118 lines
3.3 KiB
Go
118 lines
3.3 KiB
Go
package physical
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import "fmt"
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const DefaultParallelOperations = 128
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// Backend is the interface required for a physical
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// backend. A physical backend is used to durably store
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// data outside of Vault. As such, it is completely untrusted,
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// and is only accessed via a security barrier. The backends
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// must represent keys in a hierarchical manner. All methods
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// are expected to be thread safe.
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type Backend interface {
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// Put is used to insert or update an entry
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Put(entry *Entry) error
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// Get is used to fetch an entry
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Get(key string) (*Entry, error)
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// Delete is used to permanently delete an entry
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Delete(key string) error
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// List is used ot list all the keys under a given
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// prefix, up to the next prefix.
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List(prefix string) ([]string, error)
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}
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// HABackend is an extentions to the standard physical
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// backend to support high-availability. Vault only expects to
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// use mutual exclusion to allow multiple instances to act as a
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// hot standby for a leader that services all requests.
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type HABackend interface {
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// LockWith is used for mutual exclusion based on the given key.
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LockWith(key, value string) (Lock, error)
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}
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// AdvertiseDetect is an optional interface that an HABackend
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// can implement. If they do, an advertise address can be automatically
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// detected.
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type AdvertiseDetect interface {
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// DetectHostAddr is used to detect the host address
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DetectHostAddr() (string, error)
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}
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type Lock interface {
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// Lock is used to acquire the given lock
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// The stopCh is optional and if closed should interrupt the lock
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// acquisition attempt. The return struct should be closed when
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// leadership is lost.
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Lock(stopCh <-chan struct{}) (<-chan struct{}, error)
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// Unlock is used to release the lock
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Unlock() error
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// Returns the value of the lock and if it is held
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Value() (bool, string, error)
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}
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// Entry is used to represent data stored by the physical backend
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type Entry struct {
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Key string
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Value []byte
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}
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// Factory is the factory function to create a physical backend.
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type Factory func(map[string]string) (Backend, error)
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// NewBackend returns a new backend with the given type and configuration.
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// The backend is looked up in the BuiltinBackends variable.
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func NewBackend(t string, conf map[string]string) (Backend, error) {
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f, ok := BuiltinBackends[t]
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if !ok {
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return nil, fmt.Errorf("unknown physical backend type: %s", t)
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}
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return f(conf)
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}
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// BuiltinBackends is the list of built-in physical backends that can
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// be used with NewBackend.
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var BuiltinBackends = map[string]Factory{
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"inmem": func(map[string]string) (Backend, error) {
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return NewInmem(), nil
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},
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"consul": newConsulBackend,
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"zookeeper": newZookeeperBackend,
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"file": newFileBackend,
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"s3": newS3Backend,
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"etcd": newEtcdBackend,
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"mysql": newMySQLBackend,
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}
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// PermitPool is a wrapper around a semaphore library to keep things
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// agnostic
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type PermitPool struct {
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sem chan int
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}
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// NewPermitPool returns a new permit pool with the provided
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// number of permits
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func NewPermitPool(permits int) *PermitPool {
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if permits < 1 {
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permits = DefaultParallelOperations
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}
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return &PermitPool{
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sem: make(chan int, permits),
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}
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}
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// Acquire returns when a permit has been acquired
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func (c *PermitPool) Acquire() {
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c.sem <- 1
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}
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// Release returns a permit to the pool
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func (c *PermitPool) Release() {
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<-c.sem
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}
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