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ccb3851281
When using the main branch, I found that some changed code didn't have comments. This PR adds some comments.
103 lines
3.6 KiB
Go
103 lines
3.6 KiB
Go
// Copyright 2022 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package dbfs
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import (
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"context"
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"os"
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"code.gitea.io/gitea/models/db"
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)
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/*
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The reasons behind the DBFS (database-filesystem) package:
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When a Gitea action is running, the Gitea action server should collect and store all the logs.
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The requirements are:
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* The running logs must be stored across the cluster if the Gitea servers are deployed as a cluster.
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* The logs will be archived to Object Storage (S3/MinIO, etc.) after a period of time.
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* The Gitea action UI should be able to render the running logs and the archived logs.
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Some possible solutions for the running logs:
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* [Not ideal] Using local temp file: it can not be shared across the cluster.
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* [Not ideal] Using shared file in the filesystem of git repository: although at the moment, the Gitea cluster's
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git repositories must be stored in a shared filesystem, in the future, Gitea may need a dedicated Git Service Server
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to decouple the shared filesystem. Then the action logs will become a blocker.
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* [Not ideal] Record the logs in a database table line by line: it has a couple of problems:
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- It's difficult to make multiple increasing sequence (log line number) for different databases.
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- The database table will have a lot of rows and be affected by the big-table performance problem.
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- It's difficult to load logs by using the same interface as other storages.
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- It's difficult to calculate the size of the logs.
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The DBFS solution:
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* It can be used in a cluster.
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* It can share the same interface (Read/Write/Seek) as other storages.
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* It's very friendly to database because it only needs to store much fewer rows than the log-line solution.
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* In the future, when Gitea action needs to limit the log size (other CI/CD services also do so), it's easier to calculate the log file size.
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* Even sometimes the UI needs to render the tailing lines, the tailing lines can be found be counting the "\n" from the end of the file by seek.
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The seeking and finding is not the fastest way, but it's still acceptable and won't affect the performance too much.
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*/
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type dbfsMeta struct {
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ID int64 `xorm:"pk autoincr"`
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FullPath string `xorm:"VARCHAR(500) UNIQUE NOT NULL"`
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BlockSize int64 `xorm:"BIGINT NOT NULL"`
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FileSize int64 `xorm:"BIGINT NOT NULL"`
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CreateTimestamp int64 `xorm:"BIGINT NOT NULL"`
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ModifyTimestamp int64 `xorm:"BIGINT NOT NULL"`
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}
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type dbfsData struct {
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ID int64 `xorm:"pk autoincr"`
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Revision int64 `xorm:"BIGINT NOT NULL"`
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MetaID int64 `xorm:"BIGINT index(meta_offset) NOT NULL"`
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BlobOffset int64 `xorm:"BIGINT index(meta_offset) NOT NULL"`
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BlobSize int64 `xorm:"BIGINT NOT NULL"`
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BlobData []byte `xorm:"BLOB NOT NULL"`
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}
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func init() {
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db.RegisterModel(new(dbfsMeta))
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db.RegisterModel(new(dbfsData))
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}
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func OpenFile(ctx context.Context, name string, flag int) (File, error) {
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f, err := newDbFile(ctx, name)
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if err != nil {
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return nil, err
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}
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err = f.open(flag)
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if err != nil {
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_ = f.Close()
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return nil, err
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}
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return f, nil
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}
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func Open(ctx context.Context, name string) (File, error) {
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return OpenFile(ctx, name, os.O_RDONLY)
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}
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func Create(ctx context.Context, name string) (File, error) {
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return OpenFile(ctx, name, os.O_RDWR|os.O_CREATE|os.O_TRUNC)
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}
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func Rename(ctx context.Context, oldPath, newPath string) error {
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f, err := newDbFile(ctx, oldPath)
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if err != nil {
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return err
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}
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defer f.Close()
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return f.renameTo(newPath)
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}
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func Remove(ctx context.Context, name string) error {
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f, err := newDbFile(ctx, name)
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if err != nil {
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return err
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}
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defer f.Close()
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return f.delete()
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}
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