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JSONRPC: Increase network performance by reducing the reallocation count

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The `all_data_cb` callback was called by `libcurl` with small buffers
causing frequent reallocations, which killed network performance on large
block templates.

The new code decouples content length from allocation size. It starts out
by allocating a minimum of 16 KiB and doubles the buffer size every time
the allocation gets too small. The maximum allowed increase after doubling
is capped to 8 MiB.
This commit is contained in:
Axel Gembe 2020-11-10 13:37:43 +07:00
parent 173a497e60
commit cdb1c92c82
No known key found for this signature in database
GPG key ID: 1CB3AA2143109AAC
1 changed files with 31 additions and 10 deletions
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35
util.c
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@ -41,6 +41,7 @@
struct data_buffer {
void *buf;
size_t len;
size_t allocated;
};
struct header_info {
@ -182,21 +183,41 @@ static size_t all_data_cb(const void *ptr, size_t size, size_t nmemb,
{
struct data_buffer *db = user_data;
size_t len = size * nmemb;
size_t oldlen, newlen;
size_t newalloc, reqalloc;
void *newmem;
static const unsigned char zero = 0;
static const size_t max_realloc_increase = 8 * 1024 * 1024;
static const size_t initial_alloc = 16 * 1024;
oldlen = db->len;
newlen = oldlen + len;
/* minimum required allocation size */
reqalloc = db->len + len + 1;
newmem = realloc(db->buf, newlen + 1);
if (reqalloc > db->allocated) {
if (db->len > 0)
newalloc = db->allocated * 2;
else
newalloc = initial_alloc;
/* limit the maximum buffer increase */
if (newalloc - db->allocated > max_realloc_increase)
newalloc = db->allocated + max_realloc_increase;
/* ensure we have a big enough allocation */
if (reqalloc > newalloc)
newalloc = reqalloc;
newmem = realloc(db->buf, newalloc);
if (!newmem)
return 0;
db->buf = newmem;
db->len = newlen;
memcpy(db->buf + oldlen, ptr, len);
memcpy(db->buf + newlen, &zero, 1); /* null terminate */
db->allocated = newalloc;
}
memcpy(db->buf + db->len, ptr, len); /* append new data */
memcpy(db->buf + db->len + len, &zero, 1); /* null terminate */
db->len += len;
return len;
}