Remove mutex from default sqlite

Switched sqlite to use WAL journaling for concurrent read and writes Added automatic query retry for rare cases of concurrent writes (rollback at the same time as heavy inserts)
QuiltServerTools · May 27, 2024 · 0d6abc8 · 0d6abc8
1 parent abc1627
commit 0d6abc8
Show file tree

Hide file tree

Showing 2 changed files with 18 additions and 13 deletions.
diff --git a/docs/parameters.md b/docs/parameters.md
@@ -83,7 +83,7 @@ An easy way to remember the difference between `before:1d` and `after:1d` is to
 If you go back in time 1 day, do you want everything that happened `before` then or `after` then.
 Usually you want `after`.
 
-### Rollback Status
+## Rollback Status
 Key - `rolledback:`  
 Value - `true` or `false`  
 Negative Allowed - `No`  

diff --git a/src/main/kotlin/com/github/quiltservertools/ledger/database/DatabaseManager.kt b/src/main/kotlin/com/github/quiltservertools/ledger/database/DatabaseManager.kt
@@ -14,12 +14,7 @@ import com.github.quiltservertools.ledger.registry.ActionRegistry
 import com.github.quiltservertools.ledger.utility.Negatable
 import com.github.quiltservertools.ledger.utility.PlayerResult
 import com.mojang.authlib.GameProfile
-import java.time.Instant
-import java.time.temporal.ChronoUnit
-import java.util.*
-import javax.sql.DataSource
 import kotlinx.coroutines.delay
-import kotlinx.coroutines.sync.Mutex
 import net.minecraft.util.Identifier
 import net.minecraft.util.WorldSavePath
 import net.minecraft.util.math.BlockPos
@@ -30,7 +25,6 @@ import org.jetbrains.exposed.sql.Op
 import org.jetbrains.exposed.sql.Query
 import org.jetbrains.exposed.sql.SchemaUtils
 import org.jetbrains.exposed.sql.SortOrder
-import org.jetbrains.exposed.sql.SqlExpressionBuilder.eq
 import org.jetbrains.exposed.sql.SqlExpressionBuilder.inSubQuery
 import org.jetbrains.exposed.sql.SqlExpressionBuilder.lessEq
 import org.jetbrains.exposed.sql.SqlLogger
@@ -53,10 +47,19 @@ import org.jetbrains.exposed.sql.statements.expandArgs
 import org.jetbrains.exposed.sql.transactions.experimental.newSuspendedTransaction
 import org.jetbrains.exposed.sql.transactions.transaction
 import org.jetbrains.exposed.sql.update
+import org.sqlite.SQLiteConfig
 import org.sqlite.SQLiteDataSource
+import java.time.Instant
+import java.time.temporal.ChronoUnit
+import java.util.*
+import javax.sql.DataSource
 import kotlin.io.path.pathString
 import kotlin.math.ceil
 
+const val MAX_QUERY_RETRIES = 10
+const val MIN_RETRY_DELAY = 1000L
+const val MAX_RETRY_DELAY = 300_000L
+
 object DatabaseManager {
 
     // These values are initialised late to allow the database to be created at server start,
@@ -66,8 +69,6 @@ object DatabaseManager {
         get() = database.dialect.name
 
     private val cache = DatabaseCacheService
-    private val dbMutex = Mutex()
-    private var enforceMutex = false
 
     fun setup(dataSource: DataSource?) {
         val source = dataSource ?: getDefaultDatasource()
@@ -76,8 +77,9 @@ object DatabaseManager {
 
     private fun getDefaultDatasource(): DataSource {
         val dbFilepath = Ledger.server.getSavePath(WorldSavePath.ROOT).resolve("ledger.sqlite").pathString
-        enforceMutex = true
-        return SQLiteDataSource().apply {
+        return SQLiteDataSource(SQLiteConfig().apply {
+            setJournalMode(SQLiteConfig.JournalMode.WAL)
+        }).apply {
             url = "jdbc:sqlite:$dbFilepath"
         }
     }
@@ -354,12 +356,15 @@ object DatabaseManager {
         }
 
     private suspend fun <T : Any?> execute(body: suspend Transaction.() -> T): T {
-        if (enforceMutex) dbMutex.lock()
         while (Ledger.server.overworld?.savingDisabled != false) {
             delay(timeMillis = 1000)
         }
 
         return newSuspendedTransaction(db = database) {
+            repetitionAttempts = MAX_QUERY_RETRIES
+            minRepetitionDelay = MIN_RETRY_DELAY
+            maxRepetitionDelay = MAX_RETRY_DELAY
+
             if (Ledger.config[DatabaseSpec.logSQL]) {
                 addLogger(object : SqlLogger {
                     override fun log(context: StatementContext, transaction: Transaction) {
@@ -368,7 +373,7 @@ object DatabaseManager {
                 })
             }
             body(this)
-        }.also { if (enforceMutex) dbMutex.unlock() }
+        }
     }
 
     suspend fun purgeActions(params: ActionSearchParams) {