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// Copyright 2020 New Relic Corporation. All rights reserved.
// SPDX-License-Identifier: Apache-2.0
package internal
import (
"bytes"
"container/heap"
"sort"
"time"
"github.com/newrelic/go-agent/internal/jsonx"
)
// See https://source.datanerd.us/agents/agent-specs/blob/master/Transaction-Trace-LEGACY.md
type traceNodeHeap []traceNode
type traceNodeParams struct {
attributes map[SpanAttribute]jsonWriter
StackTrace StackTrace
TransactionGUID string
exclusiveDurationMillis *float64
}
type traceNode struct {
start segmentTime
stop segmentTime
threadID uint64
duration time.Duration
traceNodeParams
name string
}
func (h traceNodeHeap) Len() int { return len(h) }
func (h traceNodeHeap) Less(i, j int) bool { return h[i].duration < h[j].duration }
func (h traceNodeHeap) Swap(i, j int) { h[i], h[j] = h[j], h[i] }
// Push and Pop are unused: only heap.Init and heap.Fix are used.
func (h traceNodeHeap) Push(x interface{}) {}
func (h traceNodeHeap) Pop() interface{} { return nil }
// TxnTrace contains the work in progress transaction trace.
type TxnTrace struct {
Enabled bool
SegmentThreshold time.Duration
StackTraceThreshold time.Duration
nodes traceNodeHeap
maxNodes int
}
// getMaxNodes allows the maximum number of nodes to be overwritten for unit
// tests.
func (trace *TxnTrace) getMaxNodes() int {
if 0 != trace.maxNodes {
return trace.maxNodes
}
return maxTxnTraceNodes
}
// considerNode exists to prevent unnecessary calls to witnessNode: constructing
// the metric name and params map requires allocations.
func (trace *TxnTrace) considerNode(end segmentEnd) bool {
return trace.Enabled && (end.duration >= trace.SegmentThreshold)
}
func (trace *TxnTrace) witnessNode(end segmentEnd, name string, attrs spanAttributeMap, externalGUID string) {
node := traceNode{
start: end.start,
stop: end.stop,
duration: end.duration,
threadID: end.threadID,
name: name,
}
node.attributes = attrs
node.TransactionGUID = externalGUID
if !trace.considerNode(end) {
return
}
if trace.nodes == nil {
trace.nodes = make(traceNodeHeap, 0, startingTxnTraceNodes)
}
if end.exclusive >= trace.StackTraceThreshold {
node.StackTrace = GetStackTrace()
}
if max := trace.getMaxNodes(); len(trace.nodes) < max {
trace.nodes = append(trace.nodes, node)
if len(trace.nodes) == max {
heap.Init(trace.nodes)
}
return
}
if node.duration <= trace.nodes[0].duration {
return
}
trace.nodes[0] = node
heap.Fix(trace.nodes, 0)
}
// HarvestTrace contains a finished transaction trace ready for serialization to
// the collector.
type HarvestTrace struct {
TxnEvent
Trace TxnTrace
}
type nodeDetails struct {
name string
relativeStart time.Duration
relativeStop time.Duration
traceNodeParams
}
func printNodeStart(buf *bytes.Buffer, n nodeDetails) {
// time.Seconds() is intentionally not used here. Millisecond
// precision is enough.
relativeStartMillis := n.relativeStart.Nanoseconds() / (1000 * 1000)
relativeStopMillis := n.relativeStop.Nanoseconds() / (1000 * 1000)
buf.WriteByte('[')
jsonx.AppendInt(buf, relativeStartMillis)
buf.WriteByte(',')
jsonx.AppendInt(buf, relativeStopMillis)
buf.WriteByte(',')
jsonx.AppendString(buf, n.name)
buf.WriteByte(',')
w := jsonFieldsWriter{buf: buf}
buf.WriteByte('{')
if nil != n.StackTrace {
w.writerField("backtrace", n.StackTrace)
}
if nil != n.exclusiveDurationMillis {
w.floatField("exclusive_duration_millis", *n.exclusiveDurationMillis)
}
if "" != n.TransactionGUID {
w.stringField("transaction_guid", n.TransactionGUID)
}
for k, v := range n.attributes {
w.writerField(k.String(), v)
}
buf.WriteByte('}')
buf.WriteByte(',')
buf.WriteByte('[')
}
func printChildren(buf *bytes.Buffer, traceStart time.Time, nodes sortedTraceNodes, next int, stop *segmentStamp, threadID uint64) int {
firstChild := true
for {
if next >= len(nodes) {
// No more children to print.
break
}
if nodes[next].threadID != threadID {
// The next node is not of the same thread. Due to the
// node sorting, all nodes of the same thread should be
// together.
break
}
if stop != nil && nodes[next].start.Stamp >= *stop {
// Make sure this node is a child of the parent that is
// being printed.
break
}
if firstChild {
firstChild = false
} else {
buf.WriteByte(',')
}
printNodeStart(buf, nodeDetails{
name: nodes[next].name,
relativeStart: nodes[next].start.Time.Sub(traceStart),
relativeStop: nodes[next].stop.Time.Sub(traceStart),
traceNodeParams: nodes[next].traceNodeParams,
})
next = printChildren(buf, traceStart, nodes, next+1, &nodes[next].stop.Stamp, threadID)
buf.WriteString("]]")
}
return next
}
type sortedTraceNodes []*traceNode
func (s sortedTraceNodes) Len() int { return len(s) }
func (s sortedTraceNodes) Less(i, j int) bool {
// threadID is the first sort key and start.Stamp is the second key.
if s[i].threadID == s[j].threadID {
return s[i].start.Stamp < s[j].start.Stamp
}
return s[i].threadID < s[j].threadID
}
func (s sortedTraceNodes) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
// MarshalJSON is used for testing.
//
// TODO: Eliminate this entirely by using harvestTraces.Data().
func (trace *HarvestTrace) MarshalJSON() ([]byte, error) {
buf := bytes.NewBuffer(make([]byte, 0, 100+100*trace.Trace.nodes.Len()))
trace.writeJSON(buf)
return buf.Bytes(), nil
}
func (trace *HarvestTrace) writeJSON(buf *bytes.Buffer) {
nodes := make(sortedTraceNodes, len(trace.Trace.nodes))
for i := 0; i < len(nodes); i++ {
nodes[i] = &trace.Trace.nodes[i]
}
sort.Sort(nodes)
buf.WriteByte('[') // begin trace
jsonx.AppendInt(buf, trace.Start.UnixNano()/1000)
buf.WriteByte(',')
jsonx.AppendFloat(buf, trace.Duration.Seconds()*1000.0)
buf.WriteByte(',')
jsonx.AppendString(buf, trace.FinalName)
buf.WriteByte(',')
if uri, _ := trace.Attrs.GetAgentValue(attributeRequestURI, destTxnTrace); "" != uri {
jsonx.AppendString(buf, uri)
} else {
buf.WriteString("null")
}
buf.WriteByte(',')
buf.WriteByte('[') // begin trace data
// If the trace string pool is used, insert another array here.
jsonx.AppendFloat(buf, 0.0) // unused timestamp
buf.WriteByte(',') //
buf.WriteString("{}") // unused: formerly request parameters
buf.WriteByte(',') //
buf.WriteString("{}") // unused: formerly custom parameters
buf.WriteByte(',') //
printNodeStart(buf, nodeDetails{ // begin outer root
name: "ROOT",
relativeStart: 0,
relativeStop: trace.Duration,
})
// exclusive_duration_millis field is added to fix the transaction trace
// summary tab. If exclusive_duration_millis is not provided, the UIs
// will calculate exclusive time, which doesn't work for this root node
// since all async goroutines are children of this root.
exclusiveDurationMillis := trace.Duration.Seconds() * 1000.0
details := nodeDetails{ // begin inner root
name: trace.FinalName,
relativeStart: 0,
relativeStop: trace.Duration,
}
details.exclusiveDurationMillis = &exclusiveDurationMillis
printNodeStart(buf, details)
for next := 0; next < len(nodes); {
if next > 0 {
buf.WriteByte(',')
}
// We put each thread's nodes into the root node instead of the
// node that spawned the thread. This approach is simple and
// works when the segment which spawned a thread has been pruned
// from the trace. Each call to printChildren prints one
// thread.
next = printChildren(buf, trace.Start, nodes, next, nil, nodes[next].threadID)
}
buf.WriteString("]]") // end outer root
buf.WriteString("]]") // end inner root
buf.WriteByte(',')
buf.WriteByte('{')
buf.WriteString(`"agentAttributes":`)
agentAttributesJSON(trace.Attrs, buf, destTxnTrace)
buf.WriteByte(',')
buf.WriteString(`"userAttributes":`)
userAttributesJSON(trace.Attrs, buf, destTxnTrace, nil)
buf.WriteByte(',')
buf.WriteString(`"intrinsics":`)
intrinsicsJSON(&trace.TxnEvent, buf)
buf.WriteByte('}')
// If the trace string pool is used, end another array here.
buf.WriteByte(']') // end trace data
// catGUID
buf.WriteByte(',')
if trace.CrossProcess.Used() && trace.CrossProcess.GUID != "" {
jsonx.AppendString(buf, trace.CrossProcess.GUID)
} else if trace.BetterCAT.Enabled {
jsonx.AppendString(buf, trace.BetterCAT.TraceID())
} else {
buf.WriteString(`""`)
}
buf.WriteByte(',') //
buf.WriteString(`null`) // reserved for future use
buf.WriteByte(',') //
buf.WriteString(`false`) // ForcePersist is not yet supported
buf.WriteByte(',') //
buf.WriteString(`null`) // X-Ray sessions not supported
buf.WriteByte(',') //
// Synthetics are supported:
if trace.CrossProcess.IsSynthetics() {
jsonx.AppendString(buf, trace.CrossProcess.Synthetics.ResourceID)
} else {
buf.WriteString(`""`)
}
buf.WriteByte(']') // end trace
}
type txnTraceHeap []*HarvestTrace
func (h *txnTraceHeap) isEmpty() bool {
return 0 == len(*h)
}
func newTxnTraceHeap(max int) *txnTraceHeap {
h := make(txnTraceHeap, 0, max)
heap.Init(&h)
return &h
}
// Implement sort.Interface.
func (h txnTraceHeap) Len() int { return len(h) }
func (h txnTraceHeap) Less(i, j int) bool { return h[i].Duration < h[j].Duration }
func (h txnTraceHeap) Swap(i, j int) { h[i], h[j] = h[j], h[i] }
// Implement heap.Interface.
func (h *txnTraceHeap) Push(x interface{}) { *h = append(*h, x.(*HarvestTrace)) }
func (h *txnTraceHeap) Pop() interface{} {
old := *h
n := len(old)
x := old[n-1]
*h = old[0 : n-1]
return x
}
func (h *txnTraceHeap) isKeeper(t *HarvestTrace) bool {
if len(*h) < cap(*h) {
return true
}
return t.Duration >= (*h)[0].Duration
}
func (h *txnTraceHeap) addTxnTrace(t *HarvestTrace) {
if len(*h) < cap(*h) {
heap.Push(h, t)
return
}
if t.Duration <= (*h)[0].Duration {
return
}
heap.Pop(h)
heap.Push(h, t)
}
type harvestTraces struct {
regular *txnTraceHeap
synthetics *txnTraceHeap
}
func newHarvestTraces() *harvestTraces {
return &harvestTraces{
regular: newTxnTraceHeap(maxRegularTraces),
synthetics: newTxnTraceHeap(maxSyntheticsTraces),
}
}
func (traces *harvestTraces) Len() int {
return traces.regular.Len() + traces.synthetics.Len()
}
func (traces *harvestTraces) Witness(trace HarvestTrace) {
traceHeap := traces.regular
if trace.CrossProcess.IsSynthetics() {
traceHeap = traces.synthetics
}
if traceHeap.isKeeper(&trace) {
cpy := new(HarvestTrace)
*cpy = trace
traceHeap.addTxnTrace(cpy)
}
}
func (traces *harvestTraces) Data(agentRunID string, harvestStart time.Time) ([]byte, error) {
if traces.Len() == 0 {
return nil, nil
}
// This estimate is used to guess the size of the buffer. No worries if
// the estimate is small since the buffer will be lengthened as
// necessary. This is just about minimizing reallocations.
estimate := 512
for _, t := range *traces.regular {
estimate += 100 * t.Trace.nodes.Len()
}
for _, t := range *traces.synthetics {
estimate += 100 * t.Trace.nodes.Len()
}
buf := bytes.NewBuffer(make([]byte, 0, estimate))
buf.WriteByte('[')
jsonx.AppendString(buf, agentRunID)
buf.WriteByte(',')
buf.WriteByte('[')
// use a function to add traces to the buffer to avoid duplicating comma
// logic in both loops
firstTrace := true
addTrace := func(trace *HarvestTrace) {
if firstTrace {
firstTrace = false
} else {
buf.WriteByte(',')
}
trace.writeJSON(buf)
}
for _, trace := range *traces.regular {
addTrace(trace)
}
for _, trace := range *traces.synthetics {
addTrace(trace)
}
buf.WriteByte(']')
buf.WriteByte(']')
return buf.Bytes(), nil
}
func (traces *harvestTraces) slice() []*HarvestTrace {
out := make([]*HarvestTrace, 0, traces.Len())
out = append(out, (*traces.regular)...)
out = append(out, (*traces.synthetics)...)
return out
}
func (traces *harvestTraces) MergeIntoHarvest(h *Harvest) {}
func (traces *harvestTraces) EndpointMethod() string {
return cmdTxnTraces
}
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