github.com/cranelv/ethereum_mpc@v0.0.0-20191031014521-23aeb1415092/consensus_pbft/pbft/deduplicator.go (about)

     1  /*
     2  Copyright IBM Corp. 2016 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 pbft
    18  
    19  import (
    20  	"github.com/ethereum/go-ethereum/consensus_pbft/message"
    21  	"github.com/ethereum/go-ethereum/consensus_pbft/pbftTypes"
    22  )
    23  
    24  // deduplicator maintains the most recent Request timestamp for each
    25  // replica.  Two timestamps are maintained per replica.  One timestamp
    26  // tracks the most recent Request received from a replica, the other
    27  // timeout tracks the most recent executed Request.
    28  type deduplicator struct {
    29  	reqTimestamps  map[pbftTypes.ReplicaID]uint64
    30  	execTimestamps map[pbftTypes.ReplicaID]uint64
    31  }
    32  
    33  // newDeduplicator creates a new deduplicator.
    34  func newDeduplicator() *deduplicator {
    35  	d := &deduplicator{}
    36  	d.reqTimestamps = make(map[pbftTypes.ReplicaID]uint64)
    37  	d.execTimestamps = make(map[pbftTypes.ReplicaID]uint64)
    38  	return d
    39  }
    40  
    41  // Request updates the received request timestamp for the submitting
    42  // replica.  If the request is older than any previously received or
    43  // executed request, Request() will return false, indicating a stale
    44  // request.
    45  func (d *deduplicator) Request(req *message.Request) bool {
    46  	if req.Timestamp <= d.reqTimestamps[req.ReplicaId] ||
    47  		req.Timestamp <= d.execTimestamps[req.ReplicaId] {
    48  		return false
    49  	}
    50  	d.reqTimestamps[req.ReplicaId] = req.Timestamp
    51  	return true
    52  }
    53  
    54  // Execute updates the executed request timestamp for the submitting
    55  // replica.  If the request is older than any previously executed
    56  // request from the same replica, Execute() will return false,
    57  // indicating a stale request.
    58  func (d *deduplicator) Execute(req *message.Request) bool {
    59  	if req.Timestamp <= d.execTimestamps[req.ReplicaId] {
    60  		return false
    61  	}
    62  	d.execTimestamps[req.ReplicaId] = req.Timestamp
    63  	return true
    64  }
    65  
    66  // IsNew returns true if this Request is newer than any previously
    67  // executed request of the submitting replica.
    68  func (d *deduplicator) IsNew(req *message.Request) bool {
    69  	return req.Timestamp > d.execTimestamps[req.ReplicaId]
    70  }