vitess.io/vitess@v0.16.2/go/vt/vtctl/vtctlclient/interface.go (about)

     1  /*
     2  Copyright 2019 The Vitess Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  // Package vtctlclient contains the generic client side of the remote vtctl protocol.
    18  package vtctlclient
    19  
    20  import (
    21  	"context"
    22  	"fmt"
    23  	"time"
    24  
    25  	"github.com/spf13/pflag"
    26  
    27  	"vitess.io/vitess/go/vt/log"
    28  	"vitess.io/vitess/go/vt/logutil"
    29  	"vitess.io/vitess/go/vt/servenv"
    30  )
    31  
    32  // vtctlClientProtocol specifics which RPC client implementation should be used.
    33  var vtctlClientProtocol = "grpc"
    34  
    35  func RegisterFlags(fs *pflag.FlagSet) {
    36  	fs.StringVar(&vtctlClientProtocol, "vtctl_client_protocol", vtctlClientProtocol, "Protocol to use to talk to the vtctl server.")
    37  }
    38  
    39  func init() {
    40  	for _, cmd := range []string{
    41  		"vtctlclient",
    42  		"vttestserver",
    43  	} {
    44  		servenv.OnParseFor(cmd, RegisterFlags)
    45  	}
    46  }
    47  
    48  // VtctlClient defines the interface used to send remote vtctl commands
    49  type VtctlClient interface {
    50  	// ExecuteVtctlCommand will execute the command remotely
    51  	ExecuteVtctlCommand(ctx context.Context, args []string, actionTimeout time.Duration) (logutil.EventStream, error)
    52  
    53  	// Close will terminate the connection. This object won't be
    54  	// used after this.
    55  	Close()
    56  }
    57  
    58  // Factory functions are registered by client implementations
    59  type Factory func(addr string) (VtctlClient, error)
    60  
    61  var factories = make(map[string]Factory)
    62  
    63  // RegisterFactory allows a client implementation to register itself.
    64  func RegisterFactory(name string, factory Factory) {
    65  	if _, ok := factories[name]; ok {
    66  		log.Fatalf("RegisterFactory: %s already exists", name)
    67  	}
    68  	factories[name] = factory
    69  }
    70  
    71  // UnregisterFactoryForTest allows to unregister a client implementation from the static map.
    72  // This function is used by unit tests to cleanly unregister any fake implementations.
    73  // This way, a test package can use the same name for different fakes and no dangling fakes are
    74  // left behind in the static factories map after the test.
    75  func UnregisterFactoryForTest(name string) {
    76  	if _, ok := factories[name]; !ok {
    77  		log.Fatalf("UnregisterFactoryForTest: %s is not registered", name)
    78  	}
    79  	delete(factories, name)
    80  }
    81  
    82  // New allows a user of the client library to get its implementation.
    83  func New(addr string) (VtctlClient, error) {
    84  	factory, ok := factories[vtctlClientProtocol]
    85  	if !ok {
    86  		return nil, fmt.Errorf("unknown vtctl client protocol: %v", vtctlClientProtocol)
    87  	}
    88  	return factory(addr)
    89  }