Recover-strategy to detect an updated server without a reload

client/src/app/core/core-services/autoupdate.service.ts

@@ -166,6 +166,7 @@ export class AutoupdateService {
      * Does a full update: Requests all data from the server and sets the DS to the fresh data.
      */
     public async doFullUpdate(): Promise<void> {
+        const oldChangeId = this.DS.maxChangeId;
         const response = await this.websocketService.sendAndGetResponse<{}, AutoupdateFormat>('getElements', {});
 
         const updateSlot = await this.DSUpdateManager.getNewUpdateSlot(this.DS);
@@ -180,5 +181,7 @@ export class AutoupdateService {
 
         await this.DS.set(allModels, response.to_change_id);
         this.DSUpdateManager.commit(updateSlot);
+
+        console.log(`Full update done from ${oldChangeId} to ${response.to_change_id}`);
     }
 }

client/src/app/core/core-services/constants.service.ts

@@ -29,11 +29,6 @@ export class ConstantsService {
      */
     private constants: Constants;
 
-    /**
-     * Flag, if the websocket connection is open.
-     */
-    private websocketOpen = false;
-
     /**
      * Flag, if constants are requested, but the server hasn't send them yet.
      */
@@ -54,18 +49,26 @@ export class ConstantsService {
             if (this.pending) {
                 // send constants to subscribers that await constants.
                 this.pending = false;
-                Object.keys(this.pendingSubject).forEach(key => {
+                this.informSubjects();
-                    this.pendingSubject[key].next(this.constants[key]);
-                });
             }
         });
 
         // We can request constants, if the websocket connection opens.
-        websocketService.connectEvent.subscribe(() => {
+        // On retries, the `refresh()` method is called by the OpenSlidesService, so
-            if (!this.websocketOpen && this.pending) {
+        // here we do not need to take care about this.
+        websocketService.noRetryConnectEvent.subscribe(() => {
+            if (this.pending) {
                 this.websocketService.send('constants', {});
             }
-            this.websocketOpen = true;
+        });
+    }
+
+    /**
+     * Inform subjects about changes.
+     */
+    private informSubjects(): void {
+        Object.keys(this.pendingSubject).forEach(key => {
+            this.pendingSubject[key].next(this.constants[key]);
         });
     }
 
@@ -81,7 +84,7 @@ export class ConstantsService {
             if (!this.pending) {
                 this.pending = true;
                 // if the connection is open, we directly can send the request.
-                if (this.websocketOpen) {
+                if (this.websocketService.isConnected) {
                     this.websocketService.send('constants', {});
                 }
             }
@@ -91,4 +94,15 @@ export class ConstantsService {
             return this.pendingSubject[key].asObservable() as Observable<T>;
         }
     }
+
+    /**
+     * Refreshed the constants
+     */
+    public async refresh(): Promise<void> {
+        if (!this.websocketService.isConnected) {
+            return;
+        }
+        this.constants = await this.websocketService.sendAndGetResponse('constants', {});
+        this.informSubjects();
+    }
 }

client/src/app/core/core-services/data-store-upgrade.service.ts

@@ -1,10 +1,12 @@
 import { Injectable } from '@angular/core';
 
+import { take } from 'rxjs/operators';
+
 import { ConstantsService } from './constants.service';
 import { AutoupdateService } from './autoupdate.service';
 import { StorageService } from './storage.service';
 
-const MIGRATIONVERSION = 'MigrationVersion';
+const DB_SCHEMA_VERSION = 'DbSchemaVersion';
 
 /**
  * Manages upgrading the DataStore, if the migration version from the server is higher than the current one.
@@ -19,16 +21,28 @@ export class DataStoreUpgradeService {
      * @param storageService
      */
     public constructor(
-        autoupdateService: AutoupdateService,
+        private autoupdateService: AutoupdateService,
-        constantsService: ConstantsService,
+        private constantsService: ConstantsService,
-        storageService: StorageService
+        private storageService: StorageService
     ) {
-        constantsService.get<number>(MIGRATIONVERSION).subscribe(async version => {
+        this.checkForUpgrade();
-            const currentVersion = await storageService.get<number>(MIGRATIONVERSION);
+    }
-            await storageService.set(MIGRATIONVERSION, version);
+
-            if (currentVersion && currentVersion !== version) {
+    public async checkForUpgrade(): Promise<boolean> {
-                autoupdateService.doFullUpdate();
+        const version = await this.constantsService
-            }
+            .get<string | number>(DB_SCHEMA_VERSION)
-        });
+            .pipe(take(1))
+            .toPromise();
+        console.log('DB schema version:', version);
+        const currentVersion = await this.storageService.get<string>(DB_SCHEMA_VERSION);
+        await this.storageService.set(DB_SCHEMA_VERSION, version);
+        const doUpgrade = version !== currentVersion;
+
+        if (doUpgrade) {
+            console.log(`DB schema version changed from ${currentVersion} to ${version}`);
+            await this.autoupdateService.doFullUpdate();
+        }
+
+        return doUpgrade;
     }
 }

client/src/app/core/core-services/openslides.service.ts

@@ -6,6 +6,8 @@ import { OperatorService } from './operator.service';
 import { StorageService } from './storage.service';
 import { AutoupdateService } from './autoupdate.service';
 import { DataStoreService } from './data-store.service';
+import { ConstantsService } from './constants.service';
+import { DataStoreUpgradeService } from './data-store-upgrade.service';
 
 /**
  * Handles the bootup/showdown of this application.
@@ -44,7 +46,9 @@ export class OpenSlidesService {
         private websocketService: WebsocketService,
         private router: Router,
         private autoupdateService: AutoupdateService,
-        private DS: DataStoreService
+        private DS: DataStoreService,
+        private constantsService: ConstantsService,
+        private dataStoreUpgradeService: DataStoreUpgradeService
     ) {
         // Handler that gets called, if the websocket connection reconnects after a disconnection.
         // There might have changed something on the server, so we check the operator, if he changed.
@@ -170,8 +174,24 @@ export class OpenSlidesService {
                 await this.reboot();
             } else if (requestChanges) {
                 // User is still the same, but check for missed autoupdates.
-                this.autoupdateService.requestChanges();
+                await this.recoverAfterReconnect();
             }
         }
     }
+
+    /**
+     * The cache-refresh strategy, if there was an reconnect and the user didn't changed.
+     */
+    private async recoverAfterReconnect(): Promise<void> {
+        // Reload constants to get either new one (in general) and especially
+        // the "DbSchemaVersion" one, to check, if the DB has changed (e.g. due
+        // to an update)
+        await this.constantsService.refresh();
+
+        // If the DB schema version didn't change, request normal changes.
+        // If so, then a full update is implicit triggered, so we do not need to to anything.
+        if (!(await this.dataStoreUpgradeService.checkForUpgrade())) {
+            this.autoupdateService.requestChanges();
+        }
+    }
 }

client/src/app/core/core-services/ping.service.ts

@@ -55,7 +55,7 @@ export class PingService {
 
         // Connects the ping-pong mechanism to the opening and closing of the connection.
         this.websocketService.closeEvent.subscribe(() => this.stopPing());
-        this.websocketService.connectEvent.subscribe(() => this.startPing());
+        this.websocketService.generalConnectEvent.subscribe(() => this.startPing());
         if (this.websocketService.isConnected) {
             this.startPing();
         }

client/src/app/core/core-services/projector-data.service.ts

@@ -51,7 +51,7 @@ export class ProjectorDataService {
             });
         });
 
-        this.websocketService.connectEvent.subscribe(() => this.updateProjectorDataSubscription());
+        this.websocketService.generalConnectEvent.subscribe(() => this.updateProjectorDataSubscription());
     }
 
     /**

client/src/app/core/core-services/websocket.service.ts

@@ -90,16 +90,29 @@ export class WebsocketService {
         return this._retryReconnectEvent;
     }
 
+    /**
+     * Subjects that will be called, if connect took place, but not a retry reconnect.
+     * THis is the complement from the generalConnectEvent to the retryReconnectEvent.
+     */
+    private readonly _noRetryConnectEvent: EventEmitter<void> = new EventEmitter<void>();
+
+    /**
+     * Getter for the no-retry connect event.
+     */
+    public get noRetryConnectEvent(): EventEmitter<void> {
+        return this._noRetryConnectEvent;
+    }
+
     /**
      * Listeners will be nofitied, if the wesocket connection is establiched.
      */
-    private readonly _connectEvent: EventEmitter<void> = new EventEmitter<void>();
+    private readonly _generalConnectEvent: EventEmitter<void> = new EventEmitter<void>();
 
     /**
      * Getter for the connect event.
      */
-    public get connectEvent(): EventEmitter<void> {
+    public get generalConnectEvent(): EventEmitter<void> {
-        return this._connectEvent;
+        return this._generalConnectEvent;
     }
 
     /**
@@ -234,12 +247,14 @@ export class WebsocketService {
                     return;
                 }
 
+                this._connectionOpen = true;
                 if (retry) {
                     this.dismissConnectionErrorNotice();
                     this._retryReconnectEvent.emit();
+                } else {
+                    this._noRetryConnectEvent.emit();
                 }
-                this._connectionOpen = true;
+                this._generalConnectEvent.emit();
-                this._connectEvent.emit();
                 this.sendQueueWhileNotConnected.forEach(entry => {
                     this.websocket.send(entry);
                 });

openslides/core/apps.py

@@ -1,3 +1,5 @@
+import hashlib
+import logging
 import os
 import sys
 from collections import OrderedDict
@@ -10,6 +12,9 @@ from django.db.models import Max
 from django.db.models.signals import post_migrate, pre_delete
 
 
+logger = logging.getLogger("openslides.core")
+
+
 class CoreAppConfig(AppConfig):
     name = "openslides.core"
     verbose_name = "OpenSlides Core"
@@ -60,9 +65,7 @@ class CoreAppConfig(AppConfig):
         )
 
         post_migrate.connect(
-            call_save_default_values,
+            manage_config, sender=self, dispatch_uid="core_manage_config"
-            sender=self,
-            dispatch_uid="core_save_config_default_values",
         )
         pre_delete.connect(
             autoupdate_for_many_to_many_relations,
@@ -175,17 +178,33 @@ class CoreAppConfig(AppConfig):
         # get max migration id -> the "version" of the DB
         from django.db.migrations.recorder import MigrationRecorder
 
-        constants["MigrationVersion"] = MigrationRecorder.Migration.objects.aggregate(
+        migration_version = MigrationRecorder.Migration.objects.aggregate(Max("id"))[
-            Max("id")
+            "id__max"
-        )["id__max"]
+        ]
+        config_version = config["config_version"]
+        hash = hashlib.sha1(
+            f"{migration_version}#{config_version}".encode()
+        ).hexdigest()
+        constants["DbSchemaVersion"] = hash
+        logger.info(f"DbSchemaVersion={hash}")
 
         return constants
 
 
-def call_save_default_values(**kwargs):
+def manage_config(**kwargs):
+    """
+    Should be run after every migration. Saves default values
+    of all non db-existing config objects into the db. Deletes all
+    unnecessary old config values, e.g. all db entries, that does
+    not have a config_variable anymore. Increments the config version,
+    if at least one of the operations altered some data.
+    """
     from .config import config
 
-    config.save_default_values()
+    altered = config.save_default_values()
+    altered = config.cleanup_old_config_values() or altered
+    if altered:
+        config.increment_version()
 
 
 def startup():
@@ -201,6 +220,6 @@ def startup():
     from openslides.utils.cache import element_cache
     from openslides.core.models import History
 
-    set_constants(get_constants_from_apps())
     element_cache.ensure_cache()
+    set_constants(get_constants_from_apps())
     History.objects.build_history()

openslides/core/config.py

@@ -205,13 +205,14 @@ class ConfigHandler:
 
         self.config_variables.update(item_index)
 
-    def save_default_values(self) -> None:
+    def save_default_values(self) -> bool:
         """
-        Saves the default values to the database.
+        Saves the default values to the database. Does also build the dictonary key_to_id.
 
-        Does also build the dictonary key_to_id.
+        Returns True, if something in the DB was changed.
         """
         self.key_to_id = {}
+        altered_config = False
         for item in self.config_variables.values():
             try:
                 db_value = ConfigStore.objects.get(key=item.name)
@@ -220,7 +221,29 @@ class ConfigHandler:
                 db_value.key = item.name
                 db_value.value = item.default_value
                 db_value.save(skip_autoupdate=True)
+                altered_config = True
             self.key_to_id[db_value.key] = db_value.id
+        return altered_config
+
+    def increment_version(self) -> None:
+        """
+        Increments the config key "config_version"
+        """
+        db_value = ConfigStore.objects.get(key="config_version")
+        db_value.value = db_value.value + 1
+        db_value.save(skip_autoupdate=True)
+
+    def cleanup_old_config_values(self) -> bool:
+        """
+        Deletes all config variable in the database, if the keys are not
+        in key_to_id. This required a fully build key_to_id!
+        Returns True, if something in the DB was changed.
+        """
+        key_to_id = key_to_id = cast(Dict[str, int], self.key_to_id)
+        queryset = ConfigStore.objects.exclude(key__in=key_to_id.keys())
+        altered_config = queryset.exists()
+        queryset.delete()
+        return altered_config
 
     def get_collection_string(self) -> str:
         """

openslides/core/config_variables.py

@@ -401,3 +401,12 @@ def get_config_variables():
         weight=1000,
         group="Custom translations",
     )
+
+    # Config version
+    yield ConfigVariable(
+        name="config_version",
+        input_type="integer",
+        default_value=1,
+        group="Version",
+        hidden=True,
+    )

tests/conftest.py

@@ -55,9 +55,10 @@ def pytest_collection_modifyitems(items):
 
 
 @pytest.fixture(autouse=True)
-def constants(request):
+def constants(request, reset_cache):
     """
-    Resets the constants on every test.
+    Resets the constants on every test. The filled cache is needed to
+    build the constants, because some of them depends on the config.
 
     Uses fake constants, if the db is not in use.
     """