Merge release 1.21.1 to main.

CHANGELOG.md

@@ -1,5 +1,10 @@
 ## Unreleased
 
+## 1.21.1 / 2025-03-04
+
+* [BUGFIX] prometheus: Revert of `Inc`, `Add` and `Observe` cumulative metric CAS optimizations (#1661), causing regressions on low contention cases.
+* [BUGFIX] prometheus: Fix GOOS=ios build, broken due to process_collector_* wrong build tags.
+
 ## 1.21.0 / 2025-02-17
 
 :warning: This release contains potential breaking change if you upgrade `github.com/prometheus/common` to 0.62+ together with client_golang. :warning:

VERSION

@@ -1 +1 @@
-1.21.0
+1.21.1

prometheus/counter.go

@@ -134,9 +134,13 @@ func (c *counter) Add(v float64) {
 		return
 	}
 
-	atomicUpdateFloat(&c.valBits, func(oldVal float64) float64 {
-		return oldVal + v
-	})
+	for {
+		oldBits := atomic.LoadUint64(&c.valBits)
+		newBits := math.Float64bits(math.Float64frombits(oldBits) + v)
+		if atomic.CompareAndSwapUint64(&c.valBits, oldBits, newBits) {
+			return
+		}
+	}
 }
 
 func (c *counter) AddWithExemplar(v float64, e Labels) {

prometheus/gauge.go

@@ -120,9 +120,13 @@ func (g *gauge) Dec() {
 }
 
 func (g *gauge) Add(val float64) {
-	atomicUpdateFloat(&g.valBits, func(oldVal float64) float64 {
-		return oldVal + val
-	})
+	for {
+		oldBits := atomic.LoadUint64(&g.valBits)
+		newBits := math.Float64bits(math.Float64frombits(oldBits) + val)
+		if atomic.CompareAndSwapUint64(&g.valBits, oldBits, newBits) {
+			return
+		}
+	}
 }
 
 func (g *gauge) Sub(val float64) {

prometheus/histogram.go

@@ -1647,9 +1647,13 @@ func waitForCooldown(count uint64, counts *histogramCounts) {
 // atomicAddFloat adds the provided float atomically to another float
 // represented by the bit pattern the bits pointer is pointing to.
 func atomicAddFloat(bits *uint64, v float64) {
-	atomicUpdateFloat(bits, func(oldVal float64) float64 {
-		return oldVal + v
-	})
+	for {
+		loadedBits := atomic.LoadUint64(bits)
+		newBits := math.Float64bits(math.Float64frombits(loadedBits) + v)
+		if atomic.CompareAndSwapUint64(bits, loadedBits, newBits) {
+			break
+		}
+	}
 }
 
 // atomicDecUint32 atomically decrements the uint32 p points to.  See

prometheus/process_collector_darwin.go

@@ -11,6 +11,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//go:build darwin && !ios
+
 package prometheus
 
 import (

prometheus/process_collector_cgo_darwin.c → prometheus/process_collector_mem_cgo_darwin.c

@@ -11,7 +11,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build darwin && cgo
+//go:build darwin && !ios && cgo
 
 #include <mach/mach_init.h>
 #include <mach/task.h>

prometheus/process_collector_cgo_darwin.go → prometheus/process_collector_mem_cgo_darwin.go

@@ -11,7 +11,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build darwin && cgo
+//go:build darwin && !ios && cgo
 
 package prometheus
 

prometheus/process_collector_nocgo_darwin.go → prometheus/process_collector_mem_nocgo_darwin.go

@@ -11,7 +11,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build darwin && !cgo
+//go:build darwin && !ios && !cgo
 
 package prometheus
 

prometheus/process_collector_wasip1_js.go → prometheus/process_collector_not_supported.go

@@ -11,8 +11,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build wasip1 || js
-// +build wasip1 js
+//go:build wasip1 || js || ios
+// +build wasip1 js ios
 
 package prometheus
 

prometheus/summary.go

@@ -471,9 +471,13 @@ func (s *noObjectivesSummary) Observe(v float64) {
 	n := atomic.AddUint64(&s.countAndHotIdx, 1)
 	hotCounts := s.counts[n>>63]
 
-	atomicUpdateFloat(&hotCounts.sumBits, func(oldVal float64) float64 {
-		return oldVal + v
-	})
+	for {
+		oldBits := atomic.LoadUint64(&hotCounts.sumBits)
+		newBits := math.Float64bits(math.Float64frombits(oldBits) + v)
+		if atomic.CompareAndSwapUint64(&hotCounts.sumBits, oldBits, newBits) {
+			break
+		}
+	}
 	// Increment count last as we take it as a signal that the observation
 	// is complete.
 	atomic.AddUint64(&hotCounts.count, 1)
@@ -515,13 +519,14 @@ func (s *noObjectivesSummary) Write(out *dto.Metric) error {
 	// Finally add all the cold counts to the new hot counts and reset the cold counts.
 	atomic.AddUint64(&hotCounts.count, count)
 	atomic.StoreUint64(&coldCounts.count, 0)
-
-	// Use atomicUpdateFloat to update hotCounts.sumBits atomically.
-	atomicUpdateFloat(&hotCounts.sumBits, func(oldVal float64) float64 {
-		return oldVal + sum.GetSampleSum()
-	})
-	atomic.StoreUint64(&coldCounts.sumBits, 0)
-
+	for {
+		oldBits := atomic.LoadUint64(&hotCounts.sumBits)
+		newBits := math.Float64bits(math.Float64frombits(oldBits) + sum.GetSampleSum())
+		if atomic.CompareAndSwapUint64(&hotCounts.sumBits, oldBits, newBits) {
+			atomic.StoreUint64(&coldCounts.sumBits, 0)
+			break
+		}
+	}
 	return nil
 }