**Fault Tolerance**: `FaultTolerantClient` wrapper (retry, circuit breaker), `SwitchableHttpClient` for HTTP client fallback

---

## Key Components

### Core Classes

- **Crawler** (`Crawler.java`): Main orchestrator - `execute()`, `addUrl()`, `cleanup()`, `stop()`

import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.common.breaker.CircuitBreaker;
import org.elasticsearch.common.breaker.NoopCircuitBreaker;
import org.elasticsearch.common.lucene.search.TopDocsAndMaxScore;
import org.elasticsearch.index.Index;
import org.elasticsearch.index.shard.ShardId;
import org.elasticsearch.indices.breaker.NoneCircuitBreakerService;
import org.elasticsearch.search.DocValueFormat;

 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */
package org.elasticsearch.benchmark.indices.breaker;

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Measurement;

import org.elasticsearch.index.mapper.NumberFieldMapper.NumberFieldType;
import org.elasticsearch.index.mapper.NumberFieldMapper.NumberType;
import org.elasticsearch.indices.breaker.CircuitBreakerService;
import org.elasticsearch.indices.breaker.NoneCircuitBreakerService;
import org.elasticsearch.plugins.PluginsService;
import org.elasticsearch.plugins.ScriptPlugin;
import org.elasticsearch.script.DocReader;

	"github.com/minio/minio/internal/s3select/jstream"
	"github.com/minio/minio/internal/s3select/sql"
)

// PReader - JSON record reader for S3Select.
// Operates concurrently on line-delimited JSON.
type PReader struct {
	args        *ReaderArgs
	readCloser  io.ReadCloser             // raw input
	buf         *bufio.Reader             // input to the splitter
	current     []jstream.KVS             // current block of results to be returned

import (
	"errors"
	"io"
	"unicode/utf8"
)

// A Reader implements the [io.Reader], [io.ReaderAt], [io.WriterTo], [io.Seeker],
// [io.ByteScanner], and [io.RuneScanner] interfaces by reading from
// a byte slice.
// Unlike a [Buffer], a Reader is read-only and supports seeking.
// The zero value for Reader operates like a Reader of an empty slice.
type Reader struct {
	s        []byte
	i        int64 // current reading index

//
//	// Now, we need an io.Reader that can access
//	// the ETag computed over the content.
//	reader := etag.Wrap(encryptedContent, content)
func Wrap(wrapped, content io.Reader) io.Reader {
	if t, ok := content.(Tagger); ok {
		return wrapReader{
			Reader: wrapped,
			Tagger: t,
		}
	}
	return wrapReader{
		Reader: wrapped,
	}
}

// A Reader wraps an io.Reader and computes the

}

// NewElementReader - creates new JSON reader using readCloser.
func NewElementReader(ch chan simdjson.Object, err *error, args *json.ReaderArgs) *Reader {
	return &Reader{
		args:       args,
		decoded:    ch,
		err:        err,
		readCloser: nil,
	}
}

// safeCloser will wrap a Reader as a ReadCloser.
// It is safe to call Close while the reader is being used.
type safeCloser struct {
	closed uint32

	"github.com/minio/minio/internal/s3select/sql"
)

// Reader implements reading records from parquet input.
type Reader struct {
	io.Closer
	r *parquetgo.FileReader
}

// NewParquetReader creates a Reader2 from a io.ReadSeekCloser.
func NewParquetReader(rsc io.ReadSeekCloser, _ *ReaderArgs) (r *Reader, err error) {
	fr, err := parquetgo.NewFileReader(rsc)
	if err != nil {

// NewMonitoredReader returns reference to a monitored reader that throttles reads to configured bandwidth for the
// bucket.
func NewMonitoredReader(ctx context.Context, m *Monitor, r io.Reader, opts *MonitorReaderOptions) *MonitoredReader {
	reader := MonitoredReader{
		r:        r,
		throttle: m.throttle(opts.BucketOptions),
		m:        m,
		opts:     opts,
		ctx:      ctx,
	}
	reader.m.init(opts.BucketOptions)
	return &reader