/
RandomIdGenerator.ts
56 lines (49 loc) · 1.89 KB
/
RandomIdGenerator.ts
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/*
* 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 { IdGenerator } from '../../IdGenerator';
const SPAN_ID_BYTES = 8;
const TRACE_ID_BYTES = 16;
export class RandomIdGenerator implements IdGenerator {
/**
* Returns a random 16-byte trace ID formatted/encoded as a 32 lowercase hex
* characters corresponding to 128 bits.
*/
generateTraceId = getIdGenerator(TRACE_ID_BYTES);
/**
* Returns a random 8-byte span ID formatted/encoded as a 16 lowercase hex
* characters corresponding to 64 bits.
*/
generateSpanId = getIdGenerator(SPAN_ID_BYTES);
}
const SHARED_BUFFER = Buffer.allocUnsafe(TRACE_ID_BYTES);
function getIdGenerator(bytes: number): () => string {
return function generateId() {
for (let i = 0; i < bytes / 4; i++) {
// unsigned right shift drops decimal part of the number
// it is required because if a number between 2**32 and 2**32 - 1 is generated, an out of range error is thrown by writeUInt32BE
SHARED_BUFFER.writeUInt32BE((Math.random() * 2 ** 32) >>> 0, i * 4);
}
// If buffer is all 0, set the last byte to 1 to guarantee a valid w3c id is generated
for (let i = 0; i < bytes; i++) {
if (SHARED_BUFFER[i] > 0) {
break;
} else if (i === bytes - 1) {
SHARED_BUFFER[bytes - 1] = 1;
}
}
return SHARED_BUFFER.toString('hex', 0, bytes);
};
}