feat: logger exporter ConsoleLogRecordExporter and InMemoryLogRecordExporter

lib/src/api/logs/logger.dart

@@ -2,12 +2,11 @@
 // Licensed under the Apache License, Version 2.0. Please see https://github.com/Workiva/opentelemetry-dart/blob/master/LICENSE for more information
 
 import '../../../api.dart' as api;
-import '../../../sdk.dart' as sdk;
 import 'log_record.dart';
 
 abstract class Logger {
   void emit({
-    sdk.Attributes? attributes,
+    List<api.Attribute> attributes = const <api.Attribute>[],
     api.Context? context,
     dynamic body,
     DateTime? observedTimestamp,

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/api/logs/noop/noop_logger.dart

@@ -1,17 +1,17 @@
 // 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/api/common/attribute.dart';
 import 'package:opentelemetry/src/api/context/context.dart';
 import 'package:opentelemetry/src/api/logs/log_record.dart';
 import 'package:opentelemetry/src/api/logs/logger.dart';
-import 'package:opentelemetry/src/sdk/common/attributes.dart';
 
 class NoopLogger implements Logger {
   const NoopLogger();
 
   @override
   void emit({
-    Attributes? attributes,
+    List<Attribute> attributes = const <Attribute>[],
     Context? context,
     dynamic body,
     DateTime? observedTimestamp,

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 +6,17 @@ 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/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

@@ -4,11 +4,11 @@ import 'package:meta/meta.dart';
 
 import '../../../api.dart' as api;
 import '../../../sdk.dart' as sdk;
+import '../../experimental_sdk.dart' as sdk;
 
 /// Applies given [sdk.SpanLimits] to a list of [api.SpanLink]s.
 @protected
-List<api.SpanLink> applyLinkLimits(
-    List<api.SpanLink> links, sdk.SpanLimits limits) {
+List<api.SpanLink> applyLinkLimits(List<api.SpanLink> links, sdk.SpanLimits limits) {
   final spanLink = <api.SpanLink>[];
 
   for (final link in links) {
@@ -27,8 +27,7 @@ List<api.SpanLink> applyLinkLimits(
     for (final attr in link.attributes) {
       // if attributes num is already greater than maxNumAttributesPerLink
       // and this key doesn't exist in the list, drop it.
-      if (attributeMap.length >= limits.maxNumAttributesPerLink &&
-          !attributeMap.containsKey(attr.key)) {
+      if (attributeMap.length >= limits.maxNumAttributesPerLink && !attributeMap.containsKey(attr.key)) {
         droppedAttributes++;
         continue;
       }
@@ -49,8 +48,7 @@ List<api.SpanLink> applyLinkLimits(
       }
     }
 
-    spanLink.add(api.SpanLink(link.context,
-        attributes: linkAttributes, droppedAttributes: droppedAttributes));
+    spanLink.add(api.SpanLink(link.context, attributes: linkAttributes, droppedAttributes: droppedAttributes));
   }
   return spanLink;
 }
@@ -63,20 +61,46 @@ api.Attribute applyAttributeLimits(api.Attribute attr, sdk.SpanLimits limits) {
 
   if (attr.value is String) {
     attr = api.Attribute.fromString(
-        attr.key,
-        applyAttributeLengthLimit(
-            attr.value as String, limits.maxNumAttributeLength));
+        attr.key, applyAttributeLengthLimit(attr.value as String, limits.maxNumAttributeLength));
   } 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.maxNumAttributeLength);
+      listString[j] = applyAttributeLengthLimit(listString[j], limits.maxNumAttributeLength);
     }
     attr = api.Attribute.fromStringList(attr.key, listString);
   }
   return attr;
 }
 
+@protected
+api.Attribute applyAttributeLimitsForLog(
+  api.Attribute attr,
+  sdk.LogRecordLimits limits,
+) {
+  // if maxNumAttributeLength is less than zero, then it has unlimited length.
+  if (limits.attributeValueLengthLimit < 0) return attr;
+
+  if (attr.value is String) {
+    return (attr.value as String).length > limits.attributeValueLengthLimit
+        ? api.Attribute.fromString(attr.key, (attr.value as String).substring(0, limits.attributeValueLengthLimit))
+        : attr;
+  } else if (attr.value is List<String>) {
+    final list = (attr.value as List<String>);
+    List<String>? truncated;
+    for (int i = 0; i < list.length; i++) {
+      final s = list[i];
+      if (s.length > limits.attributeValueLengthLimit) {
+        truncated ??= List<String>.from(list, growable: false);
+        truncated[i] = s.substring(0, limits.attributeValueLengthLimit);
+      }
+    }
+    if (truncated != null) {
+      return api.Attribute.fromStringList(attr.key, truncated);
+    }
+  }
+  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 +1,61 @@
+// 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;
+
+/// 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 = {};
+    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)
+            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) attribute.key: attribute.value,
+        }
+      },
+      'timestamp': log.timeStamp,
+      'severityText': log.severityText,
+      'severityNumber': log.severityNumber,
+      'body': log.body,
+      'attributes': {
+        for (final attribute in log.attributes.keys) 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();
+}