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-rw-r--r--core/module-list.c212
1 files changed, 171 insertions, 41 deletions
diff --git a/core/module-list.c b/core/module-list.c
index 4d90d32..d69ad98 100644
--- a/core/module-list.c
+++ b/core/module-list.c
@@ -6,11 +6,13 @@
/* A list's items live in a persistent B+tree: leaves hold up to FANOUT
* items, inner nodes up to FANOUT children, and every node knows how many
- * items lie below it, their stored bytes and the leaf holding the first of
- * them. So an item is found by position, a keyed list is searched by key and
- * an item's place in the stored form is computed in O(log n), whatever the
- * list's length; a run of positions is read through a finger (the last leaf
- * a thread read) or a leaf at a time (pure_list_run).
+ * items lie below it and the leaf holding the first of them. An inner node
+ * also keeps, beside its children, how many items lie below each and (in a
+ * list keyed by a number field) each one's first key: its guide. So an item
+ * is found by position, and a keyed list searched by key, reading one node a
+ * level, in O(log n) whatever the list's length; a run of positions is read
+ * through a finger (the last leaf a thread read) or a leaf at a time
+ * (pure_list_run).
*
* A leaf keeps its items field by field: each field's cells side by side,
* numbers as binary64 values and texts as spans of bytes the list owns. So
@@ -23,18 +25,26 @@
* (the path) and retires the ones it replaced, and retires a text it lets go
* instead of freeing it. A share is then a root and a count, however long
* the list. */
-enum { FANOUT = PURE_LIST_RUN, DEPTH = 16, SPARE_NODES = 8 };
+enum { FANOUT = PURE_LIST_RUN, DEPTH = 16, SPARE_NODES = 8, PREFETCHED = 1 << 17 };
typedef struct Node {
uint64_t made; /* the list's share count when made: shared once below it */
uint32_t count; /* items (a leaf) or children */
bool leaf;
- size_t items, bytes; /* items below, and their stored bytes */
+ size_t items; /* items below */
const struct Node *first; /* the leaf holding the first item below; NULL when there is none */
- struct Node *child[]; /* an inner node's children; a leaf's columns are here instead */
+ double lead; /* the first item's key, in a list keyed by a number field (else 0) */
+ struct Node *child[]; /* an inner node's children, then its guide; a leaf's columns are here instead */
} Node;
-enum { INNER_SIZE = sizeof(Node) + FANOUT * sizeof(Node *) };
+/* An inner node's guide, after its children: the items before each child
+ * and each child's lead, kept by sum; past the last child the counts and
+ * keys are above any position and key. So a level is searched in one node,
+ * by a binary search of fixed length whose steps are selections, not
+ * branches (upper). */
+typedef struct { uint32_t before[FANOUT]; double keys[FANOUT]; } Guide;
+
+enum { INNER_SIZE = sizeof(Node) + FANOUT * sizeof(Node *) + sizeof(Guide) };
/* Where a leaf keeps each field's cells, and what an item stores. */
typedef struct {
@@ -44,12 +54,13 @@ typedef struct {
uint32_t column[16]; /* where each field's cells start in a leaf */
size_t leaf_size;
size_t number_bytes; /* an item's numbers, stored */
+ int key; /* the number field whose order the list keeps (its leads), or -1 */
} Layout;
struct PureList {
Layout layout;
Node *root; /* NULL when the list has no item */
- size_t count;
+ size_t count, bytes; /* items, and their stored bytes */
/* A stored list's changes since they were last taken, as records
* (pure_list_replay); none are kept while journaled is false. */
bool journaled;
@@ -87,6 +98,26 @@ static uint64_t lists_made;
static _Thread_local struct { uint64_t id, version; const Node *leaf; size_t start; } finger;
static Node *child(const Node *node, unsigned i) { return node->child[i]; }
+static Guide *guide(const Node *node) { return (Guide *)((char *)node + sizeof(Node) + FANOUT * sizeof(Node *)); }
+
+/* How many of n (at least one) ascending values are at or below key (upper)
+ * or below it (lower). */
+static unsigned upper(const double *values, unsigned n, double key) {
+ const double *base = values;
+ for (; n > 1; n -= n / 2) base = base[n / 2] <= key ? base + n / 2 : base;
+ return (unsigned)(base - values) + (*base <= key);
+}
+static unsigned lower(const double *values, unsigned n, double key) {
+ const double *base = values;
+ for (; n > 1; n -= n / 2) base = base[n / 2] < key ? base + n / 2 : base;
+ return (unsigned)(base - values) + (*base < key);
+}
+/* The child of an inner node holding its item at (counted from the node's first). */
+static unsigned child_at(const Node *node, size_t at) {
+ const uint32_t *before = guide(node)->before + 1, *base = before;
+ for (unsigned n = FANOUT - 1; n > 1; n -= n / 2) base = base[n / 2] <= at ? base + n / 2 : base;
+ return (unsigned)(base - before) + (*base <= at);
+}
static double *numbers(const Layout *l, const Node *leaf, unsigned f) { return (double *)((char *)leaf + l->column[f]); }
static PureSpan *texts(const Layout *l, const Node *leaf, unsigned f) { return (PureSpan *)((char *)leaf + l->column[f]); }
@@ -174,8 +205,9 @@ static Node *new_node(PureList *list, bool leaf) {
node->made = list->shares;
node->count = 0;
node->leaf = leaf;
- node->items = node->bytes = 0;
+ node->items = 0;
node->first = NULL;
+ node->lead = 0;
return node;
}
@@ -196,22 +228,39 @@ static void drop_node(PureList *list, Node *node) {
static size_t cell_bytes(const Layout *l, unsigned field, PureCell cell) { return l->text_fields[field] ? 4 + cell.size : 8; }
-/* A node's summary, from its items or children. */
+static size_t cells_bytes(const Layout *l, const PureCell *cells) {
+ size_t size = l->number_bytes;
+ for (unsigned t = 0; t < l->texts; ++t) size += 4 + cells[l->text_field[t]].size;
+ return size;
+}
+
+static size_t item_bytes(const Layout *l, const Node *leaf, unsigned i) {
+ size_t size = l->number_bytes;
+ for (unsigned t = 0; t < l->texts; ++t) size += 4 + texts(l, leaf, l->text_field[t])[i].size;
+ return size;
+}
+
+/* A node's summary, from its items or all its children. */
static void sum(const PureList *list, Node *node) {
const Layout *l = &list->layout;
- size_t items = 0, bytes = 0;
if (node->leaf) {
- items = node->count;
- bytes = items * l->number_bytes;
- for (unsigned t = 0; t < l->texts; ++t) {
- const PureSpan *column = texts(l, node, l->text_field[t]);
- for (unsigned i = 0; i < node->count; ++i) bytes += 4 + column[i].size;
- }
- } else
- for (unsigned i = 0; i < node->count; ++i) items += child(node, i)->items, bytes += child(node, i)->bytes;
+ node->items = node->count;
+ node->first = node->count ? node : NULL;
+ node->lead = l->key >= 0 && node->count ? numbers(l, node, (unsigned)l->key)[0] : 0;
+ return;
+ }
+ Guide *g = guide(node);
+ size_t items = 0;
+ for (unsigned i = 0; i < node->count; ++i) {
+ const Node *below = child(node, i);
+ g->before[i] = (uint32_t)items;
+ g->keys[i] = below->lead;
+ items += below->items;
+ }
+ for (unsigned i = node->count; i < FANOUT; ++i) g->before[i] = UINT32_MAX, g->keys[i] = INFINITY;
node->items = items;
- node->bytes = bytes;
- node->first = !node->count ? NULL : node->leaf ? node : child(node, 0)->first;
+ node->first = node->count ? child(node, 0)->first : NULL;
+ node->lead = node->count ? g->keys[0] : 0;
}
/* ---- Finding positions */
@@ -229,8 +278,8 @@ static const Node *leaf_of(const PureList *list, size_t at, size_t *within) {
const Node *node = list->root;
size_t start = 0;
while (!node->leaf) {
- unsigned i = 0;
- while (i + 1 < node->count && at - start >= child(node, i)->items) start += child(node, i)->items, ++i;
+ unsigned i = child_at(node, at - start);
+ start += guide(node)->before[i];
node = child(node, i);
}
finger.id = list->id, finger.version = list->version, finger.leaf = node, finger.start = start;
@@ -274,16 +323,35 @@ static unsigned descend(PureList *list, size_t at, Step path[DEPTH], unsigned *w
for (unsigned d = depth; d-- > 0;) path[d].node->first = child(path[d].node, 0)->first;
return depth + 1;
}
- unsigned i = 0;
- while (i + 1 < node->count && at >= child(node, i)->items) at -= child(node, i)->items, ++i;
+ unsigned i = child_at(node, at);
+ at -= guide(node)->before[i];
path[depth] = (Step){node, i};
place = &node->child[i];
}
return 0;
}
+/* After a change below the path's last node: that node summed whole, and
+ * each above it through the one child on the path (the others are as they
+ * were). */
static void sum_path(const PureList *list, const Step *path, unsigned depth) {
- for (unsigned d = depth; d-- > 0;) sum(list, path[d].node);
+ if (!depth) return;
+ sum(list, path[depth - 1].node);
+ for (unsigned d = depth - 1; d-- > 0;) {
+ Node *node = path[d].node;
+ unsigned i = path[d].index;
+ const Node *below = child(node, i);
+ Guide *g = guide(node);
+ size_t was = (i + 1 < node->count ? g->before[i + 1] : node->items) - g->before[i];
+ if (below->items != was) {
+ uint32_t moved = (uint32_t)(below->items - was); /* modulo 2^32: an item fewer is all ones */
+ for (unsigned j = i + 1; j < node->count; ++j) g->before[j] += moved;
+ node->items += below->items - was;
+ }
+ g->keys[i] = below->lead;
+ node->first = child(node, 0)->first;
+ node->lead = g->keys[0];
+ }
}
/* ---- Placing and removing */
@@ -436,10 +504,33 @@ PureList *pure_list_new(unsigned fields, const uint8_t *text_fields) {
else l->number_bytes += 8;
}
l->leaf_size = at;
+ l->key = -1;
list->id = __atomic_add_fetch(&lists_made, 1, __ATOMIC_RELAXED);
return list;
}
+/* Every node below *place the list's own, summed again. */
+static bool rekey(PureList *list, Node **place) {
+ Node *node = own(list, place);
+ if (!node) return false;
+ for (unsigned i = 0; !node->leaf && i < node->count; ++i)
+ if (!rekey(list, &node->child[i])) return false;
+ sum(list, node);
+ return true;
+}
+
+PureResult pure_list_keyed(PureList *list, int field) {
+ Layout *l = &list->layout;
+ int key = field >= 0 && (unsigned)field < l->fields && !l->text_fields[field] ? field : -1;
+ if (key == l->key) return PURE_OK;
+ l->key = key;
+ if (list->root && !rekey(list, &list->root)) {
+ l->key = -1; /* searched without leads, which some nodes lack */
+ return PURE_ALLOCATION;
+ }
+ return PURE_OK;
+}
+
/* Every node and text below node let go (retired where a copy may read them). */
static void let_go_tree(PureList *list, Node *node) {
if (!node) return;
@@ -473,7 +564,7 @@ void pure_list_clear(PureList *list) {
if (!list->count) return;
let_go_tree(list, list->root);
list->root = NULL;
- list->count = 0;
+ list->count = list->bytes = 0;
++list->version;
}
@@ -482,8 +573,8 @@ size_t pure_list_count(const PureList *list) { return list->count; }
PureList *pure_list_share(PureList *list, PureRetired *retired) {
PureList *copy = malloc(sizeof(*copy));
if (!copy) return NULL;
- *copy = (PureList){.layout = list->layout, .root = list->root, .count = list->count, .id = list->id,
- .version = list->version, .refs = 1, .copy = true};
+ *copy = (PureList){.layout = list->layout, .root = list->root, .count = list->count, .bytes = list->bytes,
+ .id = list->id, .version = list->version, .refs = 1, .copy = true};
list->retired = retired;
++list->shares;
return copy;
@@ -610,7 +701,7 @@ static bool encode_leaf(void *context, const Node *leaf) {
return true;
}
-size_t pure_list_size(const PureList *list) { return list->root ? list->root->bytes : 0; }
+size_t pure_list_size(const PureList *list) { return list->bytes; }
void pure_list_encode(const PureList *list, unsigned char *out) {
Encoding encoding = {&list->layout, out};
@@ -687,6 +778,7 @@ PureResult pure_list_insert(PureList *list, size_t at, const PureCell *cells, Pu
for (unsigned f = 0; f < l->fields; ++f) end = encode_cell(l, f, item[f], end);
list->journal_size += size;
}
+ list->bytes += cells_bytes(l, item);
place(list, &p, item);
return PURE_OK;
}
@@ -723,19 +815,33 @@ PureResult pure_list_remove(PureList *list, size_t at, PureUndo *undo) {
list->journal_size += RECORD_HEAD;
}
if (undo) undo->cell_count += l->fields;
- else let_go_cells(list, cells);
+ list->bytes -= cells_bytes(l, cells);
+ if (!undo) let_go_cells(list, cells);
take_out(list, path, depth, within);
return PURE_OK;
}
+/* A field no summary follows (any but the key) changes in its leaf alone:
+ * the leaf the thread read last, when the list alone has it, else the leaf
+ * at the end of the list's own path to the item. The thread's finger keeps
+ * the leaf, so the item's other fields are read and changed there too. */
PureResult pure_list_set(PureList *list, size_t at, unsigned field, PureCell value, PureUndo *undo) {
const Layout *l = &list->layout;
if (at >= list->count) return PURE_NOT_FOUND;
Step path[DEPTH];
- unsigned within, depth = descend(list, at, path, &within);
+ unsigned within, depth = 0;
+ bool keyed = (int)field == l->key;
+ Node *leaf;
+ if (!keyed && finger.leaf && finger.id == list->id && finger.version == list->version && at >= finger.start &&
+ at < finger.start + finger.leaf->count && !shared_node(list, finger.leaf)) {
+ leaf = (Node *)finger.leaf;
+ within = (unsigned)(at - finger.start);
+ } else {
+ if (!(depth = descend(list, at, path, &within))) return PURE_ALLOCATION;
+ leaf = path[depth - 1].node;
+ }
PureCell copy;
- if (!depth || !own_cell(list, field, value, &copy)) return PURE_ALLOCATION;
- Node *leaf = path[depth - 1].node;
+ if (!own_cell(list, field, value, &copy)) return PURE_ALLOCATION;
PureCell old = cell_at(l, leaf, within, field);
size_t size = RECORD_HEAD + 1 + cell_bytes(l, field, copy);
unsigned char *record = list->journaled ? journal_room(list, size) : NULL;
@@ -750,11 +856,13 @@ PureResult pure_list_set(PureList *list, size_t at, unsigned field, PureCell val
encode_cell(l, field, copy, end);
list->journal_size += size;
}
+ list->bytes += cell_bytes(l, field, copy) - cell_bytes(l, field, old);
if (l->text_fields[field]) texts(l, leaf, field)[within] = (PureSpan){copy.text, copy.size};
else numbers(l, leaf, field)[within] = copy.num;
if (!undo) let_go_text(list, old.text);
- sum_path(list, path, depth);
+ if (keyed) sum_path(list, path, depth);
++list->version;
+ finger.id = list->id, finger.version = list->version, finger.leaf = leaf, finger.start = at - within;
return PURE_OK;
}
@@ -776,8 +884,8 @@ bool pure_list_run(const PureList *list, size_t at, PureRun *run) {
size_t start = 0;
unsigned depth = 0;
while (!node->leaf) {
- unsigned i = 0;
- while (i + 1 < node->count && at - start >= child(node, i)->items) start += child(node, i)->items, ++i;
+ unsigned i = child_at(node, at - start);
+ start += guide(node)->before[i];
run->path[depth] = node;
run->taken[depth++] = (uint8_t)i;
node = child(node, i);
@@ -825,21 +933,40 @@ static int order(const Layout *l, unsigned field, PureCell a, PureCell b) {
}
/* Down the child whose first item's key is the last at or below key (the
- * first child when none is), then the leaf's first item not below it. */
+ * first child when none is), then the leaf's first item not below it. The
+ * list's own key field is read from each node's guide; another field from
+ * the children's first leaves. */
size_t pure_list_seek(const PureList *list, unsigned field, PureCell key, bool *found) {
const Layout *l = &list->layout;
const Node *node = list->root;
size_t start = 0;
*found = false;
if (!node || !list->count) return 0;
+ if ((int)field == l->key) {
+ /* Each level: the last child whose lead is at or below key (the
+ * first when none is); then the leaf's items below key. */
+ while (!node->leaf) {
+ const Guide *g = guide(node);
+ unsigned taken = upper(g->keys + 1, FANOUT - 1, key.num);
+ start += g->before[taken];
+ node = child(node, taken);
+ }
+ const double *keys = numbers(l, node, field);
+ if (list->count > PREFETCHED) /* leaves past the caches: the leaf's keys fetched at once, not probe by probe */
+ for (unsigned i = 0; i < node->count; i += 8) __builtin_prefetch(keys + i);
+ unsigned low = lower(keys, node->count, key.num);
+ *found = low < node->count && keys[low] == key.num;
+ return start + low;
+ }
while (!node->leaf) {
+ const Guide *g = guide(node);
unsigned low = 1, high = node->count;
while (low < high) {
unsigned middle = low + (high - low) / 2;
if (order(l, field, cell_at(l, child(node, middle)->first, 0, field), key) <= 0) low = middle + 1;
else high = middle;
}
- for (unsigned i = 0; i + 1 < low; ++i) start += child(node, i)->items;
+ start += g->before[low - 1];
node = child(node, low - 1);
}
unsigned low = 0, high = node->count;
@@ -936,6 +1063,7 @@ void pure_undo_rollback(PureUndo *undo, size_t mark) {
if (e->change == REMOVED) {
Place p;
if (!prepare(list, e->at, &p)) abort();
+ list->bytes += cells_bytes(l, undo->cells + e->cells);
place(list, &p, undo->cells + e->cells);
undo->cell_count = e->cells;
continue;
@@ -943,10 +1071,12 @@ void pure_undo_rollback(PureUndo *undo, size_t mark) {
if (!(depth = descend(list, e->at, path, &within))) abort();
Node *leaf = path[depth - 1].node;
if (e->change == INSERTED) {
+ list->bytes -= item_bytes(l, leaf, within);
for (unsigned t = 0; t < l->texts; ++t) free_text(texts(l, leaf, l->text_field[t])[within].data);
take_out(list, path, depth, within);
continue;
}
+ list->bytes += cell_bytes(l, e->field, e->old) - cell_bytes(l, e->field, cell_at(l, leaf, within, e->field));
if (l->text_fields[e->field]) {
PureSpan *text = &texts(l, leaf, e->field)[within];
free_text(text->data);
generated by cgit v1.2.3 (git 2.46.0) at 2026-10-20 15:38:34 +0000