TCache 0.5 → 0.5.1

raw patch · 2 files changed

+102/−4 lines, 2 filesPVP ok

version bump matches the API change (PVP)

API changes (from Hackage documentation)

Files

• Sample.hs +98/−0
• TCache.cabal +4/−4

@@ -0,0 +1,98 @@+ module Main where+-------------------------------------------------+-- A example of Transactional cache usage (TCache.hs)+-- (Something like the Java Hibernate)+-- Author: Alberto Gómez Corona Nov 2006+-- Language: Haskell+-- Terms of use: you can do whatever you want+-- with this code as long as you keep this notice+------------------------------------------------++import Data.TCache++import Control.Concurrent+import Debug.Trace++debug a b= trace b a++--1 and 4: The data elements to be used in the example: A user will repeatedly buy Items.++data  Data=   User{uname::String, uid::String, spent:: Int} |+              Item{iname::String, iid::String, price::Int, stock::Int}+ +              deriving (Read, Show)++--3 The mappings between the cache and the phisical storage are defined by the interface IResource++--      to extract the resource unique key,++--      to read the resource from the physical storage,++--      to store it and++--      to delete the resource from the physical storage.++ ++instance IResource Data where+        keyResource         User{uid=id}= id+        keyResource         Item{iid=id}= id        +        serialize x= show x+        deserialize x= read x+        defPath _ = "data/"  -- directory where the data is stored.+        +        -- other definable methods: readResource, writeResource delResource. here the default persistence in files are used+        +-- buy is the operation to be performed in the example++--4 withResources gets a partial definition of each resource necessary for extracting the key, fill all the rest of the data structures (if found ) and return a list of Maybe Data. BuyIt is part of the domain problem. it receive this list and generates a new list of dat objects that are updated in the cache. buyIt is executed atomically.+++user `buy` item=+    withResources[user,item] buyIt++ where++    buyIt[Just us,Just it]+       | stock it > 0= [us',it'] `debug` "john buy a PC"+       | otherwise   = error "stock is empty for this product"+       +      where+       us'= us{spent=spent us + price it}+       it'= it{stock= stock it-1}+++    buyIt _ = error "either the user or the item does not exist"+++main= do+        -- create resources (acces no resources and return two new Data objects defined in items)+        withResources[]items++        --11 PCs are charged  to the John´s account in paralel, to show transactionality+        --because there are only 10 PCs in stock, the last thread must return an error++        for 11 $ forkIO $ User{uid="U12345"} `buy` Item{iid="I54321"}+        +        --wait 5 seconds        +        threadDelay 5000000++        [us,it] <-  getResources [User{uid="U12345"}, Item{iid="I54321"}]+        +        print $  "user data=" ++ show us+        print $  "item data=" ++ show it+        +        -- write the cache content in a persistent store (invoque writeResource for each resource)+        -- in a real application clearSyncCache can be used instead to adjust size and write the cache periodically++        syncCache (refcache :: Cache Data)++        -- the files have been created. the files U12345 and I54321 must contain the result of the 11 iterations++  where+        items _=+              [User "John" "U12345" 0+              ,Item "PC" "I54321" 6000 10]+              +        for 0 _ = return ()      +        for n f= f >> for (n-1) f

@@ -1,14 +1,14 @@ name:                TCache-version:             0.5-synopsis:            A Transactional cache with configurable persitence +version:             0.5.1+synopsis:            A Transactional data cache with configurable persitence  description:         -------------------------------------------------
 -- A Transactional data cache with configurable persitence -- The exported methods are documented in the TCache.hs header--- See also  http://haskellandweb.blogspot.com
+-- See also  http://haskell-web.blogspot.com
 -- (Something like a little Java Hybernate or Rails for Rubi)
 -- Author: Alberto Gómez Corona Nov 2006-2008   agocorona at gmail.com
 -- Language: Haskell
--- Version: 0.5
+-- Version: 0.5.1
 -- Terms of use: you can do whatever you want
 -- with this code as long as you keep this notice