Add TraceId and SpanId generator util (open-telemetry#35)

* Add TraceId and SpanId generator util

* minor fix

* Update file structure

Author: mayurkale22

packages/opentelemetry-core/src/common/util/id.ts

@@ -0,0 +1,35 @@
+/**
+ * Copyright 2019, 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 crypto from 'crypto';
+
+const SPAN_ID_BYTES = 8;
+
+/**
+ * Returns a random 16-byte trace ID formatted/encoded as a 32 lowercase hex
+ * characters corresponding to 128 bits.
+ */
+export function randomTraceId(): string {
+  return randomSpanId() + randomSpanId();
+}
+
+/**
+ * Returns a random 8-byte span ID formatted/encoded as a 16 lowercase hex
+ * characters corresponding to 64 bits.
+ */
+export function randomSpanId(): string {
+  return crypto.randomBytes(SPAN_ID_BYTES).toString('hex');
+}

packages/opentelemetry-core/test/util.id.test.ts

@@ -0,0 +1,32 @@
+/**
+ * Copyright 2019, 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 assert from 'assert';
+import { randomSpanId, randomTraceId } from '../src/common/util/id';
+
+describe('randomTraceId', () => {
+  it('returns different 32-char hex strings', () => {
+    const traceId = randomTraceId();
+    assert.ok(traceId.match(/[a-f0-9]{32}/));
+  });
+});
+
+describe('randomSpanId', () => {
+  it('returns different 16-char hex string', () => {
+    const spanId = randomSpanId();
+    assert.ok(spanId.match(/[a-f0-9]{16}/));
+  });
+});