Vincent Batts
4a65baf87b
I obviously bungled my attempt in #1391 so this is fixing that. Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>
82 lines
2.2 KiB
Go
82 lines
2.2 KiB
Go
package storage
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import (
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"fmt"
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"path/filepath"
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"sync"
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"time"
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"github.com/pkg/errors"
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)
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// A Locker represents a file lock where the file is used to cache an
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// identifier of the last party that made changes to whatever's being protected
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// by the lock.
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type Locker interface {
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sync.Locker
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// Touch records, for others sharing the lock, that the caller was the
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// last writer. It should only be called with the lock held.
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Touch() error
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// Modified() checks if the most recent writer was a party other than the
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// last recorded writer. It should only be called with the lock held.
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Modified() (bool, error)
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// TouchedSince() checks if the most recent writer modified the file (likely using Touch()) after the specified time.
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TouchedSince(when time.Time) bool
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// IsReadWrite() checks if the lock file is read-write
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IsReadWrite() bool
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}
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var (
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lockfiles map[string]Locker
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lockfilesLock sync.Mutex
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)
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// GetLockfile opens a read-write lock file, creating it if necessary. The
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// Locker object it returns will be returned unlocked.
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func GetLockfile(path string) (Locker, error) {
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lockfilesLock.Lock()
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defer lockfilesLock.Unlock()
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if lockfiles == nil {
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lockfiles = make(map[string]Locker)
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}
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cleanPath := filepath.Clean(path)
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if locker, ok := lockfiles[cleanPath]; ok {
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if !locker.IsReadWrite() {
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return nil, errors.Wrapf(ErrLockReadOnly, "lock %q is a read-only lock", cleanPath)
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}
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return locker, nil
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}
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locker, err := getLockFile(path, false) // platform dependent locker
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if err != nil {
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return nil, err
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}
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lockfiles[filepath.Clean(path)] = locker
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return locker, nil
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}
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// GetROLockfile opens a read-only lock file. The Locker object it returns
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// will be returned unlocked.
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func GetROLockfile(path string) (Locker, error) {
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lockfilesLock.Lock()
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defer lockfilesLock.Unlock()
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if lockfiles == nil {
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lockfiles = make(map[string]Locker)
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}
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cleanPath := filepath.Clean(path)
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if locker, ok := lockfiles[cleanPath]; ok {
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if locker.IsReadWrite() {
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return nil, fmt.Errorf("lock %q is a read-write lock", cleanPath)
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}
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return locker, nil
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}
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locker, err := getLockFile(path, true) // platform dependent locker
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if err != nil {
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return nil, err
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}
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lockfiles[filepath.Clean(path)] = locker
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return locker, nil
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}
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