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MXS-511: Made log messages about master status coherent

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The checking of the master status and the possible error logging were done
in two different steps. This led to confusing error messages when the state
of the server changed between the check and the logging of the error message.
This commit is contained in:
Markus Makela 2016-02-04 10:05:07 +02:00
parent 17234cec98
commit 26cbcb7365
1 changed files with 66 additions and 53 deletions
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119
server/modules/routing/readwritesplit/readwritesplit.c
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@ -1128,10 +1128,10 @@ static bool get_dcb(
int i;
bool succp = false;
BACKEND* master_host;
CHK_CLIENT_RSES(rses);
ss_dassert(p_dcb != NULL && *(p_dcb) == NULL);
if (p_dcb == NULL)
{
goto return_succp;
@ -1158,29 +1158,31 @@ static bool get_dcb(
if (name != NULL) /*< Choose backend by name from a hint */
{
ss_dassert(btype != BE_MASTER); /*< Master dominates and no name should be passed with it */
for (i=0; i<rses->rses_nbackends; i++)
{
BACKEND* b = backend_ref[i].bref_backend;
BACKEND* b = backend_ref[i].bref_backend;
SERVER server;
server.status = backend_ref[i].bref_backend->backend_server->status;
/**
* To become chosen:
* backend must be in use, name must match,
* root master node must be found,
* backend's role must be either slave, relay
* backend's role must be either slave, relay
* server, or master.
*/
if (BREF_IS_IN_USE((&backend_ref[i])) &&
(strncasecmp(
name,
b->backend_server->unique_name,
b->backend_server->unique_name,
PATH_MAX) == 0) &&
master_bref->bref_backend != NULL &&
(SERVER_IS_SLAVE(b->backend_server) ||
SERVER_IS_RELAY_SERVER(b->backend_server) ||
SERVER_IS_MASTER(b->backend_server)))
master_bref->bref_backend != NULL &&
(SERVER_IS_SLAVE(&server) ||
SERVER_IS_RELAY_SERVER(&server) ||
SERVER_IS_MASTER(&server)))
{
*p_dcb = backend_ref[i].bref_dcb;
succp = true;
succp = true;
ss_dassert(backend_ref[i].bref_dcb->state != DCB_STATE_ZOMBIE);
break;
}
@ -1194,7 +1196,7 @@ static bool get_dcb(
btype = BE_SLAVE;
}
}
if (btype == BE_SLAVE)
{
backend_ref_t* candidate_bref = NULL;
@ -1202,31 +1204,35 @@ static bool get_dcb(
for (i=0; i<rses->rses_nbackends; i++)
{
BACKEND* b = (&backend_ref[i])->bref_backend;
/**
SERVER server;
SERVER candidate;
server.status = backend_ref[i].bref_backend->backend_server->status;
/**
* Unused backend or backend which is not master nor
* slave can't be used
* slave can't be used
*/
if (!BREF_IS_IN_USE(&backend_ref[i]) ||
(!SERVER_IS_MASTER(b->backend_server) &&
!SERVER_IS_SLAVE(b->backend_server)))
if (!BREF_IS_IN_USE(&backend_ref[i]) ||
(!SERVER_IS_MASTER(&server) &&
!SERVER_IS_SLAVE(&server)))
{
continue;
}
/**
/**
* If there are no candidates yet accept both master or
* slave.
*/
else if (candidate_bref == NULL)
{
/**
* Ensure that master has not changed dunring
/**
* Ensure that master has not changed dunring
* session and abort if it has.
*/
if (SERVER_IS_MASTER(b->backend_server) &&
if (SERVER_IS_MASTER(&server) &&
&backend_ref[i] == master_bref)
{
/** found master */
candidate_bref = &backend_ref[i];
candidate_bref = &backend_ref[i];
candidate.status = candidate_bref->bref_backend->backend_server->status;
succp = true;
}
/**
@ -1240,15 +1246,16 @@ static bool get_dcb(
{
/** found slave */
candidate_bref = &backend_ref[i];
candidate.status = candidate_bref->bref_backend->backend_server->status;
succp = true;
}
}
/**
* If candidate is master, any slave which doesn't break
* If candidate is master, any slave which doesn't break
* replication lag limits replaces it.
*/
else if (SERVER_IS_MASTER(candidate_bref->bref_backend->backend_server) &&
SERVER_IS_SLAVE(b->backend_server) &&
else if (SERVER_IS_MASTER(&candidate) &&
SERVER_IS_SLAVE(&server) &&
(max_rlag == MAX_RLAG_UNDEFINED ||
(b->backend_server->rlag != MAX_RLAG_NOT_AVAILABLE &&
b->backend_server->rlag <= max_rlag)) &&
@ -1256,14 +1263,15 @@ static bool get_dcb(
{
/** found slave */
candidate_bref = &backend_ref[i];
succp = true;
candidate.status = candidate_bref->bref_backend->backend_server->status;
succp = true;
}
/**
/**
* When candidate exists, compare it against the current
* backend and update assign it to new candidate if
* backend and update assign it to new candidate if
* necessary.
*/
else if (SERVER_IS_SLAVE(b->backend_server))
else if (SERVER_IS_SLAVE(&server))
{
if (max_rlag == MAX_RLAG_UNDEFINED ||
(b->backend_server->rlag != MAX_RLAG_NOT_AVAILABLE &&
@ -1273,6 +1281,7 @@ static bool get_dcb(
candidate_bref,
&backend_ref[i],
rses->rses_config.rw_slave_select_criteria);
candidate.status = candidate_bref->bref_backend->backend_server->status;
}
else
{
@ -1289,34 +1298,38 @@ static bool get_dcb(
{
*p_dcb = candidate_bref->bref_dcb;
}
goto return_succp;
} /*< if (btype == BE_SLAVE) */
/**
* If target was originally master only then the execution jumps
* directly here.
*/
if (btype == BE_MASTER)
/**
* If target was originally master only then the execution jumps
* directly here.
*/
if (btype == BE_MASTER)
{
/** It is possible for the server status to change at any point in time
* so copying it locally will make possible error messages
* easier to understand */
SERVER server;
server.status = master_bref->bref_backend->backend_server->status;
if (BREF_IS_IN_USE(master_bref) && SERVER_IS_MASTER(&server))
{
if (BREF_IS_IN_USE(master_bref) &&
SERVER_IS_MASTER(master_bref->bref_backend->backend_server))
{
*p_dcb = master_bref->bref_dcb;
succp = true;
/** if bref is in use DCB should not be closed */
ss_dassert(master_bref->bref_dcb->state != DCB_STATE_ZOMBIE);
}
else
{
MXS_ERROR("Server at %s:%d should be master but "
"is %s instead and can't be chosen to master.",
master_bref->bref_backend->backend_server->name,
master_bref->bref_backend->backend_server->port,
STRSRVSTATUS(master_bref->bref_backend->backend_server));
succp = false;
}
*p_dcb = master_bref->bref_dcb;
succp = true;
/** if bref is in use DCB should not be closed */
ss_dassert(master_bref->bref_dcb->state != DCB_STATE_ZOMBIE);
}
else
{
MXS_ERROR("Server at %s:%d should be master but "
"is %s instead and can't be chosen to master.",
master_bref->bref_backend->backend_server->name,
master_bref->bref_backend->backend_server->port,
STRSRVSTATUS(&server));
succp = false;
}
}
return_succp:
return succp;
}