distribution/storagedriver/ipc/server.go

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package ipc
import (
"bytes"
"io"
"io/ioutil"
"net"
"os"
"reflect"
"github.com/docker/docker-registry/storagedriver"
"github.com/docker/libchan"
"github.com/docker/libchan/spdy"
)
// StorageDriverServer runs a new IPC server handling requests for the given
// storagedriver.StorageDriver
// This explicitly uses file descriptor 3 for IPC communication, as storage drivers are spawned in
// client.go
//
// To create a new out-of-process driver, create a main package which calls StorageDriverServer with
// a storagedriver.StorageDriver
func StorageDriverServer(driver storagedriver.StorageDriver) error {
childSocket := os.NewFile(3, "childSocket")
defer childSocket.Close()
conn, err := net.FileConn(childSocket)
if err != nil {
panic(err)
}
defer conn.Close()
if transport, err := spdy.NewServerTransport(conn); err != nil {
panic(err)
} else {
for {
receiver, err := transport.WaitReceiveChannel()
if err == io.EOF {
return nil
} else if err != nil {
panic(err)
}
go receive(driver, receiver)
}
}
}
// receive receives new storagedriver.StorageDriver method requests and creates a new goroutine to
// handle each request
// Requests are expected to be of type ipc.Request as the parameters are unknown until the request
// type is deserialized
func receive(driver storagedriver.StorageDriver, receiver libchan.Receiver) {
for {
var request Request
err := receiver.Receive(&request)
if err == io.EOF {
return
} else if err != nil {
panic(err)
}
go handleRequest(driver, request)
}
}
// handleRequest handles storagedriver.StorageDriver method requests as defined in client.go
// Responds to requests using the Request.ResponseChannel
func handleRequest(driver storagedriver.StorageDriver, request Request) {
switch request.Type {
case "Version":
err := request.ResponseChannel.Send(&VersionResponse{Version: storagedriver.CurrentVersion})
if err != nil {
panic(err)
}
case "GetContent":
path, _ := request.Parameters["Path"].(string)
content, err := driver.GetContent(path)
var response ReadStreamResponse
if err != nil {
response = ReadStreamResponse{Error: WrapError(err)}
} else {
response = ReadStreamResponse{Reader: ioutil.NopCloser(bytes.NewReader(content))}
}
err = request.ResponseChannel.Send(&response)
if err != nil {
panic(err)
}
case "PutContent":
path, _ := request.Parameters["Path"].(string)
reader, _ := request.Parameters["Reader"].(io.ReadCloser)
contents, err := ioutil.ReadAll(reader)
defer reader.Close()
if err == nil {
err = driver.PutContent(path, contents)
}
response := WriteStreamResponse{
Error: WrapError(err),
}
err = request.ResponseChannel.Send(&response)
if err != nil {
panic(err)
}
case "ReadStream":
path, _ := request.Parameters["Path"].(string)
// Depending on serialization method, Offset may be convereted to any int/uint type
offset := reflect.ValueOf(request.Parameters["Offset"]).Convert(reflect.TypeOf(uint64(0))).Uint()
reader, err := driver.ReadStream(path, offset)
var response ReadStreamResponse
if err != nil {
response = ReadStreamResponse{Error: WrapError(err)}
} else {
response = ReadStreamResponse{Reader: reader}
}
err = request.ResponseChannel.Send(&response)
if err != nil {
panic(err)
}
case "WriteStream":
path, _ := request.Parameters["Path"].(string)
// Depending on serialization method, Offset may be convereted to any int/uint type
offset := reflect.ValueOf(request.Parameters["Offset"]).Convert(reflect.TypeOf(uint64(0))).Uint()
// Depending on serialization method, Size may be convereted to any int/uint type
size := reflect.ValueOf(request.Parameters["Size"]).Convert(reflect.TypeOf(uint64(0))).Uint()
reader, _ := request.Parameters["Reader"].(io.ReadCloser)
err := driver.WriteStream(path, offset, size, reader)
response := WriteStreamResponse{
Error: WrapError(err),
}
err = request.ResponseChannel.Send(&response)
if err != nil {
panic(err)
}
case "CurrentSize":
path, _ := request.Parameters["Path"].(string)
position, err := driver.CurrentSize(path)
response := CurrentSizeResponse{
Position: position,
Error: WrapError(err),
}
err = request.ResponseChannel.Send(&response)
if err != nil {
panic(err)
}
case "List":
path, _ := request.Parameters["Path"].(string)
keys, err := driver.List(path)
response := ListResponse{
Keys: keys,
Error: WrapError(err),
}
err = request.ResponseChannel.Send(&response)
if err != nil {
panic(err)
}
case "Move":
sourcePath, _ := request.Parameters["SourcePath"].(string)
destPath, _ := request.Parameters["DestPath"].(string)
err := driver.Move(sourcePath, destPath)
response := MoveResponse{
Error: WrapError(err),
}
err = request.ResponseChannel.Send(&response)
if err != nil {
panic(err)
}
case "Delete":
path, _ := request.Parameters["Path"].(string)
err := driver.Delete(path)
response := DeleteResponse{
Error: WrapError(err),
}
err = request.ResponseChannel.Send(&response)
if err != nil {
panic(err)
}
default:
panic(request)
}
}