[tarantool-patches] Re: [PATCH v5 4/4] box: introduce multikey indexes in memtx
Kirill Shcherbatov
kshcherbatov at tarantool.org
Mon May 6 19:35:10 MSK 2019
>
> How's it going to work in case the field map stored in a tuple is
> greater than field_map_size?
>
> I think we should calculate the real size of the field map here
> in case the format allows multikey indexes.
Consider this diff (not on branch yet):
diff --git a/src/box/field_map.c b/src/box/field_map.c
index 5d25e3032..a917d4a25 100644
--- a/src/box/field_map.c
+++ b/src/box/field_map.c
@@ -105,12 +105,28 @@ field_map_build(struct field_map_builder *builder, char *buffer)
struct field_map_builder_slot_extent *extent =
builder->slots[i].extent;
/** Retrive memory for the extent. */
- uint32_t sz = sizeof(struct field_map_builder_slot_extent) +
- extent->size * sizeof(uint32_t);
field_map[i] =
(uint32_t)((char *)extent_wptr - (char *)field_map);
- memcpy(extent_wptr, extent, sz);
- extent_wptr += sz;
+ *(uint32_t *)extent_wptr = extent->size;
+ uint32_t extent_offset_sz = extent->size * sizeof(uint32_t);
+ memcpy(&((uint32_t *) extent_wptr)[1], extent->offset,
+ extent_offset_sz);
+ extent_wptr += sizeof(uint32_t) + extent_offset_sz;
}
assert(extent_wptr == buffer + builder->extents_size);
}
+
+uint32_t
+field_map_get_size(const uint32_t *field_map, uint32_t format_field_map_sz)
+{
+ uint32_t total = format_field_map_sz;
+ int32_t field_map_items = format_field_map_sz / sizeof(uint32_t);
+ for (int32_t slot = -1; slot >= -field_map_items; slot--) {
+ if ((int32_t)field_map[slot] >= 0)
+ continue;
+ uint32_t *extent = (uint32_t *)((char *)field_map +
+ (int32_t)field_map[slot]);
+ total += (1 + extent[0]) * sizeof(uint32_t);
+ }
+ return total;
+}
diff --git a/src/box/field_map.h b/src/box/field_map.h
index 0fd35c3e1..78c96e4f7 100644
--- a/src/box/field_map.h
+++ b/src/box/field_map.h
@@ -163,6 +163,19 @@ field_map_get_offset(const uint32_t *field_map, int32_t offset_slot,
return offset;
}
+/**
+ * Get size of the tuple field_map using
+ * field_map pointer and format root field_map size.
+ *
+ * In case of multikey indexes the real field_map size may be
+ * greater than the size of format root field_map. To calculate
+ * the total size of the field_map extentions, routine relies
+ * on the fact that all field_map slots that has an extention
+ * use negative offset as a marker.
+ */
+uint32_t
+field_map_get_size(const uint32_t *field_map, uint32_t format_field_map_sz);
+
/**
* Initialize field_map_builder.
*
diff --git a/src/box/memtx_engine.c b/src/box/memtx_engine.c
index 65e8804a4..ab4913035 100644
--- a/src/box/memtx_engine.c
+++ b/src/box/memtx_engine.c
@@ -1180,6 +1180,8 @@ memtx_tuple_new(struct tuple_format *format, const char *data, const char *end)
char *raw = (char *) tuple + tuple->data_offset;
field_map_build(&builder, raw - field_map_size);
memcpy(raw, data, tuple_len);
+ assert(field_map_get_size((uint32_t *)raw,
+ format->field_map_size) == field_map_size);
say_debug("%s(%zu) = %p", __func__, tuple_len, memtx_tuple);
end:
region_truncate(region, region_svp);
@@ -1192,8 +1194,9 @@ memtx_tuple_delete(struct tuple_format *format, struct tuple *tuple)
struct memtx_engine *memtx = (struct memtx_engine *)format->engine;
say_debug("%s(%p)", __func__, tuple);
assert(tuple->refs == 0);
- size_t total = sizeof(struct memtx_tuple) + format->field_map_size +
- tuple->bsize;
+ const uint32_t *field_map = tuple_field_map(tuple);
+ size_t total = sizeof(struct memtx_tuple) + tuple->bsize +
+ field_map_get_size(field_map, format->field_map_size);
tuple_format_unref(format);
struct memtx_tuple *memtx_tuple =
container_of(tuple, struct memtx_tuple, base);
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