diff --git a/go.mod b/go.mod index 63ee7f190..cd131add8 100644 --- a/go.mod +++ b/go.mod @@ -46,7 +46,7 @@ require ( github.com/mitchellh/mapstructure v1.5.0 github.com/ncruces/go-sqlite3 v0.18.1 github.com/oklog/ulid v1.3.1 - github.com/prometheus/client_golang v1.20.2 + github.com/prometheus/client_golang v1.20.3 github.com/spf13/cobra v1.8.1 github.com/spf13/viper v1.19.0 github.com/stretchr/testify v1.9.0 diff --git a/go.sum b/go.sum index fb4d75015..dfc72ad54 100644 --- a/go.sum +++ b/go.sum @@ -468,8 +468,8 @@ github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 h1:Jamvg5psRI github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4= github.com/prashantv/gostub v1.1.0 h1:BTyx3RfQjRHnUWaGF9oQos79AlQ5k8WNktv7VGvVH4g= github.com/prashantv/gostub v1.1.0/go.mod h1:A5zLQHz7ieHGG7is6LLXLz7I8+3LZzsrV0P1IAHhP5U= -github.com/prometheus/client_golang v1.20.2 h1:5ctymQzZlyOON1666svgwn3s6IKWgfbjsejTMiXIyjg= -github.com/prometheus/client_golang v1.20.2/go.mod h1:PIEt8X02hGcP8JWbeHyeZ53Y/jReSnHgO035n//V5WE= +github.com/prometheus/client_golang v1.20.3 h1:oPksm4K8B+Vt35tUhw6GbSNSgVlVSBH0qELP/7u83l4= +github.com/prometheus/client_golang v1.20.3/go.mod h1:PIEt8X02hGcP8JWbeHyeZ53Y/jReSnHgO035n//V5WE= github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA= github.com/prometheus/client_model v0.6.1 h1:ZKSh/rekM+n3CeS952MLRAdFwIKqeY8b62p8ais2e9E= github.com/prometheus/client_model v0.6.1/go.mod h1:OrxVMOVHjw3lKMa8+x6HeMGkHMQyHDk9E3jmP2AmGiY= diff --git a/vendor/github.com/prometheus/client_golang/prometheus/histogram.go b/vendor/github.com/prometheus/client_golang/prometheus/histogram.go index 8d35f2d8a..8a4f49a4c 100644 --- a/vendor/github.com/prometheus/client_golang/prometheus/histogram.go +++ b/vendor/github.com/prometheus/client_golang/prometheus/histogram.go @@ -1658,7 +1658,10 @@ func addAndResetCounts(hot, cold *histogramCounts) { type nativeExemplars struct { sync.Mutex - ttl time.Duration + // Time-to-live for exemplars, it is set to -1 if exemplars are disabled, that is NativeHistogramMaxExemplars is below 0. + // The ttl is used on insertion to remove an exemplar that is older than ttl, if present. + ttl time.Duration + exemplars []*dto.Exemplar } @@ -1673,6 +1676,7 @@ func makeNativeExemplars(ttl time.Duration, maxCount int) nativeExemplars { if maxCount < 0 { maxCount = 0 + ttl = -1 } return nativeExemplars{ @@ -1682,20 +1686,18 @@ func makeNativeExemplars(ttl time.Duration, maxCount int) nativeExemplars { } func (n *nativeExemplars) addExemplar(e *dto.Exemplar) { - if cap(n.exemplars) == 0 { + if n.ttl == -1 { return } n.Lock() defer n.Unlock() - // The index where to insert the new exemplar. - var nIdx int = -1 - // When the number of exemplars has not yet exceeded or // is equal to cap(n.exemplars), then // insert the new exemplar directly. if len(n.exemplars) < cap(n.exemplars) { + var nIdx int for nIdx = 0; nIdx < len(n.exemplars); nIdx++ { if *e.Value < *n.exemplars[nIdx].Value { break @@ -1705,17 +1707,46 @@ func (n *nativeExemplars) addExemplar(e *dto.Exemplar) { return } + if len(n.exemplars) == 1 { + // When the number of exemplars is 1, then + // replace the existing exemplar with the new exemplar. + n.exemplars[0] = e + return + } + // From this point on, the number of exemplars is greater than 1. + // When the number of exemplars exceeds the limit, remove one exemplar. var ( - rIdx int // The index where to remove the old exemplar. + ot = time.Time{} // Oldest timestamp seen. Initial value doesn't matter as we replace it due to otIdx == -1 in the loop. + otIdx = -1 // Index of the exemplar with the oldest timestamp. - ot = time.Now() // Oldest timestamp seen. - otIdx = -1 // Index of the exemplar with the oldest timestamp. + md = -1.0 // Logarithm of the delta of the closest pair of exemplars. - md = -1.0 // Logarithm of the delta of the closest pair of exemplars. - mdIdx = -1 // Index of the older exemplar within the closest pair. - cLog float64 // Logarithm of the current exemplar. - pLog float64 // Logarithm of the previous exemplar. + // The insertion point of the new exemplar in the exemplars slice after insertion. + // This is calculated purely based on the order of the exemplars by value. + // nIdx == len(n.exemplars) means the new exemplar is to be inserted after the end. + nIdx = -1 + + // rIdx is ultimately the index for the exemplar that we are replacing with the new exemplar. + // The aim is to keep a good spread of exemplars by value and not let them bunch up too much. + // It is calculated in 3 steps: + // 1. First we set rIdx to the index of the older exemplar within the closest pair by value. + // That is the following will be true (on log scale): + // either the exemplar pair on index (rIdx-1, rIdx) or (rIdx, rIdx+1) will have + // the closest values to each other from all pairs. + // For example, suppose the values are distributed like this: + // |-----------x-------------x----------------x----x-----| + // ^--rIdx as this is older. + // Or like this: + // |-----------x-------------x----------------x----x-----| + // ^--rIdx as this is older. + // 2. If there is an exemplar that expired, then we simple reset rIdx to that index. + // 3. We check if by inserting the new exemplar we would create a closer pair at + // (nIdx-1, nIdx) or (nIdx, nIdx+1) and set rIdx to nIdx-1 or nIdx accordingly to + // keep the spread of exemplars by value; otherwise we keep rIdx as it is. + rIdx = -1 + cLog float64 // Logarithm of the current exemplar. + pLog float64 // Logarithm of the previous exemplar. ) for i, exemplar := range n.exemplars { @@ -1726,7 +1757,7 @@ func (n *nativeExemplars) addExemplar(e *dto.Exemplar) { } // Find the index at which to insert new the exemplar. - if *e.Value <= *exemplar.Value && nIdx == -1 { + if nIdx == -1 && *e.Value <= *exemplar.Value { nIdx = i } @@ -1738,11 +1769,13 @@ func (n *nativeExemplars) addExemplar(e *dto.Exemplar) { } diff := math.Abs(cLog - pLog) if md == -1 || diff < md { + // The closest exemplar pair is at index: i-1, i. + // Choose the exemplar with the older timestamp for replacement. md = diff if n.exemplars[i].Timestamp.AsTime().Before(n.exemplars[i-1].Timestamp.AsTime()) { - mdIdx = i + rIdx = i } else { - mdIdx = i - 1 + rIdx = i - 1 } } @@ -1753,8 +1786,12 @@ func (n *nativeExemplars) addExemplar(e *dto.Exemplar) { if nIdx == -1 { nIdx = len(n.exemplars) } + // Here, we have the following relationships: + // n.exemplars[nIdx-1].Value < e.Value (if nIdx > 0) + // e.Value <= n.exemplars[nIdx].Value (if nIdx < len(n.exemplars)) if otIdx != -1 && e.Timestamp.AsTime().Sub(ot) > n.ttl { + // If the oldest exemplar has expired, then replace it with the new exemplar. rIdx = otIdx } else { // In the previous for loop, when calculating the closest pair of exemplars, @@ -1764,23 +1801,26 @@ func (n *nativeExemplars) addExemplar(e *dto.Exemplar) { if nIdx > 0 { diff := math.Abs(elog - math.Log(n.exemplars[nIdx-1].GetValue())) if diff < md { + // The value we are about to insert is closer to the previous exemplar at the insertion point than what we calculated before in rIdx. + // v--rIdx + // |-----------x-n-----------x----------------x----x-----| + // nIdx-1--^ ^--new exemplar value + // Do not make the spread worse, replace nIdx-1 and not rIdx. md = diff - mdIdx = nIdx - if n.exemplars[nIdx-1].Timestamp.AsTime().Before(e.Timestamp.AsTime()) { - mdIdx = nIdx - 1 - } + rIdx = nIdx - 1 } } if nIdx < len(n.exemplars) { diff := math.Abs(math.Log(n.exemplars[nIdx].GetValue()) - elog) if diff < md { - mdIdx = nIdx - if n.exemplars[nIdx].Timestamp.AsTime().Before(e.Timestamp.AsTime()) { - mdIdx = nIdx - } + // The value we are about to insert is closer to the next exemplar at the insertion point than what we calculated before in rIdx. + // v--rIdx + // |-----------x-----------n-x----------------x----x-----| + // new exemplar value--^ ^--nIdx + // Do not make the spread worse, replace nIdx-1 and not rIdx. + rIdx = nIdx } } - rIdx = mdIdx } // Adjust the slice according to rIdx and nIdx. diff --git a/vendor/modules.txt b/vendor/modules.txt index 3132ca140..5a04b2f5d 100644 --- a/vendor/modules.txt +++ b/vendor/modules.txt @@ -561,7 +561,7 @@ github.com/pkg/errors # github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 ## explicit github.com/pmezard/go-difflib/difflib -# github.com/prometheus/client_golang v1.20.2 +# github.com/prometheus/client_golang v1.20.3 ## explicit; go 1.20 github.com/prometheus/client_golang/internal/github.com/golang/gddo/httputil github.com/prometheus/client_golang/internal/github.com/golang/gddo/httputil/header