[英]How to achieve concurrency with Kotlin coroutines?
我有輪播列表,並在每個輪播上運行,並且基於輪播query
我做fetchAssets()和fetchAssets()是Kotlin暫停的函數,但是問題是在上一個函數完成后會調用每個函數,我想實現並發性嗎?
uiScope.launch {
carousels.mapIndexed { index, carousel ->
when (val assetsResult = assetRepository.fetchAssets(carousel.query)) {
is Response.Success<List<Asset>> -> {
if (assetsResult.data.isNotEmpty()) {
val contentRow = ContentRow(assetsResult.data)
contentRows.add(contentRow)
contentRowsmutableData.postValue(contentRows)
}
}
is Response.Failure -> {
}
}
}
}
override suspend fun fetchAssets(query: String): Response<List<Asset>> {
return suspendCoroutine { cont ->doHttp(assetsEndpoint, JsonHttpCall("GET"),
object : JsonReaderResponseHandler() {
override fun onSuccess(jsonReader: JsonReader) {
val apiAsset = ApiAssetList(jsonReader)
cont.resume(Response.Success(apiAsset.items))
}
override fun onError(error: Error) {
cont.resume(Response.Failure("errorMessage"))
}
})
}
}```
您必須將您的suspend函數包裝在async
塊中,然后等待所有異步操作完成:
uiScope.launch {
val asyncList = carousels.map { carousel ->
async { assetRepository.fetchAssets(carousel.query) }
}
val results = asyncList.awaitAll()
results.forEach { result ->
when (result) {
is Response.Success -> TODO()
is Response.Failure -> TODO()
}
}
}
suspend fun fetchAssets(query: String): Response<List<Asset>>
編輯:如果要在每個完成時更新UI,則需要像這樣更改它:
carousels.forEach { carousel ->
uiScope.launch {
val result = fetchAssets(carousel.query)
when (result) {
is Response.Success -> {
if (result.data.isNotEmpty()) {
val contentRow = ContentRow(result.data)
contentRows.add(contentRow)
contentRowsmutableData.postValue(contentRows)
}
}
is Response.Failure -> TODO()
}
}
}
檢查此與協程的並發性。
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