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rpc_client.go
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rpc_client.go
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package rpc
import (
"context"
"errors"
"fmt"
"net"
"sync"
"sync/atomic"
"time"
"google.golang.org/grpc"
"github.com/google/uuid"
"github.com/zrepl/zrepl/replication/logic"
"github.com/zrepl/zrepl/replication/logic/pdu"
"github.com/zrepl/zrepl/rpc/dataconn"
"github.com/zrepl/zrepl/rpc/grpcclientidentity/grpchelper"
"github.com/zrepl/zrepl/rpc/versionhandshake"
"github.com/zrepl/zrepl/transport"
"github.com/zrepl/zrepl/util/envconst"
"github.com/zrepl/zrepl/zfs"
)
// Client implements the active side of a replication setup.
// It satisfies the Endpoint, Sender and Receiver interface defined by package replication.
type Client struct {
dataClient *dataconn.Client
controlClient pdu.ReplicationClient // this the grpc client instance, see constructor
controlConn *grpc.ClientConn
loggers Loggers
closed chan struct{}
}
var _ logic.Endpoint = &Client{}
var _ logic.Sender = &Client{}
var _ logic.Receiver = &Client{}
type DialContextFunc = func(ctx context.Context, network string, addr string) (net.Conn, error)
// config must be validated, NewClient will panic if it is not valid
func NewClient(cn transport.Connecter, loggers Loggers) *Client {
cn = versionhandshake.Connecter(cn, envconst.Duration("ZREPL_RPC_CLIENT_VERSIONHANDSHAKE_TIMEOUT", 10*time.Second))
muxedConnecter := mux(cn)
c := &Client{
loggers: loggers,
closed: make(chan struct{}),
}
grpcConn := grpchelper.ClientConn(muxedConnecter.control, loggers.Control)
go func() {
ctx, cancel := context.WithCancel(context.Background())
go func() {
<-c.closed
cancel()
}()
defer cancel()
for ctx.Err() == nil {
state := grpcConn.GetState()
loggers.General.WithField("grpc_state", state.String()).Debug("grpc state change")
grpcConn.WaitForStateChange(ctx, state)
}
}()
c.controlClient = pdu.NewReplicationClient(grpcConn)
c.controlConn = grpcConn
c.dataClient = dataconn.NewClient(muxedConnecter.data, loggers.Data)
return c
}
func (c *Client) Close() {
close(c.closed)
if err := c.controlConn.Close(); err != nil {
c.loggers.General.WithError(err).Error("cannot close control connection")
}
// TODO c.dataClient should have Close()
}
// callers must ensure that the returned io.ReadCloser is closed
// TODO expose dataClient interface to the outside world
func (c *Client) Send(ctx context.Context, r *pdu.SendReq) (*pdu.SendRes, zfs.StreamCopier, error) {
// TODO the returned sendStream may return a read error created by the remote side
res, streamCopier, err := c.dataClient.ReqSend(ctx, r)
if err != nil {
return nil, nil, err
}
if streamCopier == nil {
return res, nil, nil
}
return res, streamCopier, nil
}
func (c *Client) Receive(ctx context.Context, req *pdu.ReceiveReq, streamCopier zfs.StreamCopier) (*pdu.ReceiveRes, error) {
return c.dataClient.ReqRecv(ctx, req, streamCopier)
}
func (c *Client) ListFilesystems(ctx context.Context, in *pdu.ListFilesystemReq) (*pdu.ListFilesystemRes, error) {
return c.controlClient.ListFilesystems(ctx, in)
}
func (c *Client) ListFilesystemVersions(ctx context.Context, in *pdu.ListFilesystemVersionsReq) (*pdu.ListFilesystemVersionsRes, error) {
return c.controlClient.ListFilesystemVersions(ctx, in)
}
func (c *Client) DestroySnapshots(ctx context.Context, in *pdu.DestroySnapshotsReq) (*pdu.DestroySnapshotsRes, error) {
return c.controlClient.DestroySnapshots(ctx, in)
}
func (c *Client) ReplicationCursor(ctx context.Context, in *pdu.ReplicationCursorReq) (*pdu.ReplicationCursorRes, error) {
return c.controlClient.ReplicationCursor(ctx, in)
}
func (c *Client) WaitForConnectivity(ctx context.Context) error {
ctx, cancel := context.WithCancel(ctx)
defer cancel()
msg := uuid.New().String()
req := pdu.PingReq{Message: msg}
var ctrlOk, dataOk int32
loggers := GetLoggersOrPanic(ctx)
var wg sync.WaitGroup
wg.Add(2)
checkRes := func(res *pdu.PingRes, err error, logger Logger, okVar *int32) {
if err == nil && res.GetEcho() != req.GetMessage() {
err = errors.New("pilot message not echoed correctly")
}
if err == context.Canceled {
err = nil
}
if err != nil {
logger.WithError(err).Error("ping failed")
atomic.StoreInt32(okVar, 0)
cancel()
} else {
atomic.StoreInt32(okVar, 1)
}
}
go func() {
defer wg.Done()
ctrl, ctrlErr := c.controlClient.Ping(ctx, &req, grpc.FailFast(false))
checkRes(ctrl, ctrlErr, loggers.Control, &ctrlOk)
}()
go func() {
defer wg.Done()
for ctx.Err() == nil {
data, dataErr := c.dataClient.ReqPing(ctx, &req)
// dataClient uses transport.Connecter, which doesn't expose FailFast(false)
// => we need to mask dial timeouts
if err, ok := dataErr.(interface{ Temporary() bool }); ok && err.Temporary() {
// Rate-limit pings here in case Temporary() is a mis-classification
// or returns immediately (this is a tight loop in that case)
// TODO keep this in lockstep with controlClient
// => don't use FailFast for control, but check that both control and data worked
time.Sleep(envconst.Duration("ZREPL_RPC_DATACONN_PING_SLEEP", 1*time.Second))
continue
}
// it's not a dial timeout,
checkRes(data, dataErr, loggers.Data, &dataOk)
return
}
}()
wg.Wait()
var what string
if ctrlOk == 1 && dataOk == 1 {
return nil
}
if ctrlOk == 0 {
what += "control"
}
if dataOk == 0 {
if len(what) > 0 {
what += " and data"
} else {
what += "data"
}
}
return fmt.Errorf("%s rpc failed to respond to ping rpcs", what)
}
func (c *Client) ResetConnectBackoff() {
c.controlConn.ResetConnectBackoff()
}