pebble: Index | Files

package vfs

import ""


Package Files

clone.go dir_unix.go disk_health.go disk_usage_unix.go errors_unix.go fadvise_linux.go fd.go file_lock_unix.go mem_fs.go preallocate_linux.go prefetch_linux.go syncing_file.go syncing_file_linux.go vfs.go

func Clone Uses

func Clone(srcFS, dstFS FS, srcPath, dstPath string) (bool, error)

Clone recursively copies a directory structure from srcFS to dstFS. srcPath specifies the path in srcFS to copy from and must be compatible with the srcFS path format. dstDir is the target directory in dstFS and must be compatible with the dstFS path format. Returns (true,nil) on a successful copy, (false,nil) if srcPath does not exist, and (false,err) if an error occurred.

func Copy Uses

func Copy(fs FS, oldname, newname string) error

Copy copies the contents of oldname to newname. If newname exists, it will be overwritten.

func IsNoSpaceError Uses

func IsNoSpaceError(err error) bool

IsNoSpaceError returns true if the given error indicates that the disk is out of space.

func LimitedCopy Uses

func LimitedCopy(fs FS, oldname, newname string, maxBytes int64) error

LimitedCopy copies up to maxBytes from oldname to newname. If newname exists, it will be overwritten.

func LinkOrCopy Uses

func LinkOrCopy(fs FS, oldname, newname string) error

LinkOrCopy creates newname as a hard link to the oldname file. If creating the hard link fails, LinkOrCopy falls back to copying the file (which may also fail if newname doesn't exist or oldname already exists).

func Prefetch Uses

func Prefetch(file uintptr, offset uint64, size uint64) error

Prefetch signals the OS (on supported platforms) to fetch the next size bytes in file (as returned by os.File.Fd()) after offset into cache. Any subsequent reads in that range will not issue disk IO.

type FS Uses

type FS interface {
    // Create creates the named file for writing, truncating it if it already
    // exists.
    Create(name string) (File, error)

    // Link creates newname as a hard link to the oldname file.
    Link(oldname, newname string) error

    // Open opens the named file for reading. openOptions provides
    Open(name string, opts ...OpenOption) (File, error)

    // OpenDir opens the named directory for syncing.
    OpenDir(name string) (File, error)

    // Remove removes the named file or directory.
    Remove(name string) error

    // Remove removes the named file or directory and any children it
    // contains. It removes everything it can but returns the first error it
    // encounters.
    RemoveAll(name string) error

    // Rename renames a file. It overwrites the file at newname if one exists,
    // the same as os.Rename.
    Rename(oldname, newname string) error

    // ReuseForWrite attempts to reuse the file with oldname by renaming it to newname and opening
    // it for writing without truncation. It is acceptable for the implementation to choose not
    // to reuse oldname, and simply create the file with newname -- in this case the implementation
    // should delete oldname. If the caller calls this function with an oldname that does not exist,
    // the implementation may return an error.
    ReuseForWrite(oldname, newname string) (File, error)

    // MkdirAll creates a directory and all necessary parents. The permission
    // bits perm have the same semantics as in os.MkdirAll. If the directory
    // already exists, MkdirAll does nothing and returns nil.
    MkdirAll(dir string, perm os.FileMode) error

    // Lock locks the given file, creating the file if necessary, and
    // truncating the file if it already exists. The lock is an exclusive lock
    // (a write lock), but locked files should neither be read from nor written
    // to. Such files should have zero size and only exist to co-ordinate
    // ownership across processes.
    // A nil Closer is returned if an error occurred. Otherwise, close that
    // Closer to release the lock.
    // On Linux and OSX, a lock has the same semantics as fcntl(2)'s advisory
    // locks. In particular, closing any other file descriptor for the same
    // file will release the lock prematurely.
    // Attempting to lock a file that is already locked by the current process
    // returns an error and leaves the existing lock untouched.
    // Lock is not yet implemented on other operating systems, and calling it
    // will return an error.
    Lock(name string) (io.Closer, error)

    // List returns a listing of the given directory. The names returned are
    // relative to dir.
    List(dir string) ([]string, error)

    // Stat returns an os.FileInfo describing the named file.
    Stat(name string) (os.FileInfo, error)

    // PathBase returns the last element of path. Trailing path separators are
    // removed before extracting the last element. If the path is empty, PathBase
    // returns ".".  If the path consists entirely of separators, PathBase returns a
    // single separator.
    PathBase(path string) string

    // PathJoin joins any number of path elements into a single path, adding a
    // separator if necessary.
    PathJoin(elem ...string) string

    // PathDir returns all but the last element of path, typically the path's directory.
    PathDir(path string) string

    // GetFreeSpace returns the amount of free disk space for the filesystem
    // where path is any file or directory within that filesystem.
    GetFreeSpace(path string) (uint64, error)

FS is a namespace for files.

The names are filepath names: they may be / separated or \ separated, depending on the underlying operating system.

var Default FS = defaultFS{}

Default is a FS implementation backed by the underlying operating system's file system.

func Root Uses

func Root(fs FS) FS

Root returns the base FS implementation, unwrapping all nested FSs that expose an Unwrap method.

func WithDiskHealthChecks Uses

func WithDiskHealthChecks(
    fs FS, diskSlowThreshold time.Duration, onSlowDisk func(string, time.Duration),
) FS

WithDiskHealthChecks wraps an FS and ensures that all write-oriented created with that FS are wrapped with disk health detection checks. Disk operations that are observed to take longer than diskSlowThreshold trigger an onSlowDisk call.

type File Uses

type File interface {
    // Unlike the specification for io.Writer.Write(), the vfs.File.Write()
    // method *is* allowed to modify the slice passed in, whether temporarily
    // or permanently. Callers of Write() need to take this into account.
    Stat() (os.FileInfo, error)
    Sync() error

File is a readable, writable sequence of bytes.

Typically, it will be an *os.File, but test code may choose to substitute memory-backed implementations.

func NewMemFile Uses

func NewMemFile(data []byte) File

NewMemFile returns a memory-backed File implementation. The memory-backed file takes ownership of data.

func NewSyncingFile Uses

func NewSyncingFile(f File, opts SyncingFileOptions) File

NewSyncingFile wraps a writable file and ensures that data is synced periodically as it is written. The syncing does not provide persistency guarantees for these periodic syncs, but is used to avoid latency spikes if the OS automatically decides to write out a large chunk of dirty filesystem buffers. The underlying file is fully synced upon close.

func WithFd Uses

func WithFd(inner, outer File) File

WithFd takes an inner (unwrapped) and an outer (wrapped) vfs.File, and returns an fdFileWrapper if the inner file has an Fd() method. Use this method to fix the hiding of the Fd() method and the subsequent unintentional disabling of Fd-related file optimizations.

type MemFS Uses

type MemFS struct {
    // contains filtered or unexported fields

MemFS implements FS.

func NewMem Uses

func NewMem() *MemFS

NewMem returns a new memory-backed FS implementation.

func NewStrictMem Uses

func NewStrictMem() *MemFS

NewStrictMem returns a "strict" memory-backed FS implementation. The behaviour is strict wrt needing a Sync() call on files or directories for the state changes to be finalized. Any changes that are not finalized are visible to reads until MemFS.ResetToSyncedState() is called, at which point they are discarded and no longer visible.

Expected usage:

strictFS := NewStrictMem()
db := Open(..., &Options{FS: strictFS})
// Do and commit various operations.
// Prevent any more changes to finalized state.
// This will finish any ongoing background flushes, compactions but none of these writes will
// be finalized since syncs are being ignored.
// Discard unsynced state.
// Allow changes to finalized state.
// Open the DB. This DB should have the same state as if the earlier strictFS operations and
// db.Close() were not called.
db := Open(..., &Options{FS: strictFS})

func (*MemFS) Create Uses

func (y *MemFS) Create(fullname string) (File, error)

Create implements FS.Create.

func (*MemFS) GetFreeSpace Uses

func (*MemFS) GetFreeSpace(string) (uint64, error)

GetFreeSpace implements FS.GetFreeSpace.

func (y *MemFS) Link(oldname, newname string) error

Link implements FS.Link.

func (*MemFS) List Uses

func (y *MemFS) List(dirname string) ([]string, error)

List implements FS.List.

func (*MemFS) Lock Uses

func (y *MemFS) Lock(fullname string) (io.Closer, error)

Lock implements FS.Lock.

func (*MemFS) MkdirAll Uses

func (y *MemFS) MkdirAll(dirname string, perm os.FileMode) error

MkdirAll implements FS.MkdirAll.

func (*MemFS) Open Uses

func (y *MemFS) Open(fullname string, opts ...OpenOption) (File, error)

Open implements FS.Open.

func (*MemFS) OpenDir Uses

func (y *MemFS) OpenDir(fullname string) (File, error)

OpenDir implements FS.OpenDir.

func (*MemFS) PathBase Uses

func (*MemFS) PathBase(p string) string

PathBase implements FS.PathBase.

func (*MemFS) PathDir Uses

func (*MemFS) PathDir(p string) string

PathDir implements FS.PathDir.

func (*MemFS) PathJoin Uses

func (*MemFS) PathJoin(elem ...string) string

PathJoin implements FS.PathJoin.

func (*MemFS) Remove Uses

func (y *MemFS) Remove(fullname string) error

Remove implements FS.Remove.

func (*MemFS) RemoveAll Uses

func (y *MemFS) RemoveAll(fullname string) error

RemoveAll implements FS.RemoveAll.

func (*MemFS) Rename Uses

func (y *MemFS) Rename(oldname, newname string) error

Rename implements FS.Rename.

func (*MemFS) ResetToSyncedState Uses

func (y *MemFS) ResetToSyncedState()

ResetToSyncedState discards state in the FS that is not synced. See the usage comment with NewStrictMem() for details.

func (*MemFS) ReuseForWrite Uses

func (y *MemFS) ReuseForWrite(oldname, newname string) (File, error)

ReuseForWrite implements FS.ReuseForWrite.

func (*MemFS) SetIgnoreSyncs Uses

func (y *MemFS) SetIgnoreSyncs(ignoreSyncs bool)

SetIgnoreSyncs sets the MemFS.ignoreSyncs field. See the usage comment with NewStrictMem() for details.

func (*MemFS) Stat Uses

func (y *MemFS) Stat(name string) (os.FileInfo, error)

Stat implements FS.Stat.

func (*MemFS) String Uses

func (y *MemFS) String() string

String dumps the contents of the MemFS.

type OpenOption Uses

type OpenOption interface {
    // Apply is called on the file handle after it's opened.

OpenOption provide an interface to do work on file handles in the Open() call.

var RandomReadsOption OpenOption = &randomReadsOption{}

RandomReadsOption is an OpenOption that optimizes opened file handle for random reads, by calling fadvise() with POSIX_FADV_RANDOM on Linux systems to disable readahead.

var SequentialReadsOption OpenOption = &sequentialReadsOption{}

SequentialReadsOption is an OpenOption that optimizes opened file handle for sequential reads, by calling fadvise() with POSIX_FADV_SEQUENTIAL on Linux systems to enable readahead.

type SyncingFileOptions Uses

type SyncingFileOptions struct {
    BytesPerSync    int
    PreallocateSize int

SyncingFileOptions holds the options for a syncingFile.

Package vfs imports 17 packages (graph) and is imported by 24 packages. Updated 2021-01-20. Refresh now. Tools for package owners.