feat(database): 更改数据库命名方式.

由于 BotToken 可以更换, 所以旧版命名方式将会有迁移的问题, 故更改为通过 Bot AccountId 来命名数据库.

CLOSED #3

scalabot-app/src/main/kotlin/AppMain.kt

@@ -112,7 +112,7 @@ internal class Launcher : AutoCloseable {
         )
 
         val bot = ScalaBot(
-            BotDBMaker.getBotMaker(account),
+            BotDBMaker.getBotDbInstance(account),
             botOption,
             extensionPackageFinders,
             botConfig

scalabot-app/src/main/kotlin/BotDBMaker.kt

@@ -1,23 +1,190 @@
 package net.lamgc.scalabot
 
+import com.google.common.io.Files
+import mu.KotlinLogging
 import net.lamgc.scalabot.util.toHaxString
+import org.mapdb.DB
+import org.mapdb.DBException
 import org.mapdb.DBMaker
 import org.telegram.abilitybots.api.db.DBContext
 import org.telegram.abilitybots.api.db.MapDBContext
+import java.io.File
 import java.nio.charset.StandardCharsets
 import java.security.MessageDigest
 
+/**
+ * 数据库适配器.
+ *
+ * 应按照新到旧的顺序放置, 新的适配器应该在上面.
+ */
+private val adapters = arrayListOf<DbAdapter>(
+    BotAccountIdDbAdapter, // since [v0.2.0 ~ latest)
+    BotTokenDbAdapter // since [v0.0.1 ~ v0.2.0)
+)
+private const val FIELD_DB_VERSION = "::DB_VERSION"
+
 internal object BotDBMaker {
-    fun getBotMaker(botAccount: BotAccount): DBContext {
+    private val logger = KotlinLogging.logger { }
-        val digest: MessageDigest = MessageDigest.getInstance("SHA-256")
+
-        val digestBytes = digest.digest(botAccount.token.toByteArray(StandardCharsets.UTF_8))
+    fun getBotDbInstance(botAccount: BotAccount): DBContext {
-        val dbPath = AppPaths.DATA_DB.path + "${digestBytes.toHaxString()}.db"
+        for (adapter in adapters) {
-        val db = DBMaker.fileDB(dbPath)
+            val botDb = try {
+                adapter.getBotDb(botAccount, create = false) ?: continue
+            } catch (e: Exception) {
+                logger.error(e) { "适配器 ${adapter::class.java} 打开数据库时发生异常." }
+                continue
+            }
+            if (!adapter.dbVersionMatches(botDb)) {
+                logger.warn {
+                    "数据库版本号与适配器不符. " +
+                            "(Adapter: ${adapter::class.java};(${adapter.dbVersion})," +
+                            " DatabaseVer: ${adapter.getDbVersion(botDb)})"
+                }
+                botDb.close()
+                continue
+            } else {
+                if (adapter != adapters[0]) {
+                    logger.debug {
+                        "数据库适配器不是最新的, 正在升级数据库... " +
+                                "(Old: ${adapter::class.java}; New: ${adapters[0]::class.java})"
+                    }
+                    val db = try {
+                        botDb.close()
+                        val newDb = adapters[0].migrateDb(botAccount, adapter)
+                        logger.debug { "数据库版本升级完成." }
+                        newDb
+                    } catch (e: Exception) {
+                        logger.warn(e) { "Bot 数据库版本升级失败, 将继续使用旧版数据库." }
+                        adapter.getBotDb(botAccount, create = false) ?: continue
+                    }
+                    return MapDBContext(db)
+                }
+                return MapDBContext(botDb)
+            }
+        }
+
+        logger.debug { "没有适配器成功打开数据库, 使用最新的适配器创建数据库. (Adapter: ${adapters[0]::class.java})" }
+        val newDb = adapters[0].getBotDb(botAccount, create = true)
+            ?: throw IllegalStateException("No adapter is available to get the database.")
+        adapters[0].setDbVersion(newDb, adapters[0].dbVersion)
+        return MapDBContext(newDb)
+    }
+
+}
+
+/**
+ * 数据库适配器.
+ *
+ * 用于解决数据库格式更新带来的问题, 通过迁移机制, 将数据库从旧版本迁移到新版本, 或者只通过旧版本适配器访问而不迁移.
+ * @param dbVersion 数据库格式版本. 格式为: `{格式标识}_{最后使用的版本号}`, 如果为最新版适配器, 则不需要填写最后使用的版本号.
+ */
+private abstract class DbAdapter(val dbVersion: String) {
+
+    /**
+     * 获取 Bot 专有的 [DBContext].
+     * @param botAccount Bot 账号信息.
+     */
+    abstract fun getBotDb(botAccount: BotAccount, create: Boolean = false): DB?
+
+    /**
+     * 通过 Bot 账号信息获取数据库文件.
+     */
+    abstract fun getBotDbFile(botAccount: BotAccount): File
+
+    /**
+     * 将旧版数据库迁移到当前版本.
+     *
+     * 实现时请注意不要直接修改原数据库, 以防升级过程出错导致无法回退到旧版本.
+     */
+    abstract fun migrateDb(botAccount: BotAccount, oldDbAdapter: DbAdapter): DB
+
+    /**
+     * 数据库版本是否匹配.
+     */
+    open fun dbVersionMatches(db: DB): Boolean {
+        return getDbVersion(db) == dbVersion
+    }
+
+    fun getDbVersion(db: DB): String? {
+        if (!db.exists(FIELD_DB_VERSION)) {
+            return null
+        }
+        val dbVersionField = try {
+            db.atomicString(FIELD_DB_VERSION).open()
+        } catch (e: DBException.WrongConfiguration) {
+            return null
+        }
+        return dbVersionField.get()
+    }
+
+    fun setDbVersion(db: DB, version: String) {
+        db.atomicString(FIELD_DB_VERSION).createOrOpen().set(version)
+    }
+
+}
+
+/**
+ * 抽象文件数据库适配器.
+ *
+ * 只有文件有变化的适配器.
+ */
+private abstract class FileDbAdapter(
+    dbVersion: String,
+    private val fileProvider: (BotAccount) -> File
+) : DbAdapter(dbVersion) {
+
+    @Suppress("unused")
+    constructor(dbVersion: String) : this(dbVersion,
+        { throw NotImplementedError("When using this constructor, the \"getBotDbFile\" method must be implemented") })
+
+    override fun getBotDb(botAccount: BotAccount, create: Boolean): DB? {
+        val dbFile = getBotDbFile(botAccount)
+        if (!dbFile.exists() && !create) {
+            return null
+        }
+        return DBMaker.fileDB(dbFile)
             .closeOnJvmShutdownWeakReference()
             .checksumStoreEnable()
             .fileChannelEnable()
             .make()
-        return MapDBContext(db)
     }
 
+    override fun getBotDbFile(botAccount: BotAccount): File = fileProvider(botAccount)
+
+    override fun migrateDb(botAccount: BotAccount, oldDbAdapter: DbAdapter): DB {
+        val oldFile = oldDbAdapter.getBotDbFile(botAccount)
+        val newFile = getBotDbFile(botAccount)
+        try {
+            @Suppress("UnstableApiUsage")
+            Files.copy(oldFile, newFile)
+        } catch (e: Exception) {
+            if (newFile.exists()) {
+                // 删除新文件以防止异常退出后直接读取新文件.
+                newFile.delete()
             }
+            throw e
+        }
+        oldFile.delete()
+        return getBotDb(botAccount)!!.apply {
+            setDbVersion(this, this@FileDbAdapter.dbVersion)
+        }
+    }
+}
+
+/**
+ * 使用 Bot Token 中的 Account Id 命名数据库文件名.
+ */
+private object BotAccountIdDbAdapter : FileDbAdapter("BotAccountId", { botAccount ->
+    File(AppPaths.DATA_DB.file, "${botAccount.id}.db")
+})
+
+/**
+ * 使用 Bot Token, 经过 Sha256 加密后得到文件名.
+ *
+ * **已弃用**: 由于 Token 可以重新生成, 当 Token 改变后数据库文件名也会改变, 故弃用该方法.
+ */
+private object BotTokenDbAdapter : FileDbAdapter("BotToken_v0.1.0", { botAccount ->
+    val digest: MessageDigest = MessageDigest.getInstance("SHA-256")
+    val digestBytes = digest.digest(botAccount.token.toByteArray(StandardCharsets.UTF_8))
+    File(AppPaths.DATA_DB.file, "${digestBytes.toHaxString()}.db")
+})