Software / code / prosody
Changeset
13137:b417a49cc31b
util.datamanager: Halve size of list index
Instead of storing (start, length) tuples, store the offset to the end
of items and derive length using the previous entry.
| author | Kim Alvefur <zash@zash.se> |
|---|---|
| date | Fri, 14 May 2021 05:49:35 +0200 |
| parents | 13136:396db0e7084f |
| children | 13140:7a6874f9fd40 |
| files | util/datamanager.lua |
| diffstat | 1 files changed, 15 insertions(+), 11 deletions(-) [+] |
line wrap: on
line diff
--- a/util/datamanager.lua Wed May 12 01:32:03 2021 +0200 +++ b/util/datamanager.lua Fri May 14 05:49:35 2021 +0200 @@ -260,9 +260,9 @@ local index_fmt, index_item_size, index_magic; if string.packsize then - index_fmt = "TT"; -- struct { size_t start, size_t length } + index_fmt = "T"; -- offset to the end of the item, length can be derived from two index items index_item_size = string.packsize(index_fmt); - index_magic = string.pack(index_fmt, 7767639, 1); -- Magic string: T9 for "prosody", version number + index_magic = string.pack(index_fmt, 7767639 + 1); -- Magic string: T9 for "prosody", version number end local function list_append(username, host, datastore, data) @@ -279,7 +279,7 @@ end if string.packsize then local offset = type(msg) == "number" and msg or 0; - local index_entry = string.pack(index_fmt, offset, #data); + local index_entry = string.pack(index_fmt, offset + #data); if offset == 0 then index_entry = index_magic .. index_entry; end @@ -358,7 +358,7 @@ local function store_list_index(username, host, datastore, index) local data = { index_magic }; for i, v in ipairs(index) do - data[i + 1] = string.pack(index_fmt, v.start, v.length); + data[i + 1] = string.pack(index_fmt, v.start + v.length); end local filename = getpath(username, host, datastore, "lidx"); return atomic_store(filename, t_concat(data)); @@ -366,22 +366,26 @@ local index_mt = { __index = function(t, i) - if type(i) ~= "number" or i % 1 ~= 0 or i < 1 then + if type(i) ~= "number" or i % 1 ~= 0 or i < 0 then return end - if i < 0 then - return + if i <= 0 then + return 0 end local fh = t.file; - local pos = i * index_item_size; + local pos = (i - 1) * index_item_size; if fh:seek("set", pos) ~= pos then return nil end - local data = fh:read(index_item_size); - if not data then + local data = fh:read(index_item_size * 2); + if not data or #data ~= index_item_size * 2 then return nil end - local start, length = string.unpack(index_fmt, data); + local start, next_pos = string.unpack(index_fmt .. index_fmt, data); + if pos == 0 then + start = 0 + end + local length = next_pos - start; local v = { start = start; length = length }; t[i] = v; return v;
