git-project-manager/internal/cache/cache.go

package cache

import (
	"fmt"
	"os"
	"sync"
	"time"

	"github.com/pterm/pterm"
	"gitlab.sweetwater.com/it/devops/tools/gitlab-project-manager/internal/config"
	"gitlab.sweetwater.com/it/devops/tools/gitlab-project-manager/internal/remotes"
	"gitlab.sweetwater.com/it/devops/tools/gitlab-project-manager/internal/remotes/projects"
	"gopkg.in/yaml.v3"
)

type Cache struct {
	Projects     []*projects.Project
	Aliases      []*ProjectAlias
	Updated      time.Time
	remotes      *remotes.Remotes
	config       *config.Config
	readFromFile bool
	lock         *sync.Mutex // Lock the entire cache
	contentLock  *sync.Mutex // Lock projects / aliases
	ttl          time.Duration
	file         string
	log          *pterm.Logger
	path         string
}

type CacheOpts struct {
	Path         string
	ProjectsPath string
	TTL          time.Duration
	Logger       *pterm.Logger
	Remotes      *remotes.Remotes
	Config       *config.Config
}

// Load cache, if already loaded and up to date, nothing is done.
// If the cache is not yet loaded from disk, it is loaded
// If the updated timestamp is beyond the set ttl, a refresh is triggered
func (c *Cache) Load() error {
	var err error
	if !c.readFromFile {
		c.Read()
	}
	if time.Since(c.Updated) > c.ttl {
		c.log.Info("Project cache stale, updating.")
		c.Refresh()
	}
	return err
}

func (c *Cache) UnlockCache() {
	c.log.Info("Unlocking cache")
	if err := os.Remove(c.file + ".lock"); err != nil {
		c.log.Fatal("Failed unlocking cache, manual rm may be necessary",
			c.log.Args("error", err, "lockFile", c.file+".lock"),
		)
	}
}

func (c *Cache) LockCache() {
	c.log.Info("Attempting to lock cache")
	c.checkLock()

	file, err := os.OpenFile(c.file+".lock", os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0640)
	defer file.Close()

	if err != nil {
		c.log.Fatal("Failed to lock cache", c.log.Args("error", err))
	}
}

func (c *Cache) checkLock() {
	if _, err := os.Stat(c.file + ".lock"); err == nil {
		c.log.Fatal("Can't manage cache, already locked")
	}
}

// Saves the current state of the cache to disk
func (c *Cache) write() {
	file, err := os.OpenFile(c.file, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0640)
	if err != nil {
		c.log.Error("Failed to write cache to disk", c.log.Args("error", err))
	}
	d := yaml.NewEncoder(file)
	if err = d.Encode(*c); err != nil {
		c.log.Error("Failed to Marshal cache to yaml", c.log.Args("error", err))
	} else {
		c.log.Debug("Cache saved to disk")
	}
}
func (c *Cache) Write() {
	c.lock.Lock()
	defer c.lock.Unlock()
	c.log.Debug("Saving cache to disk", c.log.Args(
		"projects", len(c.Projects),
		"aliases", len(c.Aliases),
	))
	c.write()
}

// Loads and unmarshals the project cache from disk.
func (c *Cache) Read() error {
	c.lock.Lock()
	defer c.lock.Unlock()
	c.log.Debug("Reading project cache from disk", c.log.Args("file", c.file))

	file, err := os.Open(c.file)
	if err != nil {
		c.log.Error("Failed to read project cache", c.log.Args("error", err))
		return err
	}

	d := yaml.NewDecoder(file)
	d.Decode(c)

	c.readFromFile = true
	return nil
}

// Resets projects cache and also optionally clears
// project aliase cache. Writes to disk.
func (c *Cache) clear(clearAliases bool) {
	c.log.Info("Clearing project cache")
	c.Projects = make([]*projects.Project, 0)
	if clearAliases {
		c.log.Info("Clearing project alias cache")
		c.Aliases = make([]*ProjectAlias, 0)
	}
	c.setUpdated()
}
func (c *Cache) Clear(clearAliases bool) {
	c.lock.Lock()
	defer c.lock.Unlock()
	c.clear(clearAliases)
}

func (c *Cache) refresh(remotes ...string) {
	c.log.Info("Loading project cache, this may take a while\n")
	defer c.setUpdated()
	// Fix any dangling aliases
	// For backwards-compatibility only
	c.setAliasRemotes()
	// Retrieve and add/update projects
	c.LoadRemotes(remotes...)
}

// Iterates through all GitLab projects the user has access to, updating
// the project cache where necessary
func (c *Cache) Refresh(remotes ...string) {
	c.lock.Lock()
	defer c.lock.Unlock()
	c.refresh(remotes...)
}

func (c *Cache) String() string {
	cacheString := fmt.Sprintf("Cache Updated %s: Projects %d, Aliases %d\nRemotes %d:",
		c.Updated.String(),
		len(c.Projects),
		len(c.Aliases),
		len(*c.remotes),
	)
	for _, r := range *c.remotes {
		cacheString += " " + r.GetInfo().Host
	}
	return cacheString
}

func (c *Cache) setUpdated() {
	c.Updated = time.Now()
}

func (c *Cache) SetUpdated() {
	c.lock.Lock()
	defer c.lock.Unlock()
	c.setUpdated()
}

func (c *Cache) GetUpdated() time.Time {
	return c.Updated
}

// Returns a new project cache ready to load from
// cache file.
// Cache.Load() must be called manually
func NewProjectCache(opts *CacheOpts) (*Cache, error) {
	var err error

	if _, err = os.Stat(opts.Path); err != nil {
		err = createProjectCache(opts.Path)
	}

	cache := &Cache{
		Projects:    make([]*projects.Project, 0),
		Aliases:     make([]*ProjectAlias, 0),
		config:      opts.Config,
		file:        opts.Path,
		ttl:         opts.TTL,
		lock:        &sync.Mutex{},
		contentLock: &sync.Mutex{},
		log:         opts.Logger,
		remotes:     opts.Remotes,
		path:        opts.ProjectsPath,
	}

	return cache, err
}

func createProjectCache(path string) error {
	return os.WriteFile(path, nil, 0640)
}