Class: LS4::BasicHADB

Inherits:
Object
  • Object
show all
Defined in:
lib/ls4/service/mds_ha.rb

Overview

single node:

host1:port1

master-slave:

host1:port1,host2:port2

master-slave with read weight:

host1:port1,host2:port2;0,1

dual-master:

host1:port1--host2:port2

Constant Summary collapse

DEFAULT_WEIGHT = 
10

Instance Method Summary collapse

Constructor Details

#initialize(expr) ⇒ BasicHADB

Returns a new instance of BasicHADB.



37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
 
# File 'lib/ls4/service/mds_ha.rb', line 37

def initialize(expr)
	@dbmap = {}    # {Address => DB}
	@writers = []   # [Address]
	@readers = []   # [Address]
	@readers_rr = 0

	expr.split('--').each {|line|
		nodes, weights = line.strip.split(';',2)

		addrs = nodes.strip.split(',').map {|addr|
			parse_addr(addr)
		}

		weights = (weights||"").strip.split(',').map {|x| x.to_i }

		@writers << addrs.first

		addrs.each_with_index {|addr,i|
			weight = weights[i] ||= DEFAULT_WEIGHT
			weight.times {
				@readers << addr
			}
			@dbmap[addr] = nil
		}

		$log.info "MDS -- #{addrs.join(',')};#{weights.join(',')}"
	}

	if @dbmap.empty?
		raise "empty expression"
	end

	if @dbmap.size == 1
		# single node
		@readers = [@readers[0]]
	else
		@readers = @readers.sort_by {|addr| rand }
	end

	# open remote database
	@dbmap.keys.each {|addr|
		@dbmap[addr] = open_db(addr)
	}

rescue
	@dbmap.each_pair {|addr,db|
		if db
			close_db(db) rescue nil
		end
	}
	$log.error $!
	$log.error_backtrace $!.backtrace
	raise "MDS: invlaid address expression: #{$!}"
end

Instance Method Details

#close ⇒ Object 



111
112
113
114
115
 
# File 'lib/ls4/service/mds_ha.rb', line 111

def close
	@dbmap.each_pair {|addr,db|
		close_db(db) rescue nil
	}
end

#read(shard_key, &block) ⇒ Object 



103
104
105
106
107
108
109
 
# File 'lib/ls4/service/mds_ha.rb', line 103

def read(shard_key, &block)
	@readers_rr += 1
	@readers_rr = 0 if @readers_rr >= @readers.size
	ha_call(@readers, @readers_rr) {|db|
		block.call(db)
	}
end

#write(shard_key, &block) ⇒ Object 



92
93
94
95
96
97
98
99
100
101
 
# File 'lib/ls4/service/mds_ha.rb', line 92

def write(shard_key, &block)
	if @writers.size == 1
		n = 0
	else
		n = hash_key(shard_key) % @writers.size
	end
	ha_call(@writers, n) {|db|
		block.call(db)
	}
end