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overleaf/services/document-updater/redis_cluster/redis-trib.rb

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Configure backend database as redis cluster
2016-06-07 13:38:32 -04:00
#!/usr/bin/env ruby
# TODO (temporary here, we'll move this into the Github issues once
# redis-trib initial implementation is completed).
#
# - Make sure that if the rehashing fails in the middle redis-trib will try
# to recover.
# - When redis-trib performs a cluster check, if it detects a slot move in
# progress it should prompt the user to continue the move from where it
# stopped.
# - Gracefully handle Ctrl+C in move_slot to prompt the user if really stop
# while rehashing, and performing the best cleanup possible if the user
# forces the quit.
# - When doing "fix" set a global Fix to true, and prompt the user to
# fix the problem if automatically fixable every time there is something
# to fix. For instance:
# 1) If there is a node that pretend to receive a slot, or to migrate a
# slot, but has no entries in that slot, fix it.
# 2) If there is a node having keys in slots that are not owned by it
# fix this condition moving the entries in the same node.
# 3) Perform more possibly slow tests about the state of the cluster.
# 4) When aborted slot migration is detected, fix it.
require 'rubygems'
require 'redis'
ClusterHashSlots = 16384
MigrateDefaultTimeout = 60000
MigrateDefaultPipeline = 10
RebalanceDefaultThreshold = 2
$verbose = false
def xputs(s)
case s[0..2]
when ">>>"
color="29;1"
when "[ER"
color="31;1"
when "[WA"
color="31;1"
when "[OK"
color="32"
when "[FA","***"
color="33"
else
color=nil
end
color = nil if ENV['TERM'] != "xterm"
print "\033[#{color}m" if color
print s
print "\033[0m" if color
print "\n"
end
class ClusterNode
def initialize(addr)
s = addr.split("@")[0].split(":")
if s.length < 2
puts "Invalid IP or Port (given as #{addr}) - use IP:Port format"
exit 1
end
port = s.pop # removes port from split array
ip = s.join(":") # if s.length > 1 here, it's IPv6, so restore address
@r = nil
@info = {}
@info[:host] = ip
@info[:port] = port
@info[:slots] = {}
@info[:migrating] = {}
@info[:importing] = {}
@info[:replicate] = false
@dirty = false # True if we need to flush slots info into node.
@friends = []
end
def friends
@friends
end
def slots
@info[:slots]
end
def has_flag?(flag)
@info[:flags].index(flag)
end
def to_s
"#{@info[:host]}:#{@info[:port]}"
end
def connect(o={})
return if @r
print "Connecting to node #{self}: " if $verbose
STDOUT.flush
begin
@r = Redis.new(:host => @info[:host], :port => @info[:port], :timeout => 60)
@r.ping
rescue
xputs "[ERR] Sorry, can't connect to node #{self}"
exit 1 if o[:abort]
@r = nil
end
xputs "OK" if $verbose
end
def assert_cluster
info = @r.info
if !info["cluster_enabled"] || info["cluster_enabled"].to_i == 0
xputs "[ERR] Node #{self} is not configured as a cluster node."
exit 1
end
end
def assert_empty
if !(@r.cluster("info").split("\r\n").index("cluster_known_nodes:1")) ||
(@r.info['db0'])
xputs "[ERR] Node #{self} is not empty. Either the node already knows other nodes (check with CLUSTER NODES) or contains some key in database 0."
exit 1
end
end
def load_info(o={})
self.connect
nodes = @r.cluster("nodes").split("\n")
nodes.each{|n|
# name addr flags role ping_sent ping_recv link_status slots
split = n.split
name,addr,flags,master_id,ping_sent,ping_recv,config_epoch,link_status = split[0..6]
slots = split[8..-1]
info = {
:name => name,
:addr => addr,
:flags => flags.split(","),
:replicate => master_id,
:ping_sent => ping_sent.to_i,
:ping_recv => ping_recv.to_i,
:link_status => link_status
}
info[:replicate] = false if master_id == "-"
if info[:flags].index("myself")
@info = @info.merge(info)
@info[:slots] = {}
slots.each{|s|
if s[0..0] == '['
if s.index("->-") # Migrating
slot,dst = s[1..-1].split("->-")
@info[:migrating][slot.to_i] = dst
elsif s.index("-<-") # Importing
slot,src = s[1..-1].split("-<-")
@info[:importing][slot.to_i] = src
end
elsif s.index("-")
start,stop = s.split("-")
self.add_slots((start.to_i)..(stop.to_i))
else
self.add_slots((s.to_i)..(s.to_i))
end
} if slots
@dirty = false
@r.cluster("info").split("\n").each{|e|
k,v=e.split(":")
k = k.to_sym
v.chop!
if k != :cluster_state
@info[k] = v.to_i
else
@info[k] = v
end
}
elsif o[:getfriends]
@friends << info
end
}
end
def add_slots(slots)
slots.each{|s|
@info[:slots][s] = :new
}
@dirty = true
end
def set_as_replica(node_id)
@info[:replicate] = node_id
@dirty = true
end
def flush_node_config
return if !@dirty
if @info[:replicate]
begin
@r.cluster("replicate",@info[:replicate])
rescue
# If the cluster did not already joined it is possible that
# the slave does not know the master node yet. So on errors
# we return ASAP leaving the dirty flag set, to flush the
# config later.
return
end
else
new = []
@info[:slots].each{|s,val|
if val == :new
new << s
@info[:slots][s] = true
end
}
@r.cluster("addslots",*new)
end
@dirty = false
end
def info_string
# We want to display the hash slots assigned to this node
# as ranges, like in: "1-5,8-9,20-25,30"
#
# Note: this could be easily written without side effects,
# we use 'slots' just to split the computation into steps.
# First step: we want an increasing array of integers
# for instance: [1,2,3,4,5,8,9,20,21,22,23,24,25,30]
slots = @info[:slots].keys.sort
# As we want to aggregate adjacent slots we convert all the
# slot integers into ranges (with just one element)
# So we have something like [1..1,2..2, ... and so forth.
slots.map!{|x| x..x}
# Finally we group ranges with adjacent elements.
slots = slots.reduce([]) {|a,b|
if !a.empty? && b.first == (a[-1].last)+1
a[0..-2] + [(a[-1].first)..(b.last)]
else
a + [b]
end
}
# Now our task is easy, we just convert ranges with just one
# element into a number, and a real range into a start-end format.
# Finally we join the array using the comma as separator.
slots = slots.map{|x|
x.count == 1 ? x.first.to_s : "#{x.first}-#{x.last}"
}.join(",")
role = self.has_flag?("master") ? "M" : "S"
if self.info[:replicate] and @dirty
is = "S: #{self.info[:name]} #{self.to_s}"
else
is = "#{role}: #{self.info[:name]} #{self.to_s}\n"+
" slots:#{slots} (#{self.slots.length} slots) "+
"#{(self.info[:flags]-["myself"]).join(",")}"
end
if self.info[:replicate]
is += "\n replicates #{info[:replicate]}"
elsif self.has_flag?("master") && self.info[:replicas]
is += "\n #{info[:replicas].length} additional replica(s)"
end
is
end
# Return a single string representing nodes and associated slots.
# TODO: remove slaves from config when slaves will be handled
# by Redis Cluster.
def get_config_signature
config = []
@r.cluster("nodes").each_line{|l|
s = l.split
slots = s[8..-1].select {|x| x[0..0] != "["}
next if slots.length == 0
config << s[0]+":"+(slots.sort.join(","))
}
config.sort.join("|")
end
def info
@info
end
def is_dirty?
@dirty
end
def r
@r
end
end
class RedisTrib
def initialize
@nodes = []
@fix = false
@errors = []
@timeout = MigrateDefaultTimeout
end
def check_arity(req_args, num_args)
if ((req_args > 0 and num_args != req_args) ||
(req_args < 0 and num_args < req_args.abs))
xputs "[ERR] Wrong number of arguments for specified sub command"
exit 1
end
end
def add_node(node)
@nodes << node
end
def reset_nodes
@nodes = []
end
def cluster_error(msg)
@errors << msg
xputs msg
end
# Return the node with the specified ID or Nil.
def get_node_by_name(name)
@nodes.each{|n|
return n if n.info[:name] == name.downcase
}
return nil
end
# Like get_node_by_name but the specified name can be just the first
# part of the node ID as long as the prefix in unique across the
# cluster.
def get_node_by_abbreviated_name(name)
l = name.length
candidates = []
@nodes.each{|n|
if n.info[:name][0...l] == name.downcase
candidates << n
end
}
return nil if candidates.length != 1
candidates[0]
end
# This function returns the master that has the least number of replicas
# in the cluster. If there are multiple masters with the same smaller
# number of replicas, one at random is returned.
def get_master_with_least_replicas
masters = @nodes.select{|n| n.has_flag? "master"}
sorted = masters.sort{|a,b|
a.info[:replicas].length <=> b.info[:replicas].length
}
sorted[0]
end
def check_cluster(opt={})
xputs ">>> Performing Cluster Check (using node #{@nodes[0]})"
show_nodes if !opt[:quiet]
check_config_consistency
check_open_slots
check_slots_coverage
end
def show_cluster_info
masters = 0
keys = 0
@nodes.each{|n|
if n.has_flag?("master")
puts "#{n} (#{n.info[:name][0...8]}...) -> #{n.r.dbsize} keys | #{n.slots.length} slots | "+
"#{n.info[:replicas].length} slaves."
masters += 1
keys += n.r.dbsize
end
}
xputs "[OK] #{keys} keys in #{masters} masters."
keys_per_slot = sprintf("%.2f",keys/16384.0)
puts "#{keys_per_slot} keys per slot on average."
end
# Merge slots of every known node. If the resulting slots are equal
# to ClusterHashSlots, then all slots are served.
def covered_slots
slots = {}
@nodes.each{|n|
slots = slots.merge(n.slots)
}
slots
end
def check_slots_coverage
xputs ">>> Check slots coverage..."
slots = covered_slots
if slots.length == ClusterHashSlots
xputs "[OK] All #{ClusterHashSlots} slots covered."
else
cluster_error \
"[ERR] Not all #{ClusterHashSlots} slots are covered by nodes."
fix_slots_coverage if @fix
end
end
def check_open_slots
xputs ">>> Check for open slots..."
open_slots = []
@nodes.each{|n|
if n.info[:migrating].size > 0
cluster_error \
"[WARNING] Node #{n} has slots in migrating state (#{n.info[:migrating].keys.join(",")})."
open_slots += n.info[:migrating].keys
end
if n.info[:importing].size > 0
cluster_error \
"[WARNING] Node #{n} has slots in importing state (#{n.info[:importing].keys.join(",")})."
open_slots += n.info[:importing].keys
end
}
open_slots.uniq!
if open_slots.length > 0
xputs "[WARNING] The following slots are open: #{open_slots.join(",")}"
end
if @fix
open_slots.each{|slot| fix_open_slot slot}
end
end
def nodes_with_keys_in_slot(slot)
nodes = []
@nodes.each{|n|
next if n.has_flag?("slave")
nodes << n if n.r.cluster("getkeysinslot",slot,1).length > 0
}
nodes
end
def fix_slots_coverage
not_covered = (0...ClusterHashSlots).to_a - covered_slots.keys
xputs ">>> Fixing slots coverage..."
xputs "List of not covered slots: " + not_covered.join(",")
# For every slot, take action depending on the actual condition:
# 1) No node has keys for this slot.
# 2) A single node has keys for this slot.
# 3) Multiple nodes have keys for this slot.
slots = {}
not_covered.each{|slot|
nodes = nodes_with_keys_in_slot(slot)
slots[slot] = nodes
xputs "Slot #{slot} has keys in #{nodes.length} nodes: #{nodes.join(", ")}"
}
none = slots.select {|k,v| v.length == 0}
single = slots.select {|k,v| v.length == 1}
multi = slots.select {|k,v| v.length > 1}
# Handle case "1": keys in no node.
if none.length > 0
xputs "The folowing uncovered slots have no keys across the cluster:"
xputs none.keys.join(",")
yes_or_die "Fix these slots by covering with a random node?"
none.each{|slot,nodes|
node = @nodes.sample
xputs ">>> Covering slot #{slot} with #{node}"
node.r.cluster("addslots",slot)
}
end
# Handle case "2": keys only in one node.
if single.length > 0
xputs "The folowing uncovered slots have keys in just one node:"
puts single.keys.join(",")
yes_or_die "Fix these slots by covering with those nodes?"
single.each{|slot,nodes|
xputs ">>> Covering slot #{slot} with #{nodes[0]}"
nodes[0].r.cluster("addslots",slot)
}
end
# Handle case "3": keys in multiple nodes.
if multi.length > 0
xputs "The folowing uncovered slots have keys in multiple nodes:"
xputs multi.keys.join(",")
yes_or_die "Fix these slots by moving keys into a single node?"
multi.each{|slot,nodes|
target = get_node_with_most_keys_in_slot(nodes,slot)
xputs ">>> Covering slot #{slot} moving keys to #{target}"
target.r.cluster('addslots',slot)
target.r.cluster('setslot',slot,'stable')
nodes.each{|src|
next if src == target
# Set the source node in 'importing' state (even if we will
# actually migrate keys away) in order to avoid receiving
# redirections for MIGRATE.
src.r.cluster('setslot',slot,'importing',target.info[:name])
move_slot(src,target,slot,:dots=>true,:fix=>true,:cold=>true)
src.r.cluster('setslot',slot,'stable')
}
}
end
end
# Return the owner of the specified slot
def get_slot_owners(slot)
owners = []
@nodes.each{|n|
next if n.has_flag?("slave")
n.slots.each{|s,_|
owners << n if s == slot
}
}
owners
end
# Return the node, among 'nodes' with the greatest number of keys
# in the specified slot.
def get_node_with_most_keys_in_slot(nodes,slot)
best = nil
best_numkeys = 0
@nodes.each{|n|
next if n.has_flag?("slave")
numkeys = n.r.cluster("countkeysinslot",slot)
if numkeys > best_numkeys || best == nil
best = n
best_numkeys = numkeys
end
}
return best
end
# Slot 'slot' was found to be in importing or migrating state in one or
# more nodes. This function fixes this condition by migrating keys where
# it seems more sensible.
def fix_open_slot(slot)
puts ">>> Fixing open slot #{slot}"
# Try to obtain the current slot owner, according to the current
# nodes configuration.
owners = get_slot_owners(slot)
owner = owners[0] if owners.length == 1
migrating = []
importing = []
@nodes.each{|n|
next if n.has_flag? "slave"
if n.info[:migrating][slot]
migrating << n
elsif n.info[:importing][slot]
importing << n
elsif n.r.cluster("countkeysinslot",slot) > 0 && n != owner
xputs "*** Found keys about slot #{slot} in node #{n}!"
importing << n
end
}
puts "Set as migrating in: #{migrating.join(",")}"
puts "Set as importing in: #{importing.join(",")}"
# If there is no slot owner, set as owner the slot with the biggest
# number of keys, among the set of migrating / importing nodes.
if !owner
xputs ">>> Nobody claims ownership, selecting an owner..."
owner = get_node_with_most_keys_in_slot(@nodes,slot)
# If we still don't have an owner, we can't fix it.
if !owner
xputs "[ERR] Can't select a slot owner. Impossible to fix."
exit 1
end
# Use ADDSLOTS to assign the slot.
puts "*** Configuring #{owner} as the slot owner"
owner.r.cluster("setslot",slot,"stable")
owner.r.cluster("addslots",slot)
# Make sure this information will propagate. Not strictly needed
# since there is no past owner, so all the other nodes will accept
# whatever epoch this node will claim the slot with.
owner.r.cluster("bumpepoch")
# Remove the owner from the list of migrating/importing
# nodes.
migrating.delete(owner)
importing.delete(owner)
end
# If there are multiple owners of the slot, we need to fix it
# so that a single node is the owner and all the other nodes
# are in importing state. Later the fix can be handled by one
# of the base cases above.
#
# Note that this case also covers multiple nodes having the slot
# in migrating state, since migrating is a valid state only for
# slot owners.
if owners.length > 1
owner = get_node_with_most_keys_in_slot(owners,slot)
owners.each{|n|
next if n == owner
n.r.cluster('delslots',slot)
n.r.cluster('setslot',slot,'importing',owner.info[:name])
importing.delete(n) # Avoid duplciates
importing << n
}
owner.r.cluster('bumpepoch')
end
# Case 1: The slot is in migrating state in one slot, and in
# importing state in 1 slot. That's trivial to address.
if migrating.length == 1 && importing.length == 1
move_slot(migrating[0],importing[0],slot,:dots=>true,:fix=>true)
# Case 2: There are multiple nodes that claim the slot as importing,
# they probably got keys about the slot after a restart so opened
# the slot. In this case we just move all the keys to the owner
# according to the configuration.
elsif migrating.length == 0 && importing.length > 0
xputs ">>> Moving all the #{slot} slot keys to its owner #{owner}"
importing.each {|node|
next if node == owner
move_slot(node,owner,slot,:dots=>true,:fix=>true,:cold=>true)
xputs ">>> Setting #{slot} as STABLE in #{node}"
node.r.cluster("setslot",slot,"stable")
}
# Case 3: There are no slots claiming to be in importing state, but
# there is a migrating node that actually don't have any key. We
# can just close the slot, probably a reshard interrupted in the middle.
elsif importing.length == 0 && migrating.length == 1 &&
migrating[0].r.cluster("getkeysinslot",slot,10).length == 0
migrating[0].r.cluster("setslot",slot,"stable")
else
xputs "[ERR] Sorry, Redis-trib can't fix this slot yet (work in progress). Slot is set as migrating in #{migrating.join(",")}, as importing in #{importing.join(",")}, owner is #{owner}"
end
end
# Check if all the nodes agree about the cluster configuration
def check_config_consistency
if !is_config_consistent?
cluster_error "[ERR] Nodes don't agree about configuration!"
else
xputs "[OK] All nodes agree about slots configuration."
end
end
def is_config_consistent?
signatures=[]
@nodes.each{|n|
signatures << n.get_config_signature
}
return signatures.uniq.length == 1
end
def wait_cluster_join
print "Waiting for the cluster to join"
while !is_config_consistent?
print "."
STDOUT.flush
sleep 1
end
print "\n"
end
def alloc_slots
nodes_count = @nodes.length
masters_count = @nodes.length / (@replicas+1)
masters = []
# The first step is to split instances by IP. This is useful as
# we'll try to allocate master nodes in different physical machines
# (as much as possible) and to allocate slaves of a given master in
# different physical machines as well.
#
# This code assumes just that if the IP is different, than it is more
# likely that the instance is running in a different physical host
# or at least a different virtual machine.
ips = {}
@nodes.each{|n|
ips[n.info[:host]] = [] if !ips[n.info[:host]]
ips[n.info[:host]] << n
}
# Select master instances
puts "Using #{masters_count} masters:"
interleaved = []
stop = false
while not stop do
# Take one node from each IP until we run out of nodes
# across every IP.
ips.each do |ip,nodes|
if nodes.empty?
# if this IP has no remaining nodes, check for termination
if interleaved.length == nodes_count
# stop when 'interleaved' has accumulated all nodes
stop = true
next
end
else
# else, move one node from this IP to 'interleaved'
interleaved.push nodes.shift
end
end
end
masters = interleaved.slice!(0, masters_count)
nodes_count -= masters.length
masters.each{|m| puts m}
# Alloc slots on masters
slots_per_node = ClusterHashSlots.to_f / masters_count
first = 0
cursor = 0.0
masters.each_with_index{|n,masternum|
last = (cursor+slots_per_node-1).round
if last > ClusterHashSlots || masternum == masters.length-1
last = ClusterHashSlots-1
end
last = first if last < first # Min step is 1.
n.add_slots first..last
first = last+1
cursor += slots_per_node
}
# Select N replicas for every master.
# We try to split the replicas among all the IPs with spare nodes
# trying to avoid the host where the master is running, if possible.
#
# Note we loop two times. The first loop assigns the requested
# number of replicas to each master. The second loop assigns any
# remaining instances as extra replicas to masters. Some masters
# may end up with more than their requested number of replicas, but
# all nodes will be used.
assignment_verbose = false
[:requested,:unused].each do |assign|
masters.each do |m|
assigned_replicas = 0
while assigned_replicas < @replicas
break if nodes_count == 0
if assignment_verbose
if assign == :requested
puts "Requesting total of #{@replicas} replicas " \
"(#{assigned_replicas} replicas assigned " \
"so far with #{nodes_count} total remaining)."
elsif assign == :unused
puts "Assigning extra instance to replication " \
"role too (#{nodes_count} remaining)."
end
end
# Return the first node not matching our current master
node = interleaved.find{|n| n.info[:host] != m.info[:host]}
# If we found a node, use it as a best-first match.
# Otherwise, we didn't find a node on a different IP, so we
# go ahead and use a same-IP replica.
if node
slave = node
interleaved.delete node
else
slave = interleaved.shift
end
slave.set_as_replica(m.info[:name])
nodes_count -= 1
assigned_replicas += 1
puts "Adding replica #{slave} to #{m}"
# If we are in the "assign extra nodes" loop,
# we want to assign one extra replica to each
# master before repeating masters.
# This break lets us assign extra replicas to masters
# in a round-robin way.
break if assign == :unused
end
end
end
end
def flush_nodes_config
@nodes.each{|n|
n.flush_node_config
}
end
def show_nodes
@nodes.each{|n|
xputs n.info_string
}
end
# Redis Cluster config epoch collision resolution code is able to eventually
# set a different epoch to each node after a new cluster is created, but
# it is slow compared to assign a progressive config epoch to each node
# before joining the cluster. However we do just a best-effort try here
# since if we fail is not a problem.
def assign_config_epoch
config_epoch = 1
@nodes.each{|n|
begin
n.r.cluster("set-config-epoch",config_epoch)
rescue
end
config_epoch += 1
}
end
def join_cluster
# We use a brute force approach to make sure the node will meet
# each other, that is, sending CLUSTER MEET messages to all the nodes
# about the very same node.
# Thanks to gossip this information should propagate across all the
# cluster in a matter of seconds.
first = false
@nodes.each{|n|
if !first then first = n.info; next; end # Skip the first node
n.r.cluster("meet",first[:host],first[:port])
}
end
def yes_or_die(msg)
print "#{msg} (type 'yes' to accept): "
STDOUT.flush
if !(STDIN.gets.chomp.downcase == "yes")
xputs "*** Aborting..."
exit 1
end
end
def load_cluster_info_from_node(nodeaddr)
node = ClusterNode.new(nodeaddr)
node.connect(:abort => true)
node.assert_cluster
node.load_info(:getfriends => true)
add_node(node)
node.friends.each{|f|
next if f[:flags].index("noaddr") ||
f[:flags].index("disconnected") ||
f[:flags].index("fail")
fnode = ClusterNode.new(f[:addr])
fnode.connect()
next if !fnode.r
begin
fnode.load_info()
add_node(fnode)
rescue => e
xputs "[ERR] Unable to load info for node #{fnode}"
end
}
populate_nodes_replicas_info
end
# This function is called by load_cluster_info_from_node in order to
# add additional information to every node as a list of replicas.
def populate_nodes_replicas_info
# Start adding the new field to every node.
@nodes.each{|n|
n.info[:replicas] = []
}
# Populate the replicas field using the replicate field of slave
# nodes.
@nodes.each{|n|
if n.info[:replicate]
master = get_node_by_name(n.info[:replicate])
if !master
xputs "*** WARNING: #{n} claims to be slave of unknown node ID #{n.info[:replicate]}."
else
master.info[:replicas] << n
end
end
}
end
# Given a list of source nodes return a "resharding plan"
# with what slots to move in order to move "numslots" slots to another
# instance.
def compute_reshard_table(sources,numslots)
moved = []
# Sort from bigger to smaller instance, for two reasons:
# 1) If we take less slots than instances it is better to start
# getting from the biggest instances.
# 2) We take one slot more from the first instance in the case of not
# perfect divisibility. Like we have 3 nodes and need to get 10
# slots, we take 4 from the first, and 3 from the rest. So the
# biggest is always the first.
sources = sources.sort{|a,b| b.slots.length <=> a.slots.length}
source_tot_slots = sources.inject(0) {|sum,source|
sum+source.slots.length
}
sources.each_with_index{|s,i|
# Every node will provide a number of slots proportional to the
# slots it has assigned.
n = (numslots.to_f/source_tot_slots*s.slots.length)
if i == 0
n = n.ceil
else
n = n.floor
end
s.slots.keys.sort[(0...n)].each{|slot|
if moved.length < numslots
moved << {:source => s, :slot => slot}
end
}
}
return moved
end
def show_reshard_table(table)
table.each{|e|
puts " Moving slot #{e[:slot]} from #{e[:source].info[:name]}"
}
end
# Move slots between source and target nodes using MIGRATE.
#
# Options:
# :verbose -- Print a dot for every moved key.
# :fix -- We are moving in the context of a fix. Use REPLACE.
# :cold -- Move keys without opening slots / reconfiguring the nodes.
# :update -- Update nodes.info[:slots] for source/target nodes.
# :quiet -- Don't print info messages.
def move_slot(source,target,slot,o={})
o = {:pipeline => MigrateDefaultPipeline}.merge(o)
# We start marking the slot as importing in the destination node,
# and the slot as migrating in the target host. Note that the order of
# the operations is important, as otherwise a client may be redirected
# to the target node that does not yet know it is importing this slot.
if !o[:quiet]
print "Moving slot #{slot} from #{source} to #{target}: "
STDOUT.flush
end
if !o[:cold]
target.r.cluster("setslot",slot,"importing",source.info[:name])
source.r.cluster("setslot",slot,"migrating",target.info[:name])
end
# Migrate all the keys from source to target using the MIGRATE command
while true
keys = source.r.cluster("getkeysinslot",slot,o[:pipeline])
break if keys.length == 0
begin
source.r.client.call(["migrate",target.info[:host],target.info[:port],"",0,@timeout,:keys,*keys])
rescue => e
if o[:fix] && e.to_s =~ /BUSYKEY/
xputs "*** Target key exists. Replacing it for FIX."
source.r.client.call(["migrate",target.info[:host],target.info[:port],"",0,@timeout,:replace,:keys,*keys])
else
puts ""
xputs "[ERR] Calling MIGRATE: #{e}"
exit 1
end
end
print "."*keys.length if o[:dots]
STDOUT.flush
end
puts if !o[:quiet]
# Set the new node as the owner of the slot in all the known nodes.
if !o[:cold]
@nodes.each{|n|
next if n.has_flag?("slave")
n.r.cluster("setslot",slot,"node",target.info[:name])
}
end
# Update the node logical config
if o[:update] then
source.info[:slots].delete(slot)
target.info[:slots][slot] = true
end
end
# redis-trib subcommands implementations.
def check_cluster_cmd(argv,opt)
load_cluster_info_from_node(argv[0])
check_cluster
end
def info_cluster_cmd(argv,opt)
load_cluster_info_from_node(argv[0])
show_cluster_info
end
def rebalance_cluster_cmd(argv,opt)
opt = {
'pipeline' => MigrateDefaultPipeline,
'threshold' => RebalanceDefaultThreshold
}.merge(opt)
# Load nodes info before parsing options, otherwise we can't
# handle --weight.
load_cluster_info_from_node(argv[0])
# Options parsing
threshold = opt['threshold'].to_i
autoweights = opt['auto-weights']
weights = {}
opt['weight'].each{|w|
fields = w.split("=")
node = get_node_by_abbreviated_name(fields[0])
if !node || !node.has_flag?("master")
puts "*** No such master node #{fields[0]}"
exit 1
end
weights[node.info[:name]] = fields[1].to_f
} if opt['weight']
useempty = opt['use-empty-masters']
# Assign a weight to each node, and compute the total cluster weight.
total_weight = 0
nodes_involved = 0
@nodes.each{|n|
if n.has_flag?("master")
next if !useempty && n.slots.length == 0
n.info[:w] = weights[n.info[:name]] ? weights[n.info[:name]] : 1
total_weight += n.info[:w]
nodes_involved += 1
end
}
# Check cluster, only proceed if it looks sane.
check_cluster(:quiet => true)
if @errors.length != 0
puts "*** Please fix your cluster problems before rebalancing"
exit 1
end
# Calculate the slots balance for each node. It's the number of
# slots the node should lose (if positive) or gain (if negative)
# in order to be balanced.
threshold = opt['threshold'].to_f
threshold_reached = false
@nodes.each{|n|
if n.has_flag?("master")
next if !n.info[:w]
expected = ((ClusterHashSlots.to_f / total_weight) *
n.info[:w]).to_i
n.info[:balance] = n.slots.length - expected
# Compute the percentage of difference between the
# expected number of slots and the real one, to see
# if it's over the threshold specified by the user.
over_threshold = false
if threshold > 0
if n.slots.length > 0
err_perc = (100-(100.0*expected/n.slots.length)).abs
over_threshold = true if err_perc > threshold
elsif expected > 0
over_threshold = true
end
end
threshold_reached = true if over_threshold
end
}
if !threshold_reached
xputs "*** No rebalancing needed! All nodes are within the #{threshold}% threshold."
return
end
# Only consider nodes we want to change
sn = @nodes.select{|n|
n.has_flag?("master") && n.info[:w]
}
# Because of rounding, it is possible that the balance of all nodes
# summed does not give 0. Make sure that nodes that have to provide
# slots are always matched by nodes receiving slots.
total_balance = sn.map{|x| x.info[:balance]}.reduce{|a,b| a+b}
while total_balance > 0
sn.each{|n|
if n.info[:balance] < 0 && total_balance > 0
n.info[:balance] -= 1
total_balance -= 1
end
}
end
# Sort nodes by their slots balance.
sn = sn.sort{|a,b|
a.info[:balance] <=> b.info[:balance]
}
xputs ">>> Rebalancing across #{nodes_involved} nodes. Total weight = #{total_weight}"
if $verbose
sn.each{|n|
puts "#{n} balance is #{n.info[:balance]} slots"
}
end
# Now we have at the start of the 'sn' array nodes that should get
# slots, at the end nodes that must give slots.
# We take two indexes, one at the start, and one at the end,
# incrementing or decrementing the indexes accordingly til we
# find nodes that need to get/provide slots.
dst_idx = 0
src_idx = sn.length - 1
while dst_idx < src_idx
dst = sn[dst_idx]
src = sn[src_idx]
numslots = [dst.info[:balance],src.info[:balance]].map{|n|
n.abs
}.min
if numslots > 0
puts "Moving #{numslots} slots from #{src} to #{dst}"
# Actaully move the slots.
reshard_table = compute_reshard_table([src],numslots)
if reshard_table.length != numslots
xputs "*** Assertio failed: Reshard table != number of slots"
exit 1
end
if opt['simulate']
print "#"*reshard_table.length
else
reshard_table.each{|e|
move_slot(e[:source],dst,e[:slot],
:quiet=>true,
:dots=>false,
:update=>true,
:pipeline=>opt['pipeline'])
print "#"
STDOUT.flush
}
end
puts
end
# Update nodes balance.
dst.info[:balance] += numslots
src.info[:balance] -= numslots
dst_idx += 1 if dst.info[:balance] == 0
src_idx -= 1 if src.info[:balance] == 0
end
end
def fix_cluster_cmd(argv,opt)
@fix = true
@timeout = opt['timeout'].to_i if opt['timeout']
load_cluster_info_from_node(argv[0])
check_cluster
end
def reshard_cluster_cmd(argv,opt)
opt = {'pipeline' => MigrateDefaultPipeline}.merge(opt)
load_cluster_info_from_node(argv[0])
check_cluster
if @errors.length != 0
puts "*** Please fix your cluster problems before resharding"
exit 1
end
@timeout = opt['timeout'].to_i if opt['timeout'].to_i
# Get number of slots
if opt['slots']
numslots = opt['slots'].to_i
else
numslots = 0
while numslots <= 0 or numslots > ClusterHashSlots
print "How many slots do you want to move (from 1 to #{ClusterHashSlots})? "
numslots = STDIN.gets.to_i
end
end
# Get the target instance
if opt['to']
target = get_node_by_name(opt['to'])
if !target || target.has_flag?("slave")
xputs "*** The specified node is not known or not a master, please retry."
exit 1
end
else
target = nil
while not target
print "What is the receiving node ID? "
target = get_node_by_name(STDIN.gets.chop)
if !target || target.has_flag?("slave")
xputs "*** The specified node is not known or not a master, please retry."
target = nil
end
end
end
# Get the source instances
sources = []
if opt['from']
opt['from'].split(',').each{|node_id|
if node_id == "all"
sources = "all"
break
end
src = get_node_by_name(node_id)
if !src || src.has_flag?("slave")
xputs "*** The specified node is not known or is not a master, please retry."
exit 1
end
sources << src
}
else
xputs "Please enter all the source node IDs."
xputs " Type 'all' to use all the nodes as source nodes for the hash slots."
xputs " Type 'done' once you entered all the source nodes IDs."
while true
print "Source node ##{sources.length+1}:"
line = STDIN.gets.chop
src = get_node_by_name(line)
if line == "done"
break
elsif line == "all"
sources = "all"
break
elsif !src || src.has_flag?("slave")
xputs "*** The specified node is not known or is not a master, please retry."
elsif src.info[:name] == target.info[:name]
xputs "*** It is not possible to use the target node as source node."
else
sources << src
end
end
end
if sources.length == 0
puts "*** No source nodes given, operation aborted"
exit 1
end
# Handle soures == all.
if sources == "all"
sources = []
@nodes.each{|n|
next if n.info[:name] == target.info[:name]
next if n.has_flag?("slave")
sources << n
}
end
# Check if the destination node is the same of any source nodes.
if sources.index(target)
xputs "*** Target node is also listed among the source nodes!"
exit 1
end
puts "\nReady to move #{numslots} slots."
puts " Source nodes:"
sources.each{|s| puts " "+s.info_string}
puts " Destination node:"
puts " #{target.info_string}"
reshard_table = compute_reshard_table(sources,numslots)
puts " Resharding plan:"
show_reshard_table(reshard_table)
if !opt['yes']
print "Do you want to proceed with the proposed reshard plan (yes/no)? "
yesno = STDIN.gets.chop
exit(1) if (yesno != "yes")
end
reshard_table.each{|e|
move_slot(e[:source],target,e[:slot],
:dots=>true,
:pipeline=>opt['pipeline'])
}
end
# This is an helper function for create_cluster_cmd that verifies if
# the number of nodes and the specified replicas have a valid configuration
# where there are at least three master nodes and enough replicas per node.
def check_create_parameters
masters = @nodes.length/(@replicas+1)
if masters < 3
puts "*** ERROR: Invalid configuration for cluster creation."
puts "*** Redis Cluster requires at least 3 master nodes."
puts "*** This is not possible with #{@nodes.length} nodes and #{@replicas} replicas per node."
puts "*** At least #{3*(@replicas+1)} nodes are required."
exit 1
end
end
def create_cluster_cmd(argv,opt)
opt = {'replicas' => 0}.merge(opt)
@replicas = opt['replicas'].to_i
xputs ">>> Creating cluster"
argv[0..-1].each{|n|
node = ClusterNode.new(n)
node.connect(:abort => true)
node.assert_cluster
node.load_info
node.assert_empty
add_node(node)
}
check_create_parameters
xputs ">>> Performing hash slots allocation on #{@nodes.length} nodes..."
alloc_slots
show_nodes
yes_or_die "Can I set the above configuration?"
flush_nodes_config
xputs ">>> Nodes configuration updated"
xputs ">>> Assign a different config epoch to each node"
assign_config_epoch
xputs ">>> Sending CLUSTER MEET messages to join the cluster"
join_cluster
# Give one second for the join to start, in order to avoid that
# wait_cluster_join will find all the nodes agree about the config as
# they are still empty with unassigned slots.
sleep 1
wait_cluster_join
flush_nodes_config # Useful for the replicas
check_cluster
end
def addnode_cluster_cmd(argv,opt)
xputs ">>> Adding node #{argv[0]} to cluster #{argv[1]}"
# Check the existing cluster
load_cluster_info_from_node(argv[1])
check_cluster
# If --master-id was specified, try to resolve it now so that we
# abort before starting with the node configuration.
if opt['slave']
if opt['master-id']
master = get_node_by_name(opt['master-id'])
if !master
xputs "[ERR] No such master ID #{opt['master-id']}"
end
else
master = get_master_with_least_replicas
xputs "Automatically selected master #{master}"
end
end
# Add the new node
new = ClusterNode.new(argv[0])
new.connect(:abort => true)
new.assert_cluster
new.load_info
new.assert_empty
first = @nodes.first.info
add_node(new)
# Send CLUSTER MEET command to the new node
xputs ">>> Send CLUSTER MEET to node #{new} to make it join the cluster."
new.r.cluster("meet",first[:host],first[:port])
# Additional configuration is needed if the node is added as
# a slave.
if opt['slave']
wait_cluster_join
xputs ">>> Configure node as replica of #{master}."
new.r.cluster("replicate",master.info[:name])
end
xputs "[OK] New node added correctly."
end
def delnode_cluster_cmd(argv,opt)
id = argv[1].downcase
xputs ">>> Removing node #{id} from cluster #{argv[0]}"
# Load cluster information
load_cluster_info_from_node(argv[0])
# Check if the node exists and is not empty
node = get_node_by_name(id)
if !node
xputs "[ERR] No such node ID #{id}"
exit 1
end
if node.slots.length != 0
xputs "[ERR] Node #{node} is not empty! Reshard data away and try again."
exit 1
end
# Send CLUSTER FORGET to all the nodes but the node to remove
xputs ">>> Sending CLUSTER FORGET messages to the cluster..."
@nodes.each{|n|
next if n == node
if n.info[:replicate] && n.info[:replicate].downcase == id
# Reconfigure the slave to replicate with some other node
master = get_master_with_least_replicas
xputs ">>> #{n} as replica of #{master}"
n.r.cluster("replicate",master.info[:name])
end
n.r.cluster("forget",argv[1])
}
# Finally shutdown the node
xputs ">>> SHUTDOWN the node."
node.r.shutdown
end
def set_timeout_cluster_cmd(argv,opt)
timeout = argv[1].to_i
if timeout < 100
puts "Setting a node timeout of less than 100 milliseconds is a bad idea."
exit 1
end
# Load cluster information
load_cluster_info_from_node(argv[0])
ok_count = 0
err_count = 0
# Send CLUSTER FORGET to all the nodes but the node to remove
xputs ">>> Reconfiguring node timeout in every cluster node..."
@nodes.each{|n|
begin
n.r.config("set","cluster-node-timeout",timeout)
n.r.config("rewrite")
ok_count += 1
xputs "*** New timeout set for #{n}"
rescue => e
puts "ERR setting node-timeot for #{n}: #{e}"
err_count += 1
end
}
xputs ">>> New node timeout set. #{ok_count} OK, #{err_count} ERR."
end
def call_cluster_cmd(argv,opt)
cmd = argv[1..-1]
cmd[0] = cmd[0].upcase
# Load cluster information
load_cluster_info_from_node(argv[0])
xputs ">>> Calling #{cmd.join(" ")}"
@nodes.each{|n|
begin
res = n.r.send(*cmd)
puts "#{n}: #{res}"
rescue => e
puts "#{n}: #{e}"
end
}
end
def import_cluster_cmd(argv,opt)
source_addr = opt['from']
xputs ">>> Importing data from #{source_addr} to cluster #{argv[1]}"
use_copy = opt['copy']
use_replace = opt['replace']
# Check the existing cluster.
load_cluster_info_from_node(argv[0])
check_cluster
# Connect to the source node.
xputs ">>> Connecting to the source Redis instance"
src_host,src_port = source_addr.split(":")
source = Redis.new(:host =>src_host, :port =>src_port)
if source.info['cluster_enabled'].to_i == 1
xputs "[ERR] The source node should not be a cluster node."
end
xputs "*** Importing #{source.dbsize} keys from DB 0"
# Build a slot -> node map
slots = {}
@nodes.each{|n|
n.slots.each{|s,_|
slots[s] = n
}
}
# Use SCAN to iterate over the keys, migrating to the
# right node as needed.
cursor = nil
while cursor != 0
cursor,keys = source.scan(cursor, :count => 1000)
cursor = cursor.to_i
keys.each{|k|
# Migrate keys using the MIGRATE command.
slot = key_to_slot(k)
target = slots[slot]
print "Migrating #{k} to #{target}: "
STDOUT.flush
begin
cmd = ["migrate",target.info[:host],target.info[:port],k,0,@timeout]
cmd << :copy if use_copy
cmd << :replace if use_replace
source.client.call(cmd)
rescue => e
puts e
else
puts "OK"
end
}
end
end
def help_cluster_cmd(argv,opt)
show_help
exit 0
end
# Parse the options for the specific command "cmd".
# Returns an hash populate with option => value pairs, and the index of
# the first non-option argument in ARGV.
def parse_options(cmd)
idx = 1 ; # Current index into ARGV
options={}
while idx < ARGV.length && ARGV[idx][0..1] == '--'
if ARGV[idx][0..1] == "--"
option = ARGV[idx][2..-1]
idx += 1
# --verbose is a global option
if option == "verbose"
$verbose = true
next
end
if ALLOWED_OPTIONS[cmd] == nil || ALLOWED_OPTIONS[cmd][option] == nil
puts "Unknown option '#{option}' for command '#{cmd}'"
exit 1
end
if ALLOWED_OPTIONS[cmd][option] != false
value = ARGV[idx]
idx += 1
else
value = true
end
# If the option is set to [], it's a multiple arguments
# option. We just queue every new value into an array.
if ALLOWED_OPTIONS[cmd][option] == []
options[option] = [] if !options[option]
options[option] << value
else
options[option] = value
end
else
# Remaining arguments are not options.
break
end
end
# Enforce mandatory options
if ALLOWED_OPTIONS[cmd]
ALLOWED_OPTIONS[cmd].each {|option,val|
if !options[option] && val == :required
puts "Option '--#{option}' is required "+ \
"for subcommand '#{cmd}'"
exit 1
end
}
end
return options,idx
end
end
#################################################################################
# Libraries
#
# We try to don't depend on external libs since this is a critical part
# of Redis Cluster.
#################################################################################
# This is the CRC16 algorithm used by Redis Cluster to hash keys.
# Implementation according to CCITT standards.
#
# This is actually the XMODEM CRC 16 algorithm, using the
# following parameters:
#
# Name : "XMODEM", also known as "ZMODEM", "CRC-16/ACORN"
# Width : 16 bit
# Poly : 1021 (That is actually x^16 + x^12 + x^5 + 1)
# Initialization : 0000
# Reflect Input byte : False
# Reflect Output CRC : False
# Xor constant to output CRC : 0000
# Output for "123456789" : 31C3
module RedisClusterCRC16
def RedisClusterCRC16.crc16(bytes)
crc = 0
bytes.each_byte{|b|
crc = ((crc<<8) & 0xffff) ^ XMODEMCRC16Lookup[((crc>>8)^b) & 0xff]
}
crc
end
private
XMODEMCRC16Lookup = [
0x0000,0x1021,0x2042,0x3063,0x4084,0x50a5,0x60c6,0x70e7,
0x8108,0x9129,0xa14a,0xb16b,0xc18c,0xd1ad,0xe1ce,0xf1ef,
0x1231,0x0210,0x3273,0x2252,0x52b5,0x4294,0x72f7,0x62d6,
0x9339,0x8318,0xb37b,0xa35a,0xd3bd,0xc39c,0xf3ff,0xe3de,
0x2462,0x3443,0x0420,0x1401,0x64e6,0x74c7,0x44a4,0x5485,
0xa56a,0xb54b,0x8528,0x9509,0xe5ee,0xf5cf,0xc5ac,0xd58d,
0x3653,0x2672,0x1611,0x0630,0x76d7,0x66f6,0x5695,0x46b4,
0xb75b,0xa77a,0x9719,0x8738,0xf7df,0xe7fe,0xd79d,0xc7bc,
0x48c4,0x58e5,0x6886,0x78a7,0x0840,0x1861,0x2802,0x3823,
0xc9cc,0xd9ed,0xe98e,0xf9af,0x8948,0x9969,0xa90a,0xb92b,
0x5af5,0x4ad4,0x7ab7,0x6a96,0x1a71,0x0a50,0x3a33,0x2a12,
0xdbfd,0xcbdc,0xfbbf,0xeb9e,0x9b79,0x8b58,0xbb3b,0xab1a,
0x6ca6,0x7c87,0x4ce4,0x5cc5,0x2c22,0x3c03,0x0c60,0x1c41,
0xedae,0xfd8f,0xcdec,0xddcd,0xad2a,0xbd0b,0x8d68,0x9d49,
0x7e97,0x6eb6,0x5ed5,0x4ef4,0x3e13,0x2e32,0x1e51,0x0e70,
0xff9f,0xefbe,0xdfdd,0xcffc,0xbf1b,0xaf3a,0x9f59,0x8f78,
0x9188,0x81a9,0xb1ca,0xa1eb,0xd10c,0xc12d,0xf14e,0xe16f,
0x1080,0x00a1,0x30c2,0x20e3,0x5004,0x4025,0x7046,0x6067,
0x83b9,0x9398,0xa3fb,0xb3da,0xc33d,0xd31c,0xe37f,0xf35e,
0x02b1,0x1290,0x22f3,0x32d2,0x4235,0x5214,0x6277,0x7256,
0xb5ea,0xa5cb,0x95a8,0x8589,0xf56e,0xe54f,0xd52c,0xc50d,
0x34e2,0x24c3,0x14a0,0x0481,0x7466,0x6447,0x5424,0x4405,
0xa7db,0xb7fa,0x8799,0x97b8,0xe75f,0xf77e,0xc71d,0xd73c,
0x26d3,0x36f2,0x0691,0x16b0,0x6657,0x7676,0x4615,0x5634,
0xd94c,0xc96d,0xf90e,0xe92f,0x99c8,0x89e9,0xb98a,0xa9ab,
0x5844,0x4865,0x7806,0x6827,0x18c0,0x08e1,0x3882,0x28a3,
0xcb7d,0xdb5c,0xeb3f,0xfb1e,0x8bf9,0x9bd8,0xabbb,0xbb9a,
0x4a75,0x5a54,0x6a37,0x7a16,0x0af1,0x1ad0,0x2ab3,0x3a92,
0xfd2e,0xed0f,0xdd6c,0xcd4d,0xbdaa,0xad8b,0x9de8,0x8dc9,
0x7c26,0x6c07,0x5c64,0x4c45,0x3ca2,0x2c83,0x1ce0,0x0cc1,
0xef1f,0xff3e,0xcf5d,0xdf7c,0xaf9b,0xbfba,0x8fd9,0x9ff8,
0x6e17,0x7e36,0x4e55,0x5e74,0x2e93,0x3eb2,0x0ed1,0x1ef0
]
end
# Turn a key name into the corrisponding Redis Cluster slot.
def key_to_slot(key)
# Only hash what is inside {...} if there is such a pattern in the key.
# Note that the specification requires the content that is between
# the first { and the first } after the first {. If we found {} without
# nothing in the middle, the whole key is hashed as usually.
s = key.index "{"
if s
e = key.index "}",s+1
if e && e != s+1
key = key[s+1..e-1]
end
end
RedisClusterCRC16.crc16(key) % 16384
end
#################################################################################
# Definition of commands
#################################################################################
COMMANDS={
"create" => ["create_cluster_cmd", -2, "host1:port1 ... hostN:portN"],
"check" => ["check_cluster_cmd", 2, "host:port"],
"info" => ["info_cluster_cmd", 2, "host:port"],
"fix" => ["fix_cluster_cmd", 2, "host:port"],
"reshard" => ["reshard_cluster_cmd", 2, "host:port"],
"rebalance" => ["rebalance_cluster_cmd", -2, "host:port"],
"add-node" => ["addnode_cluster_cmd", 3, "new_host:new_port existing_host:existing_port"],
"del-node" => ["delnode_cluster_cmd", 3, "host:port node_id"],
"set-timeout" => ["set_timeout_cluster_cmd", 3, "host:port milliseconds"],
"call" => ["call_cluster_cmd", -3, "host:port command arg arg .. arg"],
"import" => ["import_cluster_cmd", 2, "host:port"],
"help" => ["help_cluster_cmd", 1, "(show this help)"]
}
ALLOWED_OPTIONS={
"create" => {"replicas" => true},
"add-node" => {"slave" => false, "master-id" => true},
"import" => {"from" => :required, "copy" => false, "replace" => false},
"reshard" => {"from" => true, "to" => true, "slots" => true, "yes" => false, "timeout" => true, "pipeline" => true},
"rebalance" => {"weight" => [], "auto-weights" => false, "use-empty-masters" => false, "timeout" => true, "simulate" => false, "pipeline" => true, "threshold" => true},
"fix" => {"timeout" => MigrateDefaultTimeout},
}
def show_help
puts "Usage: redis-trib <command> <options> <arguments ...>\n\n"
COMMANDS.each{|k,v|
o = ""
puts " #{k.ljust(15)} #{v[2]}"
if ALLOWED_OPTIONS[k]
ALLOWED_OPTIONS[k].each{|optname,has_arg|
puts " --#{optname}" + (has_arg ? " <arg>" : "")
}
end
}
puts "\nFor check, fix, reshard, del-node, set-timeout you can specify the host and port of any working node in the cluster.\n"
end
# Sanity check
if ARGV.length == 0
show_help
exit 1
end
rt = RedisTrib.new
cmd_spec = COMMANDS[ARGV[0].downcase]
if !cmd_spec
puts "Unknown redis-trib subcommand '#{ARGV[0]}'"
exit 1
end
# Parse options
cmd_options,first_non_option = rt.parse_options(ARGV[0].downcase)
rt.check_arity(cmd_spec[1],ARGV.length-(first_non_option-1))
# Dispatch
rt.send(cmd_spec[0],ARGV[first_non_option..-1],cmd_options)
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