Class: ActiveRecord::Bogacs::DefaultPool
- Inherits:
-
Object
- Object
- ActiveRecord::Bogacs::DefaultPool
- Includes:
- PoolSupport, MonitorMixin
- Defined in:
- lib/active_record/bogacs/default_pool.rb
Overview
Obtaining (checking out) a connection
Connections can be obtained and used from a connection pool in several ways:
-
Simply use ActiveRecord::Base.connection as with Active Record 2.1 and
earlier (pre-connection-pooling). Eventually, when you’re done with the connection(s) and wish it to be returned to the pool, you call ActiveRecord::Base.clear_active_connections!.
-
Manually check out a connection from the pool with
ActiveRecord::Base.connection_pool.checkout. You are responsible for returning this connection to the pool when finished by calling ActiveRecord::Base.connection_pool.checkin(connection).
-
Use ActiveRecord::Base.connection_pool.with_connection(&block), which
obtains a connection, yields it as the sole argument to the block, and returns it to the pool after the block completes.
Connections in the pool are actually AbstractAdapter objects (or objects compatible with AbstractAdapter’s interface).
Options
There are several connection-pooling-related options that you can add to your database connection configuration:
-
pool: number indicating size of connection pool (default 5)
-
checkout_timeout: number of seconds to block and wait for a connection
before giving up and raising a timeout error (default 5 seconds).
-
pool_initial: number of connections to pre-initialize when the pool
is created (default 0).
-
reaping_frequency: frequency in seconds to periodically 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`, which means don’t run the periodical Reaper at all (reaping will still happen occasionally).
Defined Under Namespace
Classes: Queue
Instance Attribute Summary collapse
-
#automatic_reconnect ⇒ Object
Returns the value of attribute automatic_reconnect.
-
#checkout_timeout ⇒ Object
Returns the value of attribute checkout_timeout.
-
#connections ⇒ Object
readonly
Returns the value of attribute connections.
-
#initial_size ⇒ Object
readonly
Returns the value of attribute initial_size.
-
#reaper ⇒ Object
readonly
Returns the value of attribute reaper.
-
#size ⇒ Object
readonly
Returns the value of attribute size.
-
#spec ⇒ Object
readonly
Returns the value of attribute spec.
-
#validator ⇒ Object
readonly
Returns the value of attribute validator.
Instance Method Summary collapse
-
#active_connection? ⇒ true, false
Is there an open connection that is being used for the current thread?.
-
#checkin(conn, released = nil) ⇒ Object
Check-in a database connection back into the pool.
-
#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.
-
#clear_reloadable_connections! ⇒ Object
Clears the cache which maps classes.
-
#clear_stale_cached_connections! ⇒ Object
Return any checked-out connections back to the pool by threads that are no longer alive.
-
#connected? ⇒ true, false
Returns true if a connection has already been opened.
-
#connection ⇒ ActiveRecord::ConnectionAdapters::AbstractAdapter
Retrieve the connection associated with the current thread, or call #checkout to obtain one if necessary.
-
#disconnect! ⇒ Object
Disconnects all connections in the pool, and clears the pool.
-
#initialize(spec) ⇒ DefaultPool
constructor
Creates a new ConnectionPool object.
-
#logger ⇒ Object
@@logger = nil.
-
#reap ⇒ Object
Recover lost connections for the pool.
-
#reaper? ⇒ Boolean
NOTE: active? and reset! are >= AR 2.3.
- #reaping? ⇒ Boolean
-
#release_connection(with_id = current_connection_id) ⇒ Object
Signal that the thread is finished with the current connection.
-
#remove(conn) ⇒ ActiveRecord::ConnectionAdapters::AbstractAdapter
Remove a connection from the connection pool.
- #validating? ⇒ Boolean
- #validator? ⇒ Boolean
-
#verify_active_connections! ⇒ Object
Verify active connections and remove and disconnect connections associated with stale threads.
-
#with_connection {|ActiveRecord::ConnectionAdapters::AbstractAdapter| ... } ⇒ Object
If a connection already exists yield it to the block.
Methods included from PoolSupport
#current_connection_id, #new_connection
Constructor Details
#initialize(spec) ⇒ DefaultPool
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.
The default ConnectionPool maximum size is 5.
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# File 'lib/active_record/bogacs/default_pool.rb', line 195 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.info("pool: validator configured alongside with reaper") 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 185 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 185 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 186 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 187 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 186 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 186 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 186 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 186 def validator @validator end |
Instance Method Details
#active_connection? ⇒ true, false
Is there an open connection that is being used for the current thread?
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# File 'lib/active_record/bogacs/default_pool.rb', line 258 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
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# File 'lib/active_record/bogacs/default_pool.rb', line 378 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)
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# File 'lib/active_record/bogacs/default_pool.rb', line 364 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 311 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 343 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.
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# File 'lib/active_record/bogacs/default_pool.rb', line 293 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.
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# File 'lib/active_record/bogacs/default_pool.rb', line 245 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 298 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 433 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 406 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
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# File 'lib/active_record/bogacs/default_pool.rb', line 426 def reaper?; (@reaper ||= nil) && @reaper.frequency end |
#reaping? ⇒ Boolean
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# File 'lib/active_record/bogacs/default_pool.rb', line 427 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 270 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.
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# File 'lib/active_record/bogacs/default_pool.rb', line 392 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
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# File 'lib/active_record/bogacs/default_pool.rb', line 430 def validating?; validator? && @validator.running? end |
#validator? ⇒ Boolean
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# File 'lib/active_record/bogacs/default_pool.rb', line 429 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 331 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.
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# File 'lib/active_record/bogacs/default_pool.rb', line 282 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 |