hcache.txt

bcache
	why isn't it in maildir format?
	touch files, utime(2), to SENT_DATE
		doc crontab for cleanup
	plan to integrate offlineimap as bcache
	might need folder-name translation to match offlineimap

hcache that works offline!

use hcache to store other info?
	e.g. top tips - which are read

is hcache data hashed on fields in db, or all fields?
	i.e. why does HCACHEVER change so often

use startup hook & scripting + offline hcache
	to locally cache email
	local cache => strictly readonly

gahr, hcache
	one formatting string
	+/- override format strings
	separate code files
	autoconf hcache=X
	separate code dir?
	hcache/*
	all via hcache.h
	.so dyanamic library
	conflicts autoconf a bit
	multiple static/dynamic
	global?
	per mailbox?
	break deps on mutt structs
	rename "ctx" -- too confusing

multiple hcaches => RAID-like write many, read fastest
	two caches, local and shared?

merge hcache docs?

hcache
	when it's done, create an hcache test rig
	only use hcache API

easy task to rejig list of hcache backends
highlight current one?
	X Y (Cur) Z
	Cur (X Y Z)
hcache: x [y] z
	y = default
	only make sense after reading config?

hcache
	is it a binary blob based on HEADER?
	what causes cache invalidation?
	change of size, order? count of fields?
	change of endianness
	does hcache *need* to know about what's in the binary blob?
	just needs *key* to seed hash of data (data, len)
	hcache *doesn't* need to know about mutt
	key needs to be hashed on db name too
	when done, move to hcache/ dir

hcache files .<backend> suffix?

config "file" vs "dir/" is ugly and confusing

eliminate #ifdef USE_HCACHE for
	int mh_sync_mailbox_message(struct Context *ctx, int msgno, header_cache_t *hc);
	void * typedef if not def'd

hcache move conditionals to end of struct?

timestamp hcache entries for garbage collection
	gc may not reduce size of db file

have cache settings per account (or per folder), with flags
	PREFETCH_ALL

all hc dump functions should be const
	need to disentagle dump_char_size first

move CharsetIsUtf8 out of hcache (param)

hcache namer
	split (root, dir, name) triplet?

check header and msg cache for dirs containing whitespace
	e.g. "Bulk Mail"

split the hcache serialisation by struct
	address_serialise
	buffer_serialise
	etc
each struct calls the children it needs
put in some version numbers, or
field type and length bytes before each field

hcache pruner
	use list of mailboxes
	use list of backends (you want)
	won't work for caching files, only folders
		unless we trawl through EVERY email
		might as well cache them too

hcache auto magic everything

sync web & contrib versions of hcache benchmarks
	how?

have a NULL cache which is just a copy of the email
	might *still* need a DB of some info
	tie into offlineimap

cache files need to hash their name too
	to avoid two systems "sharing" a single hash
	and crashing

hcache2 (bitfields)
	inline, transparent

where are the magic structs in the code?
	address/address.h
	email/body.h
	email/email.h
	email/envelope.h
	email/parameter.h
	mutt/buffer.h
	mutt/list.h
separate files for each magic struct to reduce dependencies?

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the header cache keys seem to include the full path
if we have separate caches per Mailbox, then we don't need them
key should be JUST the canonical name
for maildir that means no path, no flags
	probably ought to drop the ,S=6074,W=6162 fields too

all the keys are paths, IDs or hashes
	add a separate data key with info
_NEO_DATA
	version of _NEO_DATA
	neomutt-version
	mailbox type
	path
	creation date
	CRC for this data
check this data on opening the cache

split dir and key
don't save dir for *dir* cache
eliminate UIDVALIDITY? UIDNEXT?
fold into key?
or into cache name?

#1870
strip each struct
each in separate header file
move cached first
comment marking END
store as memcpy for speed and space?

hcache leak?
	enable compression
	open hcache
	disable compression
	close hcache
see
	mutt_hcache_close()
		if (C_HeaderCacheCompressMethod)
			compr_get_ops()->close(&hc->cctx);
need to save compress ops in `hc`

add hcache warning
	I wonder if neomutt should warn me about this
	"hey you have configured header_cache=foo/ but foo is a file, not a directory"

hcache leaking
	lmdb 4 + 3*Account + 2*Mailbox objects
	maildir 2*Account + 2*Mailbox objects

hcache lazy_malloc/realloc
	who else uses similar scheme, Buffer?
	move to library
	investigate the 129 reallocs in neomutt

# Number of days to retain header/body cache records
set hcache_expiry_time=90
on first timeout, `find ~/.cache -mtime +$hcache_expiry_time -delete`
empty db files of old records too
	this means reading each record and each one having a timestamp
change this to a cli option
	neomutt [options] --tidy-cache=30 (days)
	display results to user
	x headers deleted, y messages deleted

debug tool to dump a header cache file
	need to identify *which* db type
	need to check version of neomutt (HCACHEVER)
	sanity-check the data, then dump it
	see _NEO_DATA above