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 



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# 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 



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# 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 



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# 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 



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# 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