120 lines
3.2 KiB
Go
120 lines
3.2 KiB
Go
package consul
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import (
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"fmt"
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"time"
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"github.com/armon/go-metrics"
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"github.com/hashicorp/consul/acl"
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"github.com/hashicorp/consul/agent/structs"
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)
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// Txn endpoint is used to perform multi-object atomic transactions.
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type Txn struct {
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srv *Server
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}
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// preCheck is used to verify the incoming operations before any further
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// processing takes place. This checks things like ACLs.
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func (t *Txn) preCheck(acl acl.ACL, ops structs.TxnOps) structs.TxnErrors {
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var errors structs.TxnErrors
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// Perform the pre-apply checks for any KV operations.
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for i, op := range ops {
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if op.KV != nil {
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ok, err := kvsPreApply(t.srv, acl, op.KV.Verb, &op.KV.DirEnt)
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if err != nil {
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errors = append(errors, &structs.TxnError{
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OpIndex: i,
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What: err.Error(),
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})
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} else if !ok {
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err = fmt.Errorf("failed to lock key %q due to lock delay", op.KV.DirEnt.Key)
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errors = append(errors, &structs.TxnError{
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OpIndex: i,
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What: err.Error(),
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})
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}
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}
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}
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return errors
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}
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// Apply is used to apply multiple operations in a single, atomic transaction.
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func (t *Txn) Apply(args *structs.TxnRequest, reply *structs.TxnResponse) error {
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if done, err := t.srv.forward("Txn.Apply", args, args, reply); done {
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return err
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}
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defer metrics.MeasureSince([]string{"consul", "txn", "apply"}, time.Now())
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// Run the pre-checks before we send the transaction into Raft.
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acl, err := t.srv.resolveToken(args.Token)
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if err != nil {
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return err
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}
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reply.Errors = t.preCheck(acl, args.Ops)
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if len(reply.Errors) > 0 {
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return nil
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}
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// Apply the update.
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resp, err := t.srv.raftApply(structs.TxnRequestType, args)
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if err != nil {
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t.srv.logger.Printf("[ERR] consul.txn: Apply failed: %v", err)
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return err
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}
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if respErr, ok := resp.(error); ok {
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return respErr
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}
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// Convert the return type. This should be a cheap copy since we are
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// just taking the two slices.
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if txnResp, ok := resp.(structs.TxnResponse); ok {
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if acl != nil {
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txnResp.Results = FilterTxnResults(acl, txnResp.Results)
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}
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*reply = txnResp
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} else {
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return fmt.Errorf("unexpected return type %T", resp)
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}
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return nil
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}
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// Read is used to perform a read-only transaction that doesn't modify the state
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// store. This is much more scaleable since it doesn't go through Raft and
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// supports staleness, so this should be preferred if you're just performing
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// reads.
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func (t *Txn) Read(args *structs.TxnReadRequest, reply *structs.TxnReadResponse) error {
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if done, err := t.srv.forward("Txn.Read", args, args, reply); done {
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return err
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}
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defer metrics.MeasureSince([]string{"consul", "txn", "read"}, time.Now())
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// We have to do this ourselves since we are not doing a blocking RPC.
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t.srv.setQueryMeta(&reply.QueryMeta)
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if args.RequireConsistent {
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if err := t.srv.consistentRead(); err != nil {
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return err
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}
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}
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// Run the pre-checks before we perform the read.
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acl, err := t.srv.resolveToken(args.Token)
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if err != nil {
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return err
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}
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reply.Errors = t.preCheck(acl, args.Ops)
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if len(reply.Errors) > 0 {
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return nil
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}
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// Run the read transaction.
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state := t.srv.fsm.State()
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reply.Results, reply.Errors = state.TxnRO(args.Ops)
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if acl != nil {
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reply.Results = FilterTxnResults(acl, reply.Results)
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}
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return nil
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}
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