@arturwojnar/hermes-postgresql/lib/subscribeToReplicationSlot/processInsertMessage.js

Production-Ready TypeScript Outbox Pattern for PostgreSQL

import { assert } from '@arturwojnar/hermes';
import { offset } from '../common/offset.js';
import { Bytes, MessageType, TopLevelType } from './types.js';
const readIntFn = {
    '1': 'readUInt8',
    '2': 'readUInt16BE',
    '4': 'readUInt32BE',
    '8': 'readBigUInt64BE',
};
const readUInt = (buffer, pos) => {
    const columnType = String.fromCharCode(buffer.readInt8(pos.value()));
    const columnLength = buffer.readUInt32BE(pos.addInt8()).toString();
    assert(columnType === 't', 'readUInt.columnType');
    assert(['1', '2', '4', '8'].includes(columnLength), 'readUInt.columnLength');
    const value = buffer[readIntFn[columnLength]](pos.addInt32());
    pos.add(Number(columnLength));
    return value;
};
const readBigInt = (buffer, pos) => {
    const columnType = String.fromCharCode(buffer.readInt8(pos.value()));
    const columnLength = buffer.readUInt32BE(pos.addInt8());
    assert(columnType === 't', 'readUInt.columnType');
    const strValue = buffer.subarray(pos.addInt32(), pos.value() + columnLength).toString('utf-8');
    const value = columnLength > 8 ? BigInt(strValue) : parseInt(strValue, 10);
    pos.add(columnLength);
    return value;
};
const readText = (buffer, pos) => {
    const columnType = String.fromCharCode(buffer.readInt8(pos.value()));
    const columnLength = buffer.readUInt32BE(pos.addInt8());
    assert(columnType === 't', 'readText.columnType');
    const value = buffer.subarray(pos.addInt32(), pos.add(columnLength));
    return value.toString('utf-8');
};
const readJsonb = (buffer, pos) => {
    const columnType = String.fromCharCode(buffer.readInt8(pos.value()));
    const columnLength = buffer.readUInt32BE(pos.addInt8());
    assert(columnType === 't', 'readText.readJsonb');
    const value = buffer.subarray(pos.addInt32(), pos.add(columnLength));
    return value.toString('utf-8');
};
const columnReaders = {
    uint: readUInt,
    bigint: readBigInt,
    text: readText,
    jsonb: readJsonb,
};
const processInsertMessage = (columnConfig) => {
    const entries = Object.entries(columnConfig);
    const readers = entries.map(([columnName, columnType]) => ({
        columnName,
        reader: columnReaders[columnType],
    }));
    readers.forEach(({ reader }) => assert(reader, `Unknown column type`));
    const readTuple = (pos, tuplesBuffer) => {
        return readers.reduce((result, { columnName, reader }) => {
            Object.defineProperty(result, columnName, {
                value: reader(tuplesBuffer, pos),
                writable: false,
                enumerable: true,
            });
            return result;
        }, {});
    };
    return (data) => {
        const relationId = data.readUInt32BE(Bytes.Int8);
        const newMessageId = String.fromCharCode(data.readInt8(Bytes.Int8 + Bytes.Int32));
        const TUPLE_START_BYTE = Bytes.Int8 + Bytes.Int32 + Bytes.Int8;
        const tuplesBuffer = data.subarray(TUPLE_START_BYTE);
        const columnsCount = tuplesBuffer.readInt16BE(0);
        const pos = offset(Bytes.Int16);
        const result = readTuple(pos, tuplesBuffer);
        return {
            topLevelType: TopLevelType.XLogData,
            messageType: MessageType.Insert,
            result,
        };
    };
};
export { processInsertMessage, readBigInt, readJsonb, readText, readUInt };
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