forgejo/modules/process/manager.go
zeripath 01087e9eef
Make Requests Processes and create process hierarchy. Associate OpenRepository with context. (#17125)
This PR registers requests with the process manager and manages hierarchy within the processes.

Git repos are then associated with a context, (usually the request's context) - with sub commands using this context as their base context.

Signed-off-by: Andrew Thornton <art27@cantab.net>
2021-11-30 20:06:32 +00:00

295 lines
8.3 KiB
Go

// Copyright 2014 The Gogs Authors. All rights reserved.
// Copyright 2019 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package process
import (
"bytes"
"context"
"fmt"
"io"
"os/exec"
"sort"
"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()
)
// 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
// Manager manages all processes and counts PIDs.
type Manager struct {
mutex sync.Mutex
next int64
lastTime int64
processes 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{
processes: 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) {
parentPID := GetParentPID(parent)
ctx, cancel = context.WithCancel(parent)
pid, finished := pm.Add(parentPID, description, cancel)
return &Context{
Context: ctx,
pid: pid,
}, 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 finsihed 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) {
parentPID := GetParentPID(parent)
ctx, cancel = context.WithTimeout(parent, timeout)
pid, finshed := pm.Add(parentPID, description, cancel)
return &Context{
Context: ctx,
pid: pid,
}, cancel, finshed
}
// Add create a new process
func (pm *Manager) Add(parentPID IDType, description string, cancel context.CancelFunc) (IDType, FinishedFunc) {
pm.mutex.Lock()
start, pid := pm.nextPID()
parent := pm.processes[parentPID]
if parent == nil {
parentPID = ""
}
process := &Process{
PID: pid,
ParentPID: parentPID,
Description: description,
Start: start,
Cancel: cancel,
}
finished := func() {
cancel()
pm.remove(process)
}
if parent != nil {
parent.AddChild(process)
}
pm.processes[pid] = process
pm.mutex.Unlock()
return 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
}
// Remove a process from the ProcessManager.
func (pm *Manager) Remove(pid IDType) {
pm.mutex.Lock()
delete(pm.processes, pid)
pm.mutex.Unlock()
}
func (pm *Manager) remove(process *Process) {
pm.mutex.Lock()
if p := pm.processes[process.PID]; p == process {
delete(pm.processes, process.PID)
}
parent := pm.processes[process.ParentPID]
pm.mutex.Unlock()
if parent == nil {
return
}
parent.RemoveChild(process)
}
// Cancel a process in the ProcessManager.
func (pm *Manager) Cancel(pid IDType) {
pm.mutex.Lock()
process, ok := pm.processes[pid]
pm.mutex.Unlock()
if ok {
process.Cancel()
}
}
// Processes gets the processes in a thread safe manner
func (pm *Manager) Processes(onlyRoots bool) []*Process {
pm.mutex.Lock()
processes := make([]*Process, 0, len(pm.processes))
if onlyRoots {
for _, process := range pm.processes {
if _, has := pm.processes[process.ParentPID]; !has {
processes = append(processes, process)
}
}
} else {
for _, process := range pm.processes {
processes = append(processes, process)
}
}
pm.mutex.Unlock()
sort.Slice(processes, func(i, j int) bool {
left, right := processes[i], processes[j]
return left.Start.Before(right.Start)
})
return processes
}
// Exec a command and use the default timeout.
func (pm *Manager) Exec(desc, cmdName string, args ...string) (string, string, error) {
return pm.ExecDir(-1, "", desc, cmdName, args...)
}
// ExecTimeout a command and use a specific timeout duration.
func (pm *Manager) ExecTimeout(timeout time.Duration, desc, cmdName string, args ...string) (string, string, error) {
return pm.ExecDir(timeout, "", desc, cmdName, args...)
}
// ExecDir a command and use the default timeout.
func (pm *Manager) ExecDir(timeout time.Duration, dir, desc, cmdName string, args ...string) (string, string, error) {
return pm.ExecDirEnv(timeout, dir, desc, nil, cmdName, args...)
}
// ExecDirEnv runs a command in given path and environment variables, and waits for its completion
// up to the given timeout (or DefaultTimeout if -1 is given).
// Returns its complete stdout and stderr
// outputs and an error, if any (including timeout)
func (pm *Manager) ExecDirEnv(timeout time.Duration, dir, desc string, env []string, cmdName string, args ...string) (string, string, error) {
return pm.ExecDirEnvStdIn(timeout, dir, desc, env, nil, cmdName, args...)
}
// ExecDirEnvStdIn runs a command in given path and environment variables with provided stdIN, and waits for its completion
// up to the given timeout (or DefaultTimeout if -1 is given).
// Returns its complete stdout and stderr
// outputs and an error, if any (including timeout)
func (pm *Manager) ExecDirEnvStdIn(timeout time.Duration, dir, desc string, env []string, stdIn io.Reader, cmdName string, args ...string) (string, string, error) {
if timeout == -1 {
timeout = 60 * time.Second
}
stdOut := new(bytes.Buffer)
stdErr := new(bytes.Buffer)
ctx, _, finished := pm.AddContextTimeout(DefaultContext, timeout, desc)
defer finished()
cmd := exec.CommandContext(ctx, cmdName, args...)
cmd.Dir = dir
cmd.Env = env
cmd.Stdout = stdOut
cmd.Stderr = stdErr
if stdIn != nil {
cmd.Stdin = stdIn
}
if err := cmd.Start(); err != nil {
return "", "", err
}
err := cmd.Wait()
if err != nil {
err = &Error{
PID: GetPID(ctx),
Description: desc,
Err: err,
CtxErr: ctx.Err(),
Stdout: stdOut.String(),
Stderr: stdErr.String(),
}
}
return stdOut.String(), stdErr.String(), err
}
// Error is a wrapped error describing the error results of Process Execution
type Error struct {
PID IDType
Description string
Err error
CtxErr error
Stdout string
Stderr string
}
func (err *Error) Error() string {
return fmt.Sprintf("exec(%s:%s) failed: %v(%v) stdout: %s stderr: %s", err.PID, err.Description, err.Err, err.CtxErr, err.Stdout, err.Stderr)
}
// Unwrap implements the unwrappable implicit interface for go1.13 Unwrap()
func (err *Error) Unwrap() error {
return err.Err
}