[incomplete] modify filter API to be able to rename tag

[nokute78]

To edit tag with filter plugin like fluentd, I modified filter API.
Then we can edit tag at filter plugin side.

This is a diff to rename tag with out_stdout.(just a sample)

diff --git a/plugins/filter_stdout/stdout.c b/plugins/filter_stdout/stdout.c
index 8289f4b..bfd3b7c 100644
--- a/plugins/filter_stdout/stdout.c
+++ b/plugins/filter_stdout/stdout.c
@@ -22,6 +22,8 @@
 #include <fluent-bit/flb_filter.h>
 #include <fluent-bit/flb_utils.h>
 #include <fluent-bit/flb_time.h>
+#include <fluent-bit/flb_mem.h>
+#include <fluent-bit/flb_str.h>
 
 #include <msgpack.h>
 
@@ -53,6 +55,10 @@ static int cb_stdout_filter(void *data, size_t bytes,
     struct flb_time tmp;
     msgpack_object *p;
 
+    flb_free(*tag);
+    *tag = flb_strdup("hoge");
+    *tag_len = 4;
+
     msgpack_unpacked_init(&result);
     while (msgpack_unpack_next(&result, data, bytes, &off)) {
         printf("[%zd] %s: [", cnt++, *tag);

[dawidmalina]

How this will work? Is it simillar like this fluentd plugin: rewrite_tag_filter?

[edsiper]

@nokute78 is this tested with static and dynamic tags plugins ? (e.g: in_tail ) ?

[nokute78]

@dawidmalina The PR doesn't add new function, but it will be ready to write the plugin to rewrite a tag.

[nokute78]

@edsiper Yes, this PR makes to rewrite static and dynamic tags, but I forgot to take care routing.
So, tag will be able to rewrite, but record isn't delivered...

I think dyntag helps to routing. Is there any idea ?

[repeatedly]

To edit tag with filter plugin like fluentd

Fluentd's filter doesn't allow rewriting tag.

[nokute78]

Oops, I had misunderstood. rewrite-tag-filter is output plugin..
Thank you for your comment. @repeatedly

This scheme makes routing more complex and worse performance.
I will discard this PR.

So, what we need is the way to re-emit.
It is helpful for out_flowcounter, too.