perf: merge module/cache and use ffi to pack cache data

lua/lazy/core/cache.lua

@@ -1,96 +0,0 @@
--- Simple string cache with fast saving and loading from file
-local M = {}
-
-M.dirty = false
-
-local cache_path = vim.fn.stdpath("state") .. "/lazy.state"
----@type string
-local cache_hash = ""
----@type table<string,boolean>
-local used = {}
----@type table<string,string>
-local cache = {}
-
----@return string?
-function M.get(key)
-  if cache[key] then
-    used[key] = true
-    return cache[key]
-  end
-end
-
-function M.debug()
-  local ret = {}
-  for key, value in pairs(cache) do
-    ret[key] = #value
-  end
-  return ret
-end
-
-function M.set(key, value)
-  cache[key] = value
-  used[key] = true
-  M.dirty = true
-end
-
-function M.del(key)
-  cache[key] = nil
-  M.dirty = true
-end
-
-function M.hash(file)
-  local stat = vim.loop.fs_stat(file)
-  return stat and (stat.mtime.sec .. stat.mtime.nsec .. stat.size)
-end
-
-function M.setup()
-  cache = {}
-  local f = io.open(cache_path, "rb")
-  if f then
-    cache_hash = M.hash(cache_path)
-    ---@type string
-    local data = f:read("*a")
-    f:close()
-
-    local from = 1
-    local to = data:find("\0", from, true)
-    while to do
-      local key = data:sub(from, to - 1)
-      from = to + 1
-      to = data:find("\0", from, true)
-      local len = tonumber(data:sub(from, to - 1))
-      from = to + 1
-      cache[key] = data:sub(from, from + len - 1)
-      from = from + len
-      to = data:find("\0", from, true)
-    end
-  end
-end
-
-function M.autosave()
-  vim.api.nvim_create_autocmd("VimLeavePre", {
-    callback = function()
-      if M.dirty then
-        local hash = M.hash(cache_path)
-        -- abort when the file was changed in the meantime
-        if hash == nil or cache_hash == hash then
-          M.save()
-        end
-      end
-    end,
-  })
-end
-
-function M.save()
-  require("lazy.core.module").save()
-
-  local f = assert(io.open(cache_path, "wb"))
-  for key, value in pairs(cache) do
-    if used[key] then
-      f:write(key, "\0", tostring(#value), "\0", value)
-    end
-  end
-  f:close()
-end
-
-return M