CODEWITHSUNDEEP
smalltalkpharoseaside
Jayalakshmi Lade
Jayalakshmi Lade

Reputation: 23

Seaside: CannotDeleteFileException: Could not delete the old version of fuel file

In pharo seaside application on home button click all the data will get saved in a fuel file with some class name as Test.fl. If I call the same home page at a time in two instances, both are calling this below code to save Test.fl file with latest updates,

FLSerializer
    serialize: self allObjects
    toFileNamed: self name , '.fl'**

and getting exception:

CannotDeleteFileException: Could not delete the old version of file ...\Pharo3.0\Test.fl

And I have used Mutex to allow another instance to get executed after the first instance,

mutexBlock := Mutex new.
mutexBlock critical: [
    FLSerializer
        serialize: self allObjects
        toFileNamed: self name , '.fl' ]

But still i am getting the same error

CannotDeleteFileException: Could not delete the old version of file

Please anybody help me on this to fix the error.

Upvotes: 2

Views: 121

Answers (2)

Stephan Eggermont
Stephan Eggermont

Reputation: 15907

You do not need a mutex there. Seaside in Pharo processes requests one at a time. That is, this only works if your file writing is fast, as all other connections wait for the write to finish. If it is not, you'll need to do the writing in a separate thread and then indeed control access to it

Upvotes: 0

Max Leske
Max Leske

Reputation: 5125

Your intuition is probably correct: two processes are trying to write (delete) the same file at the same time. Your Mutex approach will not work however because you create a new Mutex every time you execute that code. You have to store the Mutex in a class or instance variable (depending on how your code works) such that every process will use the same instance of the Mutex.

Your code would then look something like this:

MyClass class>>serializeProtect
    ^ SerializeProtect ifNil: [ SerializeProtect := Mutex new ]

self class serializeProtect critical: [
    FLSerializer
        serialize: self allObjects
        toFileNamed: self name , '.fl' ]

Note: it is generally not safe to initialise a Mutex lazily. I'm simply doing it here for simplicities sake.

Upvotes: 5

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