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[FIXED] Randomize discovered server URLs if allowed #319

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merged 2 commits into from
May 7, 2020
Merged

[FIXED] Randomize discovered server URLs if allowed #319

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834d9f3
[FIXED] Randomize discovered server URLs
kozlovic May 6, 2020
8cb55f2
Shuffle but leave the first URL in place.
kozlovic May 6, 2020
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15 changes: 9 additions & 6 deletions src/srvpool.c
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Original file line number Diff line number Diff line change
Expand Up @@ -183,19 +183,19 @@ _addURLToPool(natsSrvPool *pool, char *sURL, bool implicit, const char *tlsName)
}

static void
_shufflePool(natsSrvPool *pool)
_shufflePool(natsSrvPool *pool, int offset)
{
int i, j;
natsSrv *tmp;

if (pool->size <= 1)
if (pool->size <= offset+1)
return;

srand((unsigned int) nats_NowInNanoSeconds());

for (i = 0; i < pool->size; i++)
for (i = offset; i < pool->size; i++)
{
j = rand() % (i + 1);
j = offset + rand() % (i + 1 - offset);
tmp = pool->srvrs[i];
pool->srvrs[i] = pool->srvrs[j];
pool->srvrs[j] = tmp;
Expand Down Expand Up @@ -321,6 +321,8 @@ natsSrvPool_addNewURLs(natsSrvPool *pool, const natsUrl *curUrl, char **urls, in
}
s = _addURLToPool(pool, url, true, tlsName);
}
if ((s == NATS_OK) && added && pool->randomize)
_shufflePool(pool, 1);
}

natsStrHash_Destroy(tmp);
Expand Down Expand Up @@ -360,6 +362,7 @@ natsSrvPool_Create(natsSrvPool **newPool, natsOptions *opts)
// Set the current capacity. The array of urls may have to grow in
// the future.
pool->cap = poolSize;
pool->randomize = !opts->noRandomize;

// Map that helps find out if an URL is already known.
s = natsStrHash_Create(&(pool->urls), poolSize);
Expand All @@ -371,8 +374,8 @@ natsSrvPool_Create(natsSrvPool **newPool, natsOptions *opts)
if (s == NATS_OK)
{
// Randomize if allowed to
if (!(opts->noRandomize))
_shufflePool(pool);
if (pool->randomize)
_shufflePool(pool, 0);
}

// Normally, if this one is set, Options.Servers should not be,
Expand Down
1 change: 1 addition & 0 deletions src/srvpool.h
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Expand Up @@ -36,6 +36,7 @@ typedef struct __natsSrvPool
natsStrHash *urls;
int size;
int cap;
bool randomize;

} natsSrvPool;

Expand Down
53 changes: 29 additions & 24 deletions test/test.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5579,18 +5579,30 @@ _checkPool(natsConnection *nc, char **expectedURLs, int expectedURLsCount)
}

static natsStatus
checkPoolOrderDidNotChange(natsConnection *nc, char **urlsAfterPoolSetup, int initialPoolSize)
checkNewURLsAddedRandomly(natsConnection *nc, char **urlsAfterPoolSetup, int initialPoolSize)
{
natsStatus s;
int i;
char **currentPool = NULL;
int currentPoolSize = 0;

s = natsConnection_GetServers(nc, &currentPool, &currentPoolSize);
for (i= 0; (s == NATS_OK) && (i < initialPoolSize); i++)
if (s == NATS_OK)
{
if (strcmp(urlsAfterPoolSetup[i], currentPool[i]))
s = NATS_ERR;
// Reset status to error by default. If we find a new URL
// before the end of the initial list, we consider success
// and return.
s = NATS_ERR;
for (i= 0; i < initialPoolSize; i++)
{
// If one of the position in initial list is occupied
// by a new URL, we are ok.
if (strcmp(urlsAfterPoolSetup[i], currentPool[i]))
{
s = NATS_OK;
break;
}
}
}
if (currentPool != NULL)
{
Expand Down Expand Up @@ -5796,18 +5808,14 @@ test_AsyncINFO(void)
natsConnection_Destroy(nc);
nc = NULL;

// Check that pool may be randomized on setup, but new URLs are always
// added at end of pool.
// Check that new URLs are added at random places in the pool
if (s == NATS_OK)
{
int initialPoolSize = 0;
char **urlsAfterPoolSetup = NULL;
const char *newURLs[] = {
"localhost:6222",
"localhost:7222",
"localhost:8222\", \"localhost:9222",
"localhost:10222\", \"localhost:11222\", \"localhost:12222,",
};
const char *newURLs = "\"impA:4222\", \"impB:4222\", \"impC:4222\", "\
"\"impD:4222\", \"impE:4222\", \"impF:4222\", \"impG:4222\", "\
"\"impH:4222\", \"impI:4222\", \"impJ:4222\"";

s = natsOptions_Create(&opts);
if (s == NATS_OK)
Expand All @@ -5824,18 +5832,15 @@ test_AsyncINFO(void)
FAIL("Unable to setup test");

// Add new urls
for (i=0; i<(int)(sizeof(newURLs)/sizeof(char*)); i++)
{
snprintf(buf, sizeof(buf), "INFO {\"connect_urls\":[\"%s\"]}\r\n", newURLs[i]);
PARSER_START_TEST;
s = natsParser_Parse(nc, buf, (int)strlen(buf));
if (s == NATS_OK)
{
// Check that pool order does not change up to the new addition(s).
s = checkPoolOrderDidNotChange(nc, urlsAfterPoolSetup, initialPoolSize);
}
testCond((s == NATS_OK) && (nc->ps->state == OP_START));
}
snprintf(buf, sizeof(buf), "INFO {\"connect_urls\":[%s]}\r\n", newURLs);
test("New URLs are added randomly: ");
s = natsParser_Parse(nc, buf, (int)strlen(buf));
if (s == NATS_OK)
s = checkNewURLsAddedRandomly(nc, urlsAfterPoolSetup, initialPoolSize);
testCond((s == NATS_OK) && (nc->ps->state == OP_START));

test("First URL should not have been changed: ")
testCond((s == NATS_OK) && !strcmp(nc->srvPool->srvrs[0]->url->fullUrl, urlsAfterPoolSetup[0]));

if (urlsAfterPoolSetup != NULL)
{
Expand Down