[v2][query] Implement helper to buffer sequence of traces (#6401)

## Which problem is this PR solving?
- Towards #6337 

## Description of the changes
- This PR implements a helper `AggregateTraces` in the `jptrace` package
to aggregate a sequence of `[]ptrace.Traces` to `ptrace.Traces`. This
was done by combining contiguous trace chunks together based on the
traceID.

## How was this change tested?
- Added unit tests

## Checklist
- [x] I have read
https://github.com/jaegertracing/jaeger/blob/master/CONTRIBUTING_GUIDELINES.md
- [x] I have signed all commits
- [x] I have added unit tests for the new functionality
- [x] I have run lint and test steps successfully
  - for `jaeger`: `make lint test`
  - for `jaeger-ui`: `npm run lint` and `npm run test`

---------

Signed-off-by: Mahad Zaryab <[email protected]>

Author: mahadzaryab1

internal/jptrace/aggregator.go

@@ -0,0 +1,55 @@
+// Copyright (c) 2024 The Jaeger Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package jptrace
+
+import (
+	"iter"
+
+	"go.opentelemetry.io/collector/pdata/pcommon"
+	"go.opentelemetry.io/collector/pdata/ptrace"
+)
+
+// AggregateTraces aggregates a sequence of trace batches into individual traces.
+//
+// The `tracesSeq` input must adhere to the chunking requirements of tracestore.Reader.GetTraces.
+func AggregateTraces(tracesSeq iter.Seq2[[]ptrace.Traces, error]) iter.Seq2[ptrace.Traces, error] {
+	return func(yield func(trace ptrace.Traces, err error) bool) {
+		currentTrace := ptrace.NewTraces()
+		currentTraceID := pcommon.NewTraceIDEmpty()
+
+		tracesSeq(func(traces []ptrace.Traces, err error) bool {
+			if err != nil {
+				yield(ptrace.NewTraces(), err)
+				return false
+			}
+			for _, trace := range traces {
+				resources := trace.ResourceSpans()
+				traceID := resources.At(0).ScopeSpans().At(0).Spans().At(0).TraceID()
+				if currentTraceID == traceID {
+					mergeTraces(trace, currentTrace)
+				} else {
+					if currentTrace.ResourceSpans().Len() > 0 {
+						if !yield(currentTrace, nil) {
+							return false
+						}
+					}
+					currentTrace = trace
+					currentTraceID = traceID
+				}
+			}
+			return true
+		})
+		if currentTrace.ResourceSpans().Len() > 0 {
+			yield(currentTrace, nil)
+		}
+	}
+}
+
+func mergeTraces(src, dest ptrace.Traces) {
+	resources := src.ResourceSpans()
+	for i := 0; i < resources.Len(); i++ {
+		resource := resources.At(i)
+		resource.CopyTo(dest.ResourceSpans().AppendEmpty())
+	}
+}

internal/jptrace/aggregator_test.go

@@ -0,0 +1,136 @@
+// Copyright (c) 2024 The Jaeger Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package jptrace
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/collector/pdata/pcommon"
+	"go.opentelemetry.io/collector/pdata/ptrace"
+)
+
+func TestAggregateTraces_AggregatesSpansWithSameTraceID(t *testing.T) {
+	trace1 := ptrace.NewTraces()
+	resource1 := trace1.ResourceSpans().AppendEmpty()
+	scope1 := resource1.ScopeSpans().AppendEmpty()
+	span1 := scope1.Spans().AppendEmpty()
+	span1.SetTraceID(pcommon.TraceID([16]byte{1}))
+	span1.SetName("span1")
+
+	trace1Continued := ptrace.NewTraces()
+	resource2 := trace1Continued.ResourceSpans().AppendEmpty()
+	scope2 := resource2.ScopeSpans().AppendEmpty()
+	span2 := scope2.Spans().AppendEmpty()
+	span2.SetTraceID(pcommon.TraceID([16]byte{1}))
+	span2.SetName("span2")
+
+	trace2 := ptrace.NewTraces()
+	resource3 := trace2.ResourceSpans().AppendEmpty()
+	scope3 := resource3.ScopeSpans().AppendEmpty()
+	span3 := scope3.Spans().AppendEmpty()
+	span3.SetTraceID(pcommon.TraceID([16]byte{2}))
+	span3.SetName("span3")
+
+	trace3 := ptrace.NewTraces()
+	resource4 := trace3.ResourceSpans().AppendEmpty()
+	scope4 := resource4.ScopeSpans().AppendEmpty()
+	span4 := scope4.Spans().AppendEmpty()
+	span4.SetTraceID(pcommon.TraceID([16]byte{3}))
+	span4.SetName("span4")
+
+	tracesSeq := func(yield func([]ptrace.Traces, error) bool) {
+		yield([]ptrace.Traces{trace1, trace1Continued, trace2}, nil)
+		yield([]ptrace.Traces{trace3}, nil)
+	}
+
+	var result []ptrace.Traces
+	AggregateTraces(tracesSeq)(func(trace ptrace.Traces, _ error) bool {
+		result = append(result, trace)
+		return true
+	})
+
+	require.Len(t, result, 3)
+
+	require.Equal(t, 2, result[0].ResourceSpans().Len())
+	require.Equal(t, 1, result[1].ResourceSpans().Len())
+	require.Equal(t, 1, result[2].ResourceSpans().Len())
+
+	gotSpan1 := result[0].ResourceSpans().At(0).ScopeSpans().At(0).Spans().At(0)
+	require.Equal(t, gotSpan1.TraceID(), pcommon.TraceID([16]byte{1}))
+	require.Equal(t, "span1", gotSpan1.Name())
+
+	gotSpan2 := result[0].ResourceSpans().At(1).ScopeSpans().At(0).Spans().At(0)
+	require.Equal(t, gotSpan2.TraceID(), pcommon.TraceID([16]byte{1}))
+	require.Equal(t, "span2", gotSpan2.Name())
+
+	gotSpan3 := result[1].ResourceSpans().At(0).ScopeSpans().At(0).Spans().At(0)
+	require.Equal(t, gotSpan3.TraceID(), pcommon.TraceID([16]byte{2}))
+	require.Equal(t, "span3", gotSpan3.Name())
+
+	gotSpan4 := result[2].ResourceSpans().At(0).ScopeSpans().At(0).Spans().At(0)
+	require.Equal(t, gotSpan4.TraceID(), pcommon.TraceID([16]byte{3}))
+	require.Equal(t, "span4", gotSpan4.Name())
+}
+
+func TestAggregateTraces_YieldsErrorFromTracesSeq(t *testing.T) {
+	trace1 := ptrace.NewTraces()
+	resource1 := trace1.ResourceSpans().AppendEmpty()
+	scope1 := resource1.ScopeSpans().AppendEmpty()
+	span1 := scope1.Spans().AppendEmpty()
+	span1.SetTraceID(pcommon.TraceID([16]byte{1}))
+	span1.SetName("span1")
+
+	tracesSeq := func(yield func([]ptrace.Traces, error) bool) {
+		if !yield(nil, assert.AnError) {
+			return
+		}
+		yield([]ptrace.Traces{trace1}, nil) // should not get here
+	}
+	aggregatedSeq := AggregateTraces(tracesSeq)
+
+	var lastResult ptrace.Traces
+	var lastErr error
+	aggregatedSeq(func(trace ptrace.Traces, e error) bool {
+		lastResult = trace
+		if e != nil {
+			lastErr = e
+		}
+		return true
+	})
+
+	require.ErrorIs(t, lastErr, assert.AnError)
+	require.Equal(t, ptrace.NewTraces(), lastResult)
+}
+
+func TestAggregateTraces_RespectsEarlyReturn(t *testing.T) {
+	trace1 := ptrace.NewTraces()
+	resource1 := trace1.ResourceSpans().AppendEmpty()
+	scope1 := resource1.ScopeSpans().AppendEmpty()
+	span1 := scope1.Spans().AppendEmpty()
+	span1.SetTraceID(pcommon.TraceID([16]byte{1}))
+	span1.SetName("span1")
+
+	trace2 := ptrace.NewTraces()
+	resource2 := trace2.ResourceSpans().AppendEmpty()
+	scope2 := resource2.ScopeSpans().AppendEmpty()
+	span2 := scope2.Spans().AppendEmpty()
+	span2.SetTraceID(pcommon.TraceID([16]byte{2}))
+	span2.SetName("span2")
+
+	tracesSeq := func(yield func([]ptrace.Traces, error) bool) {
+		yield([]ptrace.Traces{trace1}, nil)
+		yield([]ptrace.Traces{trace2}, nil)
+	}
+	aggregatedSeq := AggregateTraces(tracesSeq)
+
+	var lastResult ptrace.Traces
+	aggregatedSeq(func(trace ptrace.Traces, _ error) bool {
+		lastResult = trace
+		return false
+	})
+
+	require.Equal(t, trace1, lastResult)
+}

storage_v2/tracestore/reader.go

@@ -22,6 +22,7 @@ type Reader interface {
 	// Chunking requirements:
 	// - A single ptrace.Traces chunk MUST NOT contain spans from multiple traces.
 	// - Large traces MAY be split across multiple, *consecutive* ptrace.Traces chunks.
+	// - Each returned ptrace.Traces object MUST NOT be empty.
 	//
 	// Edge cases:
 	// - If no spans are found for any given trace ID, the ID is ignored.