feat: bring new HDD related performance enhancements (#18239)

Optionally allows customers to enable 

- Enable an external cache to catch GET/HEAD responses 
- Enable skipping disks that are slow to respond in GET/HEAD 
  when we have already achieved a quorum

internal/config/cache/remote.go

@@ -0,0 +1,111 @@
+package cache
+
+import (
+	"net/http"
+	"regexp"
+	"strconv"
+	"time"
+
+	"github.com/minio/minio/internal/amztime"
+	xhttp "github.com/minio/minio/internal/http"
+)
+
+//go:generate msgp -file=$GOFILE
+
+// ObjectInfo represents the object information cached remotely
+type ObjectInfo struct {
+	Key        string    `json:"key"`
+	Bucket     string    `json:"bucket"`
+	ETag       string    `json:"etag"`
+	ModTime    time.Time `json:"modTime"`
+	StatusCode int       `json:"statusCode"`
+
+	// Optional elements
+	CacheControl string            `json:"cacheControl,omitempty" msg:",omitempty"`
+	Expires      string            `json:"expires,omitempty" msg:",omitempty"`
+	Metadata     map[string]string `json:"metadata,omitempty" msg:",omitempty"`
+	Range        string            `json:"range,omitempty" msg:",omitempty"`
+	PartNumber   int               `json:"partNumber,omitempty" msg:",omitempty"`
+	Size         int64             `json:"size,omitempty" msg:",omitempty"` // Full size of the object
+	Data         []byte            `json:"data,omitempty" msg:",omitempty"` // Data can container full data of the object or partial
+}
+
+// WriteHeaders writes the response headers for conditional requests
+func (oi ObjectInfo) WriteHeaders(w http.ResponseWriter, preamble, statusCode func()) {
+	preamble()
+
+	if !oi.ModTime.IsZero() {
+		w.Header().Set(xhttp.LastModified, oi.ModTime.UTC().Format(http.TimeFormat))
+	}
+
+	if oi.ETag != "" {
+		w.Header()[xhttp.ETag] = []string{"\"" + oi.ETag + "\""}
+	}
+
+	if oi.Expires != "" {
+		w.Header().Set(xhttp.Expires, oi.Expires)
+	}
+
+	if oi.CacheControl != "" {
+		w.Header().Set(xhttp.CacheControl, oi.CacheControl)
+	}
+
+	statusCode()
+}
+
+// CondCheck represents the conditional request made to the remote cache
+// for validation during GET/HEAD object requests.
+type CondCheck struct {
+	ObjectInfo
+	IfMatch           string     `json:"ifMatch,omitempty" msg:",omitempty"`
+	IfNoneMatch       string     `json:"ifNoneMatch,omitempty" msg:",omitempty"`
+	IfModifiedSince   *time.Time `json:"ifModSince,omitempty" msg:",omitempty"`
+	IfUnModifiedSince *time.Time `json:"ifUnmodSince,omitempty" msg:",omitempty"`
+	IfRange           string     `json:"ifRange,omitempty" msg:",omitempty"`
+	IfPartNumber      int        `json:"ifPartNumber,omitempty" msg:",omitempty"`
+}
+
+// IsSet tells the cache lookup to avoid sending a request
+func (r *CondCheck) IsSet() bool {
+	if r == nil {
+		return false
+	}
+	return r.IfMatch != "" || r.IfNoneMatch != "" || r.IfModifiedSince != nil || r.IfUnModifiedSince != nil || r.IfRange != ""
+}
+
+var etagRegex = regexp.MustCompile("\"*?([^\"]*?)\"*?$")
+
+// canonicalizeETag returns ETag with leading and trailing double-quotes removed,
+// if any present
+func canonicalizeETag(etag string) string {
+	return etagRegex.ReplaceAllString(etag, "$1")
+}
+
+// Init - populates the input values, initializes CondCheck
+// before sending the request remotely.
+func (r *CondCheck) Init(bucket, object string, header http.Header) {
+	r.Key = object
+	r.Bucket = bucket
+
+	ifModifiedSinceHeader := header.Get(xhttp.IfModifiedSince)
+	if ifModifiedSinceHeader != "" {
+		if givenTime, err := amztime.ParseHeader(ifModifiedSinceHeader); err == nil {
+			r.IfModifiedSince = &givenTime
+		}
+	}
+	ifUnmodifiedSinceHeader := header.Get(xhttp.IfUnmodifiedSince)
+	if ifUnmodifiedSinceHeader != "" {
+		if givenTime, err := amztime.ParseHeader(ifUnmodifiedSinceHeader); err == nil {
+			r.IfUnModifiedSince = &givenTime
+		}
+	}
+	r.IfMatch = canonicalizeETag(header.Get(xhttp.IfMatch))
+	r.IfNoneMatch = canonicalizeETag(header.Get(xhttp.IfNoneMatch))
+	r.IfRange = header.Get(xhttp.Range)
+	ifPartNumberHeader := header.Get(xhttp.PartNumber)
+	if ifPartNumberHeader != "" {
+		if partNumber, err := strconv.Atoi(ifPartNumberHeader); err == nil {
+			r.IfPartNumber = partNumber
+		}
+	}
+}