diff --git a/src/box/vy_read_iterator.c b/src/box/vy_read_iterator.c
index 2a16d916528fd6c927a9696962cb02d19ba0afea..ca4134727f55e730ecc9296b0a1aa02513d522e5 100644
--- a/src/box/vy_read_iterator.c
+++ b/src/box/vy_read_iterator.c
@@ -102,22 +102,30 @@ vy_read_iterator_add_src(struct vy_read_iterator *itr)
}
/**
- * Check if the read iterator needs to be restored.
- *
- * @retval 0 if position did not change (iterator started)
- * @retval -2 iterator is no more valid
+ * Pin all slices open by the read iterator.
+ * Used to make sure no run slice is invalidated by
+ * compaction while we are fetching data from disk.
*/
-static NODISCARD int
-vy_read_iterator_check_version(struct vy_read_iterator *itr)
+static void
+vy_read_iterator_pin_slices(struct vy_read_iterator *itr)
{
- if (itr->index->mem_list_version != itr->mem_list_version)
- return -2;
- if (itr->index->range_tree_version != itr->range_tree_version)
- return -2;
- if (itr->curr_range != NULL &&
- itr->curr_range->version != itr->range_version)
- return -2;
- return 0;
+ for (uint32_t i = itr->disk_src; i < itr->src_count; i++) {
+ struct vy_read_src *src = &itr->src[i];
+ vy_slice_pin(src->run_iterator.slice);
+ }
+}
+
+/**
+ * Unpin all slices open by the read iterator.
+ * See also: vy_read_iterator_pin_slices().
+ */
+static void
+vy_read_iterator_unpin_slices(struct vy_read_iterator *itr)
+{
+ for (uint32_t i = itr->disk_src; i < itr->src_count; i++) {
+ struct vy_read_src *src = &itr->src[i];
+ vy_slice_unpin(src->run_iterator.slice);
+ }
}
/**
@@ -358,8 +366,6 @@ vy_read_iterator_scan_disk(struct vy_read_iterator *itr,
if (rc < 0)
return -1;
- if (vy_read_iterator_check_version(itr))
- return -2;
vy_read_iterator_evaluate_src(itr, src, stop);
return 0;
@@ -421,6 +427,9 @@ vy_read_iterator_restore_mem(struct vy_read_iterator *itr)
return 0;
}
+static void
+vy_read_iterator_restore(struct vy_read_iterator *itr);
+
static void
vy_read_iterator_next_range(struct vy_read_iterator *itr);
@@ -431,7 +440,6 @@ vy_read_iterator_track_read(struct vy_read_iterator *itr, struct tuple *stmt);
* Iterate to the next key
* @retval 0 success or EOF (*ret == NULL)
* @retval -1 read error
- * @retval -2 iterator is not valid anymore
*/
static NODISCARD int
vy_read_iterator_next_key(struct vy_read_iterator *itr, struct tuple **ret)
@@ -449,10 +457,16 @@ vy_read_iterator_next_key(struct vy_read_iterator *itr, struct tuple **ret)
*ret = NULL;
return 0;
}
-
- if (vy_read_iterator_check_version(itr))
- return -2;
-
+ /*
+ * Restore the iterator position if the index has changed
+ * since the last iteration.
+ */
+ if (itr->mem_list_version != itr->index->mem_list_version ||
+ itr->range_tree_version != itr->index->range_tree_version ||
+ itr->range_version != itr->curr_range->version) {
+ vy_read_iterator_restore(itr);
+ }
+restart:
if (itr->curr_stmt != NULL)
tuple_unref(itr->curr_stmt);
itr->curr_stmt = NULL;
@@ -478,13 +492,27 @@ vy_read_iterator_next_key(struct vy_read_iterator *itr, struct tuple **ret)
}
rescan_disk:
/* The following code may yield as it needs to access disk. */
+ vy_read_iterator_pin_slices(itr);
for (i = itr->disk_src; i < itr->src_count; i++) {
- int rc = vy_read_iterator_scan_disk(itr, i, &stop);
- if (rc != 0)
- return rc;
+ if (vy_read_iterator_scan_disk(itr, i, &stop) != 0)
+ goto err_disk;
if (stop)
break;
}
+ vy_read_iterator_unpin_slices(itr);
+ /*
+ * The list of in-memory indexes and/or the range tree could
+ * have been modified by dump/compaction while we were fetching
+ * data from disk. Restart the iterator if this is the case.
+ * Note, we don't need to check the current range's version,
+ * because all slices were pinned and hence could not be
+ * removed.
+ */
+ if (itr->mem_list_version != itr->index->mem_list_version ||
+ itr->range_tree_version != itr->index->range_tree_version) {
+ vy_read_iterator_restore(itr);
+ goto restart;
+ }
/*
* The transaction write set couldn't change during the yield
* as it is owned exclusively by the current fiber so the only
@@ -515,13 +543,16 @@ vy_read_iterator_next_key(struct vy_read_iterator *itr, struct tuple **ret)
*ret = itr->curr_stmt;
return 0;
+
+err_disk:
+ vy_read_iterator_unpin_slices(itr);
+ return -1;
}
/**
* Iterate to the next (elder) version of the same key
* @retval 0 success or EOF (*ret == NULL)
* @retval -1 read error
- * @retval -2 iterator is not valid anymore
*/
static NODISCARD int
vy_read_iterator_next_lsn(struct vy_read_iterator *itr, struct tuple **ret)
@@ -565,25 +596,33 @@ vy_read_iterator_next_lsn(struct vy_read_iterator *itr, struct tuple **ret)
goto found;
}
- /* Look up the older statement in on-disk runs. */
+ /*
+ * Look up the older statement in on-disk runs.
+ *
+ * Note, we don't need to check the index version after the yield
+ * caused by the disk read, because once we've come to this point,
+ * we won't read any source except run slices, which are pinned
+ * and hence cannot be removed during the yield.
+ */
+ vy_read_iterator_pin_slices(itr);
for (i = MAX(itr->curr_src, itr->disk_src); i < itr->src_count; i++) {
src = &itr->src[i];
- if (i >= itr->skipped_src) {
- int rc = vy_read_iterator_scan_disk(itr, i, &unused);
- if (rc != 0)
- return rc;
- }
+ if (i >= itr->skipped_src &&
+ vy_read_iterator_scan_disk(itr, i, &unused) != 0)
+ goto err_disk;
if (src->front_id != itr->front_id)
continue;
if (i == itr->curr_src &&
vy_run_iterator_next_lsn(&src->run_iterator,
&src->stmt) != 0)
- return -1;
- if (vy_read_iterator_check_version(itr))
- return -2;
+ goto err_disk;
if (src->stmt != NULL)
- goto found;
+ break;
}
+ vy_read_iterator_unpin_slices(itr);
+
+ if (i < itr->src_count)
+ goto found;
/* Searched everywhere, found nothing. */
*ret = NULL;
@@ -596,6 +635,10 @@ vy_read_iterator_next_lsn(struct vy_read_iterator *itr, struct tuple **ret)
itr->curr_src = src - itr->src;
*ret = itr->curr_stmt;
return 0;
+
+err_disk:
+ vy_read_iterator_unpin_slices(itr);
+ return -1;
}
/**
@@ -603,7 +646,6 @@ vy_read_iterator_next_lsn(struct vy_read_iterator *itr, struct tuple **ret)
*
* @retval 0 success
* @retval -1 error
- * @retval -2 invalid iterator
*/
static NODISCARD int
vy_read_iterator_squash_upsert(struct vy_read_iterator *itr,
@@ -955,12 +997,8 @@ vy_read_iterator_next(struct vy_read_iterator *itr, struct tuple **result)
int rc = 0;
while (true) {
rc = vy_read_iterator_next_key(itr, &t);
- if (rc == -1)
+ if (rc != 0)
goto clear;
- if (rc == -2) {
- vy_read_iterator_restore(itr);
- continue;
- }
if (t == NULL) {
if (itr->last_stmt != NULL)
tuple_unref(itr->last_stmt);
@@ -969,12 +1007,8 @@ vy_read_iterator_next(struct vy_read_iterator *itr, struct tuple **result)
break;
}
rc = vy_read_iterator_squash_upsert(itr, &t);
- if (rc == -1)
+ if (rc != 0)
goto clear;
- if (rc == -2) {
- vy_read_iterator_restore(itr);
- continue;
- }
if (itr->last_stmt != NULL)
tuple_unref(itr->last_stmt);
itr->last_stmt = t;