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moby--moby/daemon/graphdriver/plugin.go
Brian Goff f29bbd16f5 Refcount graphdriver plugins properly
Adds 2 new methods to v2 plugin `Acquire` and `Release` which allow
refcounting directly at the plugin level instead of just the store.
Since a graphdriver is initialized exactly once, and is really managed
by a separate object, it didn't really seem right to call
`getter.Get()` to refcount graphdriver plugins.
On shutdown it was particularly weird where we'd either need to keep a
driver reference in daemon, or keep a reference to the pluggin getter in
the layer store, and even then still store extra details on if the
graphdriver is a plugin or not.

Instead the plugin proxy itself will handle calling the neccessary
refcounting methods directly on the plugin object.

Also adds a new interface in `plugingetter` to account for these new
functions which are not going to be implemented by v1 plugins.

Changes terms `plugingetter.CREATE` and `plugingetter.REMOVE` to
`ACQUIRE` and `RELEASE` respectively, which seems to be better
adjectives for what we're doing.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
2016-12-09 19:46:28 -05:00

31 lines
1.1 KiB
Go

package graphdriver
import (
"fmt"
"io"
"path/filepath"
"github.com/docker/docker/pkg/plugingetter"
)
type pluginClient interface {
// Call calls the specified method with the specified arguments for the plugin.
Call(string, interface{}, interface{}) error
// Stream calls the specified method with the specified arguments for the plugin and returns the response IO stream
Stream(string, interface{}) (io.ReadCloser, error)
// SendFile calls the specified method, and passes through the IO stream
SendFile(string, io.Reader, interface{}) error
}
func lookupPlugin(name, home string, opts []string, pg plugingetter.PluginGetter) (Driver, error) {
pl, err := pg.Get(name, "GraphDriver", plugingetter.LOOKUP)
if err != nil {
return nil, fmt.Errorf("Error looking up graphdriver plugin %s: %v", name, err)
}
return newPluginDriver(name, home, opts, pl)
}
func newPluginDriver(name, home string, opts []string, pl plugingetter.CompatPlugin) (Driver, error) {
proxy := &graphDriverProxy{name, pl.Client(), pl}
return proxy, proxy.Init(filepath.Join(home, name), opts)
}