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Optimize traversal and parts of printing trace point function and mod…
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…ify trace output layout

and adjust tests accordingly
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@archanaravindar
archanaravindar committed Apr 25, 2024
1 parent 0751612 commit 1adec73
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Showing 3 changed files with 132 additions and 69 deletions.
42 changes: 1 addition & 41 deletions cmd/dlv/dlv_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -944,7 +944,7 @@ func TestTrace2(t *testing.T) {
func TestTraceDirRecursion(t *testing.T) {
dlvbin := getDlvBin(t)

expected := []byte("1> goroutine(1): main.A(5, 5)\n 2> goroutine(1): main.A(4, 4)\n 3> goroutine(1): main.A(3, 3)\n 4> goroutine(1): main.A(2, 2)\n 4>> goroutine(1):(main.A) => (2)\n 3>> goroutine(1):(main.A) => (6)\n 2>> goroutine(1):(main.A) => (24)\n1>> goroutine(1):(main.A) => (120)\n")
expected := []byte("> goroutine(1):frame(1) main.A(5, 5)\n > goroutine(1):frame(2) main.A(4, 4)\n > goroutine(1):frame(3) main.A(3, 3)\n > goroutine(1):frame(4) main.A(2, 2)\n > goroutine(1):frame(5) main.A(1, 1)\n >> goroutine(1):frame(5) main.A => (1)\n >> goroutine(1):frame(4) main.A => (2)\n >> goroutine(1):frame(3) main.A => (6)\n >> goroutine(1):frame(2) main.A => (24)\n>> goroutine(1):frame(1) main.A => (120)\n")

fixtures := protest.FindFixturesDir()
cmd := exec.Command(dlvbin, "trace", "--output", filepath.Join(t.TempDir(), "__debug"), filepath.Join(fixtures, "leafrec.go"), "main.A", "--follow-calls", "4")
Expand Down Expand Up @@ -974,46 +974,6 @@ func TestTraceDirRecursion(t *testing.T) {
assertNoError(cmd.Wait(), t, "cmd.Wait()")
}

func TestTracePanicDefer(t *testing.T) {
dlvbin := getDlvBin(t)

expected1 := []byte("1> goroutine(1): main.F0()\n 2> goroutine(1): runtime.deferprocStack")
expected2 := []byte(" 2>> goroutine(1):(runtime.deferprocStack) => ()\n 2> goroutine(1): main.F1()\n 3> goroutine(1): main.F2()\n 4> goroutine(1): main.F3()\n1>> goroutine(1):(main.F0) => ()\n 2> goroutine(1): runtime.deferreturn()\n 2>> goroutine(1):(runtime.deferreturn) => ()\n1>> goroutine(1):(main.F0) => ()\n")

fixtures := protest.FindFixturesDir()
cmd := exec.Command(dlvbin, "trace", "--output", filepath.Join(t.TempDir(), "__debug"), filepath.Join(fixtures, "panicex.go"), "main.F0", "--follow-calls", "4")
rdr, err := cmd.StderrPipe()
assertNoError(err, t, "stderr pipe")
defer rdr.Close()

cmd.Dir = filepath.Join(fixtures, "buildtest")

assertNoError(cmd.Start(), t, "running trace")

// Parse output to ignore calls to morestack_noctxt for comparison
scan := bufio.NewScanner(rdr)
text := ""
outputtext := ""
for scan.Scan() {
text = scan.Text()
if !strings.Contains(text, "morestack_noctxt") {
outputtext += text
outputtext += "\n"
}
}
output := []byte(outputtext)

// Split expected into two to work around comparison of actual address parameter in deferprocStack
if !bytes.Contains(output, expected1) {
t.Fatalf("expected:\n%s\ngot:\n%s", string(expected1), string(output))
}
if !bytes.Contains(output, expected2) {
t.Fatalf("expected:\n%s\ngot:\n%s", string(expected2), string(output))
}
assertNoError(cmd.Wait(), t, "cmd.Wait()")

}

func TestTraceMultipleGoroutines(t *testing.T) {
dlvbin := getDlvBin(t)

Expand Down
153 changes: 125 additions & 28 deletions service/debugger/debugger.go
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Original file line number Diff line number Diff line change
Expand Up @@ -444,7 +444,6 @@ func (d *Debugger) FunctionReturnLocations(fnName string) ([]uint64, error) {
for _, instruction := range instructions {
if instruction.IsRet() {
addrs = append(addrs, instruction.Loc.PC)
//fmt.Printf("appending PC %x to return breakpoint list\n",instruction.Loc.PC)
}
}
addrs = append(addrs, proc.FindDeferReturnCalls(instructions)...)
Expand Down Expand Up @@ -1487,52 +1486,150 @@ func (d *Debugger) Functions(filter string, followCalls int) ([]string, error) {
return funcs, nil
}

type TraceFunc struct {
// Function to be traced
Func *proc.Function
// To keep track of depth in call graph relative to root function
Depth int
// To ensure we traverse only if needed
Weight int
// To ensure we dont repeatedly add the same function to the function list
visited bool
// To ensure we dont repeatedly disassemble the same function
cached bool
// To keep track of child functions
children []*proc.Function
}
type TraceFuncptr *TraceFunc

var TraceMap = make(map[string]TraceFuncptr)

func filter(fname string) bool {
idx := strings.Index(fname, "runtime.")
idx2 := strings.Index(fname, "runtime.defer")
idx3 := strings.Index(fname, "runtime.gorecover")
idx4 := strings.Index(fname, "runtime.gopanic")
// Avoid runtime/internal functions to figure in the trace function list as they dont have a stack associated
idx5 := strings.Index(fname, "runtime/internal")
if (idx != -1 || idx5 != -1) && idx2 == -1 && idx3 == -1 && idx4 == -1 {
// Except few select functions do not traverse runtime.* functions
return false
}
return true
}
func traverse(t proc.ValidTargets, f *proc.Function, depth int, FollowCalls int) ([]string, error) {

idx := strings.Index(f.Name, "runtime.")
idx2 := strings.Index(f.Name, "runtime.defer")
if idx != -1 && idx2 == -1 {
// Except defer functions do not traverse runtime.* functions
if filter(f.Name) == false {
return nil, nil
}

funcs := []string{}
if depth > FollowCalls {
// If we already reached desired depth, return
return nil, nil
}
funcs := []string{}
funcs = append(funcs, f.Name)
text, err := proc.Disassemble(t.Memory(), nil, t.Breakpoints(), t.BinInfo(), f.Entry, f.End)
if err != nil {
return nil, fmt.Errorf("disassemble failed with error %w", err)

mapnode := TraceMap[f.Name]
if mapnode == nil {
mapnode = &TraceFunc{Func: new(proc.Function), Weight: FollowCalls - depth, Depth: depth, children: []*proc.Function{}, visited: false, cached: false}
mapnode.Func = f
TraceMap[f.Name] = mapnode
}
depth++
for _, instr := range text {
if instr.IsCall() && instr.DestLoc != nil && instr.DestLoc.Fn != nil {
cf := instr.DestLoc.Fn
if cf.Name == f.Name {
continue
}
if depth <= FollowCalls {
children, err := traverse(t, cf, depth, FollowCalls)
if err != nil {
return nil, fmt.Errorf("traverse failed with error %w", err)
if mapnode.visited == false {
// Condition to avoid adding duplicates to funcs list
funcs = append(funcs, f.Name)
mapnode.visited = true
}

// no point in disassembling if we are not traversing child
if depth+1 > FollowCalls {
return funcs, nil
}
Budget := FollowCalls - (depth + 1)
deferdepth := 0
if TraceMap[f.Name].cached == false {
// Condition to avoid repeated disassembly of the same functions
text, err := proc.Disassemble(t.Memory(), nil, t.Breakpoints(), t.BinInfo(), f.Entry, f.End)
if err != nil {
return nil, fmt.Errorf("disassemble failed with error %w", err)
}
for _, instr := range text {
if instr.IsCall() && instr.DestLoc != nil && instr.DestLoc.Fn != nil {
cf := instr.DestLoc.Fn
if filter(cf.Name) == false {
continue
}
childnode := TraceMap[cf.Name]
if childnode == nil {
childnode = &TraceFunc{Func: new(proc.Function), Weight: Budget, Depth: mapnode.Depth + 1, children: []*proc.Function{}, visited: false, cached: false}
childnode.Func = cf
TraceMap[cf.Name] = childnode
TraceMap[f.Name].children = append(TraceMap[f.Name].children, cf)
} else {
if childnode.Weight > Budget || childnode.Depth < mapnode.Depth+1 {
// No more budget left for traversal, go to the next child
continue
}
if Budget > childnode.Weight {
// We have more budget left, can traverse more
if childnode.Depth > mapnode.Depth+1 {
childnode.Depth = mapnode.Depth + 1
}
childnode.Weight = Budget
TraceMap[f.Name].children = append(TraceMap[f.Name].children, cf)
}
}

if strings.Index(cf.Name, "runtime.deferreturn") != -1 {
if childnode.Depth+1 <= FollowCalls {
// flag to track defer functions
deferdepth = childnode.Depth + 1
}
}
funcs = append(funcs, children...)
}
}
TraceMap[f.Name].cached = true
}
// The following code is needed to include defer function calls as they are invoked via funcname.func1 type
// naming, so check if funcname is a prefix in candidate function to include such functions
for _, fbinary := range t.BinInfo().Functions {
if strings.HasPrefix(fbinary.Name, f.Name) && fbinary.Name != f.Name {
children, err := traverse(t, &fbinary, depth, FollowCalls)
for _, childFunc := range TraceMap[f.Name].children {
if childFunc.Name == f.Name {
// Avoid recursion
continue
}
childnode := TraceMap[childFunc.Name]
if childnode.Weight > Budget || childnode.Depth < mapnode.Depth+1 {
// No more budget left for traversal, go to the next child
continue
}
if Budget > childnode.Weight {
// We have more budget left, can traverse more
if childnode.Depth > mapnode.Depth+1 {
childnode.Depth = mapnode.Depth + 1
}
childnode.Weight = Budget

}
if childnode.Depth <= FollowCalls {
children, err := traverse(t, childnode.Func, childnode.Depth, FollowCalls)
if err != nil {
return nil, fmt.Errorf("traverse failed with error %w", err)
}
funcs = append(funcs, children...)
}
}

// The following code is needed to include defer function calls as they are invoked via funcname.func1 type
// naming, so check if funcname is a prefix in candidate function to include such functions
if deferdepth > 0 {
for _, fbinary := range t.BinInfo().Functions {
if depth <= FollowCalls && strings.HasPrefix(fbinary.Name, f.Name) && fbinary.Name != f.Name {
children, err := traverse(t, &fbinary, deferdepth, FollowCalls)
if err != nil {
return nil, fmt.Errorf("traverse failed with error %w", err)
}
funcs = append(funcs, children...)
}
}
deferdepth = 0
}
return funcs, nil

}
Expand Down
6 changes: 6 additions & 0 deletions service/test/integration2_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -831,6 +831,12 @@ func TestTraceFollowCallsCommand(t *testing.T) {
assertNoError(err, t, "ListFunctions()")
expected = []string{"fmt.Printf", "main.callA", "main.callB", "main.callC", "main.callC.func1", "main.callD", "runtime.deferprocStack", "runtime.deferreturn"}
matchFunctions(t, functions, expected, depth)

depth = 6
functions, err = c.ListFunctions("main.F0", depth)
assertNoError(err, t, "ListFunctions()")
expected = []string{"main.F0", "main.F0.func1", "main.F1", "main.F2", "main.F3", "main.F4", "runtime.deferprocStack", "runtime.deferreturn", "runtime.gopanic", "runtime.gorecover"}
matchFunctions(t, functions, expected, depth)
})
}

Expand Down

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