fix: propagate log-config changes

If Theia is started with the "--log-config" option the 'LogLevelCliContribution' watches
for file changes and fires a 'logConfigChangedEvent'. This event was not listened to.
Therefore already existing 'ILogger' levels were not updated. This is now fixed by
notifying loggers about log config changes to update their log level.

Also refactors the backend architecture to also use the existing client mechanism for
notifications.

Signed-off-by: Stefan Dirix <sdirix@eclipsesource.com>

Contributed on behalf of STMicroelectronics

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 ## v1.42.0
 
+- [core] fixed logger level propagation when log config file changes at runtime [#12566](https://github.com/eclipse-theia/theia/pull/12566) - Contributed on behalf of STMicroelectronics
 - [vsx-registry] added a hint to extension fetching ENOTFOUND errors [#12858](https://github.com/eclipse-theia/theia/pull/12858) - Contributed by STMicroelectronics
 
 ## v1.41.0 - 08/31/2023

packages/core/src/common/logger-protocol.ts

@@ -38,6 +38,7 @@ export interface ILogLevelChangedEvent {
 
 export interface ILoggerClient {
     onLogLevelChanged(event: ILogLevelChangedEvent): void;
+    onLogConfigChanged(): void;
 }
 
 @injectable()
@@ -49,6 +50,9 @@ export class DispatchingLoggerClient implements ILoggerClient {
         this.clients.forEach(client => client.onLogLevelChanged(event));
     }
 
+    onLogConfigChanged(): void {
+        this.clients.forEach(client => client.onLogConfigChanged());
+    }
 }
 
 export const rootLoggerName = 'root';

packages/core/src/common/logger-watcher.ts

@@ -22,11 +22,15 @@ import { ILoggerClient, ILogLevelChangedEvent } from './logger-protocol';
 export class LoggerWatcher {
 
     getLoggerClient(): ILoggerClient {
-        const emitter = this.onLogLevelChangedEmitter;
+        const logLevelEmitter = this.onLogLevelChangedEmitter;
+        const logConfigEmitter = this.onLogConfigChangedEmitter;
         return {
             onLogLevelChanged(event: ILogLevelChangedEvent): void {
-                emitter.fire(event);
-            }
+                logLevelEmitter.fire(event);
+            },
+            onLogConfigChanged(): void {
+                logConfigEmitter.fire();
+            },
         };
     }
 
@@ -36,8 +40,9 @@ export class LoggerWatcher {
         return this.onLogLevelChangedEmitter.event;
     }
 
-    // FIXME: get rid of it, backend services should as well set a client on the server
-    fireLogLevelChanged(event: ILogLevelChangedEvent): void {
-        this.onLogLevelChangedEmitter.fire(event);
+    private onLogConfigChangedEmitter = new Emitter<void>();
+
+    get onLogConfigChanged(): Event<void> {
+        return this.onLogConfigChangedEmitter.event;
     }
 }

packages/core/src/common/logger.ts

@@ -261,6 +261,11 @@ export class Logger implements ILogger {
                 }
             });
         });
+
+        /* Refetch log level if overall config in backend changed. */
+        this.loggerWatcher.onLogConfigChanged(() => {
+            this._logLevel = this.created.then(_ => this.server.getLogLevel(this.name));
+        });
     }
 
     setLogLevel(logLevel: number): Promise<void> {

packages/core/src/node/console-logger-server.ts

@@ -17,7 +17,7 @@
 import { inject, injectable, postConstruct } from 'inversify';
 import { LoggerWatcher } from '../common/logger-watcher';
 import { LogLevelCliContribution } from './logger-cli-contribution';
-import { ILoggerServer, ILoggerClient, ConsoleLogger } from '../common/logger-protocol';
+import { ILoggerServer, ILoggerClient, ConsoleLogger, rootLoggerName } from '../common/logger-protocol';
 
 @injectable()
 export class ConsoleLoggerServer implements ILoggerServer {
@@ -32,9 +32,13 @@ export class ConsoleLoggerServer implements ILoggerServer {
 
     @postConstruct()
     protected init(): void {
+        this.setLogLevel(rootLoggerName, this.cli.defaultLogLevel);
         for (const name of Object.keys(this.cli.logLevels)) {
             this.setLogLevel(name, this.cli.logLevels[name]);
         }
+        this.cli.onLogConfigChanged(() => {
+            this.client?.onLogConfigChanged();
+        });
     }
 
     async setLogLevel(name: string, newLogLevel: number): Promise<void> {
@@ -45,7 +49,6 @@ export class ConsoleLoggerServer implements ILoggerServer {
         if (this.client !== undefined) {
             this.client.onLogLevelChanged(event);
         }
-        this.watcher.fireLogLevelChanged(event);
     }
 
     async getLogLevel(name: string): Promise<number> {

packages/core/src/node/logger-backend-module.ts

@@ -63,7 +63,14 @@ export const loggerBackendModule = new ContainerModule(bind => {
     bind(DispatchingLoggerClient).toSelf().inSingletonScope();
     bindLogger(bind, {
         onLoggerServerActivation: ({ container }, server) => {
-            server.setClient(container.get(DispatchingLoggerClient));
+            const dispatchingLoggerClient = container.get(DispatchingLoggerClient);
+            server.setClient(dispatchingLoggerClient);
+
+            // register backend logger watcher as a client
+            const loggerWatcher = container.get(LoggerWatcher);
+            dispatchingLoggerClient.clients.add(loggerWatcher.getLoggerClient());
+
+            // make sure dispatching logger client is the only client
             server.setClient = () => {
                 throw new Error('use DispatchingLoggerClient');
             };