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Fix race on clients_to_close

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Former-commit-id: 10fa06410941121c4c9fc3cc9c553a7afe347147
This commit is contained in:
John Sully 2020-05-10 23:14:15 -04:00
parent dc131afe1c
commit f0ed02448d
1 changed files with 7 additions and 0 deletions
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7
src/networking.cpp
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@ -1590,6 +1590,8 @@ bool freeClient(client *c) {
return true; return true;
} }
fastlock lockasyncfree {"async free lock"};
/* Schedule a client to free it at a safe time in the serverCron() function. /* Schedule a client to free it at a safe time in the serverCron() function.
* This function is useful when we need to terminate a client but we are in * This function is useful when we need to terminate a client but we are in
* a context where calling freeClient() is not possible, because the client * a context where calling freeClient() is not possible, because the client
@ -1606,6 +1608,7 @@ void freeClientAsync(client *c) {
lock.arm(c); lock.arm(c);
if (c->flags & CLIENT_CLOSE_ASAP || c->flags & CLIENT_LUA) return; // race condition after we acquire the lock if (c->flags & CLIENT_CLOSE_ASAP || c->flags & CLIENT_LUA) return; // race condition after we acquire the lock
c->flags |= CLIENT_CLOSE_ASAP; c->flags |= CLIENT_CLOSE_ASAP;
std::unique_lock<fastlock> ul(lockasyncfree);
listAddNodeTail(g_pserver->clients_to_close,c); listAddNodeTail(g_pserver->clients_to_close,c);
} }
@ -1617,6 +1620,7 @@ void freeClientsInAsyncFreeQueue(int iel) {
// Store the clients in a temp vector since freeClient will modify this list // Store the clients in a temp vector since freeClient will modify this list
std::vector<client*> vecclientsFree; std::vector<client*> vecclientsFree;
std::unique_lock<fastlock> ul(lockasyncfree);
while((ln = listNext(&li))) while((ln = listNext(&li)))
{ {
client *c = (client*)listNodeValue(ln); client *c = (client*)listNodeValue(ln);
@ -1626,6 +1630,7 @@ void freeClientsInAsyncFreeQueue(int iel) {
listDelNode(g_pserver->clients_to_close, ln); listDelNode(g_pserver->clients_to_close, ln);
} }
} }
ul.unlock();
for (client *c : vecclientsFree) for (client *c : vecclientsFree)
{ {
@ -2393,11 +2398,13 @@ void readQueryFromClient(connection *conn) {
return; return;
} else { } else {
serverLog(LL_VERBOSE, "Reading from client: %s",connGetLastError(c->conn)); serverLog(LL_VERBOSE, "Reading from client: %s",connGetLastError(c->conn));
aelock.arm(c);
freeClientAsync(c); freeClientAsync(c);
return; return;
} }
} else if (nread == 0) { } else if (nread == 0) {
serverLog(LL_VERBOSE, "Client closed connection"); serverLog(LL_VERBOSE, "Client closed connection");
aelock.arm(c);
freeClientAsync(c); freeClientAsync(c);
return; return;
} else if (c->flags & CLIENT_MASTER) { } else if (c->flags & CLIENT_MASTER) {