*: Flamegraph data trimming (#2299)

* Flame graph data trimming

* [pre-commit.ci lite] apply automatic fixes

* Provision to pass the nodeCutOffFraction from the UI

* Introduced a user preference hook that supports types other than boolean and hooked in NodeCutOffThreshold prefrence for the query request

* Type-check failures fixed

* Modified trimming to happen based on the screen size

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

gen/proto/swagger/parca/query/v1alpha1/query.swagger.json

@@ -318,6 +318,14 @@
             "in": "query",
             "required": false,
             "type": "string"
+          },
+          {
+            "name": "nodeTrimThreshold",
+            "description": "node_trim_threshold is the threshold % where the nodes with Value less than this will be removed from the report",
+            "in": "query",
+            "required": false,
+            "type": "number",
+            "format": "float"
           }
         ],
         "tags": [
@@ -699,6 +707,11 @@
         "filterQuery": {
           "type": "string",
           "title": "filter_query is the query string to filter the profile samples"
+        },
+        "nodeTrimThreshold": {
+          "type": "number",
+          "format": "float",
+          "title": "node_trim_threshold is the threshold % where the nodes with Value less than this will be removed from the report"
         }
       },
       "title": "QueryRequest is a request for a profile query"
@@ -941,6 +954,11 @@
             "$ref": "#/definitions/metastorev1alpha1Function"
           },
           "description": "function deduplicated by their ID to be referenced by nodes."
+        },
+        "untrimmedTotal": {
+          "type": "string",
+          "format": "int64",
+          "title": "untrimmed_total is the total weight of the flame graph before trimming"
         }
       },
       "title": "Flamegraph is the flame graph report type"

gen/proto/swagger/parca/share/v1alpha1/share.swagger.json

@@ -413,6 +413,11 @@
             "$ref": "#/definitions/metastorev1alpha1Function"
           },
           "description": "function deduplicated by their ID to be referenced by nodes."
+        },
+        "untrimmedTotal": {
+          "type": "string",
+          "format": "int64",
+          "title": "untrimmed_total is the total weight of the flame graph before trimming"
         }
       },
       "title": "Flamegraph is the flame graph report type"

pkg/query/callgraph.go

@@ -26,7 +26,7 @@ import (
 )
 
 const (
-	NodeCutOffFraction = 0.005
+	NodeCutOffFraction = float32(0.005)
 )
 
 func GenerateCallgraph(ctx context.Context, p *profile.Profile) (*querypb.Callgraph, error) {
@@ -182,7 +182,7 @@ func prunableNodes(nodes []*querypb.CallgraphNode, c int64) []*querypb.Callgraph
 		return nodes[i].Cumulative > nodes[j].Cumulative
 	})
 	i := 0
-	cutoffValue := (float64(c) * NodeCutOffFraction)
+	cutoffValue := (float64(c) * float64(NodeCutOffFraction))
 	for ; i < len(nodes); i++ {
 		if float64(nodes[i].Cumulative) < cutoffValue {
 			break

pkg/query/columnquery.go

@@ -148,7 +148,7 @@ func (q *ColumnQueryAPI) Query(ctx context.Context, req *pb.QueryRequest) (*pb.Q
 		p = q.filterProfileData(ctx, p, *req.FilterQuery)
 	}
 
-	return q.renderReport(ctx, p, req.GetReportType())
+	return q.renderReport(ctx, p, req.GetReportType(), req.GetNodeTrimThreshold())
 }
 
 func keepSample(s *profile.SymbolizedSample, filterQuery string) bool {
@@ -177,11 +177,16 @@ func (q *ColumnQueryAPI) filterProfileData(ctx context.Context, p *profile.Profi
 	}
 }
 
-func (q *ColumnQueryAPI) renderReport(ctx context.Context, p *profile.Profile, typ pb.QueryRequest_ReportType) (*pb.QueryResponse, error) {
+func (q *ColumnQueryAPI) renderReport(ctx context.Context, p *profile.Profile, typ pb.QueryRequest_ReportType, nodeTrimThreshold float32) (*pb.QueryResponse, error) {
 	ctx, span := q.tracer.Start(ctx, "renderReport")
 	span.SetAttributes(attribute.String("reportType", typ.String()))
 	defer span.End()
 
+	nodeTrimFraction := float32(0)
+	if nodeTrimThreshold != 0 {
+		nodeTrimFraction = nodeTrimThreshold / 100
+	}
+
 	switch typ {
 	//nolint:staticcheck // SA1019: Fow now we want to support these APIs
 	case pb.QueryRequest_REPORT_TYPE_FLAMEGRAPH_UNSPECIFIED:
@@ -195,7 +200,7 @@ func (q *ColumnQueryAPI) renderReport(ctx context.Context, p *profile.Profile, t
 			},
 		}, nil
 	case pb.QueryRequest_REPORT_TYPE_FLAMEGRAPH_TABLE:
-		fg, err := GenerateFlamegraphTable(ctx, q.tracer, p)
+		fg, err := GenerateFlamegraphTable(ctx, q.tracer, p, nodeTrimFraction)
 		if err != nil {
 			return nil, status.Errorf(codes.Internal, "failed to generate flamegraph: %v", err.Error())
 		}

pkg/query/flamegraph_table.go

@@ -24,7 +24,7 @@ import (
 	"github.com/parca-dev/parca/pkg/profile"
 )
 
-func GenerateFlamegraphTable(ctx context.Context, tracer trace.Tracer, p *profile.Profile) (*querypb.Flamegraph, error) {
+func GenerateFlamegraphTable(ctx context.Context, tracer trace.Tracer, p *profile.Profile, nodeTrimFraction float32) (*querypb.Flamegraph, error) {
 	rootNode := &querypb.FlamegraphNode{}
 	current := rootNode
 
@@ -104,9 +104,10 @@ func GenerateFlamegraphTable(ctx context.Context, tracer trace.Tracer, p *profil
 			Diff:       rootNode.Diff,
 			Children:   rootNode.Children,
 		},
-		Total:  rootNode.Cumulative,
-		Unit:   p.Meta.SampleType.Unit,
-		Height: height + 1, // add one for the root
+		Total:          rootNode.Cumulative,
+		UntrimmedTotal: rootNode.Cumulative,
+		Unit:           p.Meta.SampleType.Unit,
+		Height:         height + 1, // add one for the root
 
 		StringTable: tables.Strings(),
 		Mapping:     tables.Mappings(),
@@ -120,7 +121,13 @@ func GenerateFlamegraphTable(ctx context.Context, tracer trace.Tracer, p *profil
 		f.Id = ""
 	}
 
-	return aggregateByFunctionTable(tables, flamegraph), nil
+	aggregatedFlamegraph := aggregateByFunctionTable(tables, flamegraph)
+
+	if nodeTrimFraction == 0 {
+		return aggregatedFlamegraph, nil
+	}
+
+	return TrimFlamegraph(ctx, tracer, aggregatedFlamegraph, nodeTrimFraction), nil
 }
 
 type tableConverter struct {
@@ -475,3 +482,83 @@ func equalsByNameTable(tables TableGetter, a, b *querypb.FlamegraphNode) bool {
 	strings := tables.Strings()
 	return strings[aFunction.NameStringIndex] == strings[bFunction.NameStringIndex]
 }
+
+type FlamegraphChildren []*querypb.FlamegraphNode
+
+func (n FlamegraphChildren) Cumulative() int64 {
+	cumulative := int64(0)
+	for _, child := range n {
+		cumulative += child.Cumulative
+	}
+	return cumulative
+}
+
+func (n FlamegraphChildren) Diff() int64 {
+	diff := int64(0)
+	for _, child := range n {
+		diff += child.Diff
+	}
+	return diff
+}
+
+func TrimFlamegraph(ctx context.Context, tracer trace.Tracer, graph *querypb.Flamegraph, thresholdRate float32) *querypb.Flamegraph {
+	ctx, span := tracer.Start(ctx, "trimFlamegraph")
+	defer span.End()
+	if graph == nil {
+		return nil
+	}
+	total := graph.Total
+
+	threshold := int64(float64(thresholdRate) * float64(total))
+	var children FlamegraphChildren = trimFlamegraphNodes(ctx, tracer, graph.Root.Children, threshold)
+	newTotal := int64(0)
+	newDiff := int64(0)
+	if len(graph.Root.Children) > 0 {
+		newTotal = children.Cumulative()
+		newDiff = children.Diff()
+	}
+
+	trimmedGraph := &querypb.Flamegraph{
+		Root: &querypb.FlamegraphRootNode{
+			Children:   children,
+			Cumulative: newTotal,
+			Diff:       newDiff,
+		},
+		Total:          newTotal,
+		UntrimmedTotal: graph.Total,
+		Unit:           graph.Unit,
+		Height:         graph.Height,
+		StringTable:    graph.StringTable,
+		Locations:      graph.Locations,
+		Mapping:        graph.Mapping,
+		Function:       graph.Function,
+	}
+
+	return trimmedGraph
+}
+
+func trimFlamegraphNodes(ctx context.Context, tracer trace.Tracer, nodes []*querypb.FlamegraphNode, threshold int64) []*querypb.FlamegraphNode {
+	var trimmedNodes []*querypb.FlamegraphNode
+	for _, node := range nodes {
+		if node.Cumulative < threshold {
+			continue
+		}
+		var children FlamegraphChildren = trimFlamegraphNodes(ctx, tracer, node.Children, threshold)
+		newCum := int64(0)
+		newDiff := int64(0)
+		if len(node.Children) > 0 {
+			newCum = children.Cumulative()
+			newDiff = children.Diff()
+		} else {
+			newCum = node.Cumulative
+			newDiff = node.Diff
+		}
+		trimmedNodes = append(trimmedNodes, &querypb.FlamegraphNode{
+			Meta:       node.Meta,
+			Cumulative: newCum,
+			Diff:       newDiff,
+			Children:   children,
+		})
+	}
+	return trimmedNodes
+}