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Support for prepared statement, namely support for following comands : COM_STMT_PREPARE, COM_STMT_EXECUTE, COM_STMT_SEND_LONG_DATA, COM_STMT_RESET, COM_STMT_CLOSE, SQLCOM_PREPARE, SQLCOM_EXECUTE, SQLCOM_DEALLOCATE_PREPARE (DEALLOCATE/DROP PREPARE stmt).

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All prepare commands are executed in every backend server currently connected.

All executes are routed to master. If stmt type was recorded in prepare phase in rwsplit router, read-only stmts could be routed to slaves.

COM_STMT_PREPARE gets arbitrary number of response packets from backend database. Since statements are prepared in every backend server and only one multi-packet response can be replied to client, redundant multi-packet responses are discarded. This is done in router. Mechanisms from session command handling are utilized with little changes: router must identify when response consists of multiple packets so that it knows to calculate the number of packets in response and that it is able to discard correct number of packets.

Information to the reply-handling router is provided by backend protocol, which includes a ordered list of commands of commands sent to protocol-owning backend server. A command is stored to protocol struct in mysql_backend.c:gw_MySQLWrite_backend if the statement buffer's type has GWBUF_TYPE_SINGLE_STMT set in mysql_client.c:route_by_statement. GWBUF_TYPE_SINGLE_STATEMENT indicates that there is single statement in the buffer, as opposite to Read Connection router, which accepts streaming input from client.
This commit is contained in:
VilhoRaatikka
2014-06-25 17:15:46 +03:00
parent 2d128de85f
commit 7ff14e23a5
6 changed files with 791 additions and 326 deletions
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57
server/modules/include/readwritesplit.h
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@ -30,18 +30,36 @@
*/
#include <dcb.h>
#include <hashtable.h>
#undef PREP_STMT_CACHING
#if defined(PREP_STMT_CACHING)
typedef enum prep_stmt_type {
PREP_STMT_NAME,
PREP_STMT_ID
} prep_stmt_type_t;
typedef enum prep_stmt_state {
PREP_STMT_ALLOC,
PREP_STMT_SENT,
PREP_STMT_RECV,
PREP_STMT_DROPPED
} prep_stmt_state_t;
#endif /*< PREP_STMT_CACHING */
typedef enum bref_state {
BREF_NOT_USED = 0x00,
BREF_IN_USE = 0x01,
BREF_WAITING_RESULT = 0x02, /*< for anything that responds */
BREF_CLOSED = 0x04
BREF_IN_USE = 0x01,
BREF_WAITING_RESULT = 0x02, /*< for anything that responds */
BREF_CLOSED = 0x04
} bref_state_t;
#define BREF_IS_NOT_USED(s) (s->bref_state & BREF_NOT_USED)
#define BREF_IS_IN_USE(s) (s->bref_state & BREF_IN_USE)
#define BREF_IS_WAITING_RESULT(s) (s->bref_state & BREF_WAITING_RESULT)
#define BREF_IS_CLOSED(s) (s->bref_state & BREF_CLOSED)
#define BREF_IS_NOT_USED(s) (s->bref_state & ~BREF_IN_USE)
#define BREF_IS_IN_USE(s) (s->bref_state & BREF_IN_USE)
#define BREF_IS_WAITING_RESULT(s) (s->bref_state & BREF_WAITING_RESULT)
#define BREF_IS_CLOSED(s) (s->bref_state & BREF_CLOSED)
typedef enum backend_type_t {
BE_UNDEFINED=-1,
@ -186,6 +204,25 @@ typedef struct rwsplit_config_st {
} rwsplit_config_t;
#if defined(PREP_STMT_CACHING)
typedef struct prep_stmt_st {
#if defined(SS_DEBUG)
skygw_chk_t pstmt_chk_top;
#endif
union id {
int seq;
char* name;
} pstmt_id;
prep_stmt_state_t pstmt_state;
prep_stmt_type_t pstmt_type;
#if defined(SS_DEBUG)
skygw_chk_t pstmt_chk_tail;
#endif
} prep_stmt_t;
#endif /*< PREP_STMT_CACHING */
/**
* The client session structure used within this router.
*/
@ -205,7 +242,9 @@ struct router_client_session {
int rses_capabilities; /*< input type, for example */
bool rses_autocommit_enabled;
bool rses_transaction_active;
uint64_t rses_id; /*< ID for router client session */
#if defined(PREP_STMT_CACHING)
HASHTABLE* rses_prep_stmt[2];
#endif
struct router_client_session* next;
#if defined(SS_DEBUG)
skygw_chk_t rses_chk_tail;