pack: use build time parameters for msgpack to json buffer

Setting build time parameters to determine the function
'flb_msgpack_raw_to_json_sds' buffer strategy.

The parameter 'FLB_MSGPACK_TO_JSON_INIT_BUFFER_SIZE' is a
multiplier to determine the initial buffer size to store the
conversion to json from a msgpack object. It multiplies the
size of the buffer where the msgpack object is stored to obtain
an estimate of the allocation required. e.g. A value of 2 sets
to allocate a buffer of size 2x of the received payload.

The parameter 'FLB_MSGPACK_TO_JSON_REALLOC_BUFFER_SIZE' is a
multiplier to determine the size in bytes to add in every memory
reallocation when more space is needed for the buffer. It multiplies
the size of the buffer where the msgpack object is stored to obtain
a percentage of memory to be increased each round. e.g. A value of .1
sets to increase in rounds of 10% of the original payload size.

Signed-off-by: Francisco Valente <[email protected]>

Author: franciscovalentecastro

src/flb_pack.c

@@ -723,8 +723,8 @@ flb_sds_t flb_msgpack_raw_to_json_sds(const void *in_buf, size_t in_size)
     flb_sds_t tmp_buf;
 
     /* buffer size strategy */
-    out_size = in_size * 2;
-    realloc_size = in_size * 0.10;
+    out_size = in_size * FLB_MSGPACK_TO_JSON_INIT_BUFFER_SIZE;
+    realloc_size = in_size * FLB_MSGPACK_TO_JSON_REALLOC_BUFFER_SIZE;
     if (realloc_size < 256) {
         realloc_size = 256;
     }