From 1aae12acc34a338bb7f54ab6b1c7560d92300666 Mon Sep 17 00:00:00 2001
From: Vladimir Davydov <vdavydov@tarantool.org>
Date: Mon, 17 Oct 2022 17:40:24 +0300
Subject: [PATCH] index: make index_read_view_iterator fixed size
This is a straightforward patch that makes the read view iterator struct
fixed-size so that it can be allocated on stack. This is a pre-requisite
for the raw C API for read views: the function that creates an iterator
should allocate no memory.
Closes #7813
NO_DOC=refactoring
NO_TEST=refactoring
NO_CHANGELOG=refactoring
---
src/box/index.h | 52 +++++++++++++++++++++++++++--------------
src/box/memtx_engine.cc | 22 ++++++++---------
src/box/memtx_hash.cc | 32 ++++++++++---------------
src/box/memtx_tree.cc | 38 +++++++++++++-----------------
src/box/sequence.c | 33 +++++++++++++-------------
5 files changed, 89 insertions(+), 88 deletions(-)
diff --git a/src/box/index.h b/src/box/index.h
index 87c52c2f24..7819cf7eef 100644
--- a/src/box/index.h
+++ b/src/box/index.h
@@ -650,9 +650,10 @@ struct index_read_view_vtab {
const char *key, uint32_t part_count,
const char **data, uint32_t *size);
/** Create an index read view iterator. */
- struct index_read_view_iterator *
+ int
(*create_iterator)(struct index_read_view *rv, enum iterator_type type,
- const char *key, uint32_t part_count);
+ const char *key, uint32_t part_count,
+ struct index_read_view_iterator *it);
};
/**
@@ -674,13 +675,10 @@ struct index_read_view {
struct space_read_view *space;
};
-/** Iterator over an index read view. */
-struct index_read_view_iterator {
+/** Base class for iterator over an index read view. */
+struct index_read_view_iterator_base {
/** Pointer to the index read view. */
struct index_read_view *index;
- /** Free an index read view iterator instance. */
- void
- (*free)(struct index_read_view_iterator *iterator);
/**
* Iterate to the next tuple in the read view.
*
@@ -696,6 +694,29 @@ struct index_read_view_iterator {
const char **data, uint32_t *size);
};
+/** Size of the index_read_view_iterator struct. */
+#define INDEX_READ_VIEW_ITERATOR_SIZE 48
+
+static_assert(sizeof(struct index_read_view_iterator_base) <=
+ INDEX_READ_VIEW_ITERATOR_SIZE,
+ "sizeof(struct index_read_view_iterator_base) must be less than "
+ "or equal to INDEX_READ_VIEW_ITERATOR_SIZE");
+
+/**
+ * Iterator over an index read view.
+ *
+ * Implemented as an opaque fixed-size structure so that it can be declared on
+ * stack for any kind of read view iterator.
+ */
+struct index_read_view_iterator {
+ union {
+ /* Base class. */
+ struct index_read_view_iterator_base base;
+ /* Implementation dependent content. */
+ char data[INDEX_READ_VIEW_ITERATOR_SIZE];
+ };
+};
+
/**
* Check if replacement of an old tuple with a new one is
* allowed.
@@ -954,29 +975,26 @@ index_read_view_get_raw(struct index_read_view *rv,
return rv->vtab->get_raw(rv, key, part_count, data, size);
}
-static inline struct index_read_view_iterator *
+static inline int
index_read_view_create_iterator(struct index_read_view *rv,
enum iterator_type type,
- const char *key, uint32_t part_count)
+ const char *key, uint32_t part_count,
+ struct index_read_view_iterator *it)
{
- return rv->vtab->create_iterator(rv, type, key, part_count);
+ return rv->vtab->create_iterator(rv, type, key, part_count, it);
}
static inline void
-index_read_view_iterator_delete(struct index_read_view_iterator *iterator)
+index_read_view_iterator_destroy(struct index_read_view_iterator *iterator)
{
- /*
- * A read view iterator may be deleted after the read view is closed so
- * we don't check the read view ownership here.
- */
- iterator->free(iterator);
+ TRASH(iterator);
}
static inline int
index_read_view_iterator_next_raw(struct index_read_view_iterator *iterator,
const char **data, uint32_t *size)
{
- return iterator->next_raw(iterator, data, size);
+ return iterator->base.next_raw(iterator, data, size);
}
/*
diff --git a/src/box/memtx_engine.cc b/src/box/memtx_engine.cc
index 26c4fcb6ae..d5889551d8 100644
--- a/src/box/memtx_engine.cc
+++ b/src/box/memtx_engine.cc
@@ -848,15 +848,14 @@ checkpoint_f(va_list ap)
struct index_read_view *index_rv =
space_read_view_index(space_rv, 0);
assert(index_rv != NULL);
- struct index_read_view_iterator *it =
- index_read_view_create_iterator(index_rv, ITER_ALL,
- NULL, 0);
- if (it == NULL) {
+ struct index_read_view_iterator it;
+ if (index_read_view_create_iterator(index_rv, ITER_ALL,
+ NULL, 0, &it) != 0) {
rc = -1;
break;
}
while (true) {
- rc = index_read_view_iterator_next_raw(it, &data,
+ rc = index_read_view_iterator_next_raw(&it, &data,
&size);
if (rc != 0 || data == NULL)
break;
@@ -867,7 +866,7 @@ checkpoint_f(va_list ap)
break;
fiber_gc();
}
- index_read_view_iterator_delete(it);
+ index_read_view_iterator_destroy(&it);
if (rc != 0)
break;
}
@@ -1085,17 +1084,16 @@ memtx_join_f(va_list ap)
struct index_read_view *index_rv =
space_read_view_index(space_rv, 0);
assert(index_rv != NULL);
- struct index_read_view_iterator *it =
- index_read_view_create_iterator(index_rv, ITER_ALL,
- NULL, 0);
- if (it == NULL) {
+ struct index_read_view_iterator it;
+ if (index_read_view_create_iterator(index_rv, ITER_ALL,
+ NULL, 0, &it) != 0) {
rc = -1;
break;
}
uint32_t size;
const char *data;
while (true) {
- rc = index_read_view_iterator_next_raw(it, &data,
+ rc = index_read_view_iterator_next_raw(&it, &data,
&size);
if (rc != 0 || data == NULL)
break;
@@ -1105,7 +1103,7 @@ memtx_join_f(va_list ap)
break;
fiber_gc();
}
- index_read_view_iterator_delete(it);
+ index_read_view_iterator_destroy(&it);
if (rc != 0)
break;
}
diff --git a/src/box/memtx_hash.cc b/src/box/memtx_hash.cc
index 8b9593be8d..04ec67cfdf 100644
--- a/src/box/memtx_hash.cc
+++ b/src/box/memtx_hash.cc
@@ -516,11 +516,16 @@ struct hash_read_view {
/** Read view iterator implementation. */
struct hash_read_view_iterator {
/** Base class. */
- struct index_read_view_iterator base;
+ struct index_read_view_iterator_base base;
/** Light iterator. */
struct light_index_iterator iterator;
};
+static_assert(sizeof(struct hash_read_view_iterator) <=
+ INDEX_READ_VIEW_ITERATOR_SIZE,
+ "sizeof(struct hash_read_view_iterator) must be less than or "
+ "equal to INDEX_READ_VIEW_ITERATOR_SIZE");
+
static void
hash_read_view_free(struct index_read_view *base)
{
@@ -532,14 +537,6 @@ hash_read_view_free(struct index_read_view *base)
free(rv);
}
-static void
-hash_read_view_iterator_free(struct index_read_view_iterator *iterator)
-{
- assert(iterator->free == hash_read_view_iterator_free);
- TRASH(iterator);
- free(iterator);
-}
-
#if defined(ENABLE_READ_VIEW)
# include "memtx_hash_read_view.cc"
#else /* !defined(ENABLE_READ_VIEW) */
@@ -563,10 +560,9 @@ static int
hash_read_view_iterator_next_raw(struct index_read_view_iterator *iterator,
const char **data, uint32_t *size)
{
- assert(iterator->free == hash_read_view_iterator_free);
struct hash_read_view_iterator *it =
(struct hash_read_view_iterator *)iterator;
- struct hash_read_view *rv = (struct hash_read_view *)iterator->index;
+ struct hash_read_view *rv = (struct hash_read_view *)it->base.index;
while (true) {
struct tuple **res = light_index_view_iterator_get_and_next(
@@ -611,23 +607,19 @@ hash_read_view_reset_key_def(struct hash_read_view *rv)
#endif /* !defined(ENABLE_READ_VIEW) */
/** Implementation of create_iterator index_read_view callback. */
-static struct index_read_view_iterator *
+static int
hash_read_view_create_iterator(struct index_read_view *base,
enum iterator_type type,
- const char *key, uint32_t part_count)
+ const char *key, uint32_t part_count,
+ struct index_read_view_iterator *iterator)
{
struct hash_read_view *rv = (struct hash_read_view *)base;
struct hash_read_view_iterator *it =
- (struct hash_read_view_iterator *)xmalloc(sizeof(*it));
+ (struct hash_read_view_iterator *)iterator;
it->base.index = base;
- it->base.free = hash_read_view_iterator_free;
it->base.next_raw = exhausted_index_read_view_iterator_next_raw;
light_index_view_iterator_begin(&rv->view, &it->iterator);
- if (hash_read_view_iterator_start(it, type, key, part_count) != 0) {
- index_read_view_iterator_delete(&it->base);
- return NULL;
- }
- return (struct index_read_view_iterator *)it;
+ return hash_read_view_iterator_start(it, type, key, part_count);
}
/** Implementation of create_read_view index callback. */
diff --git a/src/box/memtx_tree.cc b/src/box/memtx_tree.cc
index cbc5d94c1e..a92103f1a4 100644
--- a/src/box/memtx_tree.cc
+++ b/src/box/memtx_tree.cc
@@ -1856,13 +1856,22 @@ struct tree_read_view {
template <bool USE_HINT>
struct tree_read_view_iterator {
/** Base class. */
- struct index_read_view_iterator base;
+ struct index_read_view_iterator_base base;
/** Iterator key. */
struct memtx_tree_key_data<USE_HINT> key_data;
/** BPS tree iterator. */
memtx_tree_iterator_t<USE_HINT> tree_iterator;
};
+static_assert(sizeof(struct tree_read_view_iterator<false>) <=
+ INDEX_READ_VIEW_ITERATOR_SIZE,
+ "sizeof(struct tree_read_view_iterator<false>) must be less than "
+ "or equal to INDEX_READ_VIEW_ITERATOR_SIZE");
+static_assert(sizeof(struct tree_read_view_iterator<true>) <=
+ INDEX_READ_VIEW_ITERATOR_SIZE,
+ "sizeof(struct tree_read_view_iterator<true>) must be less than "
+ "or equal to INDEX_READ_VIEW_ITERATOR_SIZE");
+
template <bool USE_HINT>
static void
tree_read_view_free(struct index_read_view *base)
@@ -1876,15 +1885,6 @@ tree_read_view_free(struct index_read_view *base)
free(rv);
}
-template <bool USE_HINT>
-static void
-tree_read_view_iterator_free(struct index_read_view_iterator *iterator)
-{
- assert(iterator->free == &tree_read_view_iterator_free<USE_HINT>);
- TRASH(iterator);
- free(iterator);
-}
-
#if defined(ENABLE_READ_VIEW)
# include "memtx_tree_read_view.cc"
#else /* !defined(ENABLE_READ_VIEW) */
@@ -1910,11 +1910,10 @@ static int
tree_read_view_iterator_next_raw(struct index_read_view_iterator *iterator,
const char **data, uint32_t *size)
{
- assert(iterator->free == &tree_read_view_iterator_free<USE_HINT>);
struct tree_read_view_iterator<USE_HINT> *it =
(struct tree_read_view_iterator<USE_HINT> *)iterator;
struct tree_read_view<USE_HINT> *rv =
- (struct tree_read_view<USE_HINT> *)iterator->index;
+ (struct tree_read_view<USE_HINT> *)it->base.index;
while (true) {
struct memtx_tree_data<USE_HINT> *res =
@@ -1967,27 +1966,22 @@ tree_read_view_reset_key_def(struct tree_read_view<USE_HINT> *rv)
/** Implementation of create_iterator index_read_view callback. */
template <bool USE_HINT>
-static struct index_read_view_iterator *
+static int
tree_read_view_create_iterator(struct index_read_view *base,
enum iterator_type type,
- const char *key, uint32_t part_count)
+ const char *key, uint32_t part_count,
+ struct index_read_view_iterator *iterator)
{
struct tree_read_view_iterator<USE_HINT> *it =
- (struct tree_read_view_iterator<USE_HINT> *)
- xmalloc(sizeof(*it));
+ (struct tree_read_view_iterator<USE_HINT> *)iterator;
it->base.index = base;
- it->base.free = tree_read_view_iterator_free<USE_HINT>;
it->base.next_raw = exhausted_index_read_view_iterator_next_raw;
it->key_data.key = NULL;
it->key_data.part_count = 0;
if (USE_HINT)
it->key_data.set_hint(HINT_NONE);
invalidate_tree_iterator(&it->tree_iterator);
- if (tree_read_view_iterator_start(it, type, key, part_count) != 0) {
- index_read_view_iterator_delete(&it->base);
- return NULL;
- }
- return (struct index_read_view_iterator *)it;
+ return tree_read_view_iterator_start(it, type, key, part_count);
}
/** Implementation of create_read_view index callback. */
diff --git a/src/box/sequence.c b/src/box/sequence.c
index d56780be9a..7f479274cd 100644
--- a/src/box/sequence.c
+++ b/src/box/sequence.c
@@ -311,20 +311,25 @@ struct sequence_data_read_view {
/** Read view iterator implementation. */
struct sequence_data_iterator {
/** Base class. */
- struct index_read_view_iterator base;
+ struct index_read_view_iterator_base base;
/** Iterator over the data index. */
struct light_sequence_iterator iter;
};
+static_assert(sizeof(struct sequence_data_iterator) <=
+ INDEX_READ_VIEW_ITERATOR_SIZE,
+ "sizeof(struct sequence_data_iterator) must be less than or "
+ "equal to INDEX_READ_VIEW_ITERATOR_SIZE");
+
/** Implementation of next_raw index_read_view_iterator callback. */
static int
-sequence_data_iterator_next_raw(struct index_read_view_iterator *base,
+sequence_data_iterator_next_raw(struct index_read_view_iterator *iterator,
const char **data, uint32_t *size)
{
struct sequence_data_iterator *iter =
- (struct sequence_data_iterator *)base;
+ (struct sequence_data_iterator *)iterator;
struct sequence_data_read_view *rv =
- (struct sequence_data_read_view *)base->index;
+ (struct sequence_data_read_view *)iter->base.index;
struct sequence_data *sd = light_sequence_view_iterator_get_and_next(
&rv->view, &iter->iter);
@@ -348,13 +353,6 @@ sequence_data_iterator_next_raw(struct index_read_view_iterator *base,
return 0;
}
-static void
-sequence_data_iterator_free(struct index_read_view_iterator *iter)
-{
- TRASH(iter);
- free(iter);
-}
-
static inline int
sequence_data_read_view_get_raw(struct index_read_view *rv,
const char *key, uint32_t part_count,
@@ -371,26 +369,27 @@ sequence_data_read_view_get_raw(struct index_read_view *rv,
}
/** Implementation of create_iterator index_read_view callback. */
-static struct index_read_view_iterator *
+static int
sequence_data_iterator_create(struct index_read_view *base,
enum iterator_type type,
- const char *key, uint32_t part_count)
+ const char *key, uint32_t part_count,
+ struct index_read_view_iterator *iterator)
{
if (type != ITER_ALL) {
diag_set(ClientError, ER_UNSUPPORTED,
"_sequence_data read view", "requested iterator type");
- return NULL;
+ return -1;
}
(void)key;
(void)part_count;
struct sequence_data_read_view *rv =
(struct sequence_data_read_view *)base;
- struct sequence_data_iterator *iter = xmalloc(sizeof(*iter));
+ struct sequence_data_iterator *iter =
+ (struct sequence_data_iterator *)iterator;
iter->base.index = base;
iter->base.next_raw = sequence_data_iterator_next_raw;
- iter->base.free = sequence_data_iterator_free;
light_sequence_view_iterator_begin(&rv->view, &iter->iter);
- return (struct index_read_view_iterator *)iter;
+ return 0;
}
static void
--
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