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readwritesplit.c : router is changed so that it guarantees to keep the execution order of session commands and queries when they are routed to backend servers. In the same way it maintains the order of response packets and discards duplicate responses.

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For each session command a sescmd property is created and added to the end of list of session commands. List is owned by router client session and it includes all session commands from the beginning of router session.
Router maintains an individual session command cursor for each backend. A cursor refers to the first session command which the corresponding backend server haven't yet responded yet.
When response message arrives at any time from backend, first it is checked whether backend's cursor is active. Cursor is active if a session command is routed to backend and the backend haven't responded to it yet. If cursor is active, next it is checked whether the current session command property has been responded by other backend. If both are true, then response message is sent to client as is. If session command response is routed to client already, the arrived response is discarded.
This commit is contained in:
VilhoRaatikka
2014-03-16 19:43:49 +02:00
parent a3f7eebdc9
commit 90f701be8e
6 changed files with 182 additions and 211 deletions
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48
server/modules/protocol/mysql_client.c
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@ -57,7 +57,6 @@ static int route_by_statement(
ROUTER_OBJECT* router,
void* rsession,
GWBUF* read_buf);
static GWBUF* gw_MySQL_get_next_stmt(GWBUF** buffer);
/*
* The "module object" for the mysqld client protocol module.
@ -1248,51 +1247,6 @@ return_rc:
return rc;
}
/**
* Remove the first mysql statement from buffer. Return pointer to the removed
* statement or NULL if buffer is empty.
*
* Clone buf, calculate the length of included mysql stmt, and point the
* statement with cloned buffer. Move the start pointer of buf accordingly
* so that it only cover the remaining buffer.
*
*/
static GWBUF* gw_MySQL_get_next_stmt(
GWBUF** p_readbuf)
{
GWBUF* stmtbuf;
size_t buflen;
size_t strlen;
uint8_t* packet;
if (*p_readbuf == NULL)
{
stmtbuf = NULL;
goto return_stmtbuf;
}
CHK_GWBUF(*p_readbuf);
if (GWBUF_EMPTY(*p_readbuf))
{
stmtbuf = NULL;
goto return_stmtbuf;
}
buflen = GWBUF_LENGTH((*p_readbuf));
packet = GWBUF_DATA((*p_readbuf));
strlen = MYSQL_GET_PACKET_LEN(packet);
/** vraa :Multi-packet stmt is not supported as of 7.3.14 */
if (strlen-1 > buflen-5)
{
stmtbuf = NULL;
goto return_stmtbuf;
}
stmtbuf = gwbuf_clone_portion(*p_readbuf, 0, strlen+4);
*p_readbuf = gwbuf_consume(*p_readbuf, strlen+4);
return_stmtbuf:
return stmtbuf;
}
/**
* Detect if buffer includes partial mysql packet or multiple packets.
@ -1318,13 +1272,11 @@ static int route_by_statement(
CHK_GWBUF(stmtbuf);
payload = (uint8_t *)GWBUF_DATA(stmtbuf);
len += MYSQL_GET_PACKET_LEN(payload);
/**
* If message is longer than read data, suspend routing and
* add statement buffer to wait queue.
*/
rc = router->routeQuery(router_instance, rsession, stmtbuf);
len = 0; /*< if routed, reset the length indicator */
}
while (readbuf != NULL);