github.com/rsampaio/docker@v0.7.2-0.20150827203920-fdc73cc3fc31/volume/drivers/extpoint.go (about)

     1  //go:generate pluginrpc-gen -i $GOFILE -o proxy.go -type VolumeDriver -name VolumeDriver
     2  
     3  package volumedrivers
     4  
     5  import (
     6  	"fmt"
     7  	"sync"
     8  
     9  	"github.com/docker/docker/pkg/plugins"
    10  	"github.com/docker/docker/volume"
    11  )
    12  
    13  // currently created by hand. generation tool would generate this like:
    14  // $ extpoint-gen Driver > volume/extpoint.go
    15  
    16  var drivers = &driverExtpoint{extensions: make(map[string]volume.Driver)}
    17  
    18  // NewVolumeDriver returns a driver has the given name mapped on the given client.
    19  func NewVolumeDriver(name string, c client) volume.Driver {
    20  	proxy := &volumeDriverProxy{c}
    21  	return &volumeDriverAdapter{name, proxy}
    22  }
    23  
    24  type opts map[string]string
    25  
    26  // VolumeDriver defines the available functions that volume plugins must implement.
    27  type VolumeDriver interface {
    28  	// Create a volume with the given name
    29  	Create(name string, opts opts) (err error)
    30  	// Remove the volume with the given name
    31  	Remove(name string) (err error)
    32  	// Get the mountpoint of the given volume
    33  	Path(name string) (mountpoint string, err error)
    34  	// Mount the given volume and return the mountpoint
    35  	Mount(name string) (mountpoint string, err error)
    36  	// Unmount the given volume
    37  	Unmount(name string) (err error)
    38  }
    39  
    40  type driverExtpoint struct {
    41  	extensions map[string]volume.Driver
    42  	sync.Mutex
    43  }
    44  
    45  // Register associates the given driver to the given name, checking if
    46  // the name is already associated
    47  func Register(extension volume.Driver, name string) bool {
    48  	drivers.Lock()
    49  	defer drivers.Unlock()
    50  	if name == "" {
    51  		return false
    52  	}
    53  	_, exists := drivers.extensions[name]
    54  	if exists {
    55  		return false
    56  	}
    57  	drivers.extensions[name] = extension
    58  	return true
    59  }
    60  
    61  // Unregister dissociates the name from it's driver, if the association exists.
    62  func Unregister(name string) bool {
    63  	drivers.Lock()
    64  	defer drivers.Unlock()
    65  	_, exists := drivers.extensions[name]
    66  	if !exists {
    67  		return false
    68  	}
    69  	delete(drivers.extensions, name)
    70  	return true
    71  }
    72  
    73  // Lookup returns the driver associated with the given name. If a
    74  // driver with the given name has not been registered it checks if
    75  // there is a VolumeDriver plugin available with the given name.
    76  func Lookup(name string) (volume.Driver, error) {
    77  	drivers.Lock()
    78  	ext, ok := drivers.extensions[name]
    79  	drivers.Unlock()
    80  	if ok {
    81  		return ext, nil
    82  	}
    83  	pl, err := plugins.Get(name, "VolumeDriver")
    84  	if err != nil {
    85  		return nil, fmt.Errorf("Error looking up volume plugin %s: %v", name, err)
    86  	}
    87  
    88  	drivers.Lock()
    89  	defer drivers.Unlock()
    90  	if ext, ok := drivers.extensions[name]; ok {
    91  		return ext, nil
    92  	}
    93  
    94  	d := NewVolumeDriver(name, pl.Client)
    95  	drivers.extensions[name] = d
    96  	return d, nil
    97  }