improved handling of nested transactions

add nested transaction support to protocol
allow deferring validation to parent transaction
process each update request within a nested transaction

4 files changed, 49 insertions, 28 deletions

diff --git a/acf/model/model.lua b/acf/model/model.lua
index 6a9a843..aa27312 100644
--- a/acf/model/model.lua
+++ b/acf/model/model.lua
@@ -79,6 +79,13 @@ function Model:init(txn, path, addr)
       return util.map(function(f) return f.name end, mt.meta.fields)
    end
 
+   function mt.validate()
+      for _, name in ipairs(mt.members()) do
+	 local field = mt.field(name)
+	 if not field.compute then field:validate_saved() end
+      end
+   end
+
    function mt.__index(t, k)
       local f = mt.field(k)
       if f then
@@ -93,14 +100,4 @@ function Model:init(txn, path, addr)
       if not f then raise(mt.path, 'Field named '..k..' does not exist') end
       f:save(v)
    end
-
-   txn.validate[mt.path] = function() self:validate() end
-end
-
-function Model:validate()
-   local mt = getmetatable(self)
-   for _, name in ipairs(mt.members()) do
-      local field = mt.field(name)
-      if not field.compute then field:validate_saved() end
-   end
 end
diff --git a/acf/model/node.lua b/acf/model/node.lua
index 3459fce..f893d6a 100644
--- a/acf/model/node.lua
+++ b/acf/model/node.lua
@@ -48,6 +48,8 @@ function TreeNode:init(txn, path, addr)
    mt.txn = txn
    mt.path = path
    mt.addr = addr
+
+   txn.validable[path] = true
 end
 
 function TreeNode:search(path)
@@ -67,14 +69,6 @@ Collection = class(TreeNode)
 function Collection:init(txn, path, addr, field, required)
    super(self, Collection):init(txn, path, addr)
 
-   if required then
-      txn.validate[path] = function()
-			      if #txn:get(addr) == 0 then
-				 raise(path, 'Collection cannot be empty')
-			      end
-			   end
-   end
-
    self.init = nil
    self.search = nil
 
@@ -84,6 +78,14 @@ function Collection:init(txn, path, addr, field, required)
    mt.meta = {type='collection', members=mt.field:meta('$')}
    function mt.mmeta(name) return mt.meta.members end
    function mt.members() return txn:get(addr) or {} end
+
+   function mt.validate()
+      if required then
+	 if #txn:get(addr) == 0 then
+	    raise(path, 'Collection cannot be empty')
+	 end
+      end
+   end
    
    function mt.__index(t, k) return mt.field:load(k) end
    function mt.__newindex(t, k, v) mt.field:save(k, v) end
@@ -132,3 +134,4 @@ members = meta_func('members')
 meta = meta_func('meta')
 mmeta = meta_func('mmeta')
 path = meta_func('path')
+validate = meta_func('validate')
diff --git a/acf/transaction/init.lua b/acf/transaction/init.lua
index eb92c34..e9b8bbc 100644
--- a/acf/transaction/init.lua
+++ b/acf/transaction/init.lua
@@ -11,7 +11,9 @@ local object = require('acf.object')
 local super = object.super
 local pth = require('acf.path')
 local be_mod = require('acf.transaction.backend')
-local copy = require('acf.util').copy
+
+local util = require('acf.util')
+local copy = util.copy
 
 
 local function remove_list_value(list, value)
@@ -30,7 +32,7 @@ end
 
 local Transaction = object.class(be_mod.TransactionBackend)
 
-function Transaction:init(backend)
+function Transaction:init(backend, validate)
    super(self, Transaction):init()
 
    self.backend = backend
@@ -42,7 +44,8 @@ function Transaction:init(backend)
    self.modified = {}
    self.deleted = {}
 
-   self.validate = {}
+   self.validate = validate
+   self.validable = {}
 
    self.root = RootModel(self)
 end
@@ -122,11 +125,15 @@ function Transaction:search(path) return self.root:search(pth.split(path)) end
 function Transaction:commit()
    self:check()
 
-   local errors = ErrorDict()
-   for path, func in pairs(self.validate) do
-      if not self.deleted[path] then errors:collect(func) end
+   if self.validate then
+      local errors = ErrorDict()
+      for path, _ in pairs(copy(self.validable)) do
+	 if not self.deleted[path] then
+	    errors:collect(getmetatable(self:search(path)).validate)
+	 end
+      end
+      errors:raise()
    end
-   errors:raise()
 
    local mods = {}
    local handled = {}
@@ -174,8 +181,18 @@ function Transaction:commit()
    for path, _ in pairs(self.added) do insert_add(path) end
 
    self.backend:comp_and_setm(self.access_time, mods)
+
+
+   if not self.validate then
+      util.update(self.backend.validable, self.validable)
+   end
+   
    self.backend = nil
 end
 
+
 local store = require('acf.persistence').DataStore()
-function start(txn) return Transaction(txn or store) end
+
+function start(txn, defer_validation)
+   return Transaction(txn or store, not (txn and defer_validation))
+end
diff --git a/acf/util.lua b/acf/util.lua
index 9788c81..9ca287c 100644
--- a/acf/util.lua
+++ b/acf/util.lua
@@ -10,11 +10,15 @@ function setdefault(t, k, v)
    return t[k]
 end
 
-function setdefaults(dst, src)
-   for k, v in pairs(src) do if dst[k] == nil then dst[k] = v end end
+function update(dst, src, preserve)
+   for k, v in pairs(src) do
+      if not preserve or dst[k] == nil then dst[k] = v end
+   end
    return dst
 end
 
+function setdefaults(dst, src) return update(dst, src, true) end
+
 function copy(var)
    return type(var) == 'table' and setdefaults({}, var) or var
 end