distribution/storagedriver/ipc/client.go

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package ipc
import (
"bytes"
"encoding/json"
"io"
"io/ioutil"
"net"
"os"
"os/exec"
"syscall"
"github.com/docker/libchan"
"github.com/docker/libchan/spdy"
)
// StorageDriverExecutablePrefix is the prefix which the IPC storage driver loader expects driver
// executables to begin with. For example, the s3 driver should be named "registry-storage-s3".
const StorageDriverExecutablePrefix = "registry-storagedriver-"
// StorageDriverClient is a storagedriver.StorageDriver implementation using a managed child process
// communicating over IPC using libchan with a unix domain socket
type StorageDriverClient struct {
subprocess *exec.Cmd
socket *os.File
transport *spdy.Transport
sender libchan.Sender
}
// NewDriverClient constructs a new out-of-process storage driver using the driver name and
// configuration parameters
// A user must call Start on this driver client before remote method calls can be made
//
// Looks for drivers in the following locations in order:
// - Storage drivers directory (to be determined, yet not implemented)
// - $GOPATH/bin
// - $PATH
func NewDriverClient(name string, parameters map[string]string) (*StorageDriverClient, error) {
paramsBytes, err := json.Marshal(parameters)
if err != nil {
return nil, err
}
driverExecName := StorageDriverExecutablePrefix + name
driverPath, err := exec.LookPath(driverExecName)
if err != nil {
return nil, err
}
command := exec.Command(driverPath, string(paramsBytes))
return &StorageDriverClient{
subprocess: command,
}, nil
}
// Start starts the designated child process storage driver and binds a socket to this process for
// IPC method calls
func (driver *StorageDriverClient) Start() error {
fileDescriptors, err := syscall.Socketpair(syscall.AF_LOCAL, syscall.SOCK_STREAM, 0)
if err != nil {
return err
}
childSocket := os.NewFile(uintptr(fileDescriptors[0]), "childSocket")
parentSocket := os.NewFile(uintptr(fileDescriptors[1]), "parentSocket")
driver.subprocess.Stdout = os.Stdout
driver.subprocess.Stderr = os.Stderr
driver.subprocess.ExtraFiles = []*os.File{childSocket}
if err = driver.subprocess.Start(); err != nil {
parentSocket.Close()
return err
}
if err = childSocket.Close(); err != nil {
parentSocket.Close()
return err
}
connection, err := net.FileConn(parentSocket)
if err != nil {
parentSocket.Close()
return err
}
transport, err := spdy.NewClientTransport(connection)
if err != nil {
parentSocket.Close()
return err
}
sender, err := transport.NewSendChannel()
if err != nil {
transport.Close()
parentSocket.Close()
return err
}
driver.socket = parentSocket
driver.transport = transport
driver.sender = sender
return nil
}
// Stop stops the child process storage driver
// storagedriver.StorageDriver methods called after Stop will fail
func (driver *StorageDriverClient) Stop() error {
closeSenderErr := driver.sender.Close()
closeTransportErr := driver.transport.Close()
closeSocketErr := driver.socket.Close()
killErr := driver.subprocess.Process.Kill()
if closeSenderErr != nil {
return closeSenderErr
} else if closeTransportErr != nil {
return closeTransportErr
} else if closeSocketErr != nil {
return closeSocketErr
}
return killErr
}
// Implement the storagedriver.StorageDriver interface over IPC
func (driver *StorageDriverClient) GetContent(path string) ([]byte, error) {
receiver, remoteSender := libchan.Pipe()
params := map[string]interface{}{"Path": path}
err := driver.sender.Send(&Request{Type: "GetContent", Parameters: params, ResponseChannel: remoteSender})
if err != nil {
return nil, err
}
var response ReadStreamResponse
err = receiver.Receive(&response)
if err != nil {
return nil, err
}
if response.Error != nil {
return nil, response.Error
}
defer response.Reader.Close()
contents, err := ioutil.ReadAll(response.Reader)
if err != nil {
return nil, err
}
return contents, nil
}
func (driver *StorageDriverClient) PutContent(path string, contents []byte) error {
receiver, remoteSender := libchan.Pipe()
params := map[string]interface{}{"Path": path, "Reader": ioutil.NopCloser(bytes.NewReader(contents))}
err := driver.sender.Send(&Request{Type: "PutContent", Parameters: params, ResponseChannel: remoteSender})
if err != nil {
return err
}
var response WriteStreamResponse
err = receiver.Receive(&response)
if err != nil {
return err
}
if response.Error != nil {
return response.Error
}
return nil
}
func (driver *StorageDriverClient) ReadStream(path string, offset uint64) (io.ReadCloser, error) {
receiver, remoteSender := libchan.Pipe()
params := map[string]interface{}{"Path": path, "Offset": offset}
err := driver.sender.Send(&Request{Type: "ReadStream", Parameters: params, ResponseChannel: remoteSender})
if err != nil {
return nil, err
}
var response ReadStreamResponse
err = receiver.Receive(&response)
if err != nil {
return nil, err
}
if response.Error != nil {
return nil, response.Error
}
return response.Reader, nil
}
func (driver *StorageDriverClient) WriteStream(path string, offset, size uint64, reader io.ReadCloser) error {
receiver, remoteSender := libchan.Pipe()
params := map[string]interface{}{"Path": path, "Offset": offset, "Size": size, "Reader": ioutil.NopCloser(reader)}
err := driver.sender.Send(&Request{Type: "WriteStream", Parameters: params, ResponseChannel: remoteSender})
if err != nil {
return err
}
var response WriteStreamResponse
err = receiver.Receive(&response)
if err != nil {
return err
}
if response.Error != nil {
return response.Error
}
return nil
}
func (driver *StorageDriverClient) ResumeWritePosition(path string) (uint64, error) {
receiver, remoteSender := libchan.Pipe()
params := map[string]interface{}{"Path": path}
err := driver.sender.Send(&Request{Type: "ResumeWritePosition", Parameters: params, ResponseChannel: remoteSender})
if err != nil {
return 0, err
}
var response ResumeWritePositionResponse
err = receiver.Receive(&response)
if err != nil {
return 0, err
}
if response.Error != nil {
return 0, response.Error
}
return response.Position, nil
}
func (driver *StorageDriverClient) List(path string) ([]string, error) {
receiver, remoteSender := libchan.Pipe()
params := map[string]interface{}{"Path": path}
err := driver.sender.Send(&Request{Type: "List", Parameters: params, ResponseChannel: remoteSender})
if err != nil {
return nil, err
}
var response ListResponse
err = receiver.Receive(&response)
if err != nil {
return nil, err
}
if response.Error != nil {
return nil, response.Error
}
return response.Keys, nil
}
func (driver *StorageDriverClient) Move(sourcePath string, destPath string) error {
receiver, remoteSender := libchan.Pipe()
params := map[string]interface{}{"SourcePath": sourcePath, "DestPath": destPath}
err := driver.sender.Send(&Request{Type: "Move", Parameters: params, ResponseChannel: remoteSender})
if err != nil {
return err
}
var response MoveResponse
err = receiver.Receive(&response)
if err != nil {
return err
}
if response.Error != nil {
return response.Error
}
return nil
}
func (driver *StorageDriverClient) Delete(path string) error {
receiver, remoteSender := libchan.Pipe()
params := map[string]interface{}{"Path": path}
err := driver.sender.Send(&Request{Type: "Delete", Parameters: params, ResponseChannel: remoteSender})
if err != nil {
return err
}
var response DeleteResponse
err = receiver.Receive(&response)
if err != nil {
return err
}
if response.Error != nil {
return response.Error
}
return nil
}