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Client side caching: reclaim the tracking table on FLUSHALL.

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This commit is contained in:
antirez 2019-07-22 12:31:46 +02:00
parent df2e7cf4fc
commit 06de8790dc
1 changed files with 44 additions and 8 deletions
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52
src/tracking.c
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@ -185,17 +185,53 @@ void trackingInvalidateKey(robj *keyobj) {
TrackingTableUsedSlots--;
}
/* This function is called when one or all the Redis databases are flushed
* (dbid == -1 in case of FLUSHALL). Caching slots are not specific for
* each DB but are global: currently what we do is sending a special
* notification to clients with tracking enabled, invalidating the caching
* slot "-1", which means, "all the keys", in order to avoid flooding clients
* with many invalidation messages for all the keys they may hold.
*
* However trying to flush the tracking table here is very costly:
* we need scanning 16 million caching slots in the table to check
* if they are used, this introduces a big delay. So what we do is to really
* flush the table in the case of FLUSHALL. When a FLUSHDB is called instead
* we just send the invalidation message to all the clients, but don't
* flush the table: it will slowly get garbage collected as more keys
* are modified in the used caching slots. */
void trackingInvalidateKeysOnFlush(int dbid) {
UNUSED(dbid);
if (server.tracking_clients == 0) return;
listNode *ln;
listIter li;
listRewind(server.clients,&li);
while ((ln = listNext(&li)) != NULL) {
client *c = listNodeValue(ln);
if (c->flags & CLIENT_TRACKING) {
sendTrackingMessage(c,-1);
if (server.tracking_clients) {
listNode *ln;
listIter li;
listRewind(server.clients,&li);
while ((ln = listNext(&li)) != NULL) {
client *c = listNodeValue(ln);
if (c->flags & CLIENT_TRACKING) {
sendTrackingMessage(c,-1);
}
}
}
/* In case of FLUSHALL, reclaim all the memory used by tracking. */
if (dbid == -1 && TrackingTable) {
for (int j = 0; j < TRACKING_TABLE_SIZE; j++) {
if (TrackingTable[j] != NULL) {
raxFree(TrackingTable[j]);
TrackingTable[j] = NULL;
TrackingTableUsedSlots--;
if (TrackingTableUsedSlots == 0) break;
}
}
/* If there are no clients with tracking enabled, we can even
* reclaim the memory used by the table itself. The code assumes
* the table is allocated only if there is at least one client alive
* with tracking enabled. */
if (server.tracking_clients == 0) {
zfree(TrackingTable);
TrackingTable = NULL;
}
}
}