feat: logger processor

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 +6,15 @@ library experimental_sdk;
 
 import 'package:meta/meta.dart';
 
+export 'sdk/logs/export_result.dart' show ExportResult, ExportResultCode;
+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/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();
+}

lib/src/sdk/logs/log_record.dart

@@ -0,0 +1,152 @@
+// 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/api.dart' as api;
+import 'package:opentelemetry/sdk.dart' as sdk;
+import 'package:opentelemetry/src/experimental_api.dart' as api;
+import 'package:opentelemetry/src/experimental_sdk.dart' as sdk;
+import 'package:opentelemetry/src/sdk/common/limits.dart';
+
+/// https://opentelemetry.io/docs/specs/otel/logs/sdk/#readwritelogrecord
+abstract class ReadableLogRecord {
+  DateTime get timeStamp;
+
+  DateTime get observedTimestamp;
+
+  String get severityText;
+
+  api.Severity get severityNumber;
+
+  dynamic get body;
+
+  sdk.Attributes get attributes;
+
+  api.SpanContext get spanContext;
+
+  sdk.Resource get resource;
+
+  sdk.InstrumentationScope get instrumentationScope;
+
+  int get droppedAttributesCount;
+}
+
+abstract class ReadWriteLogRecord extends ReadableLogRecord {
+  set body(dynamic severity);
+
+  set severityText(String severity);
+
+  set severityNumber(api.Severity severity);
+}
+
+class LogRecord implements ReadWriteLogRecord {
+  @override
+  final sdk.InstrumentationScope instrumentationScope;
+
+  final sdk.Resource _resource;
+
+  final sdk.TimeProvider _timeProvider;
+  final api.Context _context;
+  final sdk.LogRecordLimits logRecordLimits;
+  final DateTime? _timeStamp;
+  final DateTime? _observedTimestamp;
+
+  bool _isReadonly = false;
+  String _severityText;
+  api.Severity _severityNumber;
+  dynamic _body;
+  int _totalAttributesCount = 0;
+
+  final sdk.Attributes _attributes;
+
+  @protected
+  LogRecord({
+    required this.instrumentationScope,
+    required this.logRecordLimits,
+    api.Severity? severityNumber,
+    String? severityText,
+    List<api.Attribute> attributes = const <api.Attribute>[],
+    DateTime? timeStamp,
+    DateTime? observedTimestamp,
+    api.Context? context,
+    dynamic body,
+    sdk.Resource? resource,
+    sdk.TimeProvider? timeProvider,
+  })  : _severityText = severityText ?? api.Severity.unspecified.name,
+        _resource = resource ?? sdk.Resource([]),
+        _context = context ?? api.Context.current,
+        _body = body,
+        _attributes = sdk.Attributes.empty(),
+        _severityNumber = severityNumber ?? api.Severity.unspecified,
+        _timeStamp = timeStamp,
+        _observedTimestamp = observedTimestamp,
+        _timeProvider = timeProvider ?? sdk.DateTimeTimeProvider() {
+    if (attributes.isNotEmpty) setAttributes(attributes);
+  }
+
+
+  @override
+  sdk.Resource get resource => _resource;
+
+  @override
+  sdk.Attributes get attributes => _attributes;
+
+  @override
+  dynamic get body => _body;
+
+  @override
+  set body(dynamic body) {
+    if (_isReadonly) return;
+    _body = body;
+  }
+
+  @override
+  api.SpanContext get spanContext => api.spanContextFromContext(_context);
+
+  @override
+  int get droppedAttributesCount => _totalAttributesCount - attributes.length;
+
+  @override
+  DateTime get timeStamp => _timeStamp ?? DateTime.fromMicrosecondsSinceEpoch((_timeProvider.now ~/ 1000).toInt());
+
+  @override
+  DateTime get observedTimestamp =>
+      _observedTimestamp ?? DateTime.fromMicrosecondsSinceEpoch((_timeProvider.now ~/ 1000).toInt());
+
+  @override
+  api.Severity get severityNumber => _severityNumber;
+
+  @override
+  set severityNumber(api.Severity severity) {
+    if (_isReadonly) return;
+    _severityNumber = severity;
+  }
+
+  @override
+  String get severityText => _severityText;
+
+  @override
+  set severityText(String severity) {
+    if (_isReadonly) return;
+    _severityText = severity;
+  }
+
+  void setAttributes(List<api.Attribute> attributes) {
+    attributes.forEach(setAttribute);
+  }
+
+  void setAttribute(api.Attribute attribute) {
+    if (_isReadonly) return;
+    if (attribute.key.isEmpty) return;
+    if (logRecordLimits.attributeCountLimit == 0) return;
+    _totalAttributesCount += 1;
+    _attributes.add(applyAttributeLimitsForLog(attribute, logRecordLimits));
+  }
+
+  /// A LogRecordProcessor may freely modify logRecord for the duration of the OnEmit call.
+  /// If logRecord is needed after OnEmit returns (i.e. for asynchronous processing) only reads are permitted.
+  @internal
+  void makeReadonly() {
+    _isReadonly = true;
+  }
+}

lib/src/sdk/logs/log_record_limit.dart

@@ -0,0 +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
+
+class LogRecordLimits {
+  final int _attributeCountLimit;
+  final int _attributeValueLengthLimit;
+
+  const LogRecordLimits({
+    int attributeCountLimit = 128,
+    int attributeValueLengthLimit = -1,
+  })  : _attributeCountLimit = attributeCountLimit,
+        _attributeValueLengthLimit = attributeValueLengthLimit;
+
+  int get attributeCountLimit => _attributeCountLimit;
+
+  int get attributeValueLengthLimit => _attributeValueLengthLimit;
+}