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# ⚠️ Breaking Many deprecated queue config options are removed (actually, they should have been removed in 1.18/1.19). If you see the fatal message when starting Gitea: "Please update your app.ini to remove deprecated config options", please follow the error messages to remove these options from your app.ini. Example: ``` 2023/05/06 19:39:22 [E] Removed queue option: `[indexer].ISSUE_INDEXER_QUEUE_TYPE`. Use new options in `[queue.issue_indexer]` 2023/05/06 19:39:22 [E] Removed queue option: `[indexer].UPDATE_BUFFER_LEN`. Use new options in `[queue.issue_indexer]` 2023/05/06 19:39:22 [F] Please update your app.ini to remove deprecated config options ``` Many options in `[queue]` are are dropped, including: `WRAP_IF_NECESSARY`, `MAX_ATTEMPTS`, `TIMEOUT`, `WORKERS`, `BLOCK_TIMEOUT`, `BOOST_TIMEOUT`, `BOOST_WORKERS`, they can be removed from app.ini. # The problem The old queue package has some legacy problems: * complexity: I doubt few people could tell how it works. * maintainability: Too many channels and mutex/cond are mixed together, too many different structs/interfaces depends each other. * stability: due to the complexity & maintainability, sometimes there are strange bugs and difficult to debug, and some code doesn't have test (indeed some code is difficult to test because a lot of things are mixed together). * general applicability: although it is called "queue", its behavior is not a well-known queue. * scalability: it doesn't seem easy to make it work with a cluster without breaking its behaviors. It came from some very old code to "avoid breaking", however, its technical debt is too heavy now. It's a good time to introduce a better "queue" package. # The new queue package It keeps using old config and concept as much as possible. * It only contains two major kinds of concepts: * The "base queue": channel, levelqueue, redis * They have the same abstraction, the same interface, and they are tested by the same testing code. * The "WokerPoolQueue", it uses the "base queue" to provide "worker pool" function, calls the "handler" to process the data in the base queue. * The new code doesn't do "PushBack" * Think about a queue with many workers, the "PushBack" can't guarantee the order for re-queued unhandled items, so in new code it just does "normal push" * The new code doesn't do "pause/resume" * The "pause/resume" was designed to handle some handler's failure: eg: document indexer (elasticsearch) is down * If a queue is paused for long time, either the producers blocks or the new items are dropped. * The new code doesn't do such "pause/resume" trick, it's not a common queue's behavior and it doesn't help much. * If there are unhandled items, the "push" function just blocks for a few seconds and then re-queue them and retry. * The new code doesn't do "worker booster" * Gitea's queue's handlers are light functions, the cost is only the go-routine, so it doesn't make sense to "boost" them. * The new code only use "max worker number" to limit the concurrent workers. * The new "Push" never blocks forever * Instead of creating more and more blocking goroutines, return an error is more friendly to the server and to the end user. There are more details in code comments: eg: the "Flush" problem, the strange "code.index" hanging problem, the "immediate" queue problem. Almost ready for review. TODO: * [x] add some necessary comments during review * [x] add some more tests if necessary * [x] update documents and config options * [x] test max worker / active worker * [x] re-run the CI tasks to see whether any test is flaky * [x] improve the `handleOldLengthConfiguration` to provide more friendly messages * [x] fine tune default config values (eg: length?) ## Code coverage: ![image](https://user-images.githubusercontent.com/2114189/236620635-55576955-f95d-4810-b12f-879026a3afdf.png)
111 lines
3.0 KiB
Go
111 lines
3.0 KiB
Go
// Copyright 2019 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package queue
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import (
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"context"
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"sync"
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"time"
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"code.gitea.io/gitea/modules/log"
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"code.gitea.io/gitea/modules/setting"
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)
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// Manager is a manager for the queues created by "CreateXxxQueue" functions, these queues are called "managed queues".
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type Manager struct {
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mu sync.Mutex
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qidCounter int64
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Queues map[int64]ManagedWorkerPoolQueue
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}
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type ManagedWorkerPoolQueue interface {
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GetName() string
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GetType() string
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GetItemTypeName() string
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GetWorkerNumber() int
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GetWorkerActiveNumber() int
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GetWorkerMaxNumber() int
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SetWorkerMaxNumber(num int)
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GetQueueItemNumber() int
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// FlushWithContext tries to make the handler process all items in the queue synchronously.
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// It is for testing purpose only. It's not designed to be used in a cluster.
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FlushWithContext(ctx context.Context, timeout time.Duration) error
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}
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var manager *Manager
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func init() {
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manager = &Manager{
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Queues: make(map[int64]ManagedWorkerPoolQueue),
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}
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}
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func GetManager() *Manager {
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return manager
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}
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func (m *Manager) AddManagedQueue(managed ManagedWorkerPoolQueue) {
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m.mu.Lock()
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defer m.mu.Unlock()
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m.qidCounter++
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m.Queues[m.qidCounter] = managed
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}
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func (m *Manager) GetManagedQueue(qid int64) ManagedWorkerPoolQueue {
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m.mu.Lock()
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defer m.mu.Unlock()
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return m.Queues[qid]
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}
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func (m *Manager) ManagedQueues() map[int64]ManagedWorkerPoolQueue {
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m.mu.Lock()
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defer m.mu.Unlock()
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queues := make(map[int64]ManagedWorkerPoolQueue, len(m.Queues))
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for k, v := range m.Queues {
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queues[k] = v
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}
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return queues
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}
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// FlushAll tries to make all managed queues process all items synchronously, until timeout or the queue is empty.
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// It is for testing purpose only. It's not designed to be used in a cluster.
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func (m *Manager) FlushAll(ctx context.Context, timeout time.Duration) error {
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var finalErr error
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qs := m.ManagedQueues()
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for _, q := range qs {
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if err := q.FlushWithContext(ctx, timeout); err != nil {
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finalErr = err // TODO: in Go 1.20: errors.Join
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}
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}
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return finalErr
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}
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// CreateSimpleQueue creates a simple queue from global setting config provider by name
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func CreateSimpleQueue[T any](name string, handler HandlerFuncT[T]) *WorkerPoolQueue[T] {
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return createWorkerPoolQueue(name, setting.CfgProvider, handler, false)
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}
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// CreateUniqueQueue creates a unique queue from global setting config provider by name
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func CreateUniqueQueue[T any](name string, handler HandlerFuncT[T]) *WorkerPoolQueue[T] {
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return createWorkerPoolQueue(name, setting.CfgProvider, handler, true)
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}
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func createWorkerPoolQueue[T any](name string, cfgProvider setting.ConfigProvider, handler HandlerFuncT[T], unique bool) *WorkerPoolQueue[T] {
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queueSetting, err := setting.GetQueueSettings(cfgProvider, name)
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if err != nil {
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log.Error("Failed to get queue settings for %q: %v", name, err)
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return nil
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}
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w, err := NewWorkerPoolQueueBySetting(name, queueSetting, handler, unique)
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if err != nil {
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log.Error("Failed to create queue %q: %v", name, err)
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return nil
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}
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GetManager().AddManagedQueue(w)
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return w
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}
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