[PATCH 2/2] vinyl: introduce statement flags

[Vladimir Davydov <vdavydov.dev@gmail.com>]

In the scope of #2129 we need to mark REPLACE statements for which we
generated DELETE in secondary indexes so that we don't generate DELETE
again on compaction. We also need to mark DELETE statements that were
generated on compaction so that we can skip them on SELECT.

Let's add flags field to struct vy_stmt. Flags are stored both in memory
and on disk - they are encoded in tuple meta in the latter case.

Needed for #2129
---
 src/box/vy_stmt.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/box/vy_stmt.h | 15 +++++++++++++
 2 files changed, 79 insertions(+)

diff --git a/src/box/vy_stmt.c b/src/box/vy_stmt.c
index a4b7975b..bcf3dd11 100644
--- a/src/box/vy_stmt.c
+++ b/src/box/vy_stmt.c
@@ -45,6 +45,14 @@
 #include "xrow.h"
 #include "fiber.h"
 
+/**
+ * Statement metadata keys.
+ */
+enum vy_stmt_meta_key {
+	/** Statement flags. */
+	VY_STMT_FLAGS = 0x01,
+};
+
 static struct tuple *
 vy_tuple_new(struct tuple_format *format, const char *data, const char *end)
 {
@@ -112,6 +120,7 @@ vy_stmt_alloc(struct tuple_format *format, uint32_t bsize)
 	tuple->data_offset = sizeof(struct vy_stmt) + meta_size;;
 	vy_stmt_set_lsn(tuple, 0);
 	vy_stmt_set_type(tuple, 0);
+	vy_stmt_set_flags(tuple, 0);
 	return tuple;
 }
 
@@ -485,6 +494,56 @@ vy_stmt_extract_key_raw(const char *data, const char *data_end,
 	return key;
 }
 
+/**
+ * Encode the given statement meta data in a request.
+ * Returns 0 on success, -1 on memory allocation error.
+ */
+static int
+vy_stmt_meta_encode(const struct tuple *stmt, struct request *request)
+{
+	if (vy_stmt_flags(stmt) == 0)
+		return 0; /* nothing to encode */
+
+	size_t len = mp_sizeof_map(1) * 2 * mp_sizeof_uint(UINT64_MAX);
+	char *buf = region_alloc(&fiber()->gc, len);
+	if (buf == NULL)
+		return -1;
+	char *pos = buf;
+	pos = mp_encode_map(pos, 1);
+	pos = mp_encode_uint(pos, VY_STMT_FLAGS);
+	pos = mp_encode_uint(pos, vy_stmt_flags(stmt));
+	assert(pos <= buf + len);
+
+	request->tuple_meta = buf;
+	request->tuple_meta_end = pos;
+	return 0;
+}
+
+/**
+ * Decode statement meta data from a request.
+ */
+static void
+vy_stmt_meta_decode(struct request *request, struct tuple *stmt)
+{
+	const char *data = request->tuple_meta;
+	if (data == NULL)
+		return; /* nothing to decode */
+
+	uint32_t size = mp_decode_map(&data);
+	for (uint32_t i = 0; i < size; i++) {
+		uint64_t key = mp_decode_uint(&data);
+		switch (key) {
+		case VY_STMT_FLAGS: {
+			uint64_t flags = mp_decode_uint(&data);
+			vy_stmt_set_flags(stmt, flags);
+			break;
+		}
+		default:
+			mp_next(&data); /* unknown key, ignore */
+		}
+	}
+}
+
 int
 vy_stmt_encode_primary(const struct tuple *value,
 		       const struct key_def *key_def, uint32_t space_id,
@@ -525,6 +584,8 @@ vy_stmt_encode_primary(const struct tuple *value,
 	default:
 		unreachable();
 	}
+	if (vy_stmt_meta_encode(value, &request) != 0)
+		return -1;
 	xrow->bodycnt = xrow_encode_dml(&request, xrow->body);
 	if (xrow->bodycnt < 0)
 		return -1;
@@ -556,6 +617,8 @@ vy_stmt_encode_secondary(const struct tuple *value,
 		request.key = extracted;
 		request.key_end = extracted + size;
 	}
+	if (vy_stmt_meta_encode(value, &request) != 0)
+		return -1;
 	xrow->bodycnt = xrow_encode_dml(&request, xrow->body);
 	if (xrow->bodycnt < 0)
 		return -1;
@@ -613,6 +676,7 @@ vy_stmt_decode(struct xrow_header *xrow, const struct key_def *key_def,
 	if (stmt == NULL)
 		return NULL; /* OOM */
 
+	vy_stmt_meta_decode(&request, stmt);
 	vy_stmt_set_lsn(stmt, xrow->lsn);
 	return stmt;
 }
diff --git a/src/box/vy_stmt.h b/src/box/vy_stmt.h
index e53f98ce..bcf855dd 100644
--- a/src/box/vy_stmt.h
+++ b/src/box/vy_stmt.h
@@ -103,6 +103,7 @@ struct vy_stmt {
 	struct tuple base;
 	int64_t lsn;
 	uint8_t  type; /* IPROTO_SELECT/REPLACE/UPSERT/DELETE */
+	uint8_t flags;
 	/**
 	 * Offsets array concatenated with MessagePack fields
 	 * array.
@@ -138,6 +139,20 @@ vy_stmt_set_type(struct tuple *stmt, enum iproto_type type)
 	((struct vy_stmt *) stmt)->type = type;
 }
 
+/** Get flags of the vinyl statement. */
+static inline uint8_t
+vy_stmt_flags(const struct tuple *stmt)
+{
+	return ((const struct vy_stmt *)stmt)->flags;
+}
+
+/** Set flags of the vinyl statement. */
+static inline void
+vy_stmt_set_flags(struct tuple *stmt, uint8_t flags)
+{
+	((struct vy_stmt *)stmt)->flags = flags;
+}
+
 /**
  * Get upserts count of the vinyl statement.
  * Only for UPSERT statements allocated on lsregion.
-- 
2.11.0