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moby--moby/volume/drivers/extpoint.go
Brian Goff cfb2c667ad Use fine-grained locks for plugin loading.
This helps ensure that only one thing is trying to intialize a plugin at
once while also keeping the global lock free during initialization.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
2016-01-20 13:57:52 -05:00

164 lines
4.1 KiB
Go

//go:generate pluginrpc-gen -i $GOFILE -o proxy.go -type volumeDriver -name VolumeDriver
package volumedrivers
import (
"fmt"
"sync"
"github.com/docker/docker/pkg/locker"
"github.com/docker/docker/pkg/plugins"
"github.com/docker/docker/volume"
)
// currently created by hand. generation tool would generate this like:
// $ extpoint-gen Driver > volume/extpoint.go
var drivers = &driverExtpoint{extensions: make(map[string]volume.Driver), driverLock: &locker.Locker{}}
const extName = "VolumeDriver"
// NewVolumeDriver returns a driver has the given name mapped on the given client.
func NewVolumeDriver(name string, c client) volume.Driver {
proxy := &volumeDriverProxy{c}
return &volumeDriverAdapter{name, proxy}
}
type opts map[string]string
type list []*proxyVolume
// volumeDriver defines the available functions that volume plugins must implement.
// This interface is only defined to generate the proxy objects.
// It's not intended to be public or reused.
type volumeDriver interface {
// Create a volume with the given name
Create(name string, opts opts) (err error)
// Remove the volume with the given name
Remove(name string) (err error)
// Get the mountpoint of the given volume
Path(name string) (mountpoint string, err error)
// Mount the given volume and return the mountpoint
Mount(name string) (mountpoint string, err error)
// Unmount the given volume
Unmount(name string) (err error)
// List lists all the volumes known to the driver
List() (volumes list, err error)
// Get retreives the volume with the requested name
Get(name string) (volume *proxyVolume, err error)
}
type driverExtpoint struct {
extensions map[string]volume.Driver
sync.Mutex
driverLock *locker.Locker
}
// Register associates the given driver to the given name, checking if
// the name is already associated
func Register(extension volume.Driver, name string) bool {
if name == "" {
return false
}
drivers.Lock()
defer drivers.Unlock()
_, exists := drivers.extensions[name]
if exists {
return false
}
drivers.extensions[name] = extension
return true
}
// Unregister dissociates the name from it's driver, if the association exists.
func Unregister(name string) bool {
drivers.Lock()
defer drivers.Unlock()
_, exists := drivers.extensions[name]
if !exists {
return false
}
delete(drivers.extensions, name)
return true
}
// Lookup returns the driver associated with the given name. If a
// driver with the given name has not been registered it checks if
// there is a VolumeDriver plugin available with the given name.
func Lookup(name string) (volume.Driver, error) {
drivers.driverLock.Lock(name)
defer drivers.driverLock.Unlock(name)
drivers.Lock()
ext, ok := drivers.extensions[name]
drivers.Unlock()
if ok {
return ext, nil
}
pl, err := plugins.Get(name, extName)
if err != nil {
return nil, fmt.Errorf("Error looking up volume plugin %s: %v", name, err)
}
drivers.Lock()
defer drivers.Unlock()
if ext, ok := drivers.extensions[name]; ok {
return ext, nil
}
d := NewVolumeDriver(name, pl.Client)
drivers.extensions[name] = d
return d, nil
}
// GetDriver returns a volume driver by it's name.
// If the driver is empty, it looks for the local driver.
func GetDriver(name string) (volume.Driver, error) {
if name == "" {
name = volume.DefaultDriverName
}
return Lookup(name)
}
// GetDriverList returns list of volume drivers registered.
// If no driver is registered, empty string list will be returned.
func GetDriverList() []string {
var driverList []string
drivers.Lock()
for driverName := range drivers.extensions {
driverList = append(driverList, driverName)
}
drivers.Unlock()
return driverList
}
// GetAllDrivers lists all the registered drivers
func GetAllDrivers() ([]volume.Driver, error) {
plugins, err := plugins.GetAll(extName)
if err != nil {
return nil, err
}
var ds []volume.Driver
drivers.Lock()
defer drivers.Unlock()
for _, d := range drivers.extensions {
ds = append(ds, d)
}
for _, p := range plugins {
ext, ok := drivers.extensions[p.Name]
if ok {
continue
}
ext = NewVolumeDriver(p.Name, p.Client)
drivers.extensions[p.Name] = ext
ds = append(ds, ext)
}
return ds, nil
}