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Reset persistent MySQL connections

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When a persistent connection is taken from the pool, the state is reset
with a COM_CHANGE_USER on the next write. This allows reuse of persistent
connections without having to worry about the state of the MySQL session.
This commit is contained in:
Markus Makela
2016-10-28 11:57:52 +03:00
parent e8e2933b56
commit 5085b41d20
5 changed files with 102 additions and 20 deletions
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77
server/modules/protocol/MySQL/MySQLBackend/mysql_backend.c
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@ -759,6 +759,41 @@ gw_read_and_write(DCB *dcb)
}
}
MySQLProtocol *proto = (MySQLProtocol *)dcb->protocol;
spinlock_acquire(&dcb->authlock);
if (proto->ignore_reply)
{
/** The reply to a COM_CHANGE_USER is in packet */
GWBUF *query = proto->stored_query;
uint8_t result = *((uint8_t*)GWBUF_DATA(read_buffer) + 4);
proto->stored_query = NULL;
proto->ignore_reply = false;
gwbuf_free(read_buffer);
spinlock_release(&dcb->authlock);
int rval = 0;
if (result == MYSQL_REPLY_OK)
{
rval = query ? dcb->func.write(dcb, query) : 1;
}
else if (query)
{
/** The COM_CHANGE USER failed, generate a fake hangup event to
* close the DCB and send an error to the client. */
gwbuf_free(query);
poll_fake_hangup_event(dcb);
}
return rval;
}
spinlock_release(&dcb->authlock);
/**
* If protocol has session command set, concatenate whole
* response into one buffer.
@ -911,6 +946,48 @@ static int gw_MySQLWrite_backend(DCB *dcb, GWBUF *queue)
CHK_DCB(dcb);
spinlock_acquire(&dcb->authlock);
if (dcb->was_persistent)
{
/**
* This is a DCB that was just taken out of the persistent connection pool.
* We need to sent a COM_CHANGE_USER query to the backend to reset the
* session state.
*/
if (backend_protocol->stored_query)
{
/** It is possible that the client DCB is closed before the COM_CHANGE_USER
* response is received. */
gwbuf_free(backend_protocol->stored_query);
}
dcb->was_persistent = false;
backend_protocol->ignore_reply = true;
backend_protocol->stored_query = queue;
spinlock_release(&dcb->authlock);
GWBUF *buf = gw_create_change_user_packet(dcb->session->client_dcb->data, dcb->protocol);
return dcb_write(dcb, buf) ? 1 : 0;
}
else if (backend_protocol->ignore_reply)
{
if (MYSQL_IS_COM_QUIT((uint8_t*)GWBUF_DATA(queue)))
{
gwbuf_free(queue);
}
else
{
/**
* We're still waiting on the reply to the COM_CHANGE_USER, append the
* buffer to the stored query. This is possible if the client sends
* BLOB data on the first command.
*/
backend_protocol->stored_query = gwbuf_append(backend_protocol->stored_query, queue);
}
spinlock_release(&dcb->authlock);
return 1;
}
/**
* Pick action according to state of protocol.
* If auth failed, return value is 0, write and buffered write