fix(model-server): deadlock caused by non-existing lock ordering

model-server/src/main/kotlin/org/modelix/model/server/Main.kt

@@ -58,6 +58,7 @@ import org.modelix.model.server.handlers.ui.RepositoryOverview
 import org.modelix.model.server.store.IgniteStoreClient
 import org.modelix.model.server.store.InMemoryStoreClient
 import org.modelix.model.server.store.IsolatingStore
+import org.modelix.model.server.store.RequiresTransaction
 import org.modelix.model.server.store.forGlobalRepository
 import org.modelix.model.server.store.loadDump
 import org.modelix.model.server.store.writeDump
@@ -149,9 +150,12 @@ object Main {
             }
             var i = 0
             val globalStoreClient = storeClient.forGlobalRepository()
-            while (i < cmdLineArgs.setValues.size) {
-                globalStoreClient.put(cmdLineArgs.setValues[i], cmdLineArgs.setValues[i + 1])
-                i += 2
+            @OptIn(RequiresTransaction::class)
+            globalStoreClient.getTransactionManager().runWrite {
+                while (i < cmdLineArgs.setValues.size) {
+                    globalStoreClient.put(cmdLineArgs.setValues[i], cmdLineArgs.setValues[i + 1])
+                    i += 2
+                }
             }
             val repositoriesManager = RepositoriesManager(storeClient)
             val modelServer = KeyValueLikeModelServer(repositoriesManager)

model-server/src/main/kotlin/org/modelix/model/server/handlers/HealthApiImpl.kt

@@ -7,6 +7,7 @@ import io.ktor.server.application.call
 import io.ktor.server.response.respondText
 import io.ktor.util.pipeline.PipelineContext
 import org.modelix.model.server.handlers.KeyValueLikeModelServer.Companion.PROTECTED_PREFIX
+import org.modelix.model.server.store.RequiresTransaction
 import org.modelix.model.server.store.StoreManager
 
 class HealthApiImpl(
@@ -25,9 +26,12 @@ class HealthApiImpl(
 
     private fun isHealthy(): Boolean {
         val store = stores.getGlobalStoreClient()
-        val value = toLong(store[HEALTH_KEY]) + 1
-        store.put(HEALTH_KEY, java.lang.Long.toString(value))
-        return toLong(store[HEALTH_KEY]) >= value
+        @OptIn(RequiresTransaction::class)
+        return store.getTransactionManager().runWrite {
+            val value = toLong(store[HEALTH_KEY]) + 1
+            store.put(HEALTH_KEY, java.lang.Long.toString(value))
+            toLong(store[HEALTH_KEY]) >= value
+        }
     }
 
     private fun toLong(value: String?): Long {

model-server/src/main/kotlin/org/modelix/model/server/handlers/IRepositoriesManager.kt

@@ -6,6 +6,8 @@
 import org.modelix.model.lazy.IDeserializingKeyValueStore
 import org.modelix.model.lazy.RepositoryId
 import org.modelix.model.server.store.IStoreClient
+import org.modelix.model.server.store.ITransactionManager
+import org.modelix.model.server.store.RequiresTransaction
 import org.modelix.model.server.store.StoreManager
 
 interface IRepositoriesManager {
@@ -18,31 +20,38 @@
      * If the server ID was created previously but is only stored under a legacy database key,
      * it also gets stored under the current and all legacy database keys.
      */
-    suspend fun maybeInitAndGetSeverId(): String
+    @RequiresTransaction
+    fun maybeInitAndGetSeverId(): String
+
+    @RequiresTransaction
     fun getRepositories(): Set<RepositoryId>
-    suspend fun createRepository(repositoryId: RepositoryId, userName: String?, useRoleIds: Boolean = true, legacyGlobalStorage: Boolean = false): CLVersion
-    suspend fun removeRepository(repository: RepositoryId): Boolean
 
-    fun getBranches(repositoryId: RepositoryId): Set<BranchReference>
+    @RequiresTransaction
+    fun createRepository(repositoryId: RepositoryId, userName: String?, useRoleIds: Boolean = true, legacyGlobalStorage: Boolean = false): CLVersion
 
-    suspend fun removeBranches(repository: RepositoryId, branchNames: Set<String>)
+    @RequiresTransaction
+    fun removeRepository(repository: RepositoryId): Boolean
+
+    @RequiresTransaction
+    fun getBranches(repositoryId: RepositoryId): Set<BranchReference>
 
     /**
      * Same as [removeBranches] but blocking.
      * Caller is expected to execute it outside the request thread.
      */
-    fun removeBranchesBlocking(repository: RepositoryId, branchNames: Set<String>)
-    suspend fun getVersion(branch: BranchReference): CLVersion?
-    suspend fun getVersion(repository: RepositoryId, versionHash: String): CLVersion?
-    suspend fun getVersionHash(branch: BranchReference): String?
+    @RequiresTransaction
+    fun removeBranches(repository: RepositoryId, branchNames: Set<String>)
+
+    @RequiresTransaction
+    fun getVersion(branch: BranchReference): CLVersion?
+    fun getVersion(repository: RepositoryId, versionHash: String): CLVersion?
+
+    @RequiresTransaction
+    fun getVersionHash(branch: BranchReference): String?
     suspend fun pollVersionHash(branch: BranchReference, lastKnown: String?): String
-    suspend fun mergeChanges(branch: BranchReference, newVersionHash: String): String
 
-    /**
-     * Same as [mergeChanges] but blocking.
-     * Caller is expected to execute it outside the request thread.
-     */
-    fun mergeChangesBlocking(branch: BranchReference, newVersionHash: String): String
+    @RequiresTransaction
+    fun mergeChanges(branch: BranchReference, newVersionHash: String): String
     suspend fun computeDelta(repository: RepositoryId?, versionHash: String, baseVersionHash: String?): ObjectData
 
     /**
@@ -54,14 +63,16 @@
     fun isIsolated(repository: RepositoryId): Boolean?
 
     fun getStoreManager(): StoreManager
+    fun getTransactionManager(): ITransactionManager
 }
 
+@RequiresTransaction
 fun IRepositoriesManager.getBranchNames(repositoryId: RepositoryId): Set<String> {
     return getBranches(repositoryId).map { it.branchName }.toSet()
 }
 
-fun IRepositoriesManager.getStoreClient(repository: RepositoryId?): IStoreClient {
-    return getStoreManager().getStoreClient(repository?.takeIf { isIsolated(it) ?: false })
+fun IRepositoriesManager.getStoreClient(repository: RepositoryId?, immutable: Boolean): IStoreClient {
+    return getStoreManager().getStoreClient(repository?.takeIf { isIsolated(it) ?: false }, immutable)
 }
 
 fun IRepositoriesManager.getAsyncStore(repository: RepositoryId?): IAsyncObjectStore {

model-server/src/main/kotlin/org/modelix/model/server/handlers/IdsApiImpl.kt

@@ -9,6 +9,8 @@ import io.ktor.server.routing.routing
 import io.ktor.util.pipeline.PipelineContext
 import org.modelix.authorization.getUserName
 import org.modelix.authorization.requiresLogin
+import org.modelix.model.server.store.RequiresTransaction
+import org.modelix.model.server.store.runReadIO
 
 /**
  * Implementation of the REST API that is responsible for handling client and server IDs.
@@ -24,7 +26,11 @@ class IdsApiImpl(
         //
         // Functionally, it does not matter if the server ID is created eagerly or lazily,
         // as long as the same server ID is returned from the same server.
-        val serverId = repositoriesManager.maybeInitAndGetSeverId()
+        val serverId =
+            @OptIn(RequiresTransaction::class)
+            repositoriesManager.getTransactionManager().runReadIO {
+                repositoriesManager.maybeInitAndGetSeverId()
+            }
         call.respondText(serverId)
     }
 

model-server/src/main/kotlin/org/modelix/model/server/handlers/KeyValueLikeModelServer.kt

@@ -13,7 +13,6 @@
 import io.ktor.server.response.respondText
 import io.ktor.server.routing.routing
 import io.ktor.util.pipeline.PipelineContext
-import kotlinx.coroutines.runBlocking
 import kotlinx.html.br
 import kotlinx.html.div
 import kotlinx.html.h1
@@ -29,9 +28,11 @@
 import org.modelix.model.persistent.HashUtil
 import org.modelix.model.server.ModelServerPermissionSchema
 import org.modelix.model.server.store.ObjectInRepository
+import org.modelix.model.server.store.RequiresTransaction
 import org.modelix.model.server.store.StoreManager
 import org.modelix.model.server.store.pollEntry
-import org.modelix.model.server.store.runTransactionSuspendable
+import org.modelix.model.server.store.runReadIO
+import org.modelix.model.server.store.runWriteIO
 import org.modelix.model.server.templates.PageWithMenuBar
 import java.io.IOException
 import java.util.*
@@ -61,7 +62,8 @@
         // request to initialize it lazily, would make the code less robust.
         // Each change in the logic of RepositoriesManager#maybeInitAndGetSeverId would need
         // the special conditions in the affected requests to be updated.
-        runBlocking { repositoriesManager.maybeInitAndGetSeverId() }
+        @OptIn(RequiresTransaction::class)
+        repositoriesManager.getTransactionManager().runWrite { repositoriesManager.maybeInitAndGetSeverId() }
         application.apply {
             modelServerModule()
         }
@@ -89,7 +91,8 @@
                 get<Paths.getKeyGet> {
                     val key = call.parameters["key"]!!
                     checkKeyPermission(key, EPermissionType.READ)
-                    val value = stores.getGlobalKeyValueStore()[key]
+                    @OptIn(RequiresTransaction::class)
+                    val value = runRead { stores.getGlobalStoreClient()[key] }
                     respondValue(key, value)
                 }
                 get<Paths.pollKeyGet> {
@@ -106,21 +109,25 @@
                 post<Paths.counterKeyPost> {
                     val key = call.parameters["key"]!!
                     checkKeyPermission(key, EPermissionType.WRITE)
-                    val value = stores.getGlobalStoreClient().generateId(key)
+                    val value = stores.getGlobalStoreClient(false).generateId(key)
                     call.respondText(text = value.toString())
                 }
 
                 get<Paths.getRecursivelyKeyGet> {
                     val key = call.parameters["key"]!!
                     checkKeyPermission(key, EPermissionType.READ)
-                    call.respondText(collect(key, this).toString(2), contentType = ContentType.Application.Json)
+                    @OptIn(RequiresTransaction::class)
+                    call.respondText(runRead { collect(key, this) }.toString(2), contentType = ContentType.Application.Json)
                 }
 
                 put<Paths.putKeyPut> {
                     val key = call.parameters["key"]!!
                     val value = call.receiveText()
                     try {
-                        putEntries(mapOf(key to value))
+                        @OptIn(RequiresTransaction::class)
+                        runWrite {
+                            putEntries(mapOf(key to value))
+                        }
                         call.respondText("OK")
                     } catch (e: NotFoundException) {
                         throw HttpException(HttpStatusCode.NotFound, title = "Not found", details = e.message, cause = e)
@@ -139,7 +146,10 @@
                     }
                     entries = sortByDependency(entries)
                     try {
-                        putEntries(entries)
+                        @OptIn(RequiresTransaction::class)
+                        runWrite {
+                            putEntries(entries)
+                        }
                         call.respondText(entries.size.toString() + " entries written")
                     } catch (e: NotFoundException) {
                         throw HttpException(HttpStatusCode.NotFound, title = "Not found", details = e.message, cause = e)
@@ -158,7 +168,8 @@
                         checkKeyPermission(key, EPermissionType.READ)
                         keys.add(key)
                     }
-                    val values = stores.getGlobalStoreClient().getAll(keys)
+                    @OptIn(RequiresTransaction::class)
+                    val values = runRead { stores.getGlobalStoreClient(false).getAll(keys) }
                     for (i in keys.indices) {
                         val respEntry = JSONObject()
                         respEntry.put("key", keys[i])
@@ -199,6 +210,7 @@
         return sorted
     }
 
+    @RequiresTransaction
     fun collect(rootKey: String, callContext: CallContext?): JSONArray {
         val result = JSONArray()
         val processed: MutableSet<String> = HashSet()
@@ -210,7 +222,7 @@
             if (callContext != null) {
                 keys.forEach { callContext.checkKeyPermission(it, EPermissionType.READ) }
             }
-            val values = stores.getGlobalStoreClient().getAll(keys)
+            val values = stores.getGlobalStoreClient(false).getAll(keys)
             for (i in keys.indices) {
                 val key = keys[i]
                 val value = values[i]
@@ -240,7 +252,8 @@
         return result
     }
 
-    private suspend fun CallContext.putEntries(newEntries: Map<String, String?>) {
+    @RequiresTransaction
+    private fun CallContext.putEntries(newEntries: Map<String, String?>) {
         val referencedKeys: MutableSet<String> = HashSet()
         for ((key, value) in newEntries) {
             checkKeyPermission(key, EPermissionType.WRITE)
@@ -300,17 +313,15 @@
             // We could try to move the objects later, but since this API is deprecated, it's not worth the effort.
         }
 
-        stores.getGlobalStoreClient().runTransactionSuspendable {
-            stores.genericStore.putAll(hashedObjects.mapKeys { ObjectInRepository.global(it.key) })
-            stores.genericStore.putAll(userDefinedEntries.mapKeys { ObjectInRepository.global(it.key) })
-            for ((branch, value) in branchChanges) {
-                if (value == null) {
-                    checkPermission(ModelServerPermissionSchema.branch(branch).delete)
-                    repositoriesManager.removeBranchesBlocking(branch.repositoryId, setOf(branch.branchName))
-                } else {
-                    checkPermission(ModelServerPermissionSchema.branch(branch).push)
-                    repositoriesManager.mergeChangesBlocking(branch, value)
-                }
+        stores.genericStore.putAll(hashedObjects.mapKeys { ObjectInRepository.global(it.key) })
+        stores.genericStore.putAll(userDefinedEntries.mapKeys { ObjectInRepository.global(it.key) })
+        for ((branch, value) in branchChanges) {
+            if (value == null) {
+                checkPermission(ModelServerPermissionSchema.branch(branch).delete)
+                repositoriesManager.removeBranches(branch.repositoryId, setOf(branch.branchName))
+            } else {
+                checkPermission(ModelServerPermissionSchema.branch(branch).push)
+                repositoriesManager.mergeChanges(branch, value)
             }
         }
     }
@@ -363,4 +374,12 @@
             else -> unknown()
         }
     }
+
+    private suspend fun <R> runRead(body: () -> R): R {
+        return repositoriesManager.getTransactionManager().runReadIO(body)
+    }
+
+    private suspend fun <R> runWrite(body: () -> R): R {
+        return repositoriesManager.getTransactionManager().runWriteIO(body)
+    }
 }