Added caching for document result Layers

server/build.gradle.kts

@@ -41,6 +41,9 @@ dependencies {
 
 	// json
 	implementation("com.beust:klaxon:5.6")
+
+	// cache
+	implementation("com.github.ben-manes.caffeine:caffeine:3.1.8")
 }
 
 tasks.withType<Test> {

server/src/main/kotlin/org/ivdnt/galahad/FileBackedValue.kt

@@ -2,10 +2,15 @@ package org.ivdnt.galahad
 
 import com.fasterxml.jackson.core.type.TypeReference
 import com.fasterxml.jackson.databind.ObjectMapper
+import com.github.benmanes.caffeine.cache.Cache
+import com.github.benmanes.caffeine.cache.Caffeine
+import com.github.benmanes.caffeine.cache.Weigher
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.runBlocking
 import org.apache.logging.log4j.kotlin.Logging
+import org.ivdnt.galahad.data.layer.Layer
 import java.io.File
+import kotlin.io.path.Path
 
 
 val mapper: ObjectMapper by lazy { ObjectMapper() }
@@ -41,6 +46,16 @@ open class FileBackedValue<T>(
     val initValue: T, // required to avoid null
 ) : Logging {
 
+    companion object {
+        /** Special cache for [Layer] objects because of their large size */
+        val cache: Cache<String, Layer> = Caffeine.newBuilder()
+            .recordStats()
+            .maximumWeight(100_000_000) // 100MB
+            // Weigher is used once at put() time
+            .weigher<String, Layer>(Weigher { key, value -> File(key).length().toInt() })
+            .build()
+    }
+
     init {
         file.parentFile.mkdirs()
         //file.createNewFile()//
@@ -52,12 +67,24 @@ open class FileBackedValue<T>(
         get() = file.lastModified()
 
     inline fun <reified S : T>read(): T {
+        // It was not set yet
         if( !file.exists() || file.length() == 0L ) {
-            // It was not set yet
             return initValue
         }
-        val bytes: ByteArray = runBlocking(Dispatchers.IO) { file.inputStream().use { it.readBytes() }}
-        return mapper.readValue(bytes, object : TypeReference<S>() {})
+
+        // For [Layer]s, try getting from cache
+        if (S::class == Layer::class) {
+            cache.getIfPresent(file.absolutePath)?.let { return it as T }
+        }
+
+        // else read from disk
+        val bytes: ByteArray = file.readBytes()
+        val result = mapper.readValue(bytes, object : TypeReference<S>() {})
+        // For [Layer]s, put in cache
+        if (S::class == Layer::class) {
+            cache.put(file.absolutePath, result as Layer)
+        }
+        return result
     }
 
     /**
@@ -68,13 +95,17 @@ open class FileBackedValue<T>(
      * modify<Int> { oldValue++ }
      */
     inline fun <reified S : T>modify( modification: (T) -> T ) {
-        if( !file.exists() ) {
+        if(!file.exists()) {
             file.createNewFile()
         }
         // Would love to do this atomically, but for now we won't
         val oldValue = read<S>()
         val newValue = modification(oldValue)
         val newValBytes = mapper.writeValueAsBytes(newValue)
-        runBlocking(Dispatchers.IO) { file.writeBytes(newValBytes)}
+        runBlocking(Dispatchers.IO) { file.writeBytes(newValBytes) }
+        // For [Layer]s, put in cache
+        if (S::class == Layer::class) {
+            cache.put(file.absolutePath, newValue as Layer)
+        }
     }
 }

server/src/main/kotlin/org/ivdnt/galahad/app/CacheStatsReporter.kt

@@ -0,0 +1,17 @@
+package org.ivdnt.galahad.app
+
+import org.springframework.scheduling.annotation.Scheduled
+import org.apache.logging.log4j.kotlin.Logging
+import org.ivdnt.galahad.FileBackedValue
+import org.ivdnt.galahad.util.toFixed
+import org.springframework.stereotype.Component
+import java.util.concurrent.TimeUnit
+
+@Component
+class CacheStatsReporter : Logging {
+    @Scheduled(fixedDelay = 10, timeUnit = TimeUnit.MINUTES)
+    fun reportStats() {
+        val stats = FileBackedValue.cache.stats()
+        logger.info("Cache hit rate: ${stats.hitRate().toFixed()} [hit: ${stats.hitCount()} miss: ${stats.missCount()} evictions: ${stats.evictionCount()}]")
+    }
+}

server/src/main/kotlin/org/ivdnt/galahad/app/GalahadApplication.kt

@@ -22,6 +22,7 @@ import org.springframework.context.annotation.ComponentScan
 import org.springframework.context.annotation.Configuration
 import org.springframework.http.HttpStatus
 import org.springframework.http.ResponseEntity
+import org.springframework.scheduling.annotation.EnableScheduling
 import org.springframework.web.bind.annotation.CrossOrigin
 import org.springframework.web.bind.annotation.GetMapping
 import org.springframework.web.bind.annotation.RequestMapping
@@ -96,6 +97,7 @@ fun String.runCommand(workingDir: File, timeout: Long = 60): String? {
 
 @Configuration
 @ConfigurationProperties(prefix = "")
+@EnableScheduling
 class Config {
 
     lateinit var workDir: String

server/src/main/kotlin/org/ivdnt/galahad/util/FloatExtensions.kt

@@ -3,3 +3,4 @@ package org.ivdnt.galahad.util
 import java.util.*
 
 fun Float.toFixed(n: Number=3): String = String.format(Locale.ENGLISH, "%.${n}f", this)
+fun Double.toFixed(n: Number=3): String = String.format(Locale.ENGLISH, "%.${n}f", this)