Class: ActiveRecord::Bogacs::DefaultPool

Inherits:
Object
  • Object
show all
Includes:
PoolSupport, MonitorMixin
Defined in:
lib/active_record/bogacs/default_pool.rb

Overview

A “default” ‘ActiveRecord::ConnectionAdapters::ConnectionPool`-like pool implementation with compatibility across (older) Rails versions.

Currently, mostly, based on ActiveRecord 4.2.

api.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/ConnectionPool.html

Defined Under Namespace

Classes: Queue

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from PoolSupport

#current_connection_id, #new_connection

Constructor Details

#initialize(spec) ⇒ DefaultPool

Note:

The default ConnectionPool maximum size is 5.

Creates a new ‘ConnectionPool` object. spec is a ConnectionSpecification object which describes database connection information (e.g. adapter, host name, username, password, etc), as well as the maximum size for this ConnectionPool.

wait for a connection before giving up raising a timeout (default 5 seconds). when the pool is created (default 0). run a reaper, which attempts to find and close “dead” connections (can occur if a caller forgets to close a connection at the end of a thread or a thread dies unexpectedly) default is ‘nil` - don’t run the periodical Reaper (reaping will still happen occasionally). run a connection validation (in a separate thread), to avoid potentially stale sockets when connections stay open (pooled but unused) for longer periods.

Parameters:

  • spec (Hash) —

    a ‘ConnectionSpecification`

  • spec.config (Hash) —

    a customizable set of options



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# File 'lib/active_record/bogacs/default_pool.rb', line 184

def initialize(spec)
  super()

  @spec = spec

  @checkout_timeout = ( spec.config[:checkout_timeout] ||
      spec.config[:wait_timeout] || 5.0 ).to_f # <= 3.2 supports wait_timeout
  @reaper = Reaper.new self, spec.config[:reaping_frequency]
  @reaping = !! @reaper.run

  # default max pool size to 5
  if spec.config[:pool]
    @size = spec.config[:pool].to_i
  else
    if defined? Rails.env && ( (! Rails.env.development? && ! Rails.env.test?) rescue nil )
      logger && logger.debug("pool: option not set, using default size: 5")
    end
    @size = 5
  end

  # The cache of reserved connections mapped to threads
  @reserved_connections = ThreadSafe::Map.new(:initial_capacity => @size)

  @connections = []
  @automatic_reconnect = true

  @available = Queue.new self

  initial_size = spec.config[:pool_initial] || 0
  initial_size = @size if initial_size == true
  initial_size = (@size * initial_size).to_i if initial_size <= 1.0
  # NOTE: warn on onitial_size > size !
  prefill_initial_connections if ( @initial_size = initial_size.to_i ) > 0

  if frequency = spec.config[:validate_frequency]
    require 'active_record/bogacs/validator' unless self.class.const_defined?(:Validator)
    @validator = Validator.new self, frequency, spec.config[:validate_timeout]
    if @validator.run && @reaping
      logger && logger.warn(":validate_frequency configured alongside with :reaping_frequency")
    end
  end
end

Instance Attribute Details

#automatic_reconnect ⇒ Object

Returns the value of attribute automatic_reconnect.



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# File 'lib/active_record/bogacs/default_pool.rb', line 158

def automatic_reconnect
  @automatic_reconnect
end

#checkout_timeout ⇒ Object

Returns the value of attribute checkout_timeout.



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# File 'lib/active_record/bogacs/default_pool.rb', line 158

def checkout_timeout
  @checkout_timeout
end

#connections ⇒ Object (readonly)

Returns the value of attribute connections.



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# File 'lib/active_record/bogacs/default_pool.rb', line 159

def connections
  @connections
end

#initial_size ⇒ Object (readonly)

Returns the value of attribute initial_size.



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# File 'lib/active_record/bogacs/default_pool.rb', line 160

def initial_size
  @initial_size
end

#reaper ⇒ Object (readonly)

Returns the value of attribute reaper.



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# File 'lib/active_record/bogacs/default_pool.rb', line 159

def reaper
  @reaper
end

#size ⇒ Object (readonly)

Returns the value of attribute size.



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# File 'lib/active_record/bogacs/default_pool.rb', line 159

def size
  @size
end

#spec ⇒ Object (readonly)

Returns the value of attribute spec.



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# File 'lib/active_record/bogacs/default_pool.rb', line 159

def spec
  @spec
end

#validator ⇒ Object (readonly)

Returns the value of attribute validator.



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# File 'lib/active_record/bogacs/default_pool.rb', line 159

def validator
  @validator
end

Instance Method Details

#active_connection? ⇒ true, false

Is there an open connection that is being used for the current thread?

Returns:

  • (true, false) 


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# File 'lib/active_record/bogacs/default_pool.rb', line 247

def active_connection?
  connection_id = current_connection_id
  if conn = @reserved_connections.fetch(connection_id, nil)
    !! conn.in_use? # synchronize { conn.in_use? }
  else
    false
  end
end

#checkin(conn, released = nil) ⇒ Object

Check-in a database connection back into the pool.

object, which was obtained earlier by calling #checkout on this pool

Parameters:

  • conn (ActiveRecord::ConnectionAdapters::AbstractAdapter) —

    connection

See Also:



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# File 'lib/active_record/bogacs/default_pool.rb', line 367

def checkin(conn, released = nil)
  synchronize do
    _run_checkin_callbacks(conn)

    release conn, conn.owner unless released

    @available.add conn
  end
end

#checkout ⇒ ActiveRecord::ConnectionAdapters::AbstractAdapter

Check-out a database connection from the pool, callers are expected to call #checkin when the connection is no longer needed, so that others can use it.

This is done by either returning and leasing existing connection, or by creating a new connection and leasing it.

and the pool is at capacity (meaning the number of currently leased connections is greater than or equal to the size limit set)

Returns:

  • (ActiveRecord::ConnectionAdapters::AbstractAdapter)

Raises:

  • (ActiveRecord::ConnectionTimeoutError) —

    if all connections are leased



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# File 'lib/active_record/bogacs/default_pool.rb', line 353

def checkout
  conn = nil
  synchronize do
    conn = acquire_connection
    conn.lease
  end
  checkout_and_verify(conn)
end

#clear_reloadable_connections! ⇒ Object

Clears the cache which maps classes.



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# File 'lib/active_record/bogacs/default_pool.rb', line 300

def clear_reloadable_connections!
  synchronize do
    @reserved_connections.clear
    @connections.each do |conn|
      checkin conn
      conn.disconnect! if conn.requires_reloading?
    end
    @connections.delete_if do |conn|
      conn.requires_reloading?
    end
    @available.clear
    @connections.each do |conn|
      @available.add conn
    end
  end
end

#clear_stale_cached_connections! ⇒ Object

Return any checked-out connections back to the pool by threads that are no longer alive.



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# File 'lib/active_record/bogacs/default_pool.rb', line 332

def clear_stale_cached_connections!
  keys = Thread.list.find_all { |t| t.alive? }.map(&:object_id)
  keys = @reserved_connections.keys - keys
  keys.each do |key|
    conn = @reserved_connections[key]
    checkin conn
    @reserved_connections.delete(key)
  end
end

#connected? ⇒ true, false

Returns true if a connection has already been opened.

Returns:

  • (true, false) 


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# File 'lib/active_record/bogacs/default_pool.rb', line 282

def connected?
  @connections.size > 0 # synchronize { @connections.any? }
end

#connection ⇒ ActiveRecord::ConnectionAdapters::AbstractAdapter

Retrieve the connection associated with the current thread, or call #checkout to obtain one if necessary.

#connection can be called any number of times; the connection is held in a hash keyed by the thread id.

Returns:

  • (ActiveRecord::ConnectionAdapters::AbstractAdapter) 


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# File 'lib/active_record/bogacs/default_pool.rb', line 234

def connection
  connection_id = current_connection_id
  unless conn = @reserved_connections.fetch(connection_id, nil)
    synchronize do
      conn = ( @reserved_connections[connection_id] ||= checkout )
    end
  end
  conn
end

#disconnect! ⇒ Object

Disconnects all connections in the pool, and clears the pool.



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# File 'lib/active_record/bogacs/default_pool.rb', line 287

def disconnect!
  synchronize do
    @reserved_connections.clear
    @connections.each do |conn|
      checkin conn
      conn.disconnect!
    end
    @connections.clear
    @available.clear
  end
end

#logger ⇒ Object

@@logger = nil



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# File 'lib/active_record/bogacs/default_pool.rb', line 422

def logger; ::ActiveRecord::Base.logger end

#reap ⇒ Object

Recover lost connections for the pool. A lost connection can occur if a caller forgets to #checkin a connection for a given thread when its done or a thread dies unexpectedly.



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# File 'lib/active_record/bogacs/default_pool.rb', line 395

def reap
  stale_connections = synchronize do
    @connections.select do |conn|
      conn.in_use? && !conn.owner.alive?
    end
  end

  stale_connections.each do |conn|
    synchronize do
      if conn.active?
        conn.reset!
        checkin conn
      else
        remove conn
      end
    end
  end
end

#reaper? ⇒ Boolean

NOTE: active? and reset! are >= AR 2.3

Returns:

  • (Boolean) 


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# File 'lib/active_record/bogacs/default_pool.rb', line 415

def reaper?; (@reaper ||= nil) && @reaper.frequency end

#reaping? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/bogacs/default_pool.rb', line 416

def reaping?; reaper? && @reaper.running? end

#release_connection(with_id = current_connection_id) ⇒ Object

Signal that the thread is finished with the current connection. #release_connection releases the connection-thread association and returns the connection to the pool.



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# File 'lib/active_record/bogacs/default_pool.rb', line 259

def release_connection(with_id = current_connection_id)
  #synchronize do
    conn = @reserved_connections.delete(with_id)
    checkin conn, true if conn
  #end
end

#remove(conn) ⇒ ActiveRecord::ConnectionAdapters::AbstractAdapter

Remove a connection from the connection pool. The returned connection will remain open and active but will no longer be managed by this pool.

Returns:

  • (ActiveRecord::ConnectionAdapters::AbstractAdapter) 


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# File 'lib/active_record/bogacs/default_pool.rb', line 381

def remove(conn)
  synchronize do
    @connections.delete conn
    @available.delete conn

    release conn, conn.owner

    @available.add checkout_new_connection if @available.any_waiting?
  end
end

#validating? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/bogacs/default_pool.rb', line 419

def validating?; validator? && @validator.running? end

#validator? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/bogacs/default_pool.rb', line 418

def validator?; (@validator ||= nil) && @validator.frequency end

#verify_active_connections! ⇒ Object

Verify active connections and remove and disconnect connections associated with stale threads.



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# File 'lib/active_record/bogacs/default_pool.rb', line 320

def verify_active_connections!
  synchronize do
    clear_stale_cached_connections!
    @connections.each do |connection|
      connection.verify!
    end
  end
end

#with_connection {|ActiveRecord::ConnectionAdapters::AbstractAdapter| ... } ⇒ Object

If a connection already exists yield it to the block. If no connection exists checkout a connection, yield it to the block, and checkin the connection when finished.

Yields:

  • (ActiveRecord::ConnectionAdapters::AbstractAdapter) 


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# File 'lib/active_record/bogacs/default_pool.rb', line 271

def with_connection
  connection_id = current_connection_id
  fresh_connection = true unless active_connection?
  yield connection
ensure
  release_connection(connection_id) if fresh_connection
end