Cluster: initial ability to import data from standalone instance.

src/redis-trib.rb

@@ -988,6 +988,47 @@ class RedisTrib
         }
     end
 
+    def import_cluster_cmd(argv,opt)
+        source_addr = opt['from']
+        xputs ">>> Importing data from #{source_addr} to cluster #{argv[1]}"
+
+        # 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]
+                puts "Migrating #{k} to #{target}"
+                source.client.call(["migrate",target.info[:host],target.info[:port],k,0,1000])
+            }
+        end
+    end
+
     def help_cluster_cmd(argv,opt)
         show_help
         exit 0
@@ -1021,16 +1062,107 @@ class RedisTrib
         end
 
         # Enforce mandatory options
-        ALLOWED_OPTIONS[cmd].each {|option,val|
+        if ALLOWED_OPTIONS[cmd]
-            if !options[option] && val == :required
+            ALLOWED_OPTIONS[cmd].each {|option,val|
-                puts "Option '--#{option}' is required for subcommand '#{cmd}'"
+                if !options[option] && val == :required
-                exit 1
+                    puts "Option '--#{option}' is required "+ \
-            end
+                         "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"],
@@ -1040,12 +1172,14 @@ COMMANDS={
     "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}
+    "add-node" => {"slave" => false, "master-id" => true},
+    "import" => {"from" => :required}
 }
 
 def show_help