Function getDMMFBuffered

packages/get-dmmf/src/index.ts:110–161

* Read DMMF from the handle-based buffered WASM API in chunks and parse via * chunked string decoding. This bypasses V8's string length limit by reading * the DMMF as Uint8Array chunks from a caller-owned DmmfBuffer handle. * * Requires `get_dmmf_buffered()` (returns a `DmmfBuffer` handle) from

(params: string)

 * See: https://github.com/prisma/prisma/issues/29111
 */
function getDMMFBuffered(params: string): DMMF.Document | GetDMMFError {
  const CHUNK_SIZE = 16 * 1024 * 1024 // 16MB chunks — well under V8 string limit

  if (typeof prismaSchemaWasm.get_dmmf_buffered !== 'function') {
    return {
      type: 'wasm-error' as const,
      reason: '(get-dmmf-buffered wasm)',
      error: new Error(
        "Buffered DMMF API not available. It's required for schemas that do not fit within the default V8 memory limit. Ensure you are using latest @prisma/prisma-schema-wasm.",
      ),
    }
  }

  const buffer = prismaSchemaWasm.get_dmmf_buffered(params)

  try {
    const totalBytes = buffer.len()
    debug(`DMMF buffered: ${totalBytes} bytes (${(totalBytes / 1024 / 1024).toFixed(1)}MB)`)

    // Use a streaming JSON parser that processes Uint8Array chunks directly,
    // never creating a single large string.
    const parser = new JSONParser()
    let result: DMMF.Document | undefined

    parser.onValue = ({ value, stack }) => {
      if (stack.length === 0 && value !== undefined) {
        result = value as unknown as DMMF.Document
      }
    }

    let offset = 0
    while (offset < totalBytes) {
      const len = Math.min(CHUNK_SIZE, totalBytes - offset)
      const chunk = buffer.read_chunk(offset, len)
      parser.write(chunk)
      offset += len
    }

    if (result === undefined) {
      return {
        type: 'parse-json' as const,
        reason: '(get-dmmf-buffered parse)',
        error: new Error('Streaming JSON parse produced no result'),
      }
    }

    debug(`DMMF parsed via streaming parser (${(totalBytes / 1024 / 1024).toFixed(1)}MB)`)
    return result
  } finally {
    buffer.free()
  }
}

/**
 * Check if an error is the V8 string length limit.