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/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
*
* http://www.apache.org/licenses/LICENSE-2.0
*
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package ai.platon.pulsar.skeleton.crawl.schedule
import ai.platon.pulsar.skeleton.common.message.MiscMessageWriter
import ai.platon.pulsar.common.config.CapabilityTypes
import ai.platon.pulsar.common.config.ImmutableConfig
import ai.platon.pulsar.common.config.Params
import ai.platon.pulsar.skeleton.common.persist.ext.options
import ai.platon.pulsar.skeleton.common.persist.ext.updateFetchTime
import ai.platon.pulsar.persist.CrawlStatus
import ai.platon.pulsar.persist.WebPage
import ai.platon.pulsar.persist.metadata.CrawlStatusCodes
import ai.platon.pulsar.persist.metadata.Mark
import java.time.Duration
import java.time.Instant
import java.time.temporal.ChronoUnit
/**
* This class provides common methods for implementations of
* [FetchSchedule].
*
* @author Andrzej Bialecki
*/
abstract class AbstractFetchSchedule(
val conf: ImmutableConfig,
val messageWriter: MiscMessageWriter? = null,
) : FetchSchedule {
protected var defaultInterval = conf.getDuration(CapabilityTypes.FETCH_DEFAULT_INTERVAL, Duration.ofDays(30))
protected val impreciseNow = Instant.now()
override val maxFetchInterval: Duration =
conf.getDuration(CapabilityTypes.FETCH_MAX_INTERVAL, ChronoUnit.DECADES.duration)
override fun getParams(): Params {
return Params.of(
"defaultInterval", defaultInterval,
"maxInterval", maxFetchInterval,
"maxFetchInterval", maxFetchInterval,
)
}
/**
* Initialize fetch schedule related data. Implementations should at least set
* the `fetchTime` and `fetchInterval`. The default
* implementation sets the `fetchTime` to now, using the default
* `fetchInterval`.
*
* @param page
*/
override fun initializeSchedule(page: WebPage) {
page.fetchInterval = defaultInterval
page.fetchRetries = 0
page.crawlStatus = CrawlStatus.STATUS_UNFETCHED
}
/**
* Sets the `fetchInterval` and `fetchTime` on a successfully fetched page.
* NOTE: this implementation resets the retry counter -
* extending classes should call super.setFetchSchedule() to preserve this behavior.
* @param m The modification info
*/
override fun setFetchSchedule(page: WebPage, m: ModifyInfo) {
if (page.protocolStatus.isSuccess) {
page.fetchRetries = 0
}
// page.fetchInterval = page.options.fetchInterval
page.fetchInterval = page.options.expires
// note: page.fetchTime might not be the same as the actual fetch time
val now = Instant.now()
page.updateFetchTime(now, now + page.fetchInterval)
page.modifiedTime = m.modifiedTime
page.prevModifiedTime = m.prevModifiedTime
}
/**
* This method adjusts the fetch schedule if fetching needs to be re-tried due
* to transient errors. The default implementation sets the next fetch time 1
* day in the future and increases the retry counter.
*
* @param page WebPage to retry
* @param prevFetchTime previous fetch time
* @param prevModifiedTime previous modified time
* @param fetchTime current fetch time
*/
override fun setPageRetrySchedule(
page: WebPage,
prevFetchTime: Instant,
prevModifiedTime: Instant,
fetchTime: Instant,
) {
page.fetchRetries++
// retry immediately, this is the default behaviour
val now = Instant.now()
page.fetchInterval = Duration.ofSeconds(0)
page.updateFetchTime(now, now)
val crawlStatus = if (page.fetchRetries <= page.maxRetries) CrawlStatusCodes.UNFETCHED else CrawlStatusCodes.GONE
page.setCrawlStatus(crawlStatus.toInt())
}
/**
* This method specifies how to schedule refetching of pages marked as GONE.
* Default implementation increases fetchInterval by 50% but the value may
* never exceed `maxInterval`.
*
* @param page
* @return adjusted page information, including all original information.
* NOTE: this may be a different instance than
*/
override fun setPageGoneSchedule(
page: WebPage, prevFetchTime: Instant, prevModifiedTime: Instant, fetchTime: Instant,
) {
page.fetchInterval = ChronoUnit.DECADES.duration
val now = Instant.now()
page.updateFetchTime(now, now + page.fetchInterval)
}
/**
* This method return the last fetch time of the WebPage
*
* @return the date as a long.
*/
override fun estimatePrevFetchTime(page: WebPage): Instant {
return page.fetchTime - page.fetchInterval
}
/**
* This method provides information whether the page is suitable for selection
* in the current fetchlist. NOTE: a true return value does not guarantee that
* the page will be fetched, it just allows it to be included in the further
* selection process based on scores. The default implementation checks
* `fetchTime`, if it is higher than the
*
* @param page Web page to fetch
* @param now reference time (usually set to the time when the fetchlist
* generation process was started).
* @return true, if the page should be considered for inclusion in the current
* fetchlist, otherwise false.
*/
override fun shouldFetch(page: WebPage, now: Instant): Boolean {
if (page.hasMark(Mark.INACTIVE)) {
return false
}
if (page.options.isExpired(now)) {
return true
}
// Pages are never truly GONE - we have to check them from time to time.
// pages with too long fetchInterval are adjusted so that they fit within
// maximum fetchInterval (batch retention period).
val fetchTime = page.fetchTime
// if (now + maxFetchInterval < fetchTime) {
// if (page.fetchInterval > maxFetchInterval) {
// page.setFetchInterval(maxFetchInterval.seconds * 0.9f)
// }
// page.updateFetchTime(now, now)
// }
return fetchTime < now
}
/**
* This method resets fetchTime, fetchInterval, modifiedTime,
* retriesSinceFetch and page text, so that it forces refetching.
*
* @param page
* @param asap if true, force refetch as soon as possible - this sets the
* fetchTime to now. If false, force refetch whenever the next fetch
* time is set.
*/
override fun forceRefetch(page: WebPage, prevFetchTime: Instant, asap: Boolean) {
if (page.hasMark(Mark.INACTIVE)) {
return
}
// reduce fetchInterval so that it fits within the max value
if (page.fetchInterval > maxFetchInterval) {
page.setFetchInterval(maxFetchInterval.seconds * 0.9f)
}
page.crawlStatus = CrawlStatus.STATUS_UNFETCHED
page.fetchRetries = 0
val fetchInterval = if (asap) Duration.ZERO else page.fetchInterval
val now = Instant.now()
page.updateFetchTime(now, now + fetchInterval)
}
protected fun updateRefetchTime(page: WebPage, fetchInterval: Duration, m: ModifyInfo) {
val now = Instant.now()
page.fetchInterval = fetchInterval
page.updateFetchTime(now, now + page.fetchInterval)
page.prevModifiedTime = m.prevModifiedTime
page.modifiedTime = m.modifiedTime
}
}
