src/main/kotlin/net/pterodactylus/sone/core/DefaultElementLoader.kt

   1 package net.pterodactylus.sone.core
   2
   3 import com.google.common.base.Ticker
   4 import com.google.common.cache.CacheBuilder
   5 import freenet.keys.FreenetURI
   6 import java.io.ByteArrayInputStream
   7 import java.util.concurrent.TimeUnit.MINUTES
   8 import javax.imageio.ImageIO
   9 import javax.inject.Inject
  10
  11 /**
  12  * [ElementLoader] implementation that uses a simple Guava [com.google.common.cache.Cache].
  13  */
  14 class DefaultElementLoader @Inject constructor(private val freenetInterface: FreenetInterface, ticker: Ticker = Ticker.systemTicker()) : ElementLoader {
  15
  16         private val loadingLinks = CacheBuilder.newBuilder().build<String, Boolean>()
  17         private val failureCache = CacheBuilder.newBuilder().ticker(ticker).expireAfterWrite(30, MINUTES).build<String, Boolean>()
  18         private val imageCache = CacheBuilder.newBuilder().build<String, LinkedElement>()
  19         private val callback = object : FreenetInterface.BackgroundFetchCallback {
  20                 override fun cancelForMimeType(uri: FreenetURI, mimeType: String): Boolean {
  21                         return !mimeType.startsWith("image/")
  22                 }
  23
  24                 override fun loaded(uri: FreenetURI, mimeType: String, data: ByteArray) {
  25                         if (!mimeType.startsWith("image/")) {
  26                                 return
  27                         }
  28                         ByteArrayInputStream(data).use {
  29                                 ImageIO.read(it)
  30                         }?.let {
  31                                 imageCache.get(uri.toString()) { LinkedElement(uri.toString()) }
  32                         }
  33                         removeLoadingLink(uri)
  34                 }
  35
  36                 override fun failed(uri: FreenetURI) {
  37                         failureCache.put(uri.toString(), true)
  38                         removeLoadingLink(uri)
  39                 }
  40
  41                 private fun removeLoadingLink(uri: FreenetURI) {
  42                         synchronized(loadingLinks) {
  43                                 loadingLinks.invalidate(uri.toString())
  44                         }
  45                 }
  46         }
  47
  48         override fun loadElement(link: String): LinkedElement {
  49                 synchronized(loadingLinks) {
  50                         imageCache.getIfPresent(link)?.run {
  51                                 return this
  52                         }
  53                         failureCache.getIfPresent(link)?.run {
  54                                 return LinkedElement(link, failed = true)
  55                         }
  56                         if (loadingLinks.getIfPresent(link) == null) {
  57                                 loadingLinks.put(link, true)
  58                                 freenetInterface.startFetch(FreenetURI(link), callback)
  59                         }
  60                 }
  61                 return LinkedElement(link, loading = true)
  62         }
  63
  64 }