core: disable alternative cold-GET logic; keep it for now

alex-aizman · alex-aizman · commit d41ca5daabe9 · 2025-05-20T19:04:57.000-04:00
* add temp feature flag `system-reserved`
* and invoke `cold-reopen` iff set

Signed-off-by: Alex Aizman &lt;alex.aizman@gmail.com&gt;
diff --git a/ais/tgtfcold.go b/ais/tgtfcold.go
@@ -21,6 +21,11 @@ import (
 
 const ftcg = "Warning: failed to cold-GET"
 
+// [NOTE]
+// The coldReopen path is now DISABLED by default and only enabled
+// with the `feat.SystemReserved` flag. This is (only) for internal
+// benchmarking and regression testing, and will be removed in a future
+// release. Do not enable `feat.SystemReserved` in production.
 func (goi *getOI) coldReopen(res *core.GetReaderResult) error {
 	var (
 		err    error
diff --git a/ais/tgtobj.go b/ais/tgtobj.go
@@ -724,21 +724,22 @@ do: // retry uplock or ec-recovery, the latter only once
 		goi.cold = true
 
 		//
-		// three alternative ways to cold GET
+		// alternative ways to cold GET
 		//
 		if goi.dpq.arch.path == "" && goi.dpq.arch.regx == "" &&
 			(ckconf.Type == cos.ChecksumNone || (!ckconf.ValidateColdGet && !ckconf.EnableReadRange)) {
-			if goi.ranges.Range == "" && goi.lom.IsFeatureSet(feat.StreamingColdGET) {
-				// 1)
+			switch {
+			case goi.ranges.Range == "" && goi.lom.IsFeatureSet(feat.StreamingColdGET):
 				err = goi.coldStream(&res)
-			} else {
-				// 2)
+				goi.unlocked = true
+				return 0, err
+			case goi.lom.IsFeatureSet(feat.SystemReserved): // TODO: deprecated; remove along with the feature flag
 				err = goi.coldReopen(&res)
+				goi.unlocked = true
+				return 0, err
 			}
-			goi.unlocked = true // always
-			return 0, err
 		}
-		// otherwise, 3) regular path
+		// otherwise, a regular path
 		ecode, err = goi.coldPut(&res)
 		if err != nil {
 			goi.unlocked = true
diff --git a/cmd/cli/cli/feat.go b/cmd/cli/cli/feat.go
@@ -47,6 +47,7 @@ var clusterFeatDesc = [...]string{
 	"when checking whether objects are identical trust only cryptographically secure checksums",
 	"when versioning info is requested, use ListObjectVersions API (beware: extremely slow, versioned S3 buckets only)",
 	"include (bucket, xaction) Prometheus variable labels with every GET and PUT transaction",
+	"system-reserved (do not set: the flag may be redefined or removed at any time)",
 
 	// "none" ====================
 }
diff --git a/cmn/feat/feat.go b/cmn/feat/feat.go
@@ -43,6 +43,7 @@ const (
 	TrustCryptoSafeChecksums  // when checking whether objects are identical trust only cryptographically secure checksums
 	S3ListObjectVersions      // when versioning info is requested, use ListObjectVersions API (beware: extremely slow, versioned S3 buckets only)
 	EnableDetailedPromMetrics // include (bucket, xaction) Prometheus variable labels with every GET and PUT transaction
+	SystemReserved            // reserved; do not set: the flag may be redefined or removed at any time
 )
 
 var Cluster = [...]string{
@@ -66,6 +67,7 @@ var Cluster = [...]string{
 	"Trust-Crypto-Safe-Checksums",
 	"S3-ListObjectVersions",
 	"Enable-Detailed-Prom-Metrics",
+	"System-Reserved",
 
 	// "none" ====================
 }

Original file line number	Diff line number	Diff line change
`@@ -47,6 +47,7 @@ var clusterFeatDesc = [...]string{`
`47`	`47`	`"when checking whether objects are identical trust only cryptographically secure checksums",`
`48`	`48`	`"when versioning info is requested, use ListObjectVersions API (beware: extremely slow, versioned S3 buckets only)",`
`49`	`49`	`"include (bucket, xaction) Prometheus variable labels with every GET and PUT transaction",`
	`50`	`+ "system-reserved (do not set: the flag may be redefined or removed at any time)",`
`50`	`51`
`51`	`52`	`// "none" ====================`
`52`	`53`	`}`
Original file line number	Diff line number	Diff line change
`@@ -43,6 +43,7 @@ const (`
`43`	`43`	`TrustCryptoSafeChecksums // when checking whether objects are identical trust only cryptographically secure checksums`
`44`	`44`	`S3ListObjectVersions // when versioning info is requested, use ListObjectVersions API (beware: extremely slow, versioned S3 buckets only)`
`45`	`45`	`EnableDetailedPromMetrics // include (bucket, xaction) Prometheus variable labels with every GET and PUT transaction`
	`46`	`+ SystemReserved // reserved; do not set: the flag may be redefined or removed at any time`
`46`	`47`	`)`
`47`	`48`
`48`	`49`	`var Cluster = [...]string{`
`@@ -66,6 +67,7 @@ var Cluster = [...]string{`
`66`	`67`	`"Trust-Crypto-Safe-Checksums",`
`67`	`68`	`"S3-ListObjectVersions",`
`68`	`69`	`"Enable-Detailed-Prom-Metrics",`
	`70`	`+ "System-Reserved",`
`69`	`71`
`70`	`72`	`// "none" ====================`
`71`	`73`	`}`