_new();
+    parser->tokens = g_queue_new();
     parser->token_size = 0;
 
     json_lexer_init(&parser->lexer, json_message_process_token);
@@ -117,5 +122,5 @@ int json_message_parser_flush(JSONMessageParser *parser)
 void json_message_parser_destroy(JSONMessageParser *parser)
 {
     json_lexer_destroy(&parser->lexer);
-    QDECREF(parser->tokens);
+    json_message_free_tokens(parser);
 }
diff --git a/qobject/qjson.c b/qobject/qjson.c
index 33f8ef530c..a3e6a7ca42 100644
--- a/qobject/qjson.c
+++ b/qobject/qjson.c
@@ -28,7 +28,7 @@ typedef struct JSONParsingState
     QObject *result;
 } JSONParsingState;
 
-static void parse_json(JSONMessageParser *parser, QList *tokens)
+static void parse_json(JSONMessageParser *parser, GQueue *tokens)
 {
     JSONParsingState *s = container_of(parser, JSONParsingState, parser);
     s->result = json_parser_parse(tokens, s->ap);
diff --git a/tests/libqtest.c b/tests/libqtest.c
index f6f3d7a950..9753161916 100644
--- a/tests/libqtest.c
+++ b/tests/libqtest.c
@@ -351,7 +351,7 @@ typedef struct {
     QDict *response;
 } QMPResponseParser;
 
-static void qmp_response(JSONMessageParser *parser, QList *tokens)
+static void qmp_response(JSONMessageParser *parser, GQueue *tokens)
 {
     QMPResponseParser *qmp = container_of(parser, QMPResponseParser, parser);
     QObject *obj;