@azure/cosmos
Version:
Microsoft Azure Cosmos DB Service Node.js SDK for NOSQL API
65 lines • 2.73 kB
JavaScript
// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.
import { doubleToByteArrayBigInt } from "./encoding/number.js";
import { BytePrefix } from "./encoding/prefix.js";
import MurmurHash from "./murmurHash.js";
import { concatUint8Arrays, hexStringToUint8Array, uint8ArrayToHex } from "../uint8.js";
export function hashV2PartitionKey(partitionKey) {
// Create a single Uint8Array from the concatenated prefixes for each partition key value.
const toHash = concatUint8Arrays(partitionKey.map(prefixKeyByType));
// Compute the 128-bit hash. This returns a hex string.
const hash = MurmurHash.x64.hash128(toHash);
// Convert the hex string hash to a Uint8Array and reverse it.
const reverseBuff = reverse(hexStringToUint8Array(hash));
// Mask the first byte as required.
reverseBuff[0] &= 0x3f;
// Convert the reversed buffer back to a hex string, uppercase it, and return.
return uint8ArrayToHex(reverseBuff).toUpperCase();
}
function prefixKeyByType(key) {
let bytes;
switch (typeof key) {
case "string": {
// For strings, concatenate:
// - The hex prefix for String
// - The UTF-8 bytes for the key (using Uint8Array.from should work for string iterables; alternatively use an encoder)
// - The hex prefix for Infinity
bytes = concatUint8Arrays([
hexStringToUint8Array(BytePrefix.String),
new TextEncoder().encode(key),
hexStringToUint8Array(BytePrefix.Infinity),
]);
return bytes;
}
case "number": {
const numberBytes = doubleToByteArrayBigInt(key);
bytes = concatUint8Arrays([hexStringToUint8Array(BytePrefix.Number), numberBytes]);
return bytes;
}
case "boolean": {
const prefix = key ? BytePrefix.True : BytePrefix.False;
return hexStringToUint8Array(prefix);
}
case "object": {
if (key === null) {
return hexStringToUint8Array(BytePrefix.Null);
}
return hexStringToUint8Array(BytePrefix.Undefined);
}
case "undefined": {
return hexStringToUint8Array(BytePrefix.Undefined);
}
default:
throw new Error(`Unexpected type: ${typeof key}`);
}
}
export function reverse(buff) {
// Replace Uint8Array.allocUnsafe(buff.length) with new Uint8Array(buff.length)
const uint8array = new Uint8Array(buff.length);
for (let i = 0, j = buff.length - 1; i <= j; ++i, --j) {
uint8array[i] = buff[j];
uint8array[j] = buff[i];
}
return uint8array;
}
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