feat: logger exporter ConsoleLogRecordExporter and InMemoryLogRecordExporter

lib/src/api/logs/logger_provider.dart

@@ -7,7 +7,7 @@ import 'package:opentelemetry/src/api/logs/logger.dart';
 abstract class LoggerProvider {
   /// Gets or creates a [Logger] instance.
   ///
-  /// The meter is identified by the combination of [name], [version],
+  /// The logger is identified by the combination of [name], [version],
   /// [schemaUrl] and [attributes]. The [name] SHOULD uniquely identify the
   /// instrumentation scope, such as the instrumentation library
   /// (e.g. io.opentelemetry.contrib.mongodb), package, module or class name.

lib/src/experimental_api.dart

@@ -10,13 +10,13 @@ export 'api/context/context_manager.dart' show ContextManager;
 export 'api/context/noop_context_manager.dart' show NoopContextManager;
 export 'api/context/zone_context.dart' show ZoneContext;
 export 'api/context/zone_context_manager.dart' show ZoneContextManager;
-export 'api/metrics/counter.dart' show Counter;
-export 'api/metrics/meter_provider.dart' show MeterProvider;
-export 'api/metrics/meter.dart' show Meter;
-export 'api/metrics/noop/noop_meter.dart' show NoopMeter;
-export 'api/trace/nonrecording_span.dart' show NonRecordingSpan;
-export 'api/logs/logger.dart' show Logger;
 export 'api/logs/log_record.dart' show Severity;
+export 'api/logs/logger.dart' show Logger;
 export 'api/logs/logger_provider.dart' show LoggerProvider;
 export 'api/logs/noop/noop_logger.dart' show NoopLogger;
 export 'api/logs/noop/noop_logger_provider.dart' show NoopLoggerProvider;
+export 'api/metrics/counter.dart' show Counter;
+export 'api/metrics/meter.dart' show Meter;
+export 'api/metrics/meter_provider.dart' show MeterProvider;
+export 'api/metrics/noop/noop_meter.dart' show NoopMeter;
+export 'api/trace/nonrecording_span.dart' show NonRecordingSpan;

lib/src/experimental_sdk.dart

@@ -6,7 +6,18 @@ library experimental_sdk;
 
 import 'package:meta/meta.dart';
 
+export 'sdk/logs/export_result.dart' show ExportResult, ExportResultCode;
+export 'sdk/logs/exporters/console_log_record_exporter.dart' show ConsoleLogRecordExporter;
+export 'sdk/logs/exporters/inmemory_log_record_exporter.dart' show InMemoryLogRecordExporter;
+export 'sdk/logs/exporters/log_record_exporter.dart' show LogRecordExporter;
+export 'sdk/logs/log_record.dart' show ReadableLogRecord, ReadWriteLogRecord, LogRecord;
+export 'sdk/logs/log_record_limit.dart' show LogRecordLimits;
+export 'sdk/logs/logger.dart' show Logger;
+export 'sdk/logs/logger_provider.dart' show LoggerProvider;
+export 'sdk/logs/processors/batch_log_record_processor.dart' show BatchLogRecordProcessor;
+export 'sdk/logs/processors/log_record_processor.dart' show LogRecordProcessor;
+export 'sdk/logs/processors/noop_log_processor.dart' show NoopLogRecordProcessor;
 export 'sdk/metrics/counter.dart' show Counter;
-export 'sdk/metrics/meter_provider.dart' show MeterProvider;
 export 'sdk/metrics/meter.dart' show Meter;
+export 'sdk/metrics/meter_provider.dart' show MeterProvider;
 export 'sdk/resource/resource.dart' show Resource;

lib/src/sdk/common/limits.dart

@@ -4,6 +4,7 @@ import 'package:meta/meta.dart';
 
 import '../../../api.dart' as api;
 import '../../../sdk.dart' as sdk;
+import '../logs/log_record_limit.dart';
 
 /// Applies given [sdk.SpanLimits] to a list of [api.SpanLink]s.
 @protected
@@ -77,6 +78,24 @@ api.Attribute applyAttributeLimits(api.Attribute attr, sdk.SpanLimits limits) {
   return attr;
 }
 
+@protected
+api.Attribute applyAttributeLimitsForLog(api.Attribute attr, LogRecordLimits limits) {
+  // if maxNumAttributeLength is less than zero, then it has unlimited length.
+  if (limits.attributeValueLengthLimit < 0) return attr;
+
+  if (attr.value is String) {
+    attr = api.Attribute.fromString(
+        attr.key, applyAttributeLengthLimit(attr.value as String, limits.attributeValueLengthLimit));
+  } else if (attr.value is List<String>) {
+    final listString = attr.value as List<String>;
+    for (var j = 0; j < listString.length; j++) {
+      listString[j] = applyAttributeLengthLimit(listString[j], limits.attributeValueLengthLimit);
+    }
+    attr = api.Attribute.fromStringList(attr.key, listString);
+  }
+  return attr;
+}
+
 /// Truncate just strings which length is longer than configuration.
 /// Reference: https://github.com/open-telemetry/opentelemetry-java/blob/14ffacd1cdd22f5aa556eeda4a569c7f144eadf2/sdk/common/src/main/java/io/opentelemetry/sdk/internal/AttributeUtil.java#L80
 @protected

lib/src/sdk/logs/export_result.dart

@@ -0,0 +1,15 @@
+// Copyright 2021-2022 Workiva.
+// Licensed under the Apache License, Version 2.0. Please see https://github.com/Workiva/opentelemetry-dart/blob/master/LICENSE for more information
+
+class ExportResult {
+  final ExportResultCode code;
+  final Exception? error;
+  final StackTrace? stackTrace;
+
+  ExportResult({required this.code, this.error, this.stackTrace});
+}
+
+enum ExportResultCode {
+  success,
+  failed,
+}

lib/src/sdk/logs/exporters/console_log_record_exporter.dart

@@ -0,0 +1,64 @@
+// Copyright 2021-2022 Workiva.
+// Licensed under the Apache License, Version 2.0. Please see https://github.com/Workiva/opentelemetry-dart/blob/master/LICENSE for more information
+
+import 'package:opentelemetry/api.dart' as api;
+import 'package:opentelemetry/src/experimental_sdk.dart' as sdk;
+
+/// This is implementation of [sdk.ReadWriteLogRecordExporter] that prints LogRecords to the
+/// console. This class can be used for diagnostic purposes.
+///
+/// NOTE: This [sdk.LogRecordExporter] is intended for diagnostics use only, output rendered to the console may change at any time.
+class ConsoleLogRecordExporter implements sdk.LogRecordExporter {
+  @override
+  Future<sdk.ExportResult> export(List<sdk.ReadableLogRecord> logs) async {
+    return _sendLogRecords(logs);
+  }
+
+  /// Shutdown the exporter.
+  @override
+  Future<void> shutdown() async {}
+
+  /// Showing logs  in console
+  sdk.ExportResult _sendLogRecords(List<sdk.ReadableLogRecord> logs) {
+    for (final log in logs) {
+      print(_makeObject(log));
+    }
+    return sdk.ExportResult(code: sdk.ExportResultCode.success);
+  }
+
+  /// converts logRecord info into more readable format
+  Map<String, dynamic> _makeObject(sdk.ReadableLogRecord log) {
+    final contextInfo = {};
+    if (log.spanContext != null) {
+      contextInfo.addAll({
+        'traceId': log.spanContext!.traceId,
+        'spanId': log.spanContext!.spanId,
+        'traceFlags': log.spanContext!.traceFlags,
+      });
+    }
+    return {
+      'resource': {
+        'attributes': {
+          for (final attribute in log.resource?.attributes.keys ?? <String>[])
+            attribute: log.resource!.attributes.get(attribute),
+        },
+      },
+      'instrumentationScope': {
+        'name': log.instrumentationScope?.name,
+        'version': log.instrumentationScope?.version,
+        'schemaUrl': log.instrumentationScope?.schemaUrl,
+        'attributes': {
+          for (final attribute in log.instrumentationScope?.attributes ?? <api.Attribute>[]) attribute.key: attribute.value,
+        }
+      },
+      'timestamp': log.timeStamp,
+      'severityText': log.severityText,
+      'severityNumber': log.severityNumber,
+      'body': log.body,
+      'attributes': {
+        for (final attribute in log.attributes?.keys ?? <String>[]) attribute: log.resource!.attributes.get(attribute),
+      },
+      ...contextInfo,
+    };
+  }
+}

lib/src/sdk/logs/exporters/inmemory_log_record_exporter.dart

@@ -0,0 +1,43 @@
+// Copyright 2021-2022 Workiva.
+// Licensed under the Apache License, Version 2.0. Please see https://github.com/Workiva/opentelemetry-dart/blob/master/LICENSE for more information
+
+import 'package:meta/meta.dart';
+import 'package:opentelemetry/src/experimental_sdk.dart' as sdk;
+
+/// This class can be used for testing purposes. It stores the exported LogRecords
+/// in a list in memory that can be retrieved using the `getFinishedLogRecords()`
+/// method.
+class InMemoryLogRecordExporter implements sdk.LogRecordExporter {
+  var _finishedLogRecords = <sdk.ReadableLogRecord>[];
+
+  /// Indicates if the exporter has been "shutdown."
+  /// When false, exported log records will not be stored in-memory.
+  @protected
+  bool _stopped = false;
+
+  @override
+  Future<sdk.ExportResult> export(List<sdk.ReadableLogRecord> logs) async {
+    if (_stopped) {
+      return sdk.ExportResult(
+        code: sdk.ExportResultCode.failed,
+        error: Exception('Exporter has been stopped'),
+        stackTrace: StackTrace.current,
+      );
+    }
+    _finishedLogRecords.addAll(logs);
+
+    return sdk.ExportResult(code: sdk.ExportResultCode.success);
+  }
+
+  @override
+  Future<void> shutdown() async {
+    _stopped = true;
+    reset();
+  }
+
+  List<sdk.ReadableLogRecord> get finishedLogRecords => List.unmodifiable(_finishedLogRecords);
+
+  void reset() {
+    _finishedLogRecords = <sdk.ReadableLogRecord>[];
+  }
+}

lib/src/sdk/logs/exporters/log_record_exporter.dart

@@ -0,0 +1,10 @@
+// Copyright 2021-2022 Workiva.
+// Licensed under the Apache License, Version 2.0. Please see https://github.com/Workiva/opentelemetry-dart/blob/master/LICENSE for more information
+
+import 'package:opentelemetry/src/experimental_sdk.dart' as sdk;
+
+abstract class LogRecordExporter {
+  Future<sdk.ExportResult> export(List<sdk.ReadableLogRecord> logs);
+
+  Future<void> shutdown();
+}