Merge pull request #3 from hyparam/protobuf

Add OTLP/HTTP protobuf support

Author: platypii

src/otlp/common.js

@@ -0,0 +1,192 @@
+/**
+ * Decoders for OTLP common message types (AnyValue, KeyValue, Resource,
+ * InstrumentationScope). Output matches OTLP/JSON: camelCase field names,
+ * int64 as string, bytes as base64, trace/span ids as lowercase hex.
+ *
+ * @import {DataReader} from '../types.js'
+ */
+
+import {
+  readBytes,
+  readDouble,
+  readTag,
+  readVarBigInt,
+  readVarint,
+  skipField,
+} from '../protobuf.js'
+
+const textDecoder = new TextDecoder()
+
+/**
+ * Wrap a byte slice in a DataReader for field-by-field decoding.
+ *
+ * @param {Uint8Array} bytes
+ * @returns {DataReader}
+ */
+export function makeReader(bytes) {
+  return {
+    view: new DataView(bytes.buffer, bytes.byteOffset, bytes.byteLength),
+    offset: 0,
+  }
+}
+
+/**
+ * Lowercase hex encoding for trace_id/span_id/parent_span_id fields.
+ *
+ * @param {Uint8Array} bytes
+ * @returns {string}
+ */
+export function toHex(bytes) {
+  return Buffer.from(bytes.buffer, bytes.byteOffset, bytes.byteLength).toString('hex')
+}
+
+/**
+ * Standard base64 for generic bytes fields.
+ *
+ * @param {Uint8Array} bytes
+ * @returns {string}
+ */
+export function toBase64(bytes) {
+  return Buffer.from(bytes.buffer, bytes.byteOffset, bytes.byteLength).toString('base64')
+}
+
+/**
+ * @param {Uint8Array} bytes
+ * @returns {string}
+ */
+export function decodeString(bytes) {
+  return textDecoder.decode(bytes)
+}
+
+/**
+ * @param {Uint8Array} bytes
+ * @returns {object}
+ */
+export function decodeAnyValue(bytes) {
+  const r = makeReader(bytes)
+  const end = bytes.byteLength
+  /** @type {Record<string, unknown>} */
+  const out = {}
+  while (r.offset < end) {
+    const { fieldNumber, wireType } = readTag(r)
+    switch (fieldNumber) {
+    case 1: out.stringValue = decodeString(readBytes(r)); break
+    case 2: out.boolValue = readVarint(r) !== 0; break
+    case 3: out.intValue = readVarBigInt(r).toString(); break
+    case 4: out.doubleValue = readDouble(r); break
+    case 5: out.arrayValue = decodeArrayValue(readBytes(r)); break
+    case 6: out.kvlistValue = decodeKeyValueList(readBytes(r)); break
+    case 7: out.bytesValue = toBase64(readBytes(r)); break
+    default: skipField(r, wireType)
+    }
+  }
+  return out
+}
+
+/**
+ * @param {Uint8Array} bytes
+ * @returns {{ values: object[] }}
+ */
+export function decodeArrayValue(bytes) {
+  const r = makeReader(bytes)
+  const end = bytes.byteLength
+  /** @type {object[]} */
+  const values = []
+  while (r.offset < end) {
+    const { fieldNumber, wireType } = readTag(r)
+    if (fieldNumber === 1) {
+      values.push(decodeAnyValue(readBytes(r)))
+    } else {
+      skipField(r, wireType)
+    }
+  }
+  return { values }
+}
+
+/**
+ * @param {Uint8Array} bytes
+ * @returns {{ values: object[] }}
+ */
+export function decodeKeyValueList(bytes) {
+  const r = makeReader(bytes)
+  const end = bytes.byteLength
+  /** @type {object[]} */
+  const values = []
+  while (r.offset < end) {
+    const { fieldNumber, wireType } = readTag(r)
+    if (fieldNumber === 1) {
+      values.push(decodeKeyValue(readBytes(r)))
+    } else {
+      skipField(r, wireType)
+    }
+  }
+  return { values }
+}
+
+/**
+ * @param {Uint8Array} bytes
+ * @returns {object}
+ */
+export function decodeKeyValue(bytes) {
+  const r = makeReader(bytes)
+  const end = bytes.byteLength
+  /** @type {Record<string, unknown>} */
+  const out = {}
+  while (r.offset < end) {
+    const { fieldNumber, wireType } = readTag(r)
+    switch (fieldNumber) {
+    case 1: out.key = decodeString(readBytes(r)); break
+    case 2: out.value = decodeAnyValue(readBytes(r)); break
+    default: skipField(r, wireType)
+    }
+  }
+  return out
+}
+
+/**
+ * @param {Uint8Array} bytes
+ * @returns {object}
+ */
+export function decodeInstrumentationScope(bytes) {
+  const r = makeReader(bytes)
+  const end = bytes.byteLength
+  /** @type {Record<string, unknown>} */
+  const out = {}
+  /** @type {object[]} */
+  const attributes = []
+  while (r.offset < end) {
+    const { fieldNumber, wireType } = readTag(r)
+    switch (fieldNumber) {
+    case 1: out.name = decodeString(readBytes(r)); break
+    case 2: out.version = decodeString(readBytes(r)); break
+    case 3: attributes.push(decodeKeyValue(readBytes(r))); break
+    case 4: out.droppedAttributesCount = readVarint(r); break
+    default: skipField(r, wireType)
+    }
+  }
+  if (attributes.length) out.attributes = attributes
+  return out
+}
+
+/**
+ * @param {Uint8Array} bytes
+ * @returns {object}
+ */
+export function decodeResource(bytes) {
+  const r = makeReader(bytes)
+  const end = bytes.byteLength
+  /** @type {Record<string, unknown>} */
+  const out = {}
+  /** @type {object[]} */
+  const attributes = []
+  while (r.offset < end) {
+    const { fieldNumber, wireType } = readTag(r)
+    switch (fieldNumber) {
+    case 1: attributes.push(decodeKeyValue(readBytes(r))); break
+    case 2: out.droppedAttributesCount = readVarint(r); break
+    default: skipField(r, wireType)
+    }
+  }
+  if (attributes.length) out.attributes = attributes
+  return out
+}