027's 4f-3b: no fixed count of records or of their fields in all: the header's u16s alone (16 and 128 before); a stored list's record graph (PureLayout) holds a few records itself and more on the heap, 256 at most (an image numbers them in a byte), an image or a checkpoint not written then without room for it; a record's 16 fields kept, the list engine's width (a leaf's columns, a run's columns and narrow cells, the arrays' and packs' columns), to be widened with the lists' shapes sized to their fields; unit tests: 20 records of 10 fields (200 in all), an item of the last appended; a stored list whose six records each hold a list of the next saved and read back after a restart (its graph on the heap); counts: b41 against b40 with batches BFS +0.12%, without BFS -0.09%, the rest within 0.001%; the bank's queries (s40 and s41 in turns, six each) within 0.09% (the first three's in_credit +1.16% its spread: 2.75% between runs of one build); 008 and 027

1 files changed, 18 insertions, 8 deletions

diff --git a/core/module-save.h b/core/module-save.h
index 4ec50a2..44d3b95 100644
--- a/core/module-save.h
+++ b/core/module-save.h
@@ -79,15 +79,25 @@ uint8_t pure_record_kind(const PureModule *, uint32_t field);
  * order its list fields first meet them, each its fields' kinds (PURE_CELL_...) and names, and a list field's items'
  * record by its number here. A module's graph knows each record's number in the module too. */
 typedef struct {
-    unsigned records;
-    struct {
-        unsigned count;
-        uint8_t kinds[PURE_RECORD_FIELDS], items[PURE_RECORD_FIELDS];
-        char names[PURE_RECORD_FIELDS][PURE_MODULE_NAME];
-    } record[PURE_MODULE_RECORDS];
-    uint16_t module_record[PURE_MODULE_RECORDS];
+    unsigned count;
+    uint8_t kinds[PURE_RECORD_FIELDS], items[PURE_RECORD_FIELDS];
+    char names[PURE_RECORD_FIELDS][PURE_MODULE_NAME];
+} PureLayoutRecord;
+/* Its records in record (a few in few, more on the heap: room of them), at most 256 (a store numbers them in a byte),
+ * module_record beside them. Begun (pure_layout_begin) before use, done (pure_layout_done) after; never copied. */
+typedef struct {
+    unsigned records, room;
+    PureLayoutRecord *record;
+    uint16_t *module_record;
+    PureLayoutRecord few[4];
+    uint16_t few_records[4];
 } PureLayout;
-void pure_layout_of(const PureModule *, uint32_t record, PureLayout *out);
+enum { PURE_LAYOUT_RECORDS = 256 };
+void pure_layout_begin(PureLayout *);
+bool pure_layout_room(PureLayout *, unsigned records); /* false without room, or past PURE_LAYOUT_RECORDS */
+void pure_layout_done(PureLayout *);
+/* false: no room, or a graph of more than PURE_LAYOUT_RECORDS records. */
+bool pure_layout_of(const PureModule *, uint32_t record, PureLayout *out);
 bool pure_layout_same(const PureLayout *, const PureLayout *);
 /* A list with record's fields, taking from `from` (laid out as from_layout's record 0) each field of the same name and
  * kind, or a number, a bool and an i64 from each other when the value fits (pure_cell_as), and giving the others their