feat: add tracestate implementation to api (#147)

Co-authored-by: Valentin Marchaud <contact@vmarchaud.fr>

Author: srikanthccv

src/index.ts

@@ -34,6 +34,7 @@ export * from './trace/SpanOptions';
 export * from './trace/status';
 export * from './trace/trace_flags';
 export * from './trace/trace_state';
+export { createTraceState } from './trace/internal/utils';
 export * from './trace/tracer_provider';
 export * from './trace/tracer';
 

src/trace/internal/tracestate-impl.ts

@@ -0,0 +1,110 @@
+/*
+ * 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 { TraceState } from '../trace_state';
+import { validateKey, validateValue } from './tracestate-validators';
+
+const MAX_TRACE_STATE_ITEMS = 32;
+const MAX_TRACE_STATE_LEN = 512;
+const LIST_MEMBERS_SEPARATOR = ',';
+const LIST_MEMBER_KEY_VALUE_SPLITTER = '=';
+
+/**
+ * TraceState must be a class and not a simple object type because of the spec
+ * requirement (https://www.w3.org/TR/trace-context/#tracestate-field).
+ *
+ * Here is the list of allowed mutations:
+ * - New key-value pair should be added into the beginning of the list
+ * - The value of any key can be updated. Modified keys MUST be moved to the
+ * beginning of the list.
+ */
+export class TraceStateImpl implements TraceState {
+  private _internalState: Map<string, string> = new Map();
+
+  constructor(rawTraceState?: string) {
+    if (rawTraceState) this._parse(rawTraceState);
+  }
+
+  set(key: string, value: string): TraceStateImpl {
+    // TODO: Benchmark the different approaches(map vs list) and
+    // use the faster one.
+    const traceState = this._clone();
+    if (traceState._internalState.has(key)) {
+      traceState._internalState.delete(key);
+    }
+    traceState._internalState.set(key, value);
+    return traceState;
+  }
+
+  unset(key: string): TraceStateImpl {
+    const traceState = this._clone();
+    traceState._internalState.delete(key);
+    return traceState;
+  }
+
+  get(key: string): string | undefined {
+    return this._internalState.get(key);
+  }
+
+  serialize(): string {
+    return this._keys()
+      .reduce((agg: string[], key) => {
+        agg.push(key + LIST_MEMBER_KEY_VALUE_SPLITTER + this.get(key));
+        return agg;
+      }, [])
+      .join(LIST_MEMBERS_SEPARATOR);
+  }
+
+  private _parse(rawTraceState: string) {
+    if (rawTraceState.length > MAX_TRACE_STATE_LEN) return;
+    this._internalState = rawTraceState
+      .split(LIST_MEMBERS_SEPARATOR)
+      .reverse() // Store in reverse so new keys (.set(...)) will be placed at the beginning
+      .reduce((agg: Map<string, string>, part: string) => {
+        const listMember = part.trim(); // Optional Whitespace (OWS) handling
+        const i = listMember.indexOf(LIST_MEMBER_KEY_VALUE_SPLITTER);
+        if (i !== -1) {
+          const key = listMember.slice(0, i);
+          const value = listMember.slice(i + 1, part.length);
+          if (validateKey(key) && validateValue(value)) {
+            agg.set(key, value);
+          } else {
+            // TODO: Consider to add warning log
+          }
+        }
+        return agg;
+      }, new Map());
+
+    // Because of the reverse() requirement, trunc must be done after map is created
+    if (this._internalState.size > MAX_TRACE_STATE_ITEMS) {
+      this._internalState = new Map(
+        Array.from(this._internalState.entries())
+          .reverse() // Use reverse same as original tracestate parse chain
+          .slice(0, MAX_TRACE_STATE_ITEMS)
+      );
+    }
+  }
+
+  private _keys(): string[] {
+    return Array.from(this._internalState.keys()).reverse();
+  }
+
+  private _clone(): TraceStateImpl {
+    const traceState = new TraceStateImpl();
+    traceState._internalState = new Map(this._internalState);
+    return traceState;
+  }
+}

src/trace/internal/tracestate-validators.ts

@@ -0,0 +1,45 @@
+/*
+ * 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.
+ */
+
+const VALID_KEY_CHAR_RANGE = '[_0-9a-z-*/]';
+const VALID_KEY = `[a-z]${VALID_KEY_CHAR_RANGE}{0,255}`;
+const VALID_VENDOR_KEY = `[a-z0-9]${VALID_KEY_CHAR_RANGE}{0,240}@[a-z]${VALID_KEY_CHAR_RANGE}{0,13}`;
+const VALID_KEY_REGEX = new RegExp(`^(?:${VALID_KEY}|${VALID_VENDOR_KEY})$`);
+const VALID_VALUE_BASE_REGEX = /^[ -~]{0,255}[!-~]$/;
+const INVALID_VALUE_COMMA_EQUAL_REGEX = /,|=/;
+
+/**
+ * Key is opaque string up to 256 characters printable. It MUST begin with a
+ * lowercase letter, and can only contain lowercase letters a-z, digits 0-9,
+ * underscores _, dashes -, asterisks *, and forward slashes /.
+ * For multi-tenant vendor scenarios, an at sign (@) can be used to prefix the
+ * vendor name. Vendors SHOULD set the tenant ID at the beginning of the key.
+ * see https://www.w3.org/TR/trace-context/#key
+ */
+export function validateKey(key: string): boolean {
+  return VALID_KEY_REGEX.test(key);
+}
+
+/**
+ * Value is opaque string up to 256 characters printable ASCII RFC0020
+ * characters (i.e., the range 0x20 to 0x7E) except comma , and =.
+ */
+export function validateValue(value: string): boolean {
+  return (
+    VALID_VALUE_BASE_REGEX.test(value) &&
+    !INVALID_VALUE_COMMA_EQUAL_REGEX.test(value)
+  );
+}

src/trace/internal/utils.ts

@@ -0,0 +1,23 @@
+/*
+ * 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 { TraceState } from '../trace_state';
+import { TraceStateImpl } from './tracestate-impl';
+
+
+export function createTraceState(rawTraceState?: string): TraceState {
+  return new TraceStateImpl(rawTraceState);
+}

test/trace/tracestate-validators.test.ts

@@ -0,0 +1,92 @@
+/*
+ * 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 assert from 'assert';
+import { validateKey, validateValue } from '../../src/trace/internal/tracestate-validators';
+
+describe('validators', () => {
+  describe('validateKey', () => {
+    const validKeysTestCases = [
+      'abcdefghijklmnopqrstuvwxyz0123456789-_*/',
+      'baz-',
+      'baz_',
+      'baz*',
+      'baz*bar',
+      'baz/',
+      'tracestate',
+      'fw529a3039@dt',
+      '6cab5bb-29a@dt',
+    ];
+    validKeysTestCases.forEach(testCase =>
+      it(`returns true when key contains valid chars ${testCase}`, () => {
+        assert.ok(validateKey(testCase), `${testCase} should be valid`);
+      })
+    );
+
+    const invalidKeysTestCases = [
+      '1_key',
+      'kEy_1',
+      'k'.repeat(257),
+      'key,',
+      'TrAcEsTaTE',
+      'TRACESTATE',
+      '',
+      '6num',
+    ];
+    invalidKeysTestCases.forEach(testCase =>
+      it(`returns true when key contains invalid chars ${testCase}`, () => {
+        assert.ok(!validateKey(testCase), `${testCase} should be invalid`);
+      })
+    );
+  });
+
+  describe('validateValue', () => {
+    const validValuesTestCases = [
+      'first second',
+      'baz*',
+      'baz$',
+      'baz@',
+      'first-second',
+      'baz~bar',
+      'test-v1:120',
+      '-second',
+      'first.second',
+      'TrAcEsTaTE',
+      'TRACESTATE',
+    ];
+    validValuesTestCases.forEach(testCase =>
+      it(`returns true when value contains valid chars ${testCase}`, () => {
+        assert.ok(validateValue(testCase));
+      })
+    );
+
+    const invalidValuesTestCases = [
+      'my_value=5',
+      'first,second',
+      'first ',
+      'k'.repeat(257),
+      ',baz',
+      'baz,',
+      'baz=',
+      '',
+    ];
+    invalidValuesTestCases.forEach(testCase =>
+      it(`returns true when value contains invalid chars ${testCase}`, () => {
+        assert.ok(!validateValue(testCase));
+      })
+    );
+  });
+});