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When protocol closes DCB it calls dcb_close instead of dcb->func.close. dcb_close then calls dcb->func.close. This is now changed to all protocols and routers.

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Rwsplit handles ERRACT_NEW_CONNECTION by clearing backend reference, removing callbacks and associating backend reference with new backend server. If it succeeds and the router session can continue, handleError returns true. Otherwise false. When ever false is returned it means that session must be closed.

Rwsplit now tolerates backend failures in a way that it searches new backends when monitor, backend, or client operation fails due to backend failure.
This commit is contained in:
VilhoRaatikka
2014-06-15 23:44:07 +03:00
parent 09d20d1059
commit 5bcae64538
16 changed files with 472 additions and 433 deletions
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245
server/modules/protocol/mysql_backend.c
View File

@ -371,23 +371,11 @@ static int gw_read_backend_event(DCB *dcb) {
spinlock_acquire(&session->ses_lock);
session->state = SESSION_STATE_STOPPING;
spinlock_release(&session->ses_lock);
/**
* rsession shouldn't be NULL since session
* state indicates that it was initialized
* successfully.
/**
* Start terminating the session
* by closing the client.
*/
rsession = session->router_session;
ss_dassert(rsession != NULL);
LOGIF(LD, (skygw_log_write_flush(
LOGFILE_DEBUG,
"%lu [gw_read_backend_event] "
"Call closeSession for backend's "
"router client session.",
pthread_self())));
/* close router_session */
router->closeSession(router_instance, rsession);
dcb_close(session->client);
rc = 1;
goto return_rc;
}
@ -432,35 +420,41 @@ static int gw_read_backend_event(DCB *dcb) {
/* read available backend data */
rc = dcb_read(dcb, &writebuf);
if (rc < 0) {
if (rc < 0)
{
/*< vraa : errorHandle */
/*<
* Backend generated EPOLLIN event and if backend has
* failed, connection must be closed to avoid backend
* dcb from getting hanged.
*/
#if defined(ERRHANDLE)
bool succp;
GWBUF* errbuf;
bool succp;
/**
* - send error for client
* - mark failed backend BREF_NOT_USED
* - go through all servers and select one according to
* the criteria that user specified in the beginning.
*/
errbuf = mysql_create_custom_error(
1,
0,
"Read from backend failed");
router->handleError(router_instance,
rsession,
"Read from backend failed",
errbuf,
dcb,
ERRACT_NEW_CONNECTION,
&succp);
if (!succp)
{
dcb_close(dcb);
spinlock_acquire(&session->ses_lock);
session->state = SESSION_STATE_STOPPING;
spinlock_release(&session->ses_lock);
}
#else
(dcb->func).close(dcb);
#endif
dcb_close(dcb);
rc = 0;
goto return_rc;
}
@ -469,15 +463,6 @@ static int gw_read_backend_event(DCB *dcb) {
rc = 0;
goto return_rc;
}
/* Note the gwbuf doesn't have here a valid queue->command
* descriptions as it is a fresh new one!
* We only have the copied value in dcb->command from
* previuos func.write() and this will be used by the
* router->clientReply
* and pass now the gwbuf to the router
*/
/*<
* If dcb->session->client is freed already it may be NULL.
*/
@ -598,33 +583,6 @@ gw_MySQLWrite_backend(DCB *dcb, GWBUF *queue)
MySQLProtocol *backend_protocol = dcb->protocol;
int rc = 0;
ss_dassert(dcb->state == DCB_STATE_POLLING);
#if !defined(ERRHANDLE)
/*<
* Don't write to backend if backend_dcb is not in poll set anymore.
*/
spinlock_acquire(&dcb->dcb_initlock);
if (dcb->state != DCB_STATE_POLLING)
{
/*< vraa : errorHandle */
/*< Free buffer memory */
gwbuf_consume(queue, GWBUF_LENGTH(queue));
LOGIF(LD, (skygw_log_write(
LOGFILE_DEBUG,
"%lu [gw_MySQLWrite_backend] Write to backend failed. "
"Backend dcb %p fd %d is %s.",
pthread_self(),
dcb,
dcb->fd,
STRDCBSTATE(dcb->state))));
spinlock_release(&dcb->dcb_initlock);
rc = 0;
goto return_rc;
}
spinlock_release(&dcb->dcb_initlock);
#endif
spinlock_acquire(&dcb->authlock);
/**
* Pick action according to state of protocol.
@ -697,88 +655,50 @@ return_rc:
}
/**
* Backend Error Handling for EPOLLER
*
* Error event handler.
* Create error message, pass it to router's error handler and if error
* handler fails in providing enough backend servers, mark session being
* closed and call DCB close function which triggers closing router session
* and related backends (if any exists.
*/
static int gw_error_backend_event(DCB *dcb)
{
SESSION *session;
void *rsession;
ROUTER_OBJECT *router;
ROUTER *router_instance;
int rc = 0;
SESSION* session;
void* rsession;
ROUTER_OBJECT* router;
ROUTER* router_instance;
int rc = 0;
GWBUF* errbuf;
bool succp;
CHK_DCB(dcb);
session = dcb->session;
CHK_SESSION(session);
rsession = session->router_session;
router = session->service->router;
router_instance = session->service->router_instance;
router = session->service->router;
router_instance = session->service->router_instance;
errbuf = mysql_create_custom_error(
1,
0,
"Lost connection to backend server.");
#if defined(ERRHANDLE2)
router->handleError(router_instance,
rsession,
"Connection to backend server failed",
dcb,
ERRACT_NEW_CONNECTION,
&succp);
if (!succp)
{
dcb_close(dcb);
}
#else
if (dcb->state != DCB_STATE_POLLING) {
/*< vraa : errorHandle */
/*<
* if client is not available it needs to be handled in send
* function. Session != NULL, that is known.
*/
mysql_send_custom_error(
dcb->session->client,
1,
0,
"Writing to backend failed.");
rc = 0;
} else {
/*< vraa : errorHandle */
mysql_send_custom_error(
dcb->session->client,
1,
0,
"Closed backend connection.");
rc = 1;
}
LOGIF(LE, (skygw_log_write_flush(
LOGFILE_DEBUG,
"%lu [gw_error_backend_event] Some error occurred in backend. "
"rc = %d",
pthread_self(),
rc)));
if (session->state == SESSION_STATE_ROUTER_READY)
{
rsession,
errbuf,
dcb,
ERRACT_NEW_CONNECTION,
&succp);
/** There are not required backends available, close session. */
if (!succp) {
spinlock_acquire(&session->ses_lock);
session->state = SESSION_STATE_STOPPING;
spinlock_release(&session->ses_lock);
rsession = session->router_session;
/*<
* rsession should never be NULL here.
*/
ss_dassert(rsession != NULL);
LOGIF(LD, (skygw_log_write_flush(
LOGFILE_DEBUG,
"%lu [gw_error_backend_event] "
"Call closeSession for backend "
"session.",
pthread_self())));
router->closeSession(router_instance, rsession);
}
#endif
return rc;
dcb_close(dcb);
return 1;
}
/*
@ -879,7 +799,11 @@ return_fd:
/**
* Hangup routine the backend dcb: it does nothing
* Error event handler.
* Create error message, pass it to router's error handler and if error
* handler fails in providing enough backend servers, mark session being
* closed and call DCB close function which triggers closing router session
* and related backends (if any exists.
*
* @param dcb The current Backend DCB
* @return 1 always
@ -893,6 +817,7 @@ gw_backend_hangup(DCB *dcb)
ROUTER* router_instance;
int rc = 0;
bool succp;
GWBUF* errbuf;
CHK_DCB(dcb);
session = dcb->session;
@ -901,42 +826,26 @@ gw_backend_hangup(DCB *dcb)
router = session->service->router;
router_instance = session->service->router_instance;
mysql_send_custom_error(
dcb->session->client,
1,
0,
errbuf = mysql_create_custom_error(
1,
0,
"Lost connection to backend server.");
/**
* errorHandle :
* - sulje katkennut yhteys - miten?
* - etsi riittävä määrä servereitä
* - jos epäonnistui, sammuta sessio
* - jos onnistui, jatka
*
* Jos sammutetaan :
* - dcb_close - backend->func.close()
*/
/*< vraa : errorHandle */
/*
*
- lähetä virheviesti clientille jos odottaa
errorHandle :
- etsi riittävä määrä servereitä
- jos epäonnistui, sammuta sessio
- jos onnistui, jatka
*/
router->handleError(router_instance,
rsession,
"Lost connection to backend server",
router->handleError(router_instance,
rsession,
errbuf,
dcb,
ERRACT_NEW_CONNECTION,
&succp);
if (succp) {
dcb_close(dcb);
/** There are not required backends available, close session. */
if (!succp) {
spinlock_acquire(&session->ses_lock);
session->state = SESSION_STATE_STOPPING;
spinlock_release(&session->ses_lock);
}
dcb_close(dcb);
return 1;
}
@ -948,7 +857,6 @@ gw_backend_hangup(DCB *dcb)
static int
gw_backend_close(DCB *dcb)
{
#if defined(ERRHANDLE)
DCB* client_dcb;
SESSION* session;
GWBUF* quitbuf;
@ -957,15 +865,13 @@ gw_backend_close(DCB *dcb)
CHK_DCB(dcb);
session = dcb->session;
CHK_SESSION(session);
quitbuf = mysql_create_com_quit(NULL, 0);
/** Send COM_QUIT to the backend being closed */
mysql_send_com_quit(dcb, 0, quitbuf);
if (session != NULL &&
(session->state == SESSION_STATE_ROUTER_READY ||
session->state == SESSION_STATE_READY))
if (session != NULL && session->state == SESSION_STATE_STOPPING)
{
client_dcb = session->client;
@ -976,9 +882,6 @@ gw_backend_close(DCB *dcb)
dcb_close(client_dcb);
}
}
#else
dcb_close(dcb);
#endif
return 1;
}
@ -1048,6 +951,8 @@ static int backend_write_delayqueue(DCB *dcb)
"Failed to write buffered data to back-end server. "
"Buffer was empty or back-end was disconnected during "
"operation.");
dcb->session->state = SESSION_STATE_STOPPING;
dcb_close(dcb);
}