open-consul/api/txn.go

246 lines
6.5 KiB
Go

package api
import (
"bytes"
"fmt"
"io"
"net/http"
)
// Txn is used to manipulate the Txn API
type Txn struct {
c *Client
}
// Txn is used to return a handle to the K/V apis
func (c *Client) Txn() *Txn {
return &Txn{c}
}
// TxnOp is the internal format we send to Consul. Currently only K/V and
// check operations are supported.
type TxnOp struct {
KV *KVTxnOp
Node *NodeTxnOp
Service *ServiceTxnOp
Check *CheckTxnOp
}
// TxnOps is a list of transaction operations.
type TxnOps []*TxnOp
// TxnResult is the internal format we receive from Consul.
type TxnResult struct {
KV *KVPair
Node *Node
Service *CatalogService
Check *HealthCheck
}
// TxnResults is a list of TxnResult objects.
type TxnResults []*TxnResult
// TxnError is used to return information about an operation in a transaction.
type TxnError struct {
OpIndex int
What string
}
// TxnErrors is a list of TxnError objects.
type TxnErrors []*TxnError
// TxnResponse is the internal format we receive from Consul.
type TxnResponse struct {
Results TxnResults
Errors TxnErrors
}
// KVOp constants give possible operations available in a transaction.
type KVOp string
const (
KVSet KVOp = "set"
KVDelete KVOp = "delete"
KVDeleteCAS KVOp = "delete-cas"
KVDeleteTree KVOp = "delete-tree"
KVCAS KVOp = "cas"
KVLock KVOp = "lock"
KVUnlock KVOp = "unlock"
KVGet KVOp = "get"
KVGetTree KVOp = "get-tree"
KVCheckSession KVOp = "check-session"
KVCheckIndex KVOp = "check-index"
KVCheckNotExists KVOp = "check-not-exists"
)
// KVTxnOp defines a single operation inside a transaction.
type KVTxnOp struct {
Verb KVOp
Key string
Value []byte
Flags uint64
Index uint64
Session string
Namespace string `json:",omitempty"`
Partition string `json:",omitempty"`
}
// KVTxnOps defines a set of operations to be performed inside a single
// transaction.
type KVTxnOps []*KVTxnOp
// KVTxnResponse has the outcome of a transaction.
type KVTxnResponse struct {
Results []*KVPair
Errors TxnErrors
}
// SessionOp constants give possible operations available in a transaction.
type SessionOp string
const (
SessionDelete SessionOp = "delete"
)
// SessionTxnOp defines a single operation inside a transaction.
type SessionTxnOp struct {
Verb SessionOp
Session Session
}
// NodeOp constants give possible operations available in a transaction.
type NodeOp string
const (
NodeGet NodeOp = "get"
NodeSet NodeOp = "set"
NodeCAS NodeOp = "cas"
NodeDelete NodeOp = "delete"
NodeDeleteCAS NodeOp = "delete-cas"
)
// NodeTxnOp defines a single operation inside a transaction.
type NodeTxnOp struct {
Verb NodeOp
Node Node
}
// ServiceOp constants give possible operations available in a transaction.
type ServiceOp string
const (
ServiceGet ServiceOp = "get"
ServiceSet ServiceOp = "set"
ServiceCAS ServiceOp = "cas"
ServiceDelete ServiceOp = "delete"
ServiceDeleteCAS ServiceOp = "delete-cas"
)
// ServiceTxnOp defines a single operation inside a transaction.
type ServiceTxnOp struct {
Verb ServiceOp
Node string
Service AgentService
}
// CheckOp constants give possible operations available in a transaction.
type CheckOp string
const (
CheckGet CheckOp = "get"
CheckSet CheckOp = "set"
CheckCAS CheckOp = "cas"
CheckDelete CheckOp = "delete"
CheckDeleteCAS CheckOp = "delete-cas"
)
// CheckTxnOp defines a single operation inside a transaction.
type CheckTxnOp struct {
Verb CheckOp
Check HealthCheck
}
// Txn is used to apply multiple Consul operations in a single, atomic transaction.
//
// Note that Go will perform the required base64 encoding on the values
// automatically because the type is a byte slice. Transactions are defined as a
// list of operations to perform, using the different fields in the TxnOp structure
// to define operations. If any operation fails, none of the changes are applied
// to the state store.
//
// Even though this is generally a write operation, we take a QueryOptions input
// and return a QueryMeta output. If the transaction contains only read ops, then
// Consul will fast-path it to a different endpoint internally which supports
// consistency controls, but not blocking. If there are write operations then
// the request will always be routed through raft and any consistency settings
// will be ignored.
//
// Here's an example:
//
// ops := KVTxnOps{
// &KVTxnOp{
// Verb: KVLock,
// Key: "test/lock",
// Session: "adf4238a-882b-9ddc-4a9d-5b6758e4159e",
// Value: []byte("hello"),
// },
// &KVTxnOp{
// Verb: KVGet,
// Key: "another/key",
// },
// &CheckTxnOp{
// Verb: CheckSet,
// HealthCheck: HealthCheck{
// Node: "foo",
// CheckID: "redis:a",
// Name: "Redis Health Check",
// Status: "passing",
// },
// }
// }
// ok, response, _, err := kv.Txn(&ops, nil)
//
// If there is a problem making the transaction request then an error will be
// returned. Otherwise, the ok value will be true if the transaction succeeded
// or false if it was rolled back. The response is a structured return value which
// will have the outcome of the transaction. Its Results member will have entries
// for each operation. For KV operations, Deleted keys will have a nil entry in the
// results, and to save space, the Value of each key in the Results will be nil
// unless the operation is a KVGet. If the transaction was rolled back, the Errors
// member will have entries referencing the index of the operation that failed
// along with an error message.
func (t *Txn) Txn(txn TxnOps, q *QueryOptions) (bool, *TxnResponse, *QueryMeta, error) {
return t.c.txn(txn, q)
}
func (c *Client) txn(txn TxnOps, q *QueryOptions) (bool, *TxnResponse, *QueryMeta, error) {
r := c.newRequest("PUT", "/v1/txn")
r.setQueryOptions(q)
r.obj = txn
rtt, resp, err := c.doRequest(r)
if err != nil {
return false, nil, nil, err
}
defer closeResponseBody(resp)
qm := &QueryMeta{}
parseQueryMeta(resp, qm)
qm.RequestTime = rtt
if resp.StatusCode == http.StatusOK || resp.StatusCode == http.StatusConflict {
var txnResp TxnResponse
if err := decodeBody(resp, &txnResp); err != nil {
return false, nil, nil, err
}
return resp.StatusCode == http.StatusOK, &txnResp, qm, nil
}
var buf bytes.Buffer
if _, err := io.Copy(&buf, resp.Body); err != nil {
return false, nil, nil, fmt.Errorf("Failed to read response: %v", err)
}
return false, nil, nil, fmt.Errorf("Failed request: %s", buf.String())
}