in_emitter: write msgpack buffer directly(#4049)

In previous implementation, in_emitter has 2 buffers.
- 1. rewrite_tag -> in_emitter_add_record -> msgpack_sbuffer_write
- 2. (timer thread. every 0.5 sec) cb_queue_chunks -> flb_input_chunk_append_raw

'mem_buf_limit' is for flb_input_chunk API, so the thread 1 doesn't have limits.

The patch is to modify writing sequence.
rewrite_tag -> in_emitter_add_record -> flb_input_chunk_append_raw

Signed-off-by: Takahiro Yamashita <nokute78@gmail.com>

plugins/in_emitter/emitter.c

@@ -36,7 +36,6 @@ struct em_chunk {
 };
 
 struct flb_emitter {
-    int coll_fd;                        /* collector id */
     struct mk_list chunks;              /* list of all pending chunks */
     struct flb_input_instance *ins;     /* input instance */
 };
@@ -87,6 +86,7 @@ int in_emitter_add_record(const char *tag, int tag_len,
     struct mk_list *head;
     struct em_chunk *ec = NULL;
     struct flb_emitter *ctx;
+    int ret;
 
     ctx = (struct flb_emitter *) in->context;
 
@@ -112,55 +112,28 @@ int in_emitter_add_record(const char *tag, int tag_len,
 
     /* Append raw msgpack data */
     msgpack_sbuffer_write(&ec->mp_sbuf, buf_data, buf_size);
-    return 0;
-}
-
-int in_emitter_get_collector_id(struct flb_input_instance *in)
-{
-    struct flb_emitter *ctx = (struct flb_emitter *) in->context;
-
-    return ctx->coll_fd;
-}
-
-static int cb_queue_chunks(struct flb_input_instance *in,
-                           struct flb_config *config, void *data)
-{
-    int ret;
-    struct mk_list *tmp;
-    struct mk_list *head;
-    struct em_chunk *echunk;
-    struct flb_emitter *ctx;
-
-    /* Get context */
-    ctx = (struct flb_emitter *) data;
-
-    /* Try to enqueue chunks under our limits */
-    mk_list_foreach_safe(head, tmp, &ctx->chunks) {
-        echunk = mk_list_entry(head, struct em_chunk, _head);
-
-        /* Associate this backlog chunk to this instance into the engine */
-        ret = flb_input_chunk_append_raw(in,
-                                         echunk->tag, flb_sds_len(echunk->tag),
-                                         echunk->mp_sbuf.data,
-                                         echunk->mp_sbuf.size);
-        if (ret == -1) {
-            flb_plg_error(ctx->ins, "error registering chunk with tag: %s",
-                          echunk->tag);
-            continue;
-        }
 
+    /* Associate this backlog chunk to this instance into the engine */
+    ret = flb_input_chunk_append_raw(in,
+                                     ec->tag, flb_sds_len(ec->tag),
+                                     ec->mp_sbuf.data,
+                                     ec->mp_sbuf.size);
+    if (ret == -1) {
+        flb_plg_error(ctx->ins, "error registering chunk with tag: %s",
+                      ec->tag);
         /* Release the echunk */
-        em_chunk_destroy(echunk);
+        em_chunk_destroy(ec);
+        return -1;
     }
-
+    /* Release the echunk */
+    em_chunk_destroy(ec);
     return 0;
 }
 
 /* Initialize plugin */
 static int cb_emitter_init(struct flb_input_instance *in,
                            struct flb_config *config, void *data)
 {
-    int ret;
     struct flb_emitter *ctx;
 
     ctx = flb_malloc(sizeof(struct flb_emitter));
@@ -174,38 +147,16 @@ static int cb_emitter_init(struct flb_input_instance *in,
     /* export plugin context */
     flb_input_set_context(in, ctx);
 
-    /* Set a collector to trigger the callback to queue data every 0.5 second */
-    ret = flb_input_set_collector_time(in, cb_queue_chunks, 0, 50000000, config);
-    if (ret < 0) {
-        flb_plg_error(ctx->ins, "could not create collector");
-        flb_free(ctx);
-        return -1;
-    }
-    ctx->coll_fd = ret;
     return 0;
 }
 
-static void cb_emitter_pause(void *data, struct flb_config *config)
-{
-    struct flb_emitter *ctx = data;
-    flb_input_collector_pause(ctx->coll_fd, ctx->ins);
-}
-
-static void cb_emitter_resume(void *data, struct flb_config *config)
-{
-    struct flb_emitter *ctx = data;
-    flb_input_collector_resume(ctx->coll_fd, ctx->ins);
-}
-
 static int cb_emitter_exit(void *data, struct flb_config *config)
 {
     struct mk_list *tmp;
     struct mk_list *head;
     struct flb_emitter *ctx = data;
     struct em_chunk *echunk;
 
-    flb_input_collector_pause(ctx->coll_fd, ctx->ins);
-
     mk_list_foreach_safe(head, tmp, &ctx->chunks) {
         echunk = mk_list_entry(head, struct em_chunk, _head);
         mk_list_del(&echunk->_head);
@@ -225,8 +176,8 @@ struct flb_input_plugin in_emitter_plugin = {
     .cb_collect   = NULL,
     .cb_ingest    = NULL,
     .cb_flush_buf = NULL,
-    .cb_pause     = cb_emitter_pause,
-    .cb_resume    = cb_emitter_resume,
+    .cb_pause     = NULL,
+    .cb_resume    = NULL,
     .cb_exit      = cb_emitter_exit,
 
     /* This plugin can only be configured and invoked by the Engine only */