first commit

mpv/scripts/file-browser/modules/cache.lua

@@ -0,0 +1,139 @@
+--------------------------------------------------------------------------------------------------------
+--------------------------------------Cache Implementation----------------------------------------------
+--------------------------------------------------------------------------------------------------------
+--------------------------------------------------------------------------------------------------------
+
+local msg = require 'mp.msg'
+local utils = require 'mp.utils'
+
+local g = require 'modules.globals'
+local fb_utils = require 'modules.utils'
+
+local function get_keys(t)
+    local keys = {}
+    for key in pairs(t) do
+        table.insert(keys, key)
+    end
+    return keys
+end
+
+local cache = {
+    cache = setmetatable({}, {__mode = 'kv'}),
+    traversal_stack = {},
+    history = {},
+    cached_values = {
+        "directory", "directory_label", "list", "selected", "selection", "parser", "empty_text", "co"
+    },
+    dangling_refs = {},
+}
+
+function cache:print_debug_info()
+    local cache_keys = get_keys(self.cache)
+    msg.verbose('Printing cache debug info')
+    msg.verbose('cache size:', #cache_keys)
+    msg.debug(utils.to_string(cache_keys))
+    msg.trace(utils.to_string(self.cache[cache_keys[#cache_keys]]))
+
+    msg.verbose('traversal_stack size:', #self.traversal_stack)
+    msg.debug(utils.to_string(fb_utils.list.map(self.traversal_stack, function(ref) return ref.directory end)))
+
+    msg.verbose('history size:', #self.history)
+    msg.debug(utils.to_string(fb_utils.list.map(self.history, function(ref) return ref.directory end)))
+end
+
+function cache:replace_dangling_refs(directory, ref)
+    for _, v in ipairs(self.traversal_stack) do
+        if v.directory == directory then
+            v.ref = ref
+            self.dangling_refs[directory] = nil
+        end
+    end
+    for _, v in ipairs(self.history) do
+        if v.directory == directory then
+            v.ref = ref
+            self.dangling_refs[directory] = nil
+        end
+    end
+end
+
+function cache:add_current_state()
+    local directory = g.state.directory
+    if directory == nil then return end
+
+    local t = self.cache[directory] or {}
+    for _, value in ipairs(self.cached_values) do
+        t[value] = g.state[value]
+    end
+
+    self.cache[directory] = t
+    if self.dangling_refs[directory] then
+        self:replace_dangling_refs(directory, t)
+    end
+end
+
+-- Creates a reference to the cache of a particular directory to prevent it
+-- from being garbage collected.
+function cache:get_cache_ref(directory)
+   return {
+        directory = directory,
+        ref = self.cache[directory],
+   }
+end
+
+function cache:append_history()
+    self:add_current_state()
+    local history_size = #self.history
+
+    -- We don't want to have the same directory in the history over and over again.
+    if history_size > 0 and self.history[history_size].directory == g.state.directory then return end
+
+    table.insert(self.history, self:get_cache_ref(g.state.directory))
+    if (history_size + 1) > 100 then table.remove(self.history, 1) end
+end
+
+function cache:in_cache(directory)
+    return self.cache[directory] ~= nil
+end
+
+function cache:apply(directory)
+    directory = directory or g.state.directory
+    local t = self.cache[directory]
+    if not t then return false end
+
+    msg.verbose('applying cache for', directory)
+
+    for _, value in ipairs(self.cached_values) do
+        msg.debug('setting', value, 'to', t[value])
+        g.state[value] = t[value]
+    end
+
+    return true
+end
+
+function cache:push()
+    local stack_size = #self.traversal_stack
+    if stack_size > 0 and self.traversal_stack[stack_size].directory == g.state.directory then return end
+    table.insert(self.traversal_stack, self:get_cache_ref(g.state.directory))
+end
+
+function cache:pop()
+    table.remove(self.traversal_stack)
+end
+
+function cache:clear_traversal_stack()
+    self.traversal_stack = {}
+end
+
+function cache:clear()
+    self.cache = setmetatable({}, {__mode = 'kv'})
+    for _, v in ipairs(self.traversal_stack) do
+        v.ref = nil
+        self.dangling_refs[v.directory] = true
+    end
+    for _, v in ipairs(self.history) do
+        v.ref = nil
+        self.dangling_refs[v.directory] = true
+    end
+end
+
+return cache