Fetching on a background thread #224

New Issue

2025-12-29T18:24:33+01:00

adam commented

2025-12-29 18:24:33 +01:00

Originally created by @Guferos on GitHub (Jul 31, 2018).

It might sound trivial but I cannot find a good way to do it. I need to pass a Core Data object to a background thread where I will be only performing read operations with that object.

\\ Main thread
let myCDObject = .....

\\ My background queue
actionsQueue.sync {
    // fetch myCDObject here and perform read operations safely
}

The only way I found to do it is:

\\ Main thread
let myCDObject = .....

\\ My background queue
actionsQueue.sync {
            CoreStore.perform(asynchronous: { (transaction) in
                guard let myCDObject = transaction.fetchExisting(myCDObject) else {
                    return
                }
                ...
                \\ my code where I only perform read operations on the myCDObject
                ...
            }, completion: {_ in})
  }

However it feels wrong as my code will be performed on the CoreStore queue instead of mine.
Is there a way to create a transaction inside the actionsQueue and fetch the myCDObject without wrapping it into perform asynchronous block?

Originally created by @Guferos on GitHub (Jul 31, 2018). It might sound trivial but I cannot find a good way to do it. I need to pass a Core Data object to a background thread where I will be only performing read operations with that object. ``` \\ Main thread let myCDObject = ..... \\ My background queue actionsQueue.sync { // fetch myCDObject here and perform read operations safely } ``` The only way I found to do it is: ``` \\ Main thread let myCDObject = ..... \\ My background queue actionsQueue.sync { CoreStore.perform(asynchronous: { (transaction) in guard let myCDObject = transaction.fetchExisting(myCDObject) else { return } ... \\ my code where I only perform read operations on the myCDObject ... }, completion: {_ in}) } ``` However it feels wrong as my code will be performed on the CoreStore queue instead of mine. Is there a way to create a transaction inside the actionsQueue and fetch the myCDObject without wrapping it into perform asynchronous block?

adam closed this issue

2025-12-29 18:24:33 +01:00

adam commented

2025-12-29 18:24:34 +01:00

@JohnEstropia commented on GitHub (Jul 31, 2018):

You can use CoreStore.perform(synchronous:) if your queueing mechanism isn't that complex, but you may encounter deadlocks otherwise. If you are sure to be just reading from the object, you can use CoreStore.beginUnsafe() to create a transaction that acts as a background, read-only, temporary transaction. From that you can just fetch your object within your queue.

@JohnEstropia commented on GitHub (Jul 31, 2018): You can use `CoreStore.perform(synchronous:)` if your queueing mechanism isn't that complex, but you may encounter deadlocks otherwise. If you are sure to be just reading from the object, you can use `CoreStore.beginUnsafe()` to create a transaction that acts as a background, read-only, temporary transaction. From that you can just fetch your object within your queue.

Sign in to join this conversation.

Branches Tags

develop

prototype/swift6

master

prototype/concurrency

minIOS13

prototype/containers

transactionSourceTracking

prototype/swiftui

minIOS11

swift5_3

prototype/propertyWrapperFields

prototype/propertyWrappers

prototype/propertyWrapper

Swift5

throwables

prototype/Swift_4_1

prototype/Swift_4_0

prototype/Swift_3_2

prototype/queryBuilders

temp/develop

corestore4_develop

prototype/mainContextToPSC

master_ios_7_to_9

swift_2_3

gh-pages

_corespotlight-test

1 Participants

Notifications

Due Date

No due date set.

Dependencies

No dependencies set.

Reference: starred/CoreStore-JohnEstropia#224