[Paging3] loading of data not fully triggered when using small pages. [169259468]

Fixed

Bug

Status Update

No update yet.

Description

jd...@xooloo.com

created issue #1

Sep 24, 2020 08:59AM

Component used: Paging3 Version used: alpha06 Devices/Android versions reproduced on: Android 7.1

I'm presenting a list of items using data from a room DB.

    fun getMessages(chat: Chat): Pager<Int, Message> {
        return Pager(
                PagingConfig(pageSize = 3, enablePlaceholders = true)
        ) {
            db.messages.getMessages(chat.id)
        }
    }

Note: The page size is intentionally low to try to debug paging issues, but is higher in production code.

The pager flow is used to produce PagingData passed to a PagingAdapter.

chats.getMessages(chat).flow.map {
  it.map { message -> getEntryForMessages(chatWithUsers, message) }
}.collect {
  adapter.submitList(it)
}

The RecyclerView uses a simple LinearLayoutManager.

Everything work mostly fine except that that latest entry may never be loaded while scrolling (especially when scrolling slowly). The PagingData properly provides a placeholder that is shown in the list, but it never trigger the loading of the last data, and so never replace the placeholder when reaching the end of the list.

Comments

du...@google.com <du...@google.com> #2Sep 24, 2020 01:16PM

Project: platform/frameworks/support
Branch: androidx-master-dev

commit 6f59e3d74d0da5a4bf79c8480f56964e3af47f1c
Author: Wojtek Kaliciński <wkal@google.com>
Date: Mon Jul 23 20:17:19 2018

Support more types for args

Provides support for Serializable, enums,
as well as arrays of primitive types and Parcelables
in Navigation arguments.

Only enums support default values other than @null,
in the form of the enum literal (without class name),
e.g. app:defaultValue="READ"

Test: unit tests updated
BUG: 111487504
BUG: 111316353
Change-Id: I7e5abbc8ed0950bfdef292342dbe1fb34a5c4b17

M navigation/runtime/src/androidTest/java/androidx/navigation/NavInflaterTest.kt
A navigation/runtime/src/androidTest/java/androidx/navigation/test/TestEnum.java
M navigation/runtime/src/androidTest/res/navigation/nav_default_arguments.xml
M navigation/runtime/src/main/java/androidx/navigation/NavInflater.java
M navigation/safe-args-generator/src/main/kotlin/androidx/navigation/safe/args/generator/NavParser.kt
M navigation/safe-args-generator/src/main/kotlin/androidx/navigation/safe/args/generator/NavParserErrors.kt
M navigation/safe-args-generator/src/main/kotlin/androidx/navigation/safe/args/generator/NavWriter.kt
M navigation/safe-args-generator/src/main/kotlin/androidx/navigation/safe/args/generator/Types.kt
M navigation/safe-args-generator/src/tests/kotlin/androidx/navigation/safe/args/generator/NavParserTest.kt
M navigation/safe-args-generator/src/tests/kotlin/androidx/navigation/safe/args/generator/NavWriterTest.kt
M navigation/safe-args-generator/src/tests/test-data/expected/nav_writer_test/MainFragmentArgs.java
M navigation/safe-args-generator/src/tests/test-data/expected/nav_writer_test/Next.java
M navigation/safe-args-generator/src/tests/test-data/naive_test.xml

https://android-review.googlesource.com/720246

https://goto.google.com/android-sha1/6f59e3d74d0da5a4bf79c8480f56964e3af47f1c

jd...@xooloo.com <jd...@xooloo.com> #3Sep 28, 2020 10:17AM

This is fixed internally and will be available in 1.0.0-alpha08

Screenshot_20200928-120938.png

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du...@google.com <du...@google.com> #4Sep 28, 2020 10:04PM

Accepted by du...@google.com.

Thanks!

ap...@google.com <ap...@google.com> #5Oct 1, 2020 07:51PM

Marked as fixed.

Project: platform/frameworks/support
Branch: androidx-master-dev

commit 190a76ec743552627310e024976fd5896e989acb
Author: Dustin Lam <dustinlam@google.com>
Date: Mon Sep 28 13:54:08 2020

Prioritize hints from more recent presenter state

Currently we only use itemsPresentedAfter, which only accounts for the
placeholderOffset from the last page, but this value is insufficient to
determine which hint loads more items in cases where the last/first
pageOffset changes on presenter side.

As a result, we'll drop hints that would load more items in favor of
hints that came from a past presenter state that was scroll further into
placeholders.

This change fixes the above by always prioritizing new incoming hints if
the first/last pageOffset of presenter state changes.

RelNote: "N/A"
Fixes: 169259468
Test: ./gradlew paging:paging-common:test
Change-Id: Iffda3a0eb7abe162045893367b4781daf75adb01

M paging/common/api/current.txt
M paging/common/api/public_plus_experimental_current.txt
M paging/common/api/restricted_current.txt
M paging/common/src/main/kotlin/androidx/paging/PageFetcherSnapshot.kt
M paging/common/src/test/kotlin/androidx/paging/PageFetcherSnapshotTest.kt

https://android-review.googlesource.com/1441095

Issue 169259468

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Issue summary

Comments

du...@google.com <du...@google.com> #2Sep 24, 2020 01:16PM

jd...@xooloo.com <jd...@xooloo.com> #3Sep 28, 2020 10:17AM

du...@google.com <du...@google.com> #4Sep 28, 2020 10:04PM

ap...@google.com <ap...@google.com> #5Oct 1, 2020 07:51PM

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