kotlinlang #squarelibraries

I’m using https://github.com/square/seismic to register a shake listener, and it works on a physical device, and also on an emulator via the virtual sensors, but I cannot get the shortcut to shake the emulator to work (cmd+m on mac). Is there any sort of shortcut that I can use with the emulator to trigger seismic?

andev

06/30/2020, 1:47 PM

sqldelight paging extension - DataSource is leaking, it removes itself as a listener on

invalidate()

, but if u simply exit fragment/activity, there is no reason for

invalidate()

to be called and then a leak happen

alec

06/30/2020, 1:54 PM

are you on 1.4.0

alec

06/30/2020, 1:54 PM

i assume yes

alec

06/30/2020, 1:55 PM

it shouldn’t be registering a listener unless an invalidatedCallback is added, and if there is an InvalidatedCallback added, it should also be getting removed when you exit the fragment/activity - is that the case?

andev

06/30/2020, 2:27 PM

yep, on 1.4.0.. invalidatedCallback added, listener registered, but invalidate is not called on fragment/activity destroy

andev

06/30/2020, 2:36 PM

I've read the docs, and didn't find anything that says that DataSource is lifecycle aware

andev

06/30/2020, 2:39 PM

dunno how is room doing it, maybe with weak references or something

alec

06/30/2020, 3:27 PM

Who adds the invalidated callback?

andev

06/30/2020, 3:54 PM

LivePagedListBuilder

andev

06/30/2020, 4:04 PM

Dunno if its even worth fixing it, paging2 is so buggy, should just wait for the v3.. I'll modify the QueryDataSourceFactory so I can manually release the resources from the last dataSource

alec

06/30/2020, 4:40 PM

yea i haven’t looked into paging3 yet but i wonder how it deals with invalidation

harry.singh

07/01/2020, 5:18 PM

Hey all! Are SQLDelight queries executed on a background thread? I'm reading/writing to the database from a suspend function and wondering if it is safe to call the database functions directly in there or do I have to wrap them in

withContext(<http://Dispatchers.IO|Dispatchers.IO>)

before calling them? Room allows to add suspend functions directly in the

Dao

classes and I'm wondering if SQLDelight has a similar mechanism?

myanmarking

07/02/2020, 12:23 PM

Yes, Room generated code has dispatchers context switch so no need to use for example 'Dispatchers.IO'. Retrofit the same i believe. SqlDelight is just sync and blocking, so it needs a thread switch in case of android so it doesnt block

Paul Woitaschek

07/03/2020, 1:23 PM

I'm trying to read bytes from an okio source but I have the feeling I'm doing it wrong:

Copy code

fun deSerialize(buffer: BufferedSource): Sequence<Event> {
        return generateSequence {
            while(true){
                if(buffer.request(4)){
                    break
                }
            }
            val size = buffer.readInt()
            while(true){
                if(buffer.request(size.toLong())){
                    break
                }
            }
            val eventBytes = buffer.readByteArray(size.toLong())
            protoBuf.load(Event.serializer(), eventBytes)
        }
    }

Would that be the correct approach to handle this using okio?

07/03/2020, 1:26 PM

BufferedSource

cannot be used across threads so both loops need to be removed or you need to use synchronization. If you want to transfer data across threads in real-time you should use a

Pipe

07/03/2020, 1:27 PM

And if you do use a

Pipe

, you wouldn't put hot loops on the consumer side, you would just call

readInt()

and it would block until 4 bytes are available.

Paul Woitaschek

07/03/2020, 1:36 PM

I can't find too much documentation on pipes. Shouldn't this print values?

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@Test
    fun pipe() {
        val pipe = Pipe(Long.MAX_VALUE)

        thread {
            val sink = pipe.sink.buffer()
            repeat(10){i ->
                Thread.sleep(1000)
                sink.writeInt(i)
            }
        }

        val source = pipe.source.buffer()
        while (true) {
            println(source.readInt())
        }
    }

Paul Woitaschek

07/03/2020, 1:46 PM

This works but without the buffer functions I'm back to the stone age:

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@Test
fun pipe() {
    val pipe = Pipe(Long.MAX_VALUE)

    thread {
        val sink = pipe.sink
        repeat(10) { i ->
            Thread.sleep(1000)
            val b = Buffer().apply {
                println("write $i")
                writeInt(i)
            }
            sink.write(b, b.size)
        }
    }

    while (true) {
        val sink = Buffer()
        pipe.source.read(sink, 4)
        val int = sink.readInt()
        println("read $int")
    }
}

Paul Woitaschek

07/03/2020, 1:59 PM

Got it, need to add an "emit"

07/03/2020, 2:09 PM

i'm admittedly not really familiar with its API or usage, just its purpose

Nikky

07/04/2020, 11:37 AM

can sqldelight apply migrations easily or do i still need to use flyway for that at runtime ?

alec

07/04/2020, 11:51 AM

You’ll still need to use flyway

Nikky

07/04/2020, 11:52 AM

also when trying to do some postgres stuff in sqldelight the codegen errors weirdly

DELETE or UPDATE expected, got 'UPDATE'

on this line in a create table statement

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"user"        integer               NOT NULL
        CONSTRAINT fk_websessions_user_id
            REFERENCES users
            ON UPDATE RESTRICT ON DELETE RESTRICT,

alec

07/04/2020, 12:51 PM

i think the issue there is

RESTRICT

saket

07/08/2020, 2:08 PM

Linux isn't supported yet. Wanna send a PR?

Siggi Gunnarss

07/08/2020, 3:16 PM

I see, thanks. I'll take a look, but unlikely I'll manage a PR

bod

07/13/2020, 9:15 AM

Hello, World! I'm using SQLDelight for the first time, in a Multiplatform project. In my macosX64 code, using

NativeSqliteDriver

, when my db file doesn't exist, my queries are executed but return nothing. Shouldn't there be an exception instead? If the file does exist I have the same behavior (queries return nothing) - but I suspect the file is not even read. The exact same code in the JVM target using

JdbcSqliteDriver

gives an error when the file is not present / works as expected when it is present. Ideas? Also I was wondering if there's a way to enable some logs? Right now I have no idea of what's going on. Thanks a lot!

alec

07/13/2020, 11:56 AM

There’s a LogSqliteDriver in the runtime you can use