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64 lines
3.3 KiB
Scala
64 lines
3.3 KiB
Scala
package com.twitter.home_mixer.model
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import com.twitter.home_mixer.functional_component.candidate_source.EarlybirdBottomTweetFeature
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import com.twitter.home_mixer.functional_component.candidate_source.EarlybirdResponseTruncatedFeature
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import com.twitter.product_mixer.component_library.model.cursor.UrtOrderedCursor
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import com.twitter.product_mixer.component_library.premarshaller.urt.builder.IncludeInstruction
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import com.twitter.product_mixer.core.model.marshalling.response.urt.TimelineEntry
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import com.twitter.product_mixer.core.model.marshalling.response.urt.TimelineModule
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import com.twitter.product_mixer.core.model.marshalling.response.urt.item.tweet.TweetItem
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import com.twitter.product_mixer.core.model.marshalling.response.urt.operation.GapCursor
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import com.twitter.product_mixer.core.model.marshalling.response.urt.operation.TopCursor
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import com.twitter.product_mixer.core.pipeline.HasPipelineCursor
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import com.twitter.product_mixer.core.pipeline.PipelineQuery
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/**
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* Determine whether to include a Gap Cursor in the response based on whether a timeline
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* is truncated because it has more entries than the max response size.
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* There are two ways this can happen:
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* 1) There are unused entries in Earlybird. This is determined by a flag returned from Earlybird.
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* We respect the Earlybird flag only if there are some entries after deduping and filtering
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* to ensure that we do not get stuck repeatedly serving gaps which lead to no tweets.
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* 2) Ads injection can take the response size over the max count. Goldfinch truncates tweet
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* entries in this case. We can check if the bottom tweet from Earlybird is in the response to
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* determine if all Earlybird tweets have been used.
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*
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* While scrolling down to get older tweets (BottomCursor), responses will generally be
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* truncated, but we don't want to render a gap cursor there, so we need to ensure we only
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* apply the truncation check to newer (TopCursor) or middle (GapCursor) requests.
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*
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* We return either a Gap Cursor or a Bottom Cursor, but not both, so the include instruction
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* for Bottom should be the inverse of Gap.
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*/
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object GapIncludeInstruction
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extends IncludeInstruction[PipelineQuery with HasPipelineCursor[UrtOrderedCursor]] {
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override def apply(
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query: PipelineQuery with HasPipelineCursor[UrtOrderedCursor],
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entries: Seq[TimelineEntry]
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): Boolean = {
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val wasTruncated = query.features.exists(_.getOrElse(EarlybirdResponseTruncatedFeature, false))
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// Get oldest tweet or tweets within oldest conversation module
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val tweetEntries = entries.view.reverse
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.collectFirst {
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case item: TweetItem if item.promotedMetadata.isEmpty => Seq(item.id.toString)
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case module: TimelineModule if module.items.head.item.isInstanceOf[TweetItem] =>
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module.items.map(_.item.id.toString)
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}.toSeq.flatten
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val bottomCursor =
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query.features.flatMap(_.getOrElse(EarlybirdBottomTweetFeature, None)).map(_.toString)
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// Ads truncation happened if we have at least max count entries and bottom tweet is missing
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val adsTruncation = query.requestedMaxResults.exists(_ <= entries.size) &&
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!bottomCursor.exists(tweetEntries.contains)
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query.pipelineCursor.exists(_.cursorType match {
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case Some(TopCursor) | Some(GapCursor) =>
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(wasTruncated && tweetEntries.nonEmpty) || adsTruncation
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case _ => false
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})
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}
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}
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