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redis-trib: better slots allocation strategy for resharding
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@ -287,10 +287,22 @@ class RedisTrib
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# instance.
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def compute_reshard_table(sources,numslots)
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moved = []
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sources.each{|s|
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# Sort from bigger to smaller instance, for two reasons:
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# 1) If we take less slots than instanes it is better to start getting from
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# the biggest instances.
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# 2) We take one slot more from the first instance in the case of not perfect
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# divisibility. Like we have 3 nodes and need to get 10 slots, we take
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# 4 from the first, and 3 from the rest. So the biggest is always the first.
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sources = sources.sort{|a,b| b.slots.length <=> a.slots.length}
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sources.each_with_index{|s,i|
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# Every node will provide a number of slots proportional to the
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# slots it has assigned.
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n = (numslots.to_f/4096*s.slots.length).ceil
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n = (numslots.to_f/4096*s.slots.length)
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if i == 0
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n = n.ceil
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else
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n = n.floor
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end
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s.slots.keys.sort[(0...n)].each{|slot|
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if moved.length < numslots
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moved << {:source => s, :slot => slot}
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