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Copy pathround_robin_assignment_strategy_spec.rb
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round_robin_assignment_strategy_spec.rb
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# frozen_string_literal: true
describe Kafka::RoundRobinAssignmentStrategy do
let(:strategy) { described_class.new }
it "assigns all partitions" do
members = Hash[(0...10).map {|i| ["member#{i}", double(topics: ['greetings'])] }]
partitions = (0...30).map {|i| double(:"partition#{i}", topic: "greetings", partition_id: i) }
assignments = strategy.call(cluster: nil, members: members, partitions: partitions)
partitions.each do |partition|
member = assignments.values.find {|assigned_partitions|
assigned_partitions.find {|assigned_partition|
assigned_partition == partition
}
}
expect(member).to_not be_nil
end
end
it "spreads all partitions between members" do
topics = ["topic1", "topic2"]
members = Hash[(0...10).map {|i| ["member#{i}", double(topics: topics)] }]
partitions = topics.product((0...5).to_a).map {|topic, i|
double(:"partition#{i}", topic: topic, partition_id: i)
}
assignments = strategy.call(cluster: nil, members: members, partitions: partitions)
partitions.each do |partition|
member = assignments.values.find {|assigned_partitions|
assigned_partitions.find {|assigned_partition|
assigned_partition == partition
}
}
expect(member).to_not be_nil
end
num_partitions_assigned = assignments.values.map do |assigned_partitions|
assigned_partitions.count
end
expect(num_partitions_assigned).to all eq(1)
end
Metadata = Struct.new(:topics)
[
{
name: "uneven topics",
topics: { "topic1" => [0], "topic2" => (0..50).to_a },
members: {
"member1" => Metadata.new(["topic1", "topic2"]),
"member2" => Metadata.new(["topic1", "topic2"])
},
},
{
name: "only one partition",
topics: { "topic1" => [0] },
members: {
"member1" => Metadata.new(["topic1"]),
"member2" => Metadata.new(["topic1"])
},
},
{
name: "lots of partitions",
topics: { "topic1" => (0..100).to_a },
members: { "member1" => Metadata.new(["topic1"]) },
},
{
name: "lots of members",
topics: { "topic1" => (0..10).to_a, "topic2" => (0..10).to_a },
members: Hash[(0..50).map { |i| ["member#{i}", Metadata.new(["topic1", "topic2"])] }]
},
{
name: "odd number of partitions",
topics: { "topic1" => (0..14).to_a },
members: {
"member1" => Metadata.new(["topic1"]),
"member2" => Metadata.new(["topic1"])
},
},
{
name: "five topics, 10 partitions, 3 consumers",
topics: { "topic1" => [0, 1], "topic2" => [0, 1], "topic3" => [0, 1], "topic4" => [0, 1], "topic5" => [0, 1] },
members: {
"member1" => Metadata.new(["topic1", "topic2", "topic3", "topic4", "topic5"]),
"member2" => Metadata.new(["topic1", "topic2", "topic3", "topic4", "topic5"]),
"member3" => Metadata.new(["topic1", "topic2", "topic3", "topic4", "topic5"])
},
}
].each do |options|
name, topics, members = options[:name], options[:topics], options[:members]
it name do
partitions = topics.flat_map {|topic, partition_ids|
partition_ids.map {|i|
double(:"partition#{i}", topic: topic, partition_id: i)
}
}
assignments = strategy.call(cluster: nil, members: members, partitions: partitions)
expect_all_partitions_assigned(topics, assignments)
expect_even_assignments(topics, assignments)
end
end
def expect_all_partitions_assigned(topics, assignments)
topics.each do |topic, partition_ids|
partition_ids.each do |partition_id|
assigned = assignments.values.find do |assigned_partitions|
assigned_partitions.find {|assigned_partition|
assigned_partition.topic == topic && assigned_partition.partition_id == partition_id
}
end
expect(assigned).to_not be_nil
end
end
end
def expect_even_assignments(topics, assignments)
num_partitions = topics.values.flatten.count
assignments.values.each do |assigned_partition|
num_assigned = assigned_partition.count
expect(num_assigned).to be_within(1).of(num_partitions.to_f / assignments.count)
end
end
context 'one consumer no subscriptions or topics / partitions' do
it 'returns empty assignments' do
members = { 'member1' => nil }
partitions = []
assignments = strategy.call(cluster: nil, members: members, partitions: partitions)
expect(assignments).to eq({})
end
end
context 'one consumer with subscription but no matching topic partition' do
it 'returns empty assignments' do
members = { 'member1' => double(topics: ['topic1']) }
partitions = []
assignments = strategy.call(cluster: nil, members: members, partitions: partitions)
expect(assignments).to eq({})
end
end
context 'one consumer subscribed to one topic with one partition' do
it 'assigns the partition to the consumer' do
members = { 'member1' => double(topics: ['topic1']) }
partitions = [
t1p0 = double(:"t1p0", topic: "topic1", partition_id: 0),
]
assignments = strategy.call(cluster: nil, members: members, partitions: partitions)
expect(assignments).to eq({
'member1' => [t1p0]
})
end
end
context 'one consumer subscribed to one topic with multiple partitions' do
it 'assigns all partitions to the consumer' do
members = { 'member1' => double(topics: ['topic1']) }
partitions = [
t1p0 = double(:"t1p0", topic: "topic1", partition_id: 0),
t1p1 = double(:"t1p1", topic: "topic1", partition_id: 1),
]
assignments = strategy.call(cluster: nil, members: members, partitions: partitions)
expect(assignments).to eq({
'member1' => [t1p0, t1p1]
})
end
end
context 'one consumer subscribed to one topic but with multiple different topic partitions' do
it 'only assigns partitions for the subscribed topic' do
members = { 'member1' => double(topics: ['topic1']) }
partitions = [
t1p0 = double(:"t1p0", topic: "topic1", partition_id: 0),
t1p1 = double(:"t1p1", topic: "topic1", partition_id: 1),
t2p0 = double(:"t2p0", topic: "topic2", partition_id: 0),
]
assignments = strategy.call(cluster: nil, members: members, partitions: partitions)
expect(assignments).to eq({
'member1' => [t1p0, t1p1]
})
end
end
context 'one consumer subscribed to multiple topics' do
it 'assigns all the topics partitions to the consumer' do
members = { 'member1' => double(topics: ['topic1', 'topic2']) }
partitions = [
t1p0 = double(:"t1p0", topic: "topic1", partition_id: 0),
t1p1 = double(:"t1p1", topic: "topic1", partition_id: 1),
t2p0 = double(:"t2p0", topic: "topic2", partition_id: 0),
]
assignments = strategy.call(cluster: nil, members: members, partitions: partitions)
expect(assignments).to eq({
'member1' => [t1p0, t1p1, t2p0]
})
end
end
context 'two consumers with one topic and only one partition' do
it 'only assigns the partition to one consumer' do
members = {
'member1' => double(topics: ['topic1']),
'member2' => double(topics: ['topic1'])
}
partitions = [
t1p0 = double(:"t1p0", topic: "topic1", partition_id: 0),
]
assignments = strategy.call(cluster: nil, members: members, partitions: partitions)
expect(assignments).to eq({
'member1' => [t1p0]
})
end
end
context 'two consumers subscribed to one topic with two partitions' do
it 'assigns a partition to each consumer' do
members = {
'member1' => double(topics: ['topic1']),
'member2' => double(topics: ['topic1'])
}
partitions = [
t1p0 = double(:"t1p0", topic: "topic1", partition_id: 0),
t1p1 = double(:"t1p1", topic: "topic1", partition_id: 1),
]
assignments = strategy.call(cluster: nil, members: members, partitions: partitions)
expect(assignments).to eq({
'member1' => [t1p0],
'member2' => [t1p1]
})
end
end
context 'multiple consumers with mixed topics subscriptions' do
it 'creates a balanced assignment' do
members = {
'member1' => double(topics: ['topic1']),
'member2' => double(topics: ['topic1', 'topic2']),
'member3' => double(topics: ['topic1'])
}
partitions = [
t1p0 = double(:"t1p0", topic: "topic1", partition_id: 0),
t1p1 = double(:"t1p1", topic: "topic1", partition_id: 1),
t1p2 = double(:"t1p2", topic: "topic1", partition_id: 2),
t2p0 = double(:"t2p0", topic: "topic2", partition_id: 0),
t2p1 = double(:"t2p1", topic: "topic2", partition_id: 1),
]
assignments = strategy.call(cluster: nil, members: members, partitions: partitions)
expect(assignments).to eq({
'member1' => [t1p0],
'member2' => [t1p1, t2p0, t2p1],
'member3' => [t1p2]
})
end
end
context 'two consumers subscribed to two topics with three partitions each' do
it 'creates a balanced assignment' do
members = {
'member1' => double(topics: ['topic1', 'topic2']),
'member2' => double(topics: ['topic1', 'topic2'])
}
partitions = [
t1p0 = double(:"t1p0", topic: "topic1", partition_id: 0),
t1p1 = double(:"t1p1", topic: "topic1", partition_id: 1),
t1p2 = double(:"t1p2", topic: "topic1", partition_id: 2),
t2p0 = double(:"t2p0", topic: "topic2", partition_id: 0),
t2p1 = double(:"t2p1", topic: "topic2", partition_id: 1),
t2p2 = double(:"t2p2", topic: "topic2", partition_id: 2),
]
assignments = strategy.call(cluster: nil, members: members, partitions: partitions)
expect(assignments).to eq({
'member1' => [t1p0, t1p2, t2p1],
'member2' => [t1p1, t2p0, t2p2]
})
end
end
context 'many consumers subscribed to one topic with partitions given out of order' do
it 'produces balanced assignments' do
members = {
'member1' => double(topics: ['topic1']),
'member2' => double(topics: ['topic1']),
'member3' => double(topics: ['topic2']),
}
partitions = [
t2p0 = double(:"t2p0", topic: "topic2", partition_id: 0),
t1p0 = double(:"t1p0", topic: "topic1", partition_id: 0),
t2p1 = double(:"t2p1", topic: "topic2", partition_id: 1),
t1p1 = double(:"t1p1", topic: "topic1", partition_id: 1),
]
assignments = strategy.call(cluster: nil, members: members, partitions: partitions)
# Without sorting the partitions by topic this input would produce a non balanced assignment:
# member1 => [t1p0, t1p1]
# member2 => []
# member3 => [t2p0, t2p1]
expect(assignments).to eq({
'member1' => [t1p0],
'member2' => [t1p1],
'member3' => [t2p0, t2p1]
})
end
end
end