github.com/adnan-c/fabric_e2e_couchdb@v0.6.1-preview.0.20170228180935-21ce6b23cf91/common/configvalues/root/proposer.go (about)

     1  /*
     2  Copyright IBM Corp. 2017 All Rights Reserved.
     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 config
    18  
    19  import (
    20  	"fmt"
    21  
    22  	api "github.com/hyperledger/fabric/common/configvalues"
    23  	cb "github.com/hyperledger/fabric/protos/common"
    24  
    25  	"github.com/golang/protobuf/proto"
    26  	logging "github.com/op/go-logging"
    27  )
    28  
    29  var logger = logging.MustGetLogger("common/config")
    30  
    31  // Values defines a mechanism to supply messages to unamrshal from config
    32  // and a mechanism to validate the results
    33  type Values interface {
    34  	// ProtoMsg behaves like a map lookup for key
    35  	ProtoMsg(key string) (proto.Message, bool)
    36  
    37  	// Validate should ensure that the values set into the proto messages are correct
    38  	Validate() error
    39  
    40  	// Commit should call back into the Value handler to update the config
    41  	Commit()
    42  }
    43  
    44  // Handler
    45  type Handler interface {
    46  	Allocate() Values
    47  	NewGroup(name string) (api.ValueProposer, error)
    48  }
    49  
    50  type config struct {
    51  	allocated Values
    52  	groups    map[string]api.ValueProposer
    53  }
    54  
    55  type Proposer struct {
    56  	vh      Handler
    57  	current *config
    58  	pending *config
    59  }
    60  
    61  func NewProposer(vh Handler) *Proposer {
    62  	return &Proposer{
    63  		vh: vh,
    64  	}
    65  }
    66  
    67  // BeginValueProposals called when a config proposal is begun
    68  func (p *Proposer) BeginValueProposals(groups []string) ([]api.ValueProposer, error) {
    69  	if p.pending != nil {
    70  		logger.Panicf("Duplicated BeginValueProposals without Rollback or Commit")
    71  	}
    72  
    73  	result := make([]api.ValueProposer, len(groups))
    74  
    75  	p.pending = &config{
    76  		allocated: p.vh.Allocate(),
    77  		groups:    make(map[string]api.ValueProposer),
    78  	}
    79  
    80  	for i, groupName := range groups {
    81  		var group api.ValueProposer
    82  		var ok bool
    83  
    84  		if p.current == nil {
    85  			ok = false
    86  		} else {
    87  			group, ok = p.current.groups[groupName]
    88  		}
    89  
    90  		if !ok {
    91  			var err error
    92  			group, err = p.vh.NewGroup(groupName)
    93  			if err != nil {
    94  				p.pending = nil
    95  				return nil, fmt.Errorf("Error creating group %s: %s", groupName, err)
    96  			}
    97  		}
    98  
    99  		p.pending.groups[groupName] = group
   100  		result[i] = group
   101  	}
   102  
   103  	return result, nil
   104  }
   105  
   106  // ProposeValue called when config is added to a proposal
   107  func (p *Proposer) ProposeValue(key string, configValue *cb.ConfigValue) error {
   108  	msg, ok := p.pending.allocated.ProtoMsg(key)
   109  	if !ok {
   110  		return fmt.Errorf("Unknown value key: %s", key)
   111  	}
   112  
   113  	if err := proto.Unmarshal(configValue.Value, msg); err != nil {
   114  		return fmt.Errorf("Error unmarshaling key to proto message: %s", err)
   115  	}
   116  
   117  	return nil
   118  }
   119  
   120  // Validate ensures that the new config values is a valid change
   121  func (p *Proposer) PreCommit() error {
   122  	return p.pending.allocated.Validate()
   123  }
   124  
   125  // RollbackProposals called when a config proposal is abandoned
   126  func (p *Proposer) RollbackProposals() {
   127  	p.pending = nil
   128  }
   129  
   130  // CommitProposals called when a config proposal is committed
   131  func (p *Proposer) CommitProposals() {
   132  	if p.pending == nil {
   133  		logger.Panicf("Attempted to commit with no pending values (indicates no Begin invoked)")
   134  	}
   135  	p.current = p.pending
   136  	p.current.allocated.Commit()
   137  	p.pending = nil
   138  }