[Tarantool-patches] [PATCH v3 02/10] xrow: introduce a PROMOTE entry
Serge Petrenko
sergepetrenko at tarantool.org
Wed Apr 14 17:17:12 MSK 2021
A PROMOTE entry combines effect of CONFIRM, ROLLBACK and RAFT_TERM
entries with some additional semantics on top.
PROMOTE carries the following arguments:
1) former_leader_id - the id of previous limbo owner whose entries we
want to confirm.
2) confirm_lsn - the lsn of the last former leader's transaction to be
confirmed. In this sense PROMOTE(confirm_lsn) replaces
CONFIRM(confirm_lsn) + ROLLBACK(confirm_lsn + 1).
3) replica_id - id of the instance issuing
`box.ctl.clear_synchro_queue()`
4) term - the new term the instance issuing
`box.ctl.clear_synchro_queue()` has just entered.
This entry will be written to WAL instead of the usual CONFIRM +
ROLLBACK pair on a successful `box.ctl.clear_synchro_queue()` call.
Note, the ususal CONFIRM and ROLLBACK occurrences (after a confirmed or
rolled back synchronous transaction) are here to stay.
Part of #5445
---
src/box/iproto_constants.h | 26 ++++++++++++++++--
src/box/xrow.c | 55 +++++++++++++++++++++++++++++++++-----
src/box/xrow.h | 34 ++++++++++++++++++++++-
3 files changed, 105 insertions(+), 10 deletions(-)
diff --git a/src/box/iproto_constants.h b/src/box/iproto_constants.h
index f7f46088f..7d39b0d61 100644
--- a/src/box/iproto_constants.h
+++ b/src/box/iproto_constants.h
@@ -132,6 +132,18 @@ enum iproto_key {
IPROTO_REPLICA_ANON = 0x50,
IPROTO_ID_FILTER = 0x51,
IPROTO_ERROR = 0x52,
+ /**
+ * Term. Has the same meaning as IPROTO_RAFT_TERM, but is an iproto
+ * key, rather than a raft key. Used for PROMOTE request, which needs
+ * both iproto (e.g. REPLICA_ID) and raft (RAFT_TERM) keys.
+ */
+ IPROTO_TERM = 0x53,
+ /*
+ * Be careful to not extend iproto_key values over 0x7f.
+ * iproto_keys are encoded in msgpack as positive fixnum, which ends at
+ * 0x7f, and we rely on this in some places by allocating a uint8_t to
+ * hold a msgpack-encoded key value.
+ */
IPROTO_KEY_MAX
};
@@ -226,6 +238,8 @@ enum iproto_type {
IPROTO_TYPE_STAT_MAX,
IPROTO_RAFT = 30,
+ /** PROMOTE request. */
+ IPROTO_PROMOTE = 31,
/** A confirmation message for synchronous transactions. */
IPROTO_CONFIRM = 40,
@@ -340,11 +354,19 @@ dml_request_key_map(uint32_t type)
return iproto_body_key_map[type];
}
-/** CONFIRM/ROLLBACK entries for synchronous replication. */
+/** Synchronous replication entries: CONFIRM/ROLLBACK/PROMOTE. */
static inline bool
iproto_type_is_synchro_request(uint32_t type)
{
- return type == IPROTO_CONFIRM || type == IPROTO_ROLLBACK;
+ return type == IPROTO_CONFIRM || type == IPROTO_ROLLBACK ||
+ type == IPROTO_PROMOTE;
+}
+
+/** PROMOTE entry (synchronous replication and leader elections). */
+static inline bool
+iproto_type_is_promote_request(uint32_t type)
+{
+ return type == IPROTO_PROMOTE;
}
static inline bool
diff --git a/src/box/xrow.c b/src/box/xrow.c
index cc8e43ed4..5d515ce92 100644
--- a/src/box/xrow.c
+++ b/src/box/xrow.c
@@ -884,28 +884,63 @@ xrow_encode_dml(const struct request *request, struct region *region,
return iovcnt;
}
-void
-xrow_encode_synchro(struct xrow_header *row,
- struct synchro_body_bin *body,
- const struct synchro_request *req)
+static void
+xrow_encode_synchro_body(struct synchro_body_bin *body,
+ const struct synchro_request *req)
{
/*
- * A map with two elements. We don't compress
+ * A map with two or three elements. We don't compress
* numbers to have this structure constant in size,
* which allows us to preallocate it on stack.
*/
- body->m_body = 0x80 | 2;
+ body->m_body = 0x80 | (req->type == IPROTO_PROMOTE ? 3 : 2);
body->k_replica_id = IPROTO_REPLICA_ID;
body->m_replica_id = 0xce;
body->v_replica_id = mp_bswap_u32(req->replica_id);
body->k_lsn = IPROTO_LSN;
body->m_lsn = 0xcf;
body->v_lsn = mp_bswap_u64(req->lsn);
+}
+
+void
+xrow_encode_synchro(struct xrow_header *row,
+ struct synchro_body_bin *body,
+ const struct synchro_request *req)
+{
+ assert(req->type == IPROTO_CONFIRM || req->type == IPROTO_ROLLBACK);
+
+ xrow_encode_synchro_body(body, req);
memset(row, 0, sizeof(*row));
+ row->type = req->type;
+ row->body[0].iov_base = body;
+ row->body[0].iov_len = sizeof(*body);
+ row->bodycnt = 1;
+}
+
+static inline void
+xrow_encode_promote_body(struct promote_body_bin *body,
+ const struct synchro_request *req)
+{
+ xrow_encode_synchro_body(&body->base, req);
+
+ body->k_term = IPROTO_TERM;
+ body->m_term = 0xcf;
+ body->v_term = mp_bswap_u64(req->term);
+}
+
+void
+xrow_encode_promote(struct xrow_header *row, struct promote_body_bin *body,
+ const struct synchro_request *req)
+{
+ assert(req->type == IPROTO_PROMOTE);
+
+ xrow_encode_promote_body(body, req);
+
+ memset(row, 0, sizeof(*row));
row->type = req->type;
- row->body[0].iov_base = (void *)body;
+ row->body[0].iov_base = body;
row->body[0].iov_len = sizeof(*body);
row->bodycnt = 1;
}
@@ -952,11 +987,17 @@ xrow_decode_synchro(const struct xrow_header *row, struct synchro_request *req)
case IPROTO_LSN:
req->lsn = mp_decode_uint(&d);
break;
+ case IPROTO_TERM:
+ req->term = mp_decode_uint(&d);
+ break;
default:
mp_next(&d);
}
}
+
req->type = row->type;
+ req->origin_id = row->replica_id;
+
return 0;
}
diff --git a/src/box/xrow.h b/src/box/xrow.h
index 1bb0964dc..51442f9b6 100644
--- a/src/box/xrow.h
+++ b/src/box/xrow.h
@@ -226,7 +226,10 @@ xrow_encode_dml(const struct request *request, struct region *region,
* pending synchronous transactions.
*/
struct synchro_request {
- /** Operation type - IPROTO_ROLLBACK or IPROTO_CONFIRM. */
+ /**
+ * Operation type - either IPROTO_ROLLBACK or IPROTO_CONFIRM or
+ * IPROTO_PROMOTE
+ */
uint32_t type;
/**
* ID of the instance owning the pending transactions.
@@ -236,14 +239,25 @@ struct synchro_request {
* finish transactions of an old master.
*/
uint32_t replica_id;
+ /**
+ * Id of the instance which has issued this request. Only filled on
+ * decoding, and left blank when encoding a request.
+ */
+ uint32_t origin_id;
/**
* Operation LSN.
* In case of CONFIRM it means 'confirm all
* transactions with lsn <= this value'.
* In case of ROLLBACK it means 'rollback all transactions
* with lsn >= this value'.
+ * In case of PROMOTE it means CONFIRM(lsn) + ROLLBACK(lsn+1)
*/
int64_t lsn;
+ /**
+ * The new term the instance issuing this request is in. Only used for
+ * PROMOTE request.
+ */
+ uint64_t term;
};
/** Synchro request xrow's body in MsgPack format. */
@@ -257,6 +271,14 @@ struct PACKED synchro_body_bin {
uint64_t v_lsn;
};
+/** PROMOTE request's xrow body in MsgPack format. */
+struct PACKED promote_body_bin {
+ struct synchro_body_bin base;
+ uint8_t k_term;
+ uint8_t m_term;
+ uint64_t v_term;
+};
+
/**
* Encode synchronous replication request.
* @param row xrow header.
@@ -268,6 +290,16 @@ xrow_encode_synchro(struct xrow_header *row,
struct synchro_body_bin *body,
const struct synchro_request *req);
+/**
+ * Encode a promote request.
+ * @param row xrow header.
+ * @param body A place to encode promote body.
+ * @param req Request parameters.
+ */
+void
+xrow_encode_promote(struct xrow_header *row, struct promote_body_bin *body,
+ const struct synchro_request *req);
+
/**
* Decode synchronous replication request.
* @param row xrow header.
--
2.24.3 (Apple Git-128)
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