[tracker] parser: Optimize 0-length string parsing

[Carlos Garnacho <carlosg src gnome org>]

commit 3eecd6f1bcadd7b9d46220ca111e91e8daf83822
Author: Carlos Garnacho <carlosg gnome org>
Date:   Mon Jul 20 03:12:37 2015 +0200

    parser: Optimize 0-length string parsing
    
    We were still creating the ICU parser and trying to feed it with
    data, which turned out surprisingly expensive on deletes, as
    "deleting" on FTS just replaces the text with "nothing", so we're
    creating a parser for each of these.
    
    This reduces the timing of the sparql delete in the previous commit
    further down to:
    real        1m7.029s
    user        0m0.023s
    sys 0m0.009s

 src/libtracker-common/tracker-parser-libicu.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/src/libtracker-common/tracker-parser-libicu.c b/src/libtracker-common/tracker-parser-libicu.c
index b26722c..493f864 100644
--- a/src/libtracker-common/tracker-parser-libicu.c
+++ b/src/libtracker-common/tracker-parser-libicu.c
@@ -651,6 +651,9 @@ tracker_parser_reset (TrackerParser *parser,
 
        parser->cursor = 0;
 
+       if (parser->txt_size == 0)
+               return;
+
        /* Open converter UTF-8 to UChar */
        converter = ucnv_open ("UTF-8", &error);
        if (!converter) {