feat(opencensus-shim) add ShimTracer and ShimSpan implementations (op…

…en-telemetry#3756)

Co-authored-by: Marc Pichler <[email protected]>

experimental/packages/shim-opencensus/package.json

@@ -47,6 +47,7 @@
   "devDependencies": {
     "@opentelemetry/core": "1.13.0",
     "@opentelemetry/context-async-hooks": "1.13.0",
+    "@opentelemetry/sdk-trace-base": "1.13.0",
     "@opencensus/core": "0.1.0",
     "@opentelemetry/api": "1.4.1",
     "@types/mocha": "10.0.0",

experimental/packages/shim-opencensus/src/ShimSpan.ts

@@ -0,0 +1,188 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import * as oc from '@opencensus/core';
+import { ShimTracer } from './ShimTracer';
+import { AttributeValue, Span, SpanStatusCode, diag } from '@opentelemetry/api';
+import { mapMessageEvent, reverseMapSpanContext } from './transform';
+
+// Copied from
+// https://github.com/census-instrumentation/opencensus-node/blob/v0.1.0/packages/opencensus-core/src/trace/model/span.ts#L61
+export const DEFAULT_SPAN_NAME = 'span';
+
+const STATUS_OK = {
+  code: oc.CanonicalCode.OK,
+};
+
+interface Options {
+  shimTracer: ShimTracer;
+  otelSpan: Span;
+  isRootSpan?: boolean | undefined;
+  kind?: oc.SpanKind | undefined;
+  parentSpanId?: string | undefined;
+}
+
+export class ShimSpan implements oc.Span {
+  get id(): string {
+    return this.otelSpan.spanContext().spanId;
+  }
+
+  get tracer(): oc.TracerBase {
+    return this._shimTracer;
+  }
+
+  logger: oc.Logger = diag;
+
+  /** These are not readable in OTel so we return empty values */
+  attributes: oc.Attributes = {};
+  annotations: oc.Annotation[] = [];
+  messageEvents: oc.MessageEvent[] = [];
+  spans: oc.Span[] = [];
+  links: oc.Link[] = [];
+  name = '';
+  status: oc.Status = STATUS_OK;
+  activeTraceParams: oc.TraceParams = {};
+  droppedAttributesCount = 0;
+  droppedLinksCount = 0;
+  droppedAnnotationsCount = 0;
+  droppedMessageEventsCount = 0;
+  started = true;
+  ended = false;
+  numberOfChildren = 0;
+  duration = 0;
+
+  /** Actual private attributes */
+  private _shimTracer: ShimTracer;
+  readonly otelSpan: Span;
+  private _isRootSpan: boolean;
+
+  readonly kind: oc.SpanKind;
+  readonly parentSpanId: string;
+
+  get remoteParent(): boolean {
+    return this.otelSpan.spanContext().isRemote ?? false;
+  }
+
+  /** Constructs a new SpanBaseModel instance. */
+  constructor({
+    shimTracer,
+    otelSpan,
+    isRootSpan = false,
+    kind = oc.SpanKind.UNSPECIFIED,
+    parentSpanId = '',
+  }: Options) {
+    this._shimTracer = shimTracer;
+    this.otelSpan = otelSpan;
+    this._isRootSpan = isRootSpan;
+    this.kind = kind;
+    this.parentSpanId = parentSpanId;
+  }
+
+  /** Returns whether a span is root or not. */
+  isRootSpan(): boolean {
+    return this._isRootSpan;
+  }
+
+  get traceId(): string {
+    return this.otelSpan.spanContext().traceId;
+  }
+
+  /** Gets the trace state */
+  get traceState(): oc.TraceState | undefined {
+    return this.otelSpan.spanContext().traceState?.serialize();
+  }
+
+  /** No-op implementation of this method. */
+  get startTime(): Date {
+    return new Date();
+  }
+
+  /** No-op implementation of this method. */
+  get endTime(): Date {
+    return new Date();
+  }
+
+  /** No-op implementation of this method. */
+  allDescendants(): oc.Span[] {
+    return [];
+  }
+
+  /** Gives the TraceContext of the span. */
+  get spanContext(): oc.SpanContext {
+    return reverseMapSpanContext(this.otelSpan.spanContext());
+  }
+
+  addAttribute(key: string, value: string | number | boolean | object) {
+    this.otelSpan.setAttribute(key, value as AttributeValue);
+  }
+
+  addAnnotation(
+    description: string,
+    attributes?: oc.Attributes,
+    timestamp?: number
+  ) {
+    this.otelSpan.addEvent(description, attributes, timestamp);
+  }
+
+  /** No-op implementation of this method. */
+  addLink() {
+    diag.info(
+      'Call to OpenCensus Span.addLink() is being ignored. OTel does not support ' +
+        'adding links after span creation'
+    );
+  }
+
+  /** No-op implementation of this method. */
+  addMessageEvent(
+    type: oc.MessageEventType,
+    id: number,
+    timestamp?: number,
+    uncompressedSize?: number,
+    compressedSize?: number
+  ) {
+    this.otelSpan.addEvent(
+      ...mapMessageEvent(type, id, timestamp, uncompressedSize, compressedSize)
+    );
+  }
+
+  /** No-op implementation of this method. */
+  setStatus(code: oc.CanonicalCode, message?: string) {
+    this.otelSpan.setStatus({
+      code:
+        code === oc.CanonicalCode.OK ? SpanStatusCode.OK : SpanStatusCode.ERROR,
+      message,
+    });
+  }
+
+  /** No-op implementation of this method. */
+  start() {}
+
+  end(): void {
+    this.otelSpan.end();
+  }
+
+  /** No-op implementation of this method. */
+  truncate() {}
+
+  /** Starts a new Span instance as a child of this instance */
+  startChildSpan(options?: oc.SpanOptions): oc.Span {
+    return this._shimTracer.startChildSpan({
+      name: DEFAULT_SPAN_NAME,
+      childOf: this,
+      ...options,
+    });
+  }
+}

experimental/packages/shim-opencensus/src/ShimTracer.ts

@@ -0,0 +1,162 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import * as oc from '@opencensus/core';
+
+import {
+  Context,
+  context,
+  createContextKey,
+  diag,
+  INVALID_SPAN_CONTEXT,
+  trace,
+  Tracer,
+} from '@opentelemetry/api';
+import { DEFAULT_SPAN_NAME, ShimSpan } from './ShimSpan';
+import { mapSpanContext, mapSpanKind } from './transform';
+import { shimPropagation } from './propagation';
+
+// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+const INVALID_SPAN = trace.getSpan(
+  trace.setSpanContext(context.active(), INVALID_SPAN_CONTEXT)
+)!;
+const ROOTSPAN_KEY = createContextKey('rootspan_for_oc_shim');
+
+function setRootSpan(ctx: Context, span: ShimSpan): Context {
+  return ctx.setValue(ROOTSPAN_KEY, span);
+}
+
+export function getRootSpan(ctx: Context): ShimSpan | null {
+  return ctx.getValue(ROOTSPAN_KEY) as ShimSpan | null;
+}
+
+export class ShimTracer implements oc.Tracer {
+  logger: oc.Logger = diag;
+  active: boolean = false;
+
+  /** Noop implementations */
+  sampler: oc.Sampler = new oc.AlwaysSampler();
+  activeTraceParams: oc.TraceParams = {};
+  eventListeners: oc.SpanEventListener[] = [];
+  // Uses the global OpenTelemetry propagator by default
+  propagation: oc.Propagation = shimPropagation;
+
+  constructor(private otelTracer: Tracer) {}
+
+  start({ propagation }: oc.TracerConfig): this {
+    this.active = true;
+    // Pass a propagation here if you want the shim to use an OpenCensus propagation instance
+    // instead of the OpenTelemetry global propagator.
+    if (propagation) {
+      this.propagation = propagation;
+    }
+    return this;
+  }
+
+  /** Noop implementations */
+  stop(): this {
+    this.active = false;
+    return this;
+  }
+  registerSpanEventListener(): void {}
+  unregisterSpanEventListener(): void {}
+  clearCurrentTrace(): void {}
+  onStartSpan(): void {}
+  onEndSpan(): void {}
+  setCurrentRootSpan() {
+    // This can't be correctly overriden since OTel context does not provide a way to set
+    // context without a callback. Leave noop for now.
+  }
+
+  /** Gets the current root span. */
+  get currentRootSpan(): oc.Span {
+    return (
+      getRootSpan(context.active()) ??
+      new ShimSpan({
+        shimTracer: this,
+        otelSpan: INVALID_SPAN,
+      })
+    );
+  }
+
+  /**
+   * Starts a root span.
+   * @param options A TraceOptions object to start a root span.
+   * @param fn A callback function to run after starting a root span.
+   */
+  startRootSpan<T>(
+    { name, kind, spanContext }: oc.TraceOptions,
+    fn: (root: oc.Span) => T
+  ): T {
+    const parentCtx =
+      spanContext === undefined
+        ? context.active()
+        : trace.setSpanContext(context.active(), mapSpanContext(spanContext));
+
+    const otelSpan = this.otelTracer.startSpan(
+      name,
+      { kind: mapSpanKind(kind) },
+      parentCtx
+    );
+    const shimSpan = new ShimSpan({
+      shimTracer: this,
+      otelSpan,
+      isRootSpan: true,
+      kind,
+      parentSpanId: trace.getSpanContext(parentCtx)?.spanId,
+    });
+
+    let ctx = trace.setSpan(parentCtx, otelSpan);
+    ctx = setRootSpan(ctx, shimSpan);
+    return context.with(ctx, () => fn(shimSpan));
+  }
+
+  startChildSpan(options?: oc.SpanOptions): oc.Span {
+    const { kind, name = DEFAULT_SPAN_NAME, childOf } = options ?? {};
+    const rootSpan = getRootSpan(context.active());
+
+    let ctx = context.active();
+    if (childOf) {
+      ctx = trace.setSpanContext(ctx, mapSpanContext(childOf.spanContext));
+    } else if (rootSpan) {
+      ctx = trace.setSpan(ctx, rootSpan.otelSpan);
+    }
+
+    const otelSpan = this.otelTracer.startSpan(
+      name,
+      {
+        kind: mapSpanKind(kind),
+      },
+      ctx
+    );
+    return new ShimSpan({
+      shimTracer: this,
+      otelSpan,
+      isRootSpan: false,
+      kind,
+      parentSpanId: trace.getSpanContext(ctx)?.spanId,
+    });
+  }
+
+  wrap<T>(fn: oc.Func<T>): oc.Func<T> {
+    return context.bind(context.active(), fn);
+  }
+
+  wrapEmitter(emitter: NodeJS.EventEmitter): void {
+    // Not sure if this requires returning the modified emitter
+    context.bind(context.active(), emitter);
+  }
+}

experimental/packages/shim-opencensus/src/index.ts

@@ -13,3 +13,5 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
+export { ShimTracer } from './ShimTracer';