github.com/adnan-c/fabric_e2e_couchdb@v0.6.1-preview.0.20170228180935-21ce6b23cf91/gossip/filter/filter.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 filter
    18  
    19  import (
    20  	"github.com/hyperledger/fabric/gossip/comm"
    21  	"github.com/hyperledger/fabric/gossip/discovery"
    22  	"github.com/hyperledger/fabric/gossip/util"
    23  )
    24  
    25  // RoutingFilter defines a predicate on a NetworkMember
    26  // It is used to assert whether a given NetworkMember should be
    27  // selected for be given a message
    28  type RoutingFilter func(discovery.NetworkMember) bool
    29  
    30  // CombineRoutingFilters returns the logical AND of given routing filters
    31  func CombineRoutingFilters(filters ...RoutingFilter) RoutingFilter {
    32  	return func(member discovery.NetworkMember) bool {
    33  		for _, filter := range filters {
    34  			if !filter(member) {
    35  				return false
    36  			}
    37  		}
    38  		return true
    39  	}
    40  }
    41  
    42  // SelectPeers returns a slice of peers that match a list of routing filters
    43  func SelectPeers(k int, peerPool []discovery.NetworkMember, filters ...RoutingFilter) []*comm.RemotePeer {
    44  	var filteredPeers []*comm.RemotePeer
    45  	for _, peer := range peerPool {
    46  		if CombineRoutingFilters(filters...)(peer) {
    47  			filteredPeers = append(filteredPeers, &comm.RemotePeer{PKIID: peer.PKIid, Endpoint: peer.PreferredEndpoint()})
    48  		}
    49  	}
    50  
    51  	var indices []int
    52  	if len(filteredPeers) <= k {
    53  		indices = make([]int, len(filteredPeers))
    54  		for i := 0; i < len(filteredPeers); i++ {
    55  			indices[i] = i
    56  		}
    57  	} else {
    58  		indices = util.GetRandomIndices(k, len(filteredPeers)-1)
    59  	}
    60  
    61  	var remotePeers []*comm.RemotePeer
    62  	for _, index := range indices {
    63  		remotePeers = append(remotePeers, filteredPeers[index])
    64  	}
    65  
    66  	return remotePeers
    67  }