From 89a46b4a0d507181c697f8da43d74dbf7271b32f Mon Sep 17 00:00:00 2001
From: Kaarle Ritvanen <kaarle.ritvanen@datakunkku.fi>
Date: Thu, 12 Feb 2015 13:47:48 +0200
Subject: persistence: introduce generic cache

---
 aconf/persistence/init.lua | 66 +++++++++++++++++++++++++++-------------------
 1 file changed, 39 insertions(+), 27 deletions(-)

diff --git a/aconf/persistence/init.lua b/aconf/persistence/init.lua
index 8056c16..632c191 100644
--- a/aconf/persistence/init.lua
+++ b/aconf/persistence/init.lua
@@ -10,6 +10,7 @@ local address = require('aconf.path.address')
 
 local util = require('aconf.util')
 local contains = util.contains
+local copy = util.copy
 local setdefault = util.setdefault
 
 local stringy = require('stringy')
@@ -26,8 +27,11 @@ function DataStore:init()
       loadmods('persistence/backends')
    )
    self.triggers = {pre={}, post={}}
+   self:flush_cache()
 end
 
+function DataStore:flush_cache() self.cache = {} end
+
 function DataStore:trigger(phase, path, func)
    local funcs = setdefault(self.triggers[phase], path, {})
    if not contains(funcs, func) then table.insert(funcs, func) end
@@ -42,48 +46,56 @@ function DataStore:split_path(path)
 end
 
 function DataStore:get(path)
-   local backend, comps = self:split_path(path)
-   local top = topology(path)
+   if not self.cache[path] then
+
+      local backend, comps = self:split_path(path)
+      local top = topology(path)
 
-   local value, ts = backend:get(comps, top)
+      local value, ts = backend:get(comps, top)
 
-   if top then
-      local t = top.type
-      if t and value ~= nil then
-	 local atype = type(value)
+      if top then
+	 local t = top.type
+	 if t and value ~= nil then
+	    local atype = type(value)
 
-	 if t == 'table' then assert(atype == 'table')
+	    if t == 'table' then assert(atype == 'table')
 
-	 else
-	    assert(atype ~= 'table')
+	    else
+	       assert(atype ~= 'table')
 
-	    if t == 'string' then value = tostring(value)
-	    elseif t == 'number' then value = tonumber(value)
+	       if t == 'string' then value = tostring(value)
+	       elseif t == 'number' then value = tonumber(value)
 
-	    elseif t == 'boolean' then
-	       if atype == 'string' then value = value:lower() end
-	       if value == 1 or contains(
-		  {'1', 't', 'true', 'y', 'yes'}, value
-               ) then
-		  value = true
-	       elseif value == 0 or contains(
-		  {'0', 'f', 'false', 'n', 'no'}, value
-	       ) then
-		  value = false
-	       else value = value and true or false end
+	       elseif t == 'boolean' then
+		  if atype == 'string' then value = value:lower() end
+		  if value == 1 or contains(
+		     {'1', 't', 'true', 'y', 'yes'}, value
+                  ) then
+		     value = true
+		  elseif value == 0 or contains(
+		     {'0', 'f', 'false', 'n', 'no'}, value
+	          ) then
+		     value = false
+		  else value = value and true or false end
 
-	    elseif contains({'binary', 'reference'}, t) then
-	       assert(atype == 'string')
+	       elseif contains({'binary', 'reference'}, t) then
+		  assert(atype == 'string')
 
-	    else assert(false) end
+	       else assert(false) end
+	    end
 	 end
       end
+
+      self.cache[path] = {copy(value), ts or self.mod_time[path] or 0}
    end
 
-   return util.copy(value), ts or self.mod_time[path] or 0
+   local value, ts = table.unpack(self.cache[path])
+   return copy(value), ts
 end
 
 function DataStore:_set_multiple(mods)
+   self:flush_cache()
+
    local bms = {}
    local trigger = {}
    
-- 
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