588 lines
15 KiB
Go
588 lines
15 KiB
Go
// Copyright 2016 The etcd Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package clientv3
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import (
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"context"
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"sync"
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"time"
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"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
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pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
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"google.golang.org/grpc"
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"google.golang.org/grpc/metadata"
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)
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type (
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LeaseRevokeResponse pb.LeaseRevokeResponse
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LeaseID int64
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)
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// LeaseGrantResponse wraps the protobuf message LeaseGrantResponse.
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type LeaseGrantResponse struct {
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*pb.ResponseHeader
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ID LeaseID
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TTL int64
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Error string
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}
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// LeaseKeepAliveResponse wraps the protobuf message LeaseKeepAliveResponse.
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type LeaseKeepAliveResponse struct {
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*pb.ResponseHeader
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ID LeaseID
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TTL int64
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}
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// LeaseTimeToLiveResponse wraps the protobuf message LeaseTimeToLiveResponse.
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type LeaseTimeToLiveResponse struct {
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*pb.ResponseHeader
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ID LeaseID `json:"id"`
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// TTL is the remaining TTL in seconds for the lease; the lease will expire in under TTL+1 seconds. Expired lease will return -1.
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TTL int64 `json:"ttl"`
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// GrantedTTL is the initial granted time in seconds upon lease creation/renewal.
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GrantedTTL int64 `json:"granted-ttl"`
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// Keys is the list of keys attached to this lease.
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Keys [][]byte `json:"keys"`
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}
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// LeaseStatus represents a lease status.
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type LeaseStatus struct {
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ID LeaseID `json:"id"`
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// TODO: TTL int64
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}
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// LeaseLeasesResponse wraps the protobuf message LeaseLeasesResponse.
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type LeaseLeasesResponse struct {
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*pb.ResponseHeader
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Leases []LeaseStatus `json:"leases"`
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}
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const (
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// defaultTTL is the assumed lease TTL used for the first keepalive
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// deadline before the actual TTL is known to the client.
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defaultTTL = 5 * time.Second
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// NoLease is a lease ID for the absence of a lease.
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NoLease LeaseID = 0
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// retryConnWait is how long to wait before retrying request due to an error
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retryConnWait = 500 * time.Millisecond
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)
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// LeaseResponseChSize is the size of buffer to store unsent lease responses.
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// WARNING: DO NOT UPDATE.
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// Only for testing purposes.
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var LeaseResponseChSize = 16
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// ErrKeepAliveHalted is returned if client keep alive loop halts with an unexpected error.
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//
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// This usually means that automatic lease renewal via KeepAlive is broken, but KeepAliveOnce will still work as expected.
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type ErrKeepAliveHalted struct {
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Reason error
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}
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func (e ErrKeepAliveHalted) Error() string {
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s := "etcdclient: leases keep alive halted"
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if e.Reason != nil {
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s += ": " + e.Reason.Error()
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}
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return s
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}
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type Lease interface {
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// Grant creates a new lease.
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Grant(ctx context.Context, ttl int64) (*LeaseGrantResponse, error)
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// Revoke revokes the given lease.
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Revoke(ctx context.Context, id LeaseID) (*LeaseRevokeResponse, error)
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// TimeToLive retrieves the lease information of the given lease ID.
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TimeToLive(ctx context.Context, id LeaseID, opts ...LeaseOption) (*LeaseTimeToLiveResponse, error)
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// Leases retrieves all leases.
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Leases(ctx context.Context) (*LeaseLeasesResponse, error)
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// KeepAlive keeps the given lease alive forever. If the keepalive response
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// posted to the channel is not consumed immediately, the lease client will
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// continue sending keep alive requests to the etcd server at least every
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// second until latest response is consumed.
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//
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// The returned "LeaseKeepAliveResponse" channel closes if underlying keep
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// alive stream is interrupted in some way the client cannot handle itself;
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// given context "ctx" is canceled or timed out. "LeaseKeepAliveResponse"
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// from this closed channel is nil.
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//
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// If client keep alive loop halts with an unexpected error (e.g. "etcdserver:
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// no leader") or canceled by the caller (e.g. context.Canceled), the error
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// is returned. Otherwise, it retries.
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//
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// TODO(v4.0): post errors to last keep alive message before closing
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// (see https://github.com/coreos/etcd/pull/7866)
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KeepAlive(ctx context.Context, id LeaseID) (<-chan *LeaseKeepAliveResponse, error)
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// KeepAliveOnce renews the lease once. The response corresponds to the
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// first message from calling KeepAlive. If the response has a recoverable
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// error, KeepAliveOnce will retry the RPC with a new keep alive message.
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//
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// In most of the cases, Keepalive should be used instead of KeepAliveOnce.
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KeepAliveOnce(ctx context.Context, id LeaseID) (*LeaseKeepAliveResponse, error)
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// Close releases all resources Lease keeps for efficient communication
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// with the etcd server.
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Close() error
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}
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type lessor struct {
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mu sync.Mutex // guards all fields
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// donec is closed and loopErr is set when recvKeepAliveLoop stops
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donec chan struct{}
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loopErr error
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remote pb.LeaseClient
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stream pb.Lease_LeaseKeepAliveClient
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streamCancel context.CancelFunc
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stopCtx context.Context
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stopCancel context.CancelFunc
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keepAlives map[LeaseID]*keepAlive
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// firstKeepAliveTimeout is the timeout for the first keepalive request
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// before the actual TTL is known to the lease client
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firstKeepAliveTimeout time.Duration
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// firstKeepAliveOnce ensures stream starts after first KeepAlive call.
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firstKeepAliveOnce sync.Once
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callOpts []grpc.CallOption
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}
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// keepAlive multiplexes a keepalive for a lease over multiple channels
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type keepAlive struct {
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chs []chan<- *LeaseKeepAliveResponse
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ctxs []context.Context
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// deadline is the time the keep alive channels close if no response
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deadline time.Time
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// nextKeepAlive is when to send the next keep alive message
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nextKeepAlive time.Time
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// donec is closed on lease revoke, expiration, or cancel.
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donec chan struct{}
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}
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func NewLease(c *Client) Lease {
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return NewLeaseFromLeaseClient(RetryLeaseClient(c), c, c.cfg.DialTimeout+time.Second)
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}
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func NewLeaseFromLeaseClient(remote pb.LeaseClient, c *Client, keepAliveTimeout time.Duration) Lease {
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l := &lessor{
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donec: make(chan struct{}),
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keepAlives: make(map[LeaseID]*keepAlive),
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remote: remote,
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firstKeepAliveTimeout: keepAliveTimeout,
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}
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if l.firstKeepAliveTimeout == time.Second {
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l.firstKeepAliveTimeout = defaultTTL
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}
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if c != nil {
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l.callOpts = c.callOpts
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}
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reqLeaderCtx := WithRequireLeader(context.Background())
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l.stopCtx, l.stopCancel = context.WithCancel(reqLeaderCtx)
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return l
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}
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func (l *lessor) Grant(ctx context.Context, ttl int64) (*LeaseGrantResponse, error) {
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r := &pb.LeaseGrantRequest{TTL: ttl}
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resp, err := l.remote.LeaseGrant(ctx, r, l.callOpts...)
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if err == nil {
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gresp := &LeaseGrantResponse{
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ResponseHeader: resp.GetHeader(),
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ID: LeaseID(resp.ID),
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TTL: resp.TTL,
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Error: resp.Error,
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}
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return gresp, nil
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}
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return nil, toErr(ctx, err)
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}
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func (l *lessor) Revoke(ctx context.Context, id LeaseID) (*LeaseRevokeResponse, error) {
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r := &pb.LeaseRevokeRequest{ID: int64(id)}
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resp, err := l.remote.LeaseRevoke(ctx, r, l.callOpts...)
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if err == nil {
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return (*LeaseRevokeResponse)(resp), nil
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}
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return nil, toErr(ctx, err)
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}
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func (l *lessor) TimeToLive(ctx context.Context, id LeaseID, opts ...LeaseOption) (*LeaseTimeToLiveResponse, error) {
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r := toLeaseTimeToLiveRequest(id, opts...)
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resp, err := l.remote.LeaseTimeToLive(ctx, r, l.callOpts...)
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if err == nil {
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gresp := &LeaseTimeToLiveResponse{
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ResponseHeader: resp.GetHeader(),
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ID: LeaseID(resp.ID),
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TTL: resp.TTL,
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GrantedTTL: resp.GrantedTTL,
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Keys: resp.Keys,
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}
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return gresp, nil
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}
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return nil, toErr(ctx, err)
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}
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func (l *lessor) Leases(ctx context.Context) (*LeaseLeasesResponse, error) {
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resp, err := l.remote.LeaseLeases(ctx, &pb.LeaseLeasesRequest{}, l.callOpts...)
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if err == nil {
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leases := make([]LeaseStatus, len(resp.Leases))
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for i := range resp.Leases {
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leases[i] = LeaseStatus{ID: LeaseID(resp.Leases[i].ID)}
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}
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return &LeaseLeasesResponse{ResponseHeader: resp.GetHeader(), Leases: leases}, nil
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}
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return nil, toErr(ctx, err)
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}
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func (l *lessor) KeepAlive(ctx context.Context, id LeaseID) (<-chan *LeaseKeepAliveResponse, error) {
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ch := make(chan *LeaseKeepAliveResponse, LeaseResponseChSize)
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l.mu.Lock()
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// ensure that recvKeepAliveLoop is still running
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select {
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case <-l.donec:
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err := l.loopErr
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l.mu.Unlock()
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close(ch)
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return ch, ErrKeepAliveHalted{Reason: err}
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default:
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}
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ka, ok := l.keepAlives[id]
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if !ok {
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// create fresh keep alive
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ka = &keepAlive{
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chs: []chan<- *LeaseKeepAliveResponse{ch},
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ctxs: []context.Context{ctx},
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deadline: time.Now().Add(l.firstKeepAliveTimeout),
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nextKeepAlive: time.Now(),
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donec: make(chan struct{}),
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}
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l.keepAlives[id] = ka
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} else {
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// add channel and context to existing keep alive
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ka.ctxs = append(ka.ctxs, ctx)
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ka.chs = append(ka.chs, ch)
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}
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l.mu.Unlock()
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go l.keepAliveCtxCloser(id, ctx, ka.donec)
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l.firstKeepAliveOnce.Do(func() {
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go l.recvKeepAliveLoop()
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go l.deadlineLoop()
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})
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return ch, nil
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}
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func (l *lessor) KeepAliveOnce(ctx context.Context, id LeaseID) (*LeaseKeepAliveResponse, error) {
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for {
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resp, err := l.keepAliveOnce(ctx, id)
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if err == nil {
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if resp.TTL <= 0 {
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err = rpctypes.ErrLeaseNotFound
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}
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return resp, err
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}
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if isHaltErr(ctx, err) {
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return nil, toErr(ctx, err)
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}
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}
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}
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func (l *lessor) Close() error {
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l.stopCancel()
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// close for synchronous teardown if stream goroutines never launched
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l.firstKeepAliveOnce.Do(func() { close(l.donec) })
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<-l.donec
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return nil
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}
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func (l *lessor) keepAliveCtxCloser(id LeaseID, ctx context.Context, donec <-chan struct{}) {
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select {
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case <-donec:
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return
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case <-l.donec:
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return
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case <-ctx.Done():
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}
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l.mu.Lock()
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defer l.mu.Unlock()
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ka, ok := l.keepAlives[id]
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if !ok {
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return
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}
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// close channel and remove context if still associated with keep alive
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for i, c := range ka.ctxs {
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if c == ctx {
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close(ka.chs[i])
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ka.ctxs = append(ka.ctxs[:i], ka.ctxs[i+1:]...)
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ka.chs = append(ka.chs[:i], ka.chs[i+1:]...)
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break
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}
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}
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// remove if no one more listeners
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if len(ka.chs) == 0 {
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delete(l.keepAlives, id)
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}
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}
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// closeRequireLeader scans keepAlives for ctxs that have require leader
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// and closes the associated channels.
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func (l *lessor) closeRequireLeader() {
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l.mu.Lock()
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defer l.mu.Unlock()
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for _, ka := range l.keepAlives {
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reqIdxs := 0
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// find all required leader channels, close, mark as nil
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for i, ctx := range ka.ctxs {
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md, ok := metadata.FromOutgoingContext(ctx)
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if !ok {
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continue
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}
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ks := md[rpctypes.MetadataRequireLeaderKey]
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if len(ks) < 1 || ks[0] != rpctypes.MetadataHasLeader {
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continue
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}
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close(ka.chs[i])
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ka.chs[i] = nil
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reqIdxs++
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}
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if reqIdxs == 0 {
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continue
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}
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// remove all channels that required a leader from keepalive
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newChs := make([]chan<- *LeaseKeepAliveResponse, len(ka.chs)-reqIdxs)
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newCtxs := make([]context.Context, len(newChs))
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newIdx := 0
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for i := range ka.chs {
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if ka.chs[i] == nil {
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continue
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}
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newChs[newIdx], newCtxs[newIdx] = ka.chs[i], ka.ctxs[newIdx]
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newIdx++
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}
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ka.chs, ka.ctxs = newChs, newCtxs
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}
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}
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func (l *lessor) keepAliveOnce(ctx context.Context, id LeaseID) (*LeaseKeepAliveResponse, error) {
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cctx, cancel := context.WithCancel(ctx)
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defer cancel()
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stream, err := l.remote.LeaseKeepAlive(cctx, l.callOpts...)
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if err != nil {
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return nil, toErr(ctx, err)
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}
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err = stream.Send(&pb.LeaseKeepAliveRequest{ID: int64(id)})
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if err != nil {
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return nil, toErr(ctx, err)
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}
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resp, rerr := stream.Recv()
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if rerr != nil {
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return nil, toErr(ctx, rerr)
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}
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karesp := &LeaseKeepAliveResponse{
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ResponseHeader: resp.GetHeader(),
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ID: LeaseID(resp.ID),
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TTL: resp.TTL,
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}
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return karesp, nil
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}
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func (l *lessor) recvKeepAliveLoop() (gerr error) {
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defer func() {
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l.mu.Lock()
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close(l.donec)
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l.loopErr = gerr
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for _, ka := range l.keepAlives {
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ka.close()
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}
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l.keepAlives = make(map[LeaseID]*keepAlive)
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l.mu.Unlock()
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}()
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for {
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stream, err := l.resetRecv()
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if err != nil {
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if canceledByCaller(l.stopCtx, err) {
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return err
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}
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} else {
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for {
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resp, err := stream.Recv()
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if err != nil {
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if canceledByCaller(l.stopCtx, err) {
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return err
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}
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if toErr(l.stopCtx, err) == rpctypes.ErrNoLeader {
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l.closeRequireLeader()
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}
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break
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}
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l.recvKeepAlive(resp)
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}
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}
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select {
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case <-time.After(retryConnWait):
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continue
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case <-l.stopCtx.Done():
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return l.stopCtx.Err()
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}
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}
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}
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// resetRecv opens a new lease stream and starts sending keep alive requests.
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func (l *lessor) resetRecv() (pb.Lease_LeaseKeepAliveClient, error) {
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sctx, cancel := context.WithCancel(l.stopCtx)
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stream, err := l.remote.LeaseKeepAlive(sctx, l.callOpts...)
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if err != nil {
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cancel()
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return nil, err
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}
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l.mu.Lock()
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defer l.mu.Unlock()
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if l.stream != nil && l.streamCancel != nil {
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l.streamCancel()
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}
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l.streamCancel = cancel
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l.stream = stream
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go l.sendKeepAliveLoop(stream)
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return stream, nil
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}
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// recvKeepAlive updates a lease based on its LeaseKeepAliveResponse
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func (l *lessor) recvKeepAlive(resp *pb.LeaseKeepAliveResponse) {
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karesp := &LeaseKeepAliveResponse{
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ResponseHeader: resp.GetHeader(),
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ID: LeaseID(resp.ID),
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TTL: resp.TTL,
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}
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l.mu.Lock()
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defer l.mu.Unlock()
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ka, ok := l.keepAlives[karesp.ID]
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if !ok {
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return
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}
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if karesp.TTL <= 0 {
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// lease expired; close all keep alive channels
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delete(l.keepAlives, karesp.ID)
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ka.close()
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return
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}
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// send update to all channels
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nextKeepAlive := time.Now().Add((time.Duration(karesp.TTL) * time.Second) / 3.0)
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ka.deadline = time.Now().Add(time.Duration(karesp.TTL) * time.Second)
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for _, ch := range ka.chs {
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select {
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case ch <- karesp:
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default:
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}
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// still advance in order to rate-limit keep-alive sends
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ka.nextKeepAlive = nextKeepAlive
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}
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}
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// deadlineLoop reaps any keep alive channels that have not received a response
|
|
// within the lease TTL
|
|
func (l *lessor) deadlineLoop() {
|
|
for {
|
|
select {
|
|
case <-time.After(time.Second):
|
|
case <-l.donec:
|
|
return
|
|
}
|
|
now := time.Now()
|
|
l.mu.Lock()
|
|
for id, ka := range l.keepAlives {
|
|
if ka.deadline.Before(now) {
|
|
// waited too long for response; lease may be expired
|
|
ka.close()
|
|
delete(l.keepAlives, id)
|
|
}
|
|
}
|
|
l.mu.Unlock()
|
|
}
|
|
}
|
|
|
|
// sendKeepAliveLoop sends keep alive requests for the lifetime of the given stream.
|
|
func (l *lessor) sendKeepAliveLoop(stream pb.Lease_LeaseKeepAliveClient) {
|
|
for {
|
|
var tosend []LeaseID
|
|
|
|
now := time.Now()
|
|
l.mu.Lock()
|
|
for id, ka := range l.keepAlives {
|
|
if ka.nextKeepAlive.Before(now) {
|
|
tosend = append(tosend, id)
|
|
}
|
|
}
|
|
l.mu.Unlock()
|
|
|
|
for _, id := range tosend {
|
|
r := &pb.LeaseKeepAliveRequest{ID: int64(id)}
|
|
if err := stream.Send(r); err != nil {
|
|
// TODO do something with this error?
|
|
return
|
|
}
|
|
}
|
|
|
|
select {
|
|
case <-time.After(500 * time.Millisecond):
|
|
case <-stream.Context().Done():
|
|
return
|
|
case <-l.donec:
|
|
return
|
|
case <-l.stopCtx.Done():
|
|
return
|
|
}
|
|
}
|
|
}
|
|
|
|
func (ka *keepAlive) close() {
|
|
close(ka.donec)
|
|
for _, ch := range ka.chs {
|
|
close(ch)
|
|
}
|
|
}
|