Class: ActiveRecord::ConnectionAdapters::ConnectionPool

Inherits:
Object
  • Object
show all
Defined in:
lib/active_record/fiber_patches.rb

Overview

ActiveRecord’s connection pool is based on threads. Since we are working with EM and a single thread, multiple fiber design, we need to provide our own connection pool that keys off of Fiber.current so that different fibers running in the same thread don’t try to use the same connection.

Direct Known Subclasses

WithConnection::ConnectionPool

Instance Method Summary collapse

Constructor Details

#initialize(spec) ⇒ ConnectionPool

Returns a new instance of ConnectionPool.



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# File 'lib/active_record/fiber_patches.rb', line 52

def initialize(spec)
  @spec = spec

  # The cache of reserved connections mapped to threads
  @reserved_connections = {}

  # The mutex used to synchronize pool access
  @connection_mutex = FiberedMonitor.new
  @queue = @connection_mutex.new_cond

  # default 5 second timeout unless on ruby 1.9
  @timeout = spec.config[:wait_timeout] || 5

  # default max pool size to 5
  @size = (spec.config[:pool] && spec.config[:pool].to_i) || 5

  @connections = []
  @checked_out = []
  @automatic_reconnect = true
  @tables = {}

  @columns     = Hash.new do |h, table_name|
    h[table_name] = with_connection do |conn|

      # Fetch a list of columns
      conn.columns(table_name, "#{table_name} Columns").tap do |columns|

        # set primary key information
        columns.each do |column|
          column.primary = column.name == primary_keys[table_name]
        end
      end
    end
  end

  @columns_hash = Hash.new do |h, table_name|
    h[table_name] = Hash[columns[table_name].map { |col|
      [col.name, col]
    }]
  end

  @primary_keys = Hash.new do |h, table_name|
    h[table_name] = with_connection do |conn|
      table_exists?(table_name) ? conn.primary_key(table_name) : 'id'
    end
  end
end

Instance Method Details

#clear_stale_cached_connections! ⇒ Object 



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# File 'lib/active_record/fiber_patches.rb', line 100

def clear_stale_cached_connections!
  cache = @reserved_connections
  keys = Set.new(cache.keys)

  ActiveRecord::ConnectionAdapters.fiber_pools.each do |pool|
    pool.busy_fibers.each_pair do |object_id, fiber|
      keys.delete(object_id)
    end
  end

  keys.each do |key|
    next unless cache.has_key?(key)
    checkin cache[key]
    cache.delete(key)
  end
end

#connection_with_sanity_check ⇒ Object 



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# File 'lib/active_record/fiber_patches.rb', line 123

def connection_with_sanity_check
  raise "not a busy fiber" if EM.reactor_running? && ! valid_busy_fiber?
  connection_without_sanity_check
end

#valid_busy_fiber? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/fiber_patches.rb', line 117

def valid_busy_fiber?
  ActiveRecord::ConnectionAdapters.fiber_pools.any? do |pool|
    pool.busy_fibers[current_connection_id]
  end
end