1 files changed, 353 insertions, 0 deletions
diff --git a/modules/process/manager_stacktraces.go b/modules/process/manager_stacktraces.go
new file mode 100644
index 00000000..e2608931
--- /dev/null
+++ b/modules/process/manager_stacktraces.go
@@ -0,0 +1,353 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package process
+
+import (
+	"fmt"
+	"io"
+	"runtime/pprof"
+	"sort"
+	"time"
+
+	"github.com/google/pprof/profile"
+)
+
+// StackEntry is an entry on a stacktrace
+type StackEntry struct {
+	Function string
+	File     string
+	Line     int
+}
+
+// Label represents a pprof label assigned to goroutine stack
+type Label struct {
+	Name  string
+	Value string
+}
+
+// Stack is a stacktrace relating to a goroutine. (Multiple goroutines may have the same stacktrace)
+type Stack struct {
+	Count       int64 // Number of goroutines with this stack trace
+	Description string
+	Labels      []*Label      `json:",omitempty"`
+	Entry       []*StackEntry `json:",omitempty"`
+}
+
+// A Process is a combined representation of a Process and a Stacktrace for the goroutines associated with it
+type Process struct {
+	PID         IDType
+	ParentPID   IDType
+	Description string
+	Start       time.Time
+	Type        string
+
+	Children []*Process `json:",omitempty"`
+	Stacks   []*Stack   `json:",omitempty"`
+}
+
+// Processes gets the processes in a thread safe manner
+func (pm *Manager) Processes(flat, noSystem bool) ([]*Process, int) {
+	pm.mutex.Lock()
+	processCount := len(pm.processMap)
+	processes := make([]*Process, 0, len(pm.processMap))
+	if flat {
+		for _, process := range pm.processMap {
+			if noSystem && process.Type == SystemProcessType {
+				continue
+			}
+			processes = append(processes, process.toProcess())
+		}
+	} else {
+		// We need our own processMap
+		processMap := map[IDType]*Process{}
+		for _, internalProcess := range pm.processMap {
+			process, ok := processMap[internalProcess.PID]
+			if !ok {
+				process = internalProcess.toProcess()
+				processMap[process.PID] = process
+			}
+
+			// Check its parent
+			if process.ParentPID == "" {
+				processes = append(processes, process)
+				continue
+			}
+
+			internalParentProcess, ok := pm.processMap[internalProcess.ParentPID]
+			if ok {
+				parentProcess, ok := processMap[process.ParentPID]
+				if !ok {
+					parentProcess = internalParentProcess.toProcess()
+					processMap[parentProcess.PID] = parentProcess
+				}
+				parentProcess.Children = append(parentProcess.Children, process)
+				continue
+			}
+
+			processes = append(processes, process)
+		}
+	}
+	pm.mutex.Unlock()
+
+	if !flat && noSystem {
+		for i := 0; i < len(processes); i++ {
+			process := processes[i]
+			if process.Type != SystemProcessType {
+				continue
+			}
+			processes[len(processes)-1], processes[i] = processes[i], processes[len(processes)-1]
+			processes = append(processes[:len(processes)-1], process.Children...)
+			i--
+		}
+	}
+
+	// Sort by process' start time. Oldest process appears first.
+	sort.Slice(processes, func(i, j int) bool {
+		left, right := processes[i], processes[j]
+
+		return left.Start.Before(right.Start)
+	})
+
+	return processes, processCount
+}
+
+// ProcessStacktraces gets the processes and stacktraces in a thread safe manner
+func (pm *Manager) ProcessStacktraces(flat, noSystem bool) ([]*Process, int, int64, error) {
+	var stacks *profile.Profile
+	var err error
+
+	// We cannot use the pm.ProcessMap here because we will release the mutex ...
+	processMap := map[IDType]*Process{}
+	var processCount int
+
+	// Lock the manager
+	pm.mutex.Lock()
+	processCount = len(pm.processMap)
+
+	// Add a defer to unlock in case there is a panic
+	unlocked := false
+	defer func() {
+		if !unlocked {
+			pm.mutex.Unlock()
+		}
+	}()
+
+	processes := make([]*Process, 0, len(pm.processMap))
+	if flat {
+		for _, internalProcess := range pm.processMap {
+			process := internalProcess.toProcess()
+			processMap[process.PID] = process
+			if noSystem && internalProcess.Type == SystemProcessType {
+				continue
+			}
+			processes = append(processes, process)
+		}
+	} else {
+		for _, internalProcess := range pm.processMap {
+			process, ok := processMap[internalProcess.PID]
+			if !ok {
+				process = internalProcess.toProcess()
+				processMap[process.PID] = process
+			}
+
+			// Check its parent
+			if process.ParentPID == "" {
+				processes = append(processes, process)
+				continue
+			}
+
+			internalParentProcess, ok := pm.processMap[internalProcess.ParentPID]
+			if ok {
+				parentProcess, ok := processMap[process.ParentPID]
+				if !ok {
+					parentProcess = internalParentProcess.toProcess()
+					processMap[parentProcess.PID] = parentProcess
+				}
+				parentProcess.Children = append(parentProcess.Children, process)
+				continue
+			}
+
+			processes = append(processes, process)
+		}
+	}
+
+	// Now from within the lock we need to get the goroutines.
+	// Why? If we release the lock then between between filling the above map and getting
+	// the stacktraces another process could be created which would then look like a dead process below
+	reader, writer := io.Pipe()
+	defer reader.Close()
+	go func() {
+		err := pprof.Lookup("goroutine").WriteTo(writer, 0)
+		_ = writer.CloseWithError(err)
+	}()
+	stacks, err = profile.Parse(reader)
+	if err != nil {
+		return nil, 0, 0, err
+	}
+
+	// Unlock the mutex
+	pm.mutex.Unlock()
+	unlocked = true
+
+	goroutineCount := int64(0)
+
+	// Now walk through the "Sample" slice in the goroutines stack
+	for _, sample := range stacks.Sample {
+		// In the "goroutine" pprof profile each sample represents one or more goroutines
+		// with the same labels and stacktraces.
+
+		// We will represent each goroutine by a `Stack`
+		stack := &Stack{}
+
+		// Add the non-process associated labels from the goroutine sample to the Stack
+		for name, value := range sample.Label {
+			if name == DescriptionPProfLabel || name == PIDPProfLabel || (!flat && name == PPIDPProfLabel) || name == ProcessTypePProfLabel {
+				continue
+			}
+
+			// Labels from the "goroutine" pprof profile only have one value.
+			// This is because the underlying representation is a map[string]string
+			if len(value) != 1 {
+				// Unexpected...
+				return nil, 0, 0, fmt.Errorf("label: %s in goroutine stack with unexpected number of values: %v", name, value)
+			}
+
+			stack.Labels = append(stack.Labels, &Label{Name: name, Value: value[0]})
+		}
+
+		// The number of goroutines that this sample represents is the `stack.Value[0]`
+		stack.Count = sample.Value[0]
+		goroutineCount += stack.Count
+
+		// Now we want to associate this Stack with a Process.
+		var process *Process
+
+		// Try to get the PID from the goroutine labels
+		if pidvalue, ok := sample.Label[PIDPProfLabel]; ok && len(pidvalue) == 1 {
+			pid := IDType(pidvalue[0])
+
+			// Now try to get the process from our map
+			process, ok = processMap[pid]
+			if !ok && pid != "" {
+				// This means that no process has been found in the process map - but there was a process PID
+				// Therefore this goroutine belongs to a dead process and it has escaped control of the process as it
+				// should have died with the process context cancellation.
+
+				// We need to create a dead process holder for this process and label it appropriately
+
+				// get the parent PID
+				ppid := IDType("")
+				if value, ok := sample.Label[PPIDPProfLabel]; ok && len(value) == 1 {
+					ppid = IDType(value[0])
+				}
+
+				// format the description
+				description := "(dead process)"
+				if value, ok := sample.Label[DescriptionPProfLabel]; ok && len(value) == 1 {
+					description = value[0] + " " + description
+				}
+
+				// override the type of the process to "code" but add the old type as a label on the first stack
+				ptype := NoneProcessType
+				if value, ok := sample.Label[ProcessTypePProfLabel]; ok && len(value) == 1 {
+					stack.Labels = append(stack.Labels, &Label{Name: ProcessTypePProfLabel, Value: value[0]})
+				}
+				process = &Process{
+					PID:         pid,
+					ParentPID:   ppid,
+					Description: description,
+					Type:        ptype,
+				}
+
+				// Now add the dead process back to the map and tree so we don't go back through this again.
+				processMap[process.PID] = process
+				added := false
+				if process.ParentPID != "" && !flat {
+					if parent, ok := processMap[process.ParentPID]; ok {
+						parent.Children = append(parent.Children, process)
+						added = true
+					}
+				}
+				if !added {
+					processes = append(processes, process)
+				}
+			}
+		}
+
+		if process == nil {
+			// This means that the sample we're looking has no PID label
+			var ok bool
+			process, ok = processMap[""]
+			if !ok {
+				// this is the first time we've come acrross an unassociated goroutine so create a "process" to hold them
+				process = &Process{
+					Description: "(unassociated)",
+					Type:        NoneProcessType,
+				}
+				processMap[process.PID] = process
+				processes = append(processes, process)
+			}
+		}
+
+		// The sample.Location represents a stack trace for this goroutine,
+		// however each Location can represent multiple lines (mostly due to inlining)
+		// so we need to walk the lines too
+		for _, location := range sample.Location {
+			for _, line := range location.Line {
+				entry := &StackEntry{
+					Function: line.Function.Name,
+					File:     line.Function.Filename,
+					Line:     int(line.Line),
+				}
+				stack.Entry = append(stack.Entry, entry)
+			}
+		}
+
+		// Now we need a short-descriptive name to call the stack trace if when it is folded and
+		// assuming the stack trace has some lines we'll choose the bottom of the stack (i.e. the
+		// initial function that started the stack trace.) The top of the stack is unlikely to
+		// be very helpful as a lot of the time it will be runtime.select or some other call into
+		// a std library.
+		stack.Description = "(unknown)"
+		if len(stack.Entry) > 0 {
+			stack.Description = stack.Entry[len(stack.Entry)-1].Function
+		}
+
+		process.Stacks = append(process.Stacks, stack)
+	}
+
+	// restrict to not show system processes
+	if noSystem {
+		for i := 0; i < len(processes); i++ {
+			process := processes[i]
+			if process.Type != SystemProcessType && process.Type != NoneProcessType {
+				continue
+			}
+			processes[len(processes)-1], processes[i] = processes[i], processes[len(processes)-1]
+			processes = append(processes[:len(processes)-1], process.Children...)
+			i--
+		}
+	}
+
+	// Now finally re-sort the processes. Newest process appears first
+	after := func(processes []*Process) func(i, j int) bool {
+		return func(i, j int) bool {
+			left, right := processes[i], processes[j]
+			return left.Start.After(right.Start)
+		}
+	}
+	sort.Slice(processes, after(processes))
+	if !flat {
+		var sortChildren func(process *Process)
+
+		sortChildren = func(process *Process) {
+			sort.Slice(process.Children, after(process.Children))
+			for _, child := range process.Children {
+				sortChildren(child)
+			}
+		}
+	}
+
+	return processes, processCount, goroutineCount, err
+}