Keep the outbox as a list: a save logs only the sends and trims it made

The sends not yet trimmed were written whole into the links value at
every save, as the numbers heard were: a sender whose receiver is away
or slow saved all its waiting sends again with each new one. They are
now a runtime list {output (its name), seq, payload}, in the order sent,
stored as a list state is (image "0sent" and its changes in the log). A
send is a change of the list with its event; a trim lets the sends go at
once and a failed save brings them back; the host sees the saved ones
(sent_saved). Outputs are named in the items, so a module replaced keeps
them without moving anything; one that lacks or changed an output with
sends left is refused as before. Links stored before (PLK1, PLK2) move
their sends to the list at a start and are stored again without them
(PLK3).

A list field may now hold any bytes (kind 2), unchecked, besides a number
and a UTF-8 text.

Saving 5,000 sends of 16 KB one by one took 84.8 s and left a store of
400 MB; now 0.91 s and 144 MB. 20,000 of 61 bytes: 8.4 s, now 2.9 s.

1 files changed, 2 insertions, 0 deletions

diff --git a/core/module-list.h b/core/module-list.h
index faacf4b..a4e760a 100644
--- a/core/module-list.h
+++ b/core/module-list.h
@@ -46,6 +46,8 @@ typedef struct {
 /* A list holds up to PURE_LIST_ITEMS items, a run up to PURE_LIST_RUN. */
 enum { PURE_LIST_ITEMS = 1 << 24, PURE_LIST_RUN = 32 };
 
+/* text_fields: a field's kind, 0 a number, 1 a text (UTF-8, checked when
+ * read), 2 bytes (any: a runtime list's). */
 PureList *pure_list_new(unsigned fields, const uint8_t *text_fields);
 void pure_list_free(PureList *);
 /* Let every item go (retired where a shared copy may read it). */