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// Copyright 2014 The Gogs Authors. All rights reserved.
// Copyright 2019 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package process
import (
"context"
"log"
"runtime/pprof"
"strconv"
"sync"
"time"
)
// TODO: This packages still uses a singleton for the Manager.
// Once there's a decent web framework and dependencies are passed around like they should,
// then we delete the singleton.
var (
manager *Manager
managerInit sync.Once
// DefaultContext is the default context to run processing commands in
DefaultContext = context.Background()
)
// DescriptionPProfLabel is a label set on goroutines that have a process attached
const DescriptionPProfLabel = "process-description"
// PIDPProfLabel is a label set on goroutines that have a process attached
const PIDPProfLabel = "pid"
// PPIDPProfLabel is a label set on goroutines that have a process attached
const PPIDPProfLabel = "ppid"
// ProcessTypePProfLabel is a label set on goroutines that have a process attached
const ProcessTypePProfLabel = "process-type"
// IDType is a pid type
type IDType string
// FinishedFunc is a function that marks that the process is finished and can be removed from the process table
// - it is simply an alias for context.CancelFunc and is only for documentary purposes
type FinishedFunc = context.CancelFunc
var Trace = defaultTrace // this global can be overridden by particular logging packages - thus avoiding import cycles
func defaultTrace(start bool, pid IDType, description string, parentPID IDType, typ string) {
if start && parentPID != "" {
log.Printf("start process %s: %s (from %s) (%s)", pid, description, parentPID, typ)
} else if start {
log.Printf("start process %s: %s (%s)", pid, description, typ)
} else {
log.Printf("end process %s: %s", pid, description)
}
}
// Manager manages all processes and counts PIDs.
type Manager struct {
mutex sync.Mutex
next int64
lastTime int64
processMap map[IDType]*process
}
// GetManager returns a Manager and initializes one as singleton if there's none yet
func GetManager() *Manager {
managerInit.Do(func() {
manager = &Manager{
processMap: make(map[IDType]*process),
next: 1,
}
})
return manager
}
// AddContext creates a new context and adds it as a process. Once the process is finished, finished must be called
// to remove the process from the process table. It should not be called until the process is finished but must always be called.
//
// cancel should be used to cancel the returned context, however it will not remove the process from the process table.
// finished will cancel the returned context and remove it from the process table.
//
// Most processes will not need to use the cancel function but there will be cases whereby you want to cancel the process but not immediately remove it from the
// process table.
func (pm *Manager) AddContext(parent context.Context, description string) (ctx context.Context, cancel context.CancelFunc, finished FinishedFunc) {
ctx, cancel = context.WithCancel(parent)
ctx, _, finished = pm.Add(ctx, description, cancel, NormalProcessType, true)
return ctx, cancel, finished
}
// AddTypedContext creates a new context and adds it as a process. Once the process is finished, finished must be called
// to remove the process from the process table. It should not be called until the process is finished but must always be called.
//
// cancel should be used to cancel the returned context, however it will not remove the process from the process table.
// finished will cancel the returned context and remove it from the process table.
//
// Most processes will not need to use the cancel function but there will be cases whereby you want to cancel the process but not immediately remove it from the
// process table.
func (pm *Manager) AddTypedContext(parent context.Context, description, processType string, currentlyRunning bool) (ctx context.Context, cancel context.CancelFunc, finished FinishedFunc) {
ctx, cancel = context.WithCancel(parent)
ctx, _, finished = pm.Add(ctx, description, cancel, processType, currentlyRunning)
return ctx, cancel, finished
}
// AddContextTimeout creates a new context and add it as a process. Once the process is finished, finished must be called
// to remove the process from the process table. It should not be called until the process is finished but must always be called.
//
// cancel should be used to cancel the returned context, however it will not remove the process from the process table.
// finished will cancel the returned context and remove it from the process table.
//
// Most processes will not need to use the cancel function but there will be cases whereby you want to cancel the process but not immediately remove it from the
// process table.
func (pm *Manager) AddContextTimeout(parent context.Context, timeout time.Duration, description string) (ctx context.Context, cancel context.CancelFunc, finshed FinishedFunc) {
if timeout <= 0 {
// it's meaningless to use timeout <= 0, and it must be a bug! so we must panic here to tell developers to make the timeout correct
panic("the timeout must be greater than zero, otherwise the context will be cancelled immediately")
}
ctx, cancel = context.WithTimeout(parent, timeout)
ctx, _, finshed = pm.Add(ctx, description, cancel, NormalProcessType, true)
return ctx, cancel, finshed
}
// Add create a new process
func (pm *Manager) Add(ctx context.Context, description string, cancel context.CancelFunc, processType string, currentlyRunning bool) (context.Context, IDType, FinishedFunc) {
parentPID := GetParentPID(ctx)
pm.mutex.Lock()
start, pid := pm.nextPID()
parent := pm.processMap[parentPID]
if parent == nil {
parentPID = ""
}
process := &process{
PID: pid,
ParentPID: parentPID,
Description: description,
Start: start,
Cancel: cancel,
Type: processType,
}
var finished FinishedFunc
if currentlyRunning {
finished = func() {
cancel()
pm.remove(process)
pprof.SetGoroutineLabels(ctx)
}
} else {
finished = func() {
cancel()
pm.remove(process)
}
}
pm.processMap[pid] = process
pm.mutex.Unlock()
Trace(true, pid, description, parentPID, processType)
pprofCtx := pprof.WithLabels(ctx, pprof.Labels(DescriptionPProfLabel, description, PPIDPProfLabel, string(parentPID), PIDPProfLabel, string(pid), ProcessTypePProfLabel, processType))
if currentlyRunning {
pprof.SetGoroutineLabels(pprofCtx)
}
return &Context{
Context: pprofCtx,
pid: pid,
}, pid, finished
}
// nextPID will return the next available PID. pm.mutex should already be locked.
func (pm *Manager) nextPID() (start time.Time, pid IDType) {
start = time.Now()
startUnix := start.Unix()
if pm.lastTime == startUnix {
pm.next++
} else {
pm.next = 1
}
pm.lastTime = startUnix
pid = IDType(strconv.FormatInt(start.Unix(), 16))
if pm.next == 1 {
return
}
pid = IDType(string(pid) + "-" + strconv.FormatInt(pm.next, 10))
return start, pid
}
func (pm *Manager) remove(process *process) {
deleted := false
pm.mutex.Lock()
if pm.processMap[process.PID] == process {
delete(pm.processMap, process.PID)
deleted = true
}
pm.mutex.Unlock()
if deleted {
Trace(false, process.PID, process.Description, process.ParentPID, process.Type)
}
}
// Cancel a process in the ProcessManager.
func (pm *Manager) Cancel(pid IDType) {
pm.mutex.Lock()
process, ok := pm.processMap[pid]
pm.mutex.Unlock()
if ok && process.Type != SystemProcessType {
process.Cancel()
}
}
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