106a52cbef
Previously, it would usually use 2 queries if inside a transaction, or 4 queries if outside a transaction. This replaces the UPDATE then INSERT query approach with an INSERT SELECT (UPDATE RETURNING) approach in a single query. As this is a single query and not multiple queries, it does not need a transaction. If the UPDATE does not update a row, then no rows will be inserted. This approach also opens up the ability to create multiple semaphores in a single query, if the first argument is an array or a dataset. That will be used in an upcoming commit. This changes the return value of Semaphore.incr when provided a single id from returning a Semaphore instance to returning the Semaphore uuid. Only SemSnap#incr cares about the return value, so update that to fetch the Semaphore.
58 lines
1.1 KiB
Ruby
58 lines
1.1 KiB
Ruby
# frozen_string_literal: true
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class SemSnap
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def initialize(strand_id, deferred: false)
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@deferred = deferred
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@strand_id = strand_id
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@extant = Hash.new { |h, k| h[k.intern] = [] }
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@defer_delete = []
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Semaphore.where(strand_id: @strand_id).each do |sem|
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add_semaphore_instance_to_snapshot(sem)
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end
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end
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def self.use(strand_id)
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new(strand_id, deferred: true).use do |snap|
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yield snap
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end
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end
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def use
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yield self
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ensure
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apply
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end
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def set?(name)
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name = name.intern
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@extant.include?(name)
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end
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def decr(name)
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name = name.intern
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ids = @extant.delete(name)
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return unless ids && ids.length > 0
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@defer_delete.concat(ids)
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apply unless @deferred
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end
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def incr(name)
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if (semaphore = Semaphore.incr(@strand_id, name))
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add_semaphore_instance_to_snapshot(Semaphore.with_pk(semaphore))
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end
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end
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private
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def apply
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return if @defer_delete.empty?
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Semaphore.where(strand_id: @strand_id, id: @defer_delete).destroy
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@defer_delete.clear
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end
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def add_semaphore_instance_to_snapshot(sem)
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@extant[sem.name.intern] << sem.id
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end
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end
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