go.etcd.io/etcd@v3.3.27+incompatible/clientv3/txn.go (about)

     1  // Copyright 2016 The etcd Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package clientv3
    16  
    17  import (
    18  	"context"
    19  	"sync"
    20  
    21  	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
    22  
    23  	"google.golang.org/grpc"
    24  )
    25  
    26  // Txn is the interface that wraps mini-transactions.
    27  //
    28  //	 Txn(context.TODO()).If(
    29  //	  Compare(Value(k1), ">", v1),
    30  //	  Compare(Version(k1), "=", 2)
    31  //	 ).Then(
    32  //	  OpPut(k2,v2), OpPut(k3,v3)
    33  //	 ).Else(
    34  //	  OpPut(k4,v4), OpPut(k5,v5)
    35  //	 ).Commit()
    36  //
    37  type Txn interface {
    38  	// If takes a list of comparison. If all comparisons passed in succeed,
    39  	// the operations passed into Then() will be executed. Or the operations
    40  	// passed into Else() will be executed.
    41  	If(cs ...Cmp) Txn
    42  
    43  	// Then takes a list of operations. The Ops list will be executed, if the
    44  	// comparisons passed in If() succeed.
    45  	Then(ops ...Op) Txn
    46  
    47  	// Else takes a list of operations. The Ops list will be executed, if the
    48  	// comparisons passed in If() fail.
    49  	Else(ops ...Op) Txn
    50  
    51  	// Commit tries to commit the transaction.
    52  	Commit() (*TxnResponse, error)
    53  }
    54  
    55  type txn struct {
    56  	kv  *kv
    57  	ctx context.Context
    58  
    59  	mu    sync.Mutex
    60  	cif   bool
    61  	cthen bool
    62  	celse bool
    63  
    64  	isWrite bool
    65  
    66  	cmps []*pb.Compare
    67  
    68  	sus []*pb.RequestOp
    69  	fas []*pb.RequestOp
    70  
    71  	callOpts []grpc.CallOption
    72  }
    73  
    74  func (txn *txn) If(cs ...Cmp) Txn {
    75  	txn.mu.Lock()
    76  	defer txn.mu.Unlock()
    77  
    78  	if txn.cif {
    79  		panic("cannot call If twice!")
    80  	}
    81  
    82  	if txn.cthen {
    83  		panic("cannot call If after Then!")
    84  	}
    85  
    86  	if txn.celse {
    87  		panic("cannot call If after Else!")
    88  	}
    89  
    90  	txn.cif = true
    91  
    92  	for i := range cs {
    93  		txn.cmps = append(txn.cmps, (*pb.Compare)(&cs[i]))
    94  	}
    95  
    96  	return txn
    97  }
    98  
    99  func (txn *txn) Then(ops ...Op) Txn {
   100  	txn.mu.Lock()
   101  	defer txn.mu.Unlock()
   102  
   103  	if txn.cthen {
   104  		panic("cannot call Then twice!")
   105  	}
   106  	if txn.celse {
   107  		panic("cannot call Then after Else!")
   108  	}
   109  
   110  	txn.cthen = true
   111  
   112  	for _, op := range ops {
   113  		txn.isWrite = txn.isWrite || op.isWrite()
   114  		txn.sus = append(txn.sus, op.toRequestOp())
   115  	}
   116  
   117  	return txn
   118  }
   119  
   120  func (txn *txn) Else(ops ...Op) Txn {
   121  	txn.mu.Lock()
   122  	defer txn.mu.Unlock()
   123  
   124  	if txn.celse {
   125  		panic("cannot call Else twice!")
   126  	}
   127  
   128  	txn.celse = true
   129  
   130  	for _, op := range ops {
   131  		txn.isWrite = txn.isWrite || op.isWrite()
   132  		txn.fas = append(txn.fas, op.toRequestOp())
   133  	}
   134  
   135  	return txn
   136  }
   137  
   138  func (txn *txn) Commit() (*TxnResponse, error) {
   139  	txn.mu.Lock()
   140  	defer txn.mu.Unlock()
   141  
   142  	r := &pb.TxnRequest{Compare: txn.cmps, Success: txn.sus, Failure: txn.fas}
   143  
   144  	var resp *pb.TxnResponse
   145  	var err error
   146  	resp, err = txn.kv.remote.Txn(txn.ctx, r, txn.callOpts...)
   147  	if err != nil {
   148  		return nil, toErr(txn.ctx, err)
   149  	}
   150  	return (*TxnResponse)(resp), nil
   151  }