stackrox/pkg/backgroundtasks/manager_impl.go at master · stackrox/stackrox · GitHub

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package backgroundtasks

import (

"context"

"errors"

"fmt"

"time"

"github.com/stackrox/rox/pkg/concurrency"

"github.com/stackrox/rox/pkg/sync"

"github.com/stackrox/rox/pkg/uuid"

)

var cancelExecutionMarker = func() {}

type taskWrapper struct {

// Task id.

id string

// Function to execute.

exec Task

// Metadata related to task.

metadata map[string]interface{}

// Results from execution of task.

result interface{}

// Errors from execution of task.

err error

// Cancels the execution of task.

cancel context.CancelFunc

}

func (t *taskWrapper) execute(ctx context.Context) (res interface{}, err error) {

if err = ctx.Err(); err != nil {

return

}

panicked := true

defer func() {

if p := recover(); p != nil || panicked {

err = fmt.Errorf("Panic during execution of task: %v", p)

}

}()

res, err = t.exec(ctx)

panicked = false

return

}

type managerImpl struct {

existingTasks map[string]*taskWrapper

completedTasks map[string]time.Time

pendingTasks chan *taskWrapper

existingTasksMutex sync.Mutex

completedTasksMutex sync.Mutex

cancelFuncTasksMutex *concurrency.KeyedMutex

parallel chan struct{}

completedTaskExpiryTime time.Duration

cleanUpInterval time.Duration

}

// WithExpirationCompletedTasks sets the duration after which completed tasks are cleaned up.

func WithExpirationCompletedTasks(t time.Duration) ManagerOption {

return func(m *managerImpl) {

m.completedTaskExpiryTime = t

}

// WithMaxTasksInParallel sets the max tasks that are allowed to run in parallel.

func WithMaxTasksInParallel(p int) ManagerOption {

return func(m *managerImpl) {

m.parallel = make(chan struct{}, p)

m.cancelFuncTasksMutex = concurrency.NewKeyedMutex(uint32(cap(m.parallel) + cap(m.pendingTasks)))

}

// WithMaxPendingTaskQueueSize sets the max pending job queue size.

func WithMaxPendingTaskQueueSize(sz int) ManagerOption {

return func(m *managerImpl) {

m.pendingTasks = make(chan *taskWrapper, sz)

m.cancelFuncTasksMutex = concurrency.NewKeyedMutex(uint32(cap(m.parallel) + cap(m.pendingTasks)))

}

// WithCleanUpInterval sets the duration after which the manager wakes up to perform it's clean up jobs.

func WithCleanUpInterval(t time.Duration) ManagerOption {

return func(m *managerImpl) {

m.cleanUpInterval = t

}

func (m *managerImpl) applyDefaults() {

m.parallel = make(chan struct{}, 8)

m.completedTaskExpiryTime = 20 * time.Minute

m.pendingTasks = make(chan *taskWrapper, 256)

m.cleanUpInterval = 5 * time.Minute

m.existingTasks = make(map[string]*taskWrapper)

m.completedTasks = make(map[string]time.Time)

m.cancelFuncTasksMutex = concurrency.NewKeyedMutex(uint32(cap(m.parallel) + cap(m.pendingTasks)))

}

// AddTask adds a task to its pending task list to be run as a background process and returns a jobid.

func (m *managerImpl) AddTask(metadata map[string]interface{}, task Task) (string, error) {

t := &taskWrapper{

exec: task,

metadata: metadata,

}

id := uuid.NewV4().String()

t.id = id

select {

case m.pendingTasks <- t:

default:

return "", errors.New("Cannot add task: queue full.")

}

m.existingTasksMutex.Lock()

defer m.existingTasksMutex.Unlock()

m.existingTasks[id] = t

return id, nil

}

// Start initiates the manager to accept tasks and monitor the execution.

func (m *managerImpl) Start() {

parentCtx := context.Background()

go func() {

for {

m.parallel <- struct{}{}

t := <-m.pendingTasks

ctx, cancel := context.WithCancel(parentCtx)

m.cancelFuncTasksMutex.DoWithLock(t.id, func() {

if t.cancel != nil {

cancel()

}

t.cancel = cancel

})

m.startTaskExec(ctx, t)

}

}()

go func() {

for {

select {

case <-parentCtx.Done():

return

case <-time.After(m.cleanUpInterval):

m.cleanupExpiredCompletedTasks()

}

}()

}

func (m *managerImpl) startTaskExec(ctx context.Context, t *taskWrapper) {

go func(t *taskWrapper) {

res, err := t.execute(ctx)

<-m.parallel

m.completedTasksMutex.Lock()

defer m.completedTasksMutex.Unlock()

m.completedTasks[t.id] = time.Now()

t.result = res

t.err = err

}(t)

}

func (m *managerImpl) cleanupExpiredCompletedTasks() {

m.completedTasksMutex.Lock()

defer m.completedTasksMutex.Unlock()

// check expired completed tasks.

currentTime := time.Now()

var removeIds []string

for id, t := range m.completedTasks {

if t.Add(m.completedTaskExpiryTime).Before(currentTime) {

removeIds = append(removeIds, id)

}

m.existingTasksMutex.Lock()

defer m.existingTasksMutex.Unlock()

for _, id := range removeIds {

delete(m.completedTasks, id)

delete(m.existingTasks, id)

}

// GetTaskStatus returns the status of the jobid.

func (m *managerImpl) GetTaskStatusAndMetadata(taskID string) (map[string]interface{}, interface{}, bool, error) {

m.completedTasksMutex.Lock()

defer m.completedTasksMutex.Unlock()

m.existingTasksMutex.Lock()

defer m.existingTasksMutex.Unlock()

t, ok := m.existingTasks[taskID]

if !ok {

return nil, nil, false, errors.New("id does not exist.")

}

_, completed := m.completedTasks[taskID]

return t.metadata, t.result, completed, t.err

}

func (m *managerImpl) CancelTask(taskID string) error {

m.existingTasksMutex.Lock()

defer m.existingTasksMutex.Unlock()

t, ok := m.existingTasks[taskID]

if !ok {

return errors.New("id does not exist.")

}

// We defer unlock of existingTasksMutex so that it cant be cleaned up, and we know that it exists throughout the

// completion of this fn.

m.cancelFuncTasksMutex.Lock(taskID)

defer m.cancelFuncTasksMutex.Unlock(taskID)

if t.cancel == nil {

t.cancel = cancelExecutionMarker

return nil

}

t.cancel()

return nil

}

stackrox/pkg/backgroundtasks/manager_impl.go at master · stackrox/stackrox · GitHub

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