54 lines
1.6 KiB
Ruby
54 lines
1.6 KiB
Ruby
# frozen_string_literal: true
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module Gitlab
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module Database
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module MultiThreadedMigration
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MULTI_THREAD_AR_CONNECTION = :thread_local_ar_connection
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# This overwrites the default connection method so that every thread can
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# use a thread-local connection, while still supporting all of Rails'
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# migration methods.
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def connection
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Thread.current[MULTI_THREAD_AR_CONNECTION] ||
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ActiveRecord::Base.connection
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end
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# Starts a thread-pool for N threads, along with N threads each using a
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# single connection. The provided block is yielded from inside each
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# thread.
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#
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# Example:
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#
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# with_multiple_threads(4) do
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# execute('SELECT ...')
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# end
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#
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# thread_count - The number of threads to start.
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#
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# join - When set to true this method will join the threads, blocking the
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# caller until all threads have finished running.
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#
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# Returns an Array containing the started threads.
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def with_multiple_threads(thread_count, join: true)
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pool = Gitlab::Database.create_connection_pool(thread_count)
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threads = Array.new(thread_count) do
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Thread.new do
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pool.with_connection do |connection|
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begin
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Thread.current[MULTI_THREAD_AR_CONNECTION] = connection
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yield
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ensure
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Thread.current[MULTI_THREAD_AR_CONNECTION] = nil
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end
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end
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end
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end
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threads.each(&:join) if join
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threads
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end
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end
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end
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end
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