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238
modules/process/manager.go
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238
modules/process/manager.go
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// Copyright 2014 The Gogs Authors. All rights reserved.
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// Copyright 2019 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package process
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import (
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"context"
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"runtime/pprof"
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"strconv"
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"sync"
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"sync/atomic"
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"time"
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"code.gitea.io/gitea/modules/gtprof"
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)
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// TODO: This packages still uses a singleton for the Manager.
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// Once there's a decent web framework and dependencies are passed around like they should,
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// then we delete the singleton.
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var (
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manager *Manager
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managerInit sync.Once
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// DefaultContext is the default context to run processing commands in
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DefaultContext = context.Background()
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)
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// IDType is a pid type
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type IDType string
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// FinishedFunc is a function that marks that the process is finished and can be removed from the process table
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// - it is simply an alias for context.CancelFunc and is only for documentary purposes
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type FinishedFunc = context.CancelFunc
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var (
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traceDisabled atomic.Int64
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TraceCallback = defaultTraceCallback // this global can be overridden by particular logging packages - thus avoiding import cycles
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)
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// defaultTraceCallback is a no-op. Without a proper TraceCallback (provided by the logger system), this "Trace" level messages shouldn't be outputted.
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func defaultTraceCallback(skip int, start bool, pid IDType, description string, parentPID IDType, typ string) {
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}
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// TraceLogDisable disables (or revert the disabling) the trace log for the process lifecycle.
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// eg: the logger system shouldn't print the trace log for themselves, that's cycle dependency (Logger -> ProcessManager -> TraceCallback -> Logger ...)
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// Theoretically, such trace log should only be enabled when the logger system is ready with a proper level, so the default TraceCallback is a no-op.
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func TraceLogDisable(v bool) {
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if v {
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traceDisabled.Add(1)
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} else {
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traceDisabled.Add(-1)
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}
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}
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func Trace(start bool, pid IDType, description string, parentPID IDType, typ string) {
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if traceDisabled.Load() != 0 {
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// the traceDisabled counter is mainly for recursive calls, so no concurrency problem.
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// because the counter can't be 0 since the caller function hasn't returned (decreased the counter) yet.
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return
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}
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TraceCallback(1, start, pid, description, parentPID, typ)
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}
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// Manager manages all processes and counts PIDs.
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type Manager struct {
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mutex sync.Mutex
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next int64
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lastTime int64
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processMap map[IDType]*process
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}
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// GetManager returns a Manager and initializes one as singleton if there's none yet
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func GetManager() *Manager {
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managerInit.Do(func() {
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manager = &Manager{
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processMap: make(map[IDType]*process),
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next: 1,
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}
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})
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return manager
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}
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// AddContext creates a new context and adds it as a process. Once the process is finished, finished must be called
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// to remove the process from the process table. It should not be called until the process is finished but must always be called.
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//
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// cancel should be used to cancel the returned context, however it will not remove the process from the process table.
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// finished will cancel the returned context and remove it from the process table.
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//
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// 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
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// process table.
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func (pm *Manager) AddContext(parent context.Context, description string) (ctx context.Context, cancel context.CancelFunc, finished FinishedFunc) {
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ctx, cancel = context.WithCancel(parent)
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ctx, _, finished = pm.Add(ctx, description, cancel, NormalProcessType, true)
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return ctx, cancel, finished
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}
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// AddTypedContext creates a new context and adds it as a process. Once the process is finished, finished must be called
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// to remove the process from the process table. It should not be called until the process is finished but must always be called.
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//
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// cancel should be used to cancel the returned context, however it will not remove the process from the process table.
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// finished will cancel the returned context and remove it from the process table.
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//
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// 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
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// process table.
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func (pm *Manager) AddTypedContext(parent context.Context, description, processType string, currentlyRunning bool) (ctx context.Context, cancel context.CancelFunc, finished FinishedFunc) {
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ctx, cancel = context.WithCancel(parent)
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ctx, _, finished = pm.Add(ctx, description, cancel, processType, currentlyRunning)
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return ctx, cancel, finished
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}
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// AddContextTimeout creates a new context and add it as a process. Once the process is finished, finished must be called
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// to remove the process from the process table. It should not be called until the process is finished but must always be called.
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//
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// cancel should be used to cancel the returned context, however it will not remove the process from the process table.
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// finished will cancel the returned context and remove it from the process table.
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//
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// 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
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// process table.
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func (pm *Manager) AddContextTimeout(parent context.Context, timeout time.Duration, description string) (ctx context.Context, cancel context.CancelFunc, finished FinishedFunc) {
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if timeout <= 0 {
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// 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
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panic("the timeout must be greater than zero, otherwise the context will be cancelled immediately")
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}
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ctx, cancel = context.WithTimeout(parent, timeout)
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ctx, _, finished = pm.Add(ctx, description, cancel, NormalProcessType, true)
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return ctx, cancel, finished
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}
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// Add create a new process
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func (pm *Manager) Add(ctx context.Context, description string, cancel context.CancelFunc, processType string, currentlyRunning bool) (context.Context, IDType, FinishedFunc) {
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parentPID := GetParentPID(ctx)
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pm.mutex.Lock()
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start, pid := pm.nextPID()
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parent := pm.processMap[parentPID]
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if parent == nil {
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parentPID = ""
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}
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process := &process{
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PID: pid,
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ParentPID: parentPID,
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Description: description,
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Start: start,
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Cancel: cancel,
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Type: processType,
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}
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var finished FinishedFunc
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if currentlyRunning {
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finished = func() {
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cancel()
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pm.remove(process)
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pprof.SetGoroutineLabels(ctx)
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}
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} else {
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finished = func() {
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cancel()
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pm.remove(process)
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}
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}
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pm.processMap[pid] = process
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pm.mutex.Unlock()
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Trace(true, pid, description, parentPID, processType)
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pprofCtx := pprof.WithLabels(ctx, pprof.Labels(
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gtprof.LabelProcessDescription, description,
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gtprof.LabelPpid, string(parentPID),
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gtprof.LabelPid, string(pid),
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gtprof.LabelProcessType, processType,
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))
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if currentlyRunning {
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pprof.SetGoroutineLabels(pprofCtx)
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}
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return &Context{
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Context: pprofCtx,
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pid: pid,
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}, pid, finished
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}
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// nextPID will return the next available PID. pm.mutex should already be locked.
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func (pm *Manager) nextPID() (start time.Time, pid IDType) {
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start = time.Now()
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startUnix := start.Unix()
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if pm.lastTime == startUnix {
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pm.next++
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} else {
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pm.next = 1
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}
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pm.lastTime = startUnix
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pid = IDType(strconv.FormatInt(start.Unix(), 16))
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if pm.next == 1 {
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return start, pid
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}
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pid = IDType(string(pid) + "-" + strconv.FormatInt(pm.next, 10))
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return start, pid
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}
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func (pm *Manager) remove(process *process) {
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deleted := false
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pm.mutex.Lock()
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if pm.processMap[process.PID] == process {
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delete(pm.processMap, process.PID)
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deleted = true
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}
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pm.mutex.Unlock()
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if deleted {
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Trace(false, process.PID, process.Description, process.ParentPID, process.Type)
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}
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}
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// Cancel a process in the ProcessManager.
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func (pm *Manager) Cancel(pid IDType) {
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pm.mutex.Lock()
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process, ok := pm.processMap[pid]
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pm.mutex.Unlock()
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if ok && process.Type != SystemProcessType {
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process.Cancel()
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}
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}
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