[jacodb-storage] Add ability to fine-tune Xodus K/V storage using its own EnvironmentConfig (#317)

As an example of the feature use, added a test which opens a read-only storage
listening to changes made by another R/W storage.

Author: Saloed

jacodb-storage/src/main/kotlin/org/jacodb/impl/JcErsSettings.kt

@@ -16,8 +16,10 @@
 
 package org.jacodb.impl
 
+import jetbrains.exodus.env.EnvironmentConfig
 import org.jacodb.api.storage.ers.ErsSettings
 import org.jacodb.impl.storage.kv.lmdb.LMDB_KEY_VALUE_STORAGE_SPI
+import org.jacodb.impl.storage.kv.xodus.XODUS_KEY_VALUE_STORAGE_SPI
 
 class RamErsSettings(
     val immutableDumpsPath: String? = null
@@ -31,3 +33,6 @@ open class JcKvErsSettings(val kvId: String) : ErsSettings
 // by default, mapSize is 1Gb
 class JcLmdbErsSettings(val mapSize: Long = 0x40_00_00_00) : JcKvErsSettings(LMDB_KEY_VALUE_STORAGE_SPI)
 
+class JcXodusErsSettings(val configurer: (EnvironmentConfig.() -> Unit)? = null) :
+    JcKvErsSettings(XODUS_KEY_VALUE_STORAGE_SPI)
+

jacodb-storage/src/main/kotlin/org/jacodb/impl/storage/kv/xodus/XodusKeyValueStorage.kt

@@ -17,6 +17,7 @@
 package org.jacodb.impl.storage.kv.xodus
 
 import jetbrains.exodus.env.Environment
+import jetbrains.exodus.env.EnvironmentConfig
 import jetbrains.exodus.env.Environments
 import jetbrains.exodus.env.Store
 import jetbrains.exodus.env.StoreConfig.WITHOUT_DUPLICATES_WITH_PREFIXING
@@ -25,14 +26,20 @@ import jetbrains.exodus.env.TransactionBase
 import org.jacodb.api.storage.kv.PluggableKeyValueStorage
 import org.jacodb.api.storage.kv.Transaction
 
-internal class XodusKeyValueStorage(location: String) : PluggableKeyValueStorage() {
+internal class XodusKeyValueStorage(location: String, configurer: (EnvironmentConfig.() -> Unit)?) :
+    PluggableKeyValueStorage() {
 
-    private val env: Environment = Environments.newInstance(location,
+    private val env: Environment = Environments.newInstance(
+        location,
         environmentConfig {
             logFileSize = 32768
             logCachePageSize = 65536 * 4
             gcStartIn = 600_000
             useVersion1Format = false // use v2 data format, as we use stores with prefixing, i.e., patricia trees
+
+            // If a configurer is set, apply it after default settings ^^^ are defined.
+            // This allows overriding them as well.
+            configurer?.let { it() }
         }
     )
 

jacodb-storage/src/main/kotlin/org/jacodb/impl/storage/kv/xodus/XodusKeyValueStorageSPI.kt

@@ -19,6 +19,7 @@ package org.jacodb.impl.storage.kv.xodus
 import org.jacodb.api.storage.ers.ErsSettings
 import org.jacodb.api.storage.kv.PluggableKeyValueStorage
 import org.jacodb.api.storage.kv.PluggableKeyValueStorageSPI
+import org.jacodb.impl.JcXodusErsSettings
 import kotlin.io.path.createTempDirectory
 
 const val XODUS_KEY_VALUE_STORAGE_SPI = "org.jacodb.impl.storage.kv.xodus.XodusKeyValueStorageSPI"
@@ -27,6 +28,11 @@ class XodusKeyValueStorageSPI : PluggableKeyValueStorageSPI {
 
     override val id = XODUS_KEY_VALUE_STORAGE_SPI
 
-    override fun newStorage(location: String?, settings: ErsSettings): PluggableKeyValueStorage =
-        XodusKeyValueStorage(location ?: createTempDirectory(prefix = "xodusKeyValueStorage").toString())
+    override fun newStorage(location: String?, settings: ErsSettings): PluggableKeyValueStorage {
+        val configurer = (settings as? JcXodusErsSettings)?.configurer
+        return XodusKeyValueStorage(
+            location ?: createTempDirectory(prefix = "xodusKeyValueStorage").toString(),
+            configurer
+        )
+    }
 }

jacodb-storage/src/test/kotlin/org/jacodb/testing/storage/kv/XodusKeyValueStorageTest.kt

@@ -16,9 +16,36 @@
 
 package org.jacodb.testing.storage.kv
 
+import jetbrains.exodus.io.DataReaderWriterProvider
+import org.jacodb.impl.JcXodusErsSettings
 import org.jacodb.impl.storage.kv.xodus.XODUS_KEY_VALUE_STORAGE_SPI
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertNotNull
+import org.junit.jupiter.api.Assertions.assertNull
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Test
+import java.lang.Long.getLong
 
 class XodusKeyValueStorageTest : PluggableKeyValueStorageTest() {
 
     override val kvStorageId = XODUS_KEY_VALUE_STORAGE_SPI
+
+    @Test
+    fun `test shared usage of the same db`() {
+        val settings = JcXodusErsSettings {
+            logDataReaderWriterProvider = DataReaderWriterProvider.WATCHING_READER_WRITER_PROVIDER
+        }
+        val roStorage = kvStorageSpi.newStorage(location = location, settings = settings)
+        roStorage.transactional { txn ->
+            assertTrue(txn.isReadonly)
+            assertNull(txn.get("a map", "key".asByteArray))
+        }
+        putGet()
+        Thread.sleep(getLong("jetbrains.exodus.io.watching.forceCheckEach", 3000L) + 500)
+        roStorage.transactional { txn ->
+            val got = txn.get("a map", "key".asByteArray)
+            assertNotNull(got)
+            assertEquals("value", got?.asString)
+        }
+    }
 }

jacodb-storage/src/testFixtures/kotlin/org/jacodb/testing/storage/kv/PluggableKeyValueStorageTest.kt

@@ -28,14 +28,16 @@ import org.junit.jupiter.api.Assertions.assertNull
 import org.junit.jupiter.api.Assertions.assertTrue
 import org.junit.jupiter.api.BeforeEach
 import org.junit.jupiter.api.Test
+import kotlin.io.path.createTempDirectory
 
 abstract class PluggableKeyValueStorageTest {
 
     abstract val kvStorageId: String
 
-    private val kvStorageSpi by lazy(LazyThreadSafetyMode.NONE) {
+    protected val kvStorageSpi by lazy(LazyThreadSafetyMode.NONE) {
         PluggableKeyValueStorageSPI.getProvider(kvStorageId)
     }
+    protected lateinit var location: String
     protected lateinit var storage: PluggableKeyValueStorage
 
     @Test
@@ -145,7 +147,8 @@ abstract class PluggableKeyValueStorageTest {
 
     @BeforeEach
     fun setUp() {
-        storage = kvStorageSpi.newStorage(null).apply {
+        location = createTempDirectory(prefix = "pluggableKeyValueStorage").toString()
+        storage = kvStorageSpi.newStorage(location = location).apply {
             isMapWithKeyDuplicates = { mapName -> mapName.endsWith("withDuplicates") }
         }
     }