github.com/looshlee/beatles@v0.0.0-20220727174639-742810ab631c/pkg/kvstore/client.go (about)

     1  // Copyright 2016-2019 Authors of Cilium
     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 kvstore
    16  
    17  import (
    18  	"fmt"
    19  )
    20  
    21  var (
    22  	// defaultClient is the default client initialized by initClient
    23  	defaultClient BackendOperations
    24  	// defaultClientSet is a channel that is closed whenever the defaultClient
    25  	// is set.
    26  	defaultClientSet = make(chan struct{})
    27  )
    28  
    29  func initClient(module backendModule, opts *ExtraOptions) error {
    30  	scopedLog := log.WithField(fieldKVStoreModule, module.getName())
    31  	c, errChan := module.newClient(opts)
    32  	if c == nil {
    33  		err := <-errChan
    34  		scopedLog.WithError(err).Fatal("Unable to create kvstore client")
    35  	}
    36  
    37  	defaultClient = c
    38  	select {
    39  	case <-defaultClientSet:
    40  		// avoid closing channel already closed.
    41  	default:
    42  		close(defaultClientSet)
    43  	}
    44  
    45  	go func() {
    46  		err, isErr := <-errChan
    47  		if isErr && err != nil {
    48  			scopedLog.WithError(err).Fatal("Unable to connect to kvstore")
    49  		}
    50  		deleteLegacyPrefixes()
    51  	}()
    52  
    53  	return nil
    54  }
    55  
    56  // Client returns the global kvstore client or nil if the client is not configured yet
    57  func Client() BackendOperations {
    58  	<-defaultClientSet
    59  	return defaultClient
    60  }
    61  
    62  // NewClient returns a new kvstore client based on the configuration
    63  func NewClient(selectedBackend string, opts map[string]string, options *ExtraOptions) (BackendOperations, chan error) {
    64  	// Channel used to report immediate errors, module.newClient will
    65  	// create and return a different channel, caller doesn't need to know
    66  	errChan := make(chan error, 1)
    67  	defer close(errChan)
    68  
    69  	module := getBackend(selectedBackend)
    70  	if module == nil {
    71  		errChan <- fmt.Errorf("unknown key-value store type %q. See cilium.link/err-kvstore for details", selectedBackend)
    72  		return nil, errChan
    73  	}
    74  
    75  	if err := module.setConfig(opts); err != nil {
    76  		errChan <- err
    77  		return nil, errChan
    78  	}
    79  
    80  	if err := module.setExtraConfig(options); err != nil {
    81  		errChan <- err
    82  		return nil, errChan
    83  	}
    84  
    85  	return module.newClient(options)
    86  }