Fix blocking in several KV store implementations

dependency-versions.gradle

@@ -29,7 +29,10 @@ dependencyManagement {
       entry 'kotlin-stdlib'
       entry 'kotlin-stdlib-jdk8'
     }
-    dependency('org.jetbrains.kotlinx:kotlinx-coroutines-core:0.24.0')
+    dependencySet(group: 'org.jetbrains.kotlinx', version: '0.24.0') {
+      entry 'kotlinx-coroutines-core'
+      entry 'kotlinx-coroutines-jdk8'
+    }
     dependencySet(group: 'org.jetbrains.spek', version: '1.1.5') {
       entry 'spek-api'
       entry 'spek-junit-platform-engine'

kv/build.gradle

@@ -3,6 +3,7 @@ description = 'Key value store implementations.'
 dependencies {
   compile project(':bytes')
   compile 'org.jetbrains.kotlinx:kotlinx-coroutines-core'
+  compile 'org.jetbrains.kotlinx:kotlinx-coroutines-jdk8'
   compileOnly project(':concurrent')
   compileOnly 'io.lettuce:lettuce-core'
   compileOnly 'org.fusesource.leveldbjni:leveldbjni-all'

kv/src/main/kotlin/net/consensys/cava/kv/LevelDBKeyValueStore.kt

@@ -12,7 +12,7 @@
  */
 package net.consensys.cava.kv
 
-import kotlinx.coroutines.experimental.Unconfined
+import kotlinx.coroutines.experimental.newFixedThreadPoolContext
 import kotlinx.coroutines.experimental.withContext
 import net.consensys.cava.bytes.Bytes
 import org.fusesource.leveldbjni.JniDBFactory
@@ -21,6 +21,7 @@ import org.iq80.leveldb.Options
 import java.io.IOException
 import java.nio.file.Files
 import java.nio.file.Path
+import kotlin.coroutines.experimental.CoroutineContext
 
 /**
  * A key-value store backed by LevelDB.
@@ -30,7 +31,9 @@ class LevelDBKeyValueStore
 @JvmOverloads
 constructor(
   databasePath: Path,
-  options: Options = Options().createIfMissing(true).cacheSize((100 * 1048576).toLong())
+  options: Options = Options().createIfMissing(true).cacheSize((100 * 1048576).toLong()),
+  // TODO: replace with IO context when https://github.com/Kotlin/kotlinx.coroutines/issues/79 is resolved
+  private val context: CoroutineContext = newFixedThreadPoolContext(4, "LevelDBKeyValueStore")
 ) : KeyValueStore {
 
   private val db: DB
@@ -40,7 +43,7 @@ constructor(
     db = JniDBFactory.factory.open(databasePath.toFile(), options)
   }
 
-  override suspend fun get(key: Bytes): Bytes? = withContext(Unconfined) {
+  override suspend fun get(key: Bytes): Bytes? = withContext(context) {
     val rawValue = db[key.toArrayUnsafe()]
     if (rawValue == null) {
       null
@@ -49,7 +52,7 @@ constructor(
     }
   }
 
-  override suspend fun put(key: Bytes, value: Bytes) = withContext(Unconfined) {
+  override suspend fun put(key: Bytes, value: Bytes) = withContext(context) {
     db.put(key.toArrayUnsafe(), value.toArrayUnsafe())
   }
 

kv/src/main/kotlin/net/consensys/cava/kv/MapDBKeyValueStore.kt

@@ -12,6 +12,8 @@
  */
 package net.consensys.cava.kv
 
+import kotlinx.coroutines.experimental.newFixedThreadPoolContext
+import kotlinx.coroutines.experimental.withContext
 import net.consensys.cava.bytes.Bytes
 import org.mapdb.DB
 import org.mapdb.DBMaker
@@ -21,14 +23,17 @@ import org.mapdb.HTreeMap
 import java.io.IOException
 import java.nio.file.Files
 import java.nio.file.Path
+import kotlin.coroutines.experimental.CoroutineContext
 
 /**
  * A key-value store backed by a MapDB instance.
  */
 class MapDBKeyValueStore
 @Throws(IOException::class)
 constructor(
-  databasePath: Path
+  databasePath: Path,
+  // TODO: replace with IO context when https://github.com/Kotlin/kotlinx.coroutines/issues/79 is resolved
+  private val context: CoroutineContext = newFixedThreadPoolContext(4, "MapDBKeyValueStore")
 ) : KeyValueStore {
 
   private val db: DB
@@ -40,11 +45,11 @@ constructor(
     storageData = db.hashMap("storageData", BytesSerializer(), BytesSerializer()).createOrOpen()
   }
 
-  override suspend fun get(key: Bytes): Bytes? {
-    return storageData[key]
+  override suspend fun get(key: Bytes): Bytes? = withContext(context) {
+    storageData[key]
   }
 
-  override suspend fun put(key: Bytes, value: Bytes) {
+  override suspend fun put(key: Bytes, value: Bytes) = withContext(context) {
     storageData[key] = value
     db.commit()
   }

kv/src/main/kotlin/net/consensys/cava/kv/RedisKeyValueStore.kt

@@ -17,9 +17,11 @@ import io.lettuce.core.RedisURI
 import io.lettuce.core.api.StatefulRedisConnection
 import io.lettuce.core.api.async.RedisAsyncCommands
 import io.lettuce.core.codec.RedisCodec
+import kotlinx.coroutines.experimental.future.await
 import net.consensys.cava.bytes.Bytes
 import java.net.InetAddress
 import java.nio.ByteBuffer
+import java.util.concurrent.CompletionStage
 
 class RedisKeyValueStore(uri: String)
   : KeyValueStore {
@@ -39,12 +41,11 @@ class RedisKeyValueStore(uri: String)
     asyncCommands = conn.async()
   }
 
-  override suspend fun get(key: Bytes): Bytes? {
-    return asyncCommands.get(key).get()
-  }
+  override suspend fun get(key: Bytes): Bytes? = asyncCommands.get(key).await()
 
   override suspend fun put(key: Bytes, value: Bytes) {
-    asyncCommands.set(key, value).get()
+    val future: CompletionStage<String> = asyncCommands.set(key, value)
+    future.await()
   }
 
   override fun close() {