package filesystem import ( "emperror.dev/errors" "github.com/apex/log" "github.com/karrick/godirwalk" "sync" "sync/atomic" "syscall" "time" ) type SpaceCheckingOpts struct { AllowStaleResponse bool } type usageLookupTime struct { sync.RWMutex value time.Time } // Update the last time that a disk space lookup was performed. func (ult *usageLookupTime) Set(t time.Time) { ult.Lock() ult.value = t ult.Unlock() } // Get the last time that we performed a disk space usage lookup. func (ult *usageLookupTime) Get() time.Time { ult.RLock() defer ult.RUnlock() return ult.value } // Returns the maximum amount of disk space that this Filesystem instance is allowed to use. func (fs *Filesystem) MaxDisk() int64 { fs.mu.RLock() defer fs.mu.RUnlock() return fs.diskLimit } // Sets the disk space limit for this Filesystem instance. func (fs *Filesystem) SetDiskLimit(i int64) { fs.mu.Lock() fs.diskLimit = i fs.mu.Unlock() } // Determines if the directory a file is trying to be added to has enough space available // for the file to be written to. // // Because determining the amount of space being used by a server is a taxing operation we // will load it all up into a cache and pull from that as long as the key is not expired. // // This operation will potentially block unless allowStaleValue is set to true. See the // documentation on DiskUsage for how this affects the call. func (fs *Filesystem) HasSpaceAvailable(allowStaleValue bool) bool { size, err := fs.DiskUsage(allowStaleValue) if err != nil { log.WithField("root", fs.root).WithField("error", err).Warn("failed to determine root fs directory size") } // If space is -1 or 0 just return true, means they're allowed unlimited. // // Technically we could skip disk space calculation because we don't need to check if the // server exceeds it's limit but because this method caches the disk usage it would be best // to calculate the disk usage and always return true. if fs.MaxDisk() == 0 { return true } return size <= fs.MaxDisk() } // Returns the cached value for the amount of disk space used by the filesystem. Do not rely on this // function for critical logical checks. It should only be used in areas where the actual disk usage // does not need to be perfect, e.g. API responses for server resource usage. func (fs *Filesystem) CachedUsage() int64 { fs.mu.RLock() defer fs.mu.RUnlock() return fs.diskUsed } // Internal helper function to allow other parts of the codebase to check the total used disk space // as needed without overly taxing the system. This will prioritize the value from the cache to avoid // excessive IO usage. We will only walk the filesystem and determine the size of the directory if there // is no longer a cached value. // // If "allowStaleValue" is set to true, a stale value MAY be returned to the caller if there is an // expired cache value AND there is currently another lookup in progress. If there is no cached value but // no other lookup is in progress, a fresh disk space response will be returned to the caller. // // This is primarily to avoid a bunch of I/O operations from piling up on the server, especially on servers // with a large amount of files. func (fs *Filesystem) DiskUsage(allowStaleValue bool) (int64, error) { if !fs.lastLookupTime.Get().After(time.Now().Add(time.Second * fs.diskCheckInterval * -1)) { // If we are now allowing a stale response go ahead and perform the lookup and return the fresh // value. This is a blocking operation to the calling process. if !allowStaleValue { return fs.updateCachedDiskUsage() } else if !fs.lookupInProgress.Get() { // Otherwise, if we allow a stale value and there isn't a valid item in the cache and we aren't // currently performing a lookup, just do the disk usage calculation in the background. go func(fs *Filesystem) { if _, err := fs.updateCachedDiskUsage(); err != nil { log.WithField("root", fs.root).WithField("error", err).Warn("failed to update fs disk usage from within routine") } }(fs) } } // Return the currently cached value back to the calling function. return atomic.LoadInt64(&fs.diskUsed), nil } // Updates the currently used disk space for a server. func (fs *Filesystem) updateCachedDiskUsage() (int64, error) { // Obtain an exclusive lock on this process so that we don't unintentionally run it at the same // time as another running process. Once the lock is available it'll read from the cache for the // second call rather than hitting the disk in parallel. fs.mu.Lock() defer fs.mu.Unlock() // Signal that we're currently updating the disk size so that other calls to the disk checking // functions can determine if they should queue up additional calls to this function. Ensure that // we always set this back to "false" when this process is done executing. fs.lookupInProgress.Set(true) defer fs.lookupInProgress.Set(false) // If there is no size its either because there is no data (in which case running this function // will have effectively no impact), or there is nothing in the cache, in which case we need to // grab the size of their data directory. This is a taxing operation, so we want to store it in // the cache once we've gotten it. size, err := fs.DirectorySize("/") // Always cache the size, even if there is an error. We want to always return that value // so that we don't cause an endless loop of determining the disk size if there is a temporary // error encountered. fs.lastLookupTime.Set(time.Now()) atomic.StoreInt64(&fs.diskUsed, size) return size, err } // Determines the directory size of a given location by running parallel tasks to iterate // through all of the folders. Returns the size in bytes. This can be a fairly taxing operation // on locations with tons of files, so it is recommended that you cache the output. func (fs *Filesystem) DirectorySize(dir string) (int64, error) { d, err := fs.SafePath(dir) if err != nil { return 0, errors.WithStackIf(err) } var size int64 var st syscall.Stat_t err = godirwalk.Walk(d, &godirwalk.Options{ Unsorted: true, Callback: func(p string, e *godirwalk.Dirent) error { // If this is a symlink then resolve the final destination of it before trying to continue walking // over its contents. If it resolves outside the server data directory just skip everything else for // it. Otherwise, allow it to continue. if e.IsSymlink() { if _, err := fs.SafePath(p); err != nil { if IsBadPathResolutionError(err) { return godirwalk.SkipThis } return err } } if !e.IsDir() { syscall.Lstat(p, &st) atomic.AddInt64(&size, st.Size) } return nil }, }) return size, errors.WithStackIf(err) } // Helper function to determine if a server has space available for a file of a given size. // If space is available, no error will be returned, otherwise an ErrNotEnoughSpace error // will be raised. func (fs *Filesystem) hasSpaceFor(size int64) error { if fs.MaxDisk() == 0 { return nil } s, err := fs.DiskUsage(true) if err != nil { return err } if (s + size) > fs.MaxDisk() { return ErrNotEnoughDiskSpace } return nil } // Updates the disk usage for the Filesystem instance. func (fs *Filesystem) addDisk(i int64) int64 { size := atomic.LoadInt64(&fs.diskUsed) // Sorry go gods. This is ugly but the best approach I can come up with for right // now without completely re-evaluating the logic we use for determining disk space. // // Normally I would just be using the atomic load right below, but I'm not sure about // the scenarios where it is 0 because nothing has run that would trigger a disk size // calculation? // // Perhaps that isn't even a concern for the sake of this? if !fs.isTest { size, _ = fs.DiskUsage(true) } // If we're dropping below 0 somehow just cap it to 0. if (size + i) < 0 { return atomic.SwapInt64(&fs.diskUsed, 0) } return atomic.AddInt64(&fs.diskUsed, i) }