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Fix cached master ownership lifecycle #1

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Merged
ADovgalyuk merged 4 commits into from
Jul 28, 2026
Merged

Fix cached master ownership lifecycle #1

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a1afa0c
Add one-shot workflow for cached master fix
ADovgalyuk Jul 28, 2026
a87480b
Fix cached master ownership lifecycle
github-actions[bot] Jul 28, 2026
6352aa6
Trigger cached master fix workflow
ADovgalyuk Jul 28, 2026
bd66576
Remove workflow trigger
ADovgalyuk Jul 28, 2026
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31 changes: 15 additions & 16 deletions src/replication.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2342,11 +2342,9 @@ void replicationEmptyDbCallback(void *privdata) {
* at g_pserver->master, starting from the specified file descriptor. */
void replicationCreateMasterClient(redisMaster *mi, connection *conn, int dbid) {
serverAssert(mi->master == nullptr);
replicationDiscardCachedMaster(mi);
serverAssert(mi->cached_master == nullptr);
mi->master = createClient(conn, serverTL - g_pserver->rgthreadvar);
if (mi->cached_master != nullptr) {
freeClientAsync(mi->cached_master);
mi->cached_master = nullptr;
}
if (conn)
{
serverAssert(connGetPrivateData(mi->master->conn) == mi->master);
Expand Down Expand Up @@ -4391,11 +4389,9 @@ void replicationCacheMasterUsingMyself(redisMaster *mi) {
"to synthesize a cached master: I may be able to synchronize with "
"the new master with just a partial transfer.");

if (mi->cached_master != nullptr)
{
// This can happen on first load of the RDB, the master we created in config load is stale
freeClient(mi->cached_master);
}
/* This can happen on first load of the RDB, when the master
* created during config loading is stale. */
replicationDiscardCachedMaster(mi);

/* This will be used to populate the field g_pserver->master->reploff
* by replicationCreateMasterClient(). We'll later set the created
Expand All @@ -4422,9 +4418,7 @@ void replicationCacheMasterUsingMyself(redisMaster *mi) {
*
* Assumes that the passed struct contains valid master info. */
void replicationCacheMasterUsingMaster(redisMaster *mi) {
if (mi->cached_master) {
freeClient(mi->cached_master);
}
replicationDiscardCachedMaster(mi);

replicationCreateMasterClient(mi, NULL, -1);
std::lock_guard<decltype(mi->master->lock)> lock(mi->master->lock);
Expand All @@ -4440,12 +4434,17 @@ void replicationCacheMasterUsingMaster(redisMaster *mi) {
/* Free a cached master, called when there are no longer the conditions for
* a partial resync on reconnection. */
void replicationDiscardCachedMaster(redisMaster *mi) {
if (mi->cached_master == NULL) return;
client *cached = mi->cached_master;
if (cached == nullptr) return;

serverLog(LL_NOTICE,"Discarding previously cached master state.");
mi->cached_master->flags &= ~CLIENT_MASTER;
freeClientAsync(mi->cached_master);
mi->cached_master = NULL;

/* Transfer ownership before scheduling the client for asynchronous free.
* No later replication transition may observe the queued client through
* mi->cached_master. */
mi->cached_master = nullptr;
cached->flags &= ~CLIENT_MASTER;
freeClientAsync(cached);
}

/* Turn the cached master into the current master, using the file descriptor
Expand Down
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