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.Cache
   5 import com.google.common.cache.CacheBuilder
   6 import freenet.keys.FreenetURI
   7 import java.io.ByteArrayInputStream
   8 import java.net.URLDecoder
   9 import java.text.Normalizer
  10 import java.util.concurrent.TimeUnit.MINUTES
  11 import javax.imageio.ImageIO
  12 import javax.inject.Inject
  13
  14 /**
  15  * [ElementLoader] implementation that uses a simple Guava [com.google.common.cache.Cache].
  16  */
  17 class DefaultElementLoader(private val freenetInterface: FreenetInterface, ticker: Ticker) : ElementLoader {
  18
  19         @Inject constructor(freenetInterface: FreenetInterface) : this(freenetInterface, Ticker.systemTicker())
  20
  21         private val loadingLinks: Cache<String, Boolean> = CacheBuilder.newBuilder().build<String, Boolean>()
  22         private val failureCache: Cache<String, Boolean> = CacheBuilder.newBuilder().ticker(ticker).expireAfterWrite(30, MINUTES).build<String, Boolean>()
  23         private val imageCache: Cache<String, LinkedElement> = CacheBuilder.newBuilder().build<String, LinkedElement>()
  24         private val callback = object : FreenetInterface.BackgroundFetchCallback {
  25                 override fun shouldCancel(uri: FreenetURI, mimeType: String, size: Long): Boolean {
  26                         return !mimeType.startsWith("image/") || (size > 2097152)
  27                 }
  28
  29                 override fun loaded(uri: FreenetURI, mimeType: String, data: ByteArray) {
  30                         if (!mimeType.startsWith("image/")) {
  31                                 return
  32                         }
  33                         ByteArrayInputStream(data).use {
  34                                 ImageIO.read(it)
  35                         }?.let {
  36                                 imageCache.get(uri.toString().decode().normalize()) { LinkedElement(uri.toString()) }
  37                         }
  38                         removeLoadingLink(uri)
  39                 }
  40
  41                 override fun failed(uri: FreenetURI) {
  42                         failureCache.put(uri.toString().decode().normalize(), true)
  43                         removeLoadingLink(uri)
  44                 }
  45
  46                 private fun removeLoadingLink(uri: FreenetURI) {
  47                         synchronized(loadingLinks) {
  48                                 loadingLinks.invalidate(uri.toString().decode().normalize())
  49                         }
  50                 }
  51         }
  52
  53         override fun loadElement(link: String): LinkedElement {
  54                 val normalizedLink = link.decode().normalize()
  55                 synchronized(loadingLinks) {
  56                         imageCache.getIfPresent(normalizedLink)?.run {
  57                                 return this
  58                         }
  59                         failureCache.getIfPresent(normalizedLink)?.run {
  60                                 return LinkedElement(link, failed = true)
  61                         }
  62                         if (loadingLinks.getIfPresent(normalizedLink) == null) {
  63                                 loadingLinks.put(normalizedLink, true)
  64                                 freenetInterface.startFetch(FreenetURI(link), callback)
  65                         }
  66                 }
  67                 return LinkedElement(link, loading = true)
  68         }
  69
  70         private fun String.decode() = URLDecoder.decode(this, "UTF-8")!!
  71         private fun String.normalize() = Normalizer.normalize(this, Normalizer.Form.NFC)!!
  72
  73 }