diff options
Diffstat (limited to 'activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb')
| -rw-r--r-- | activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb | 188 |
1 files changed, 104 insertions, 84 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb index b5a8011ca4..3a9db4a109 100644 --- a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb +++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb @@ -1,7 +1,8 @@ require 'thread' +require 'thread_safe' require 'monitor' require 'set' -require 'active_support/deprecation' +require 'active_support/core_ext/string/filters' module ActiveRecord # Raised when a connection could not be obtained within the connection @@ -58,13 +59,11 @@ module ActiveRecord # * +checkout_timeout+: number of seconds to block and wait for a connection # before giving up and raising a timeout error (default 5 seconds). # * +reaping_frequency+: frequency in seconds to periodically run the - # Reaper, which attempts to find and close dead connections, which can - # occur if a programmer forgets to close a connection at the end of a - # thread or a thread dies unexpectedly. (Default nil, which means don't - # run the Reaper). - # * +dead_connection_timeout+: number of seconds from last checkout - # after which the Reaper will consider a connection reapable. (default - # 5 seconds). + # Reaper, which attempts to find and recover connections from dead + # threads, which can occur if a programmer forgets to close a + # connection at the end of a thread or a thread dies unexpectedly. + # Regardless of this setting, the Reaper will be invoked before every + # blocking wait. (Default nil, which means don't schedule the Reaper). class ConnectionPool # Threadsafe, fair, FIFO queue. Meant to be used by ConnectionPool # with which it shares a Monitor. But could be a generic Queue. @@ -86,7 +85,7 @@ module ActiveRecord end end - # Return the number of threads currently waiting on this + # Returns the number of threads currently waiting on this # queue. def num_waiting synchronize do @@ -222,7 +221,7 @@ module ActiveRecord include MonitorMixin - attr_accessor :automatic_reconnect, :checkout_timeout, :dead_connection_timeout + attr_accessor :automatic_reconnect, :checkout_timeout attr_reader :spec, :connections, :size, :reaper # Creates a new ConnectionPool object. +spec+ is a ConnectionSpecification @@ -236,38 +235,31 @@ module ActiveRecord @spec = spec - # The cache of reserved connections mapped to threads - @reserved_connections = {} - - @checkout_timeout = spec.config[:checkout_timeout] || 5 - @dead_connection_timeout = spec.config[:dead_connection_timeout] + @checkout_timeout = (spec.config[:checkout_timeout] && spec.config[:checkout_timeout].to_f) || 5 @reaper = Reaper.new self, spec.config[:reaping_frequency] @reaper.run # default max pool size to 5 @size = (spec.config[:pool] && spec.config[:pool].to_i) || 5 + # The cache of reserved connections mapped to threads + @reserved_connections = ThreadSafe::Cache.new(:initial_capacity => @size) + @connections = [] @automatic_reconnect = true @available = Queue.new self end - # Hack for tests to be able to add connections. Do not call outside of tests - def insert_connection_for_test!(c) #:nodoc: - synchronize do - @connections << c - @available.add c - end - end - # 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. def connection - synchronize do + # this is correctly done double-checked locking + # (ThreadSafe::Cache's lookups have volatile semantics) + @reserved_connections[current_connection_id] || synchronize do @reserved_connections[current_connection_id] ||= checkout end end @@ -310,7 +302,7 @@ module ActiveRecord # Disconnects all connections in the pool, and clears the pool. def disconnect! synchronize do - @reserved_connections = {} + @reserved_connections.clear @connections.each do |conn| checkin conn conn.disconnect! @@ -323,14 +315,12 @@ module ActiveRecord # Clears the cache which maps classes. def clear_reloadable_connections! synchronize do - @reserved_connections = {} + @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 + @connections.delete_if(&:requires_reloading?) @available.clear @connections.each do |conn| @available.add conn @@ -338,11 +328,6 @@ module ActiveRecord end end - def clear_stale_cached_connections! # :nodoc: - reap - end - deprecate :clear_stale_cached_connections! => "Please use #reap instead" - # Check-out a database connection from the pool, indicating that you want # to use it. You should call #checkin when you no longer need this. # @@ -372,11 +357,13 @@ module ActiveRecord # calling +checkout+ on this pool. def checkin(conn) synchronize do - conn.run_callbacks :checkin do + owner = conn.owner + + conn._run_checkin_callbacks do conn.expire end - release conn + release owner @available.add conn end @@ -389,22 +376,30 @@ module ActiveRecord @connections.delete conn @available.delete conn - # FIXME: we might want to store the key on the connection so that removing - # from the reserved hash will be a little easier. - release conn + release conn.owner @available.add checkout_new_connection if @available.any_waiting? end end - # Removes dead connections from the pool. A dead connection can occur - # if a programmer forgets to close a connection at the end of a thread + # Recover lost connections for the pool. A lost connection can occur if + # a programmer forgets to checkin a connection at the end of a thread # or a thread dies unexpectedly. def reap - synchronize do - stale = Time.now - @dead_connection_timeout - connections.dup.each do |conn| - remove conn if conn.in_use? && stale > conn.last_use && !conn.active? + 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 @@ -424,20 +419,15 @@ module ActiveRecord elsif @connections.size < @size checkout_new_connection else + reap @available.poll(@checkout_timeout) end end - def release(conn) - thread_id = if @reserved_connections[current_connection_id] == conn - current_connection_id - else - @reserved_connections.keys.find { |k| - @reserved_connections[k] == conn - } - end + def release(owner) + thread_id = owner.object_id - @reserved_connections.delete thread_id if thread_id + @reserved_connections.delete thread_id end def new_connection @@ -458,7 +448,7 @@ module ActiveRecord end def checkout_and_verify(c) - c.run_callbacks :checkout do + c._run_checkout_callbacks do c.verify! end c @@ -471,30 +461,55 @@ module ActiveRecord # # For example, suppose that you have 5 models, with the following hierarchy: # - # | - # +-- Book - # | | - # | +-- ScaryBook - # | +-- GoodBook - # +-- Author - # +-- BankAccount + # class Author < ActiveRecord::Base + # end + # + # class BankAccount < ActiveRecord::Base + # end + # + # class Book < ActiveRecord::Base + # establish_connection "library_db" + # end + # + # class ScaryBook < Book + # end # - # Suppose that Book is to connect to a separate database (i.e. one other - # than the default database). Then Book, ScaryBook and GoodBook will all use - # the same connection pool. Likewise, Author and BankAccount will use the - # same connection pool. However, the connection pool used by Author/BankAccount - # is not the same as the one used by Book/ScaryBook/GoodBook. + # class GoodBook < Book + # end # - # Normally there is only a single ConnectionHandler instance, accessible via - # ActiveRecord::Base.connection_handler. Active Record models use this to - # determine the connection pool that they should use. + # And a database.yml that looked like this: + # + # development: + # database: my_application + # host: localhost + # + # library_db: + # database: library + # host: some.library.org + # + # Your primary database in the development environment is "my_application" + # but the Book model connects to a separate database called "library_db" + # (this can even be a database on a different machine). + # + # Book, ScaryBook and GoodBook will all use the same connection pool to + # "library_db" while Author, BankAccount, and any other models you create + # will use the default connection pool to "my_application". + # + # The various connection pools are managed by a single instance of + # ConnectionHandler accessible via ActiveRecord::Base.connection_handler. + # All Active Record models use this handler to determine the connection pool that they + # should use. class ConnectionHandler def initialize - # These hashes are keyed by klass.name, NOT klass. Keying them by klass + # These caches are keyed by klass.name, NOT klass. Keying them by klass # alone would lead to memory leaks in development mode as all previous # instances of the class would stay in memory. - @owner_to_pool = Hash.new { |h,k| h[k] = {} } - @class_to_pool = Hash.new { |h,k| h[k] = {} } + @owner_to_pool = ThreadSafe::Cache.new(:initial_capacity => 2) do |h,k| + h[k] = ThreadSafe::Cache.new(:initial_capacity => 2) + end + @class_to_pool = ThreadSafe::Cache.new(:initial_capacity => 2) do |h,k| + h[k] = ThreadSafe::Cache.new + end end def connection_pool_list @@ -502,15 +517,17 @@ module ActiveRecord end def connection_pools - ActiveSupport::Deprecation.warn( - "In the next release, this will return the same as #connection_pool_list. " \ - "(An array of pools, rather than a hash mapping specs to pools.)" - ) + ActiveSupport::Deprecation.warn(<<-MSG.squish) + In the next release, this will return the same as `#connection_pool_list`. + (An array of pools, rather than a hash mapping specs to pools.) + MSG + Hash[connection_pool_list.map { |pool| [pool.spec, pool] }] end def establish_connection(owner, spec) @class_to_pool.clear + raise RuntimeError, "Anonymous class is not allowed." unless owner.name owner_to_pool[owner.name] = ConnectionAdapters::ConnectionPool.new(spec) end @@ -542,7 +559,10 @@ module ActiveRecord # for (not necessarily the current class). def retrieve_connection(klass) #:nodoc: pool = retrieve_connection_pool(klass) - (pool && pool.connection) or raise ConnectionNotEstablished + raise ConnectionNotEstablished, "No connection pool for #{klass}" unless pool + conn = pool.connection + raise ConnectionNotEstablished, "No connection for #{klass} in connection pool" unless conn + conn end # Returns true if a connection that's accessible to this class has @@ -570,10 +590,10 @@ module ActiveRecord # When a connection is established or removed, we invalidate the cache. # # Ideally we would use #fetch here, as class_to_pool[klass] may sometimes be nil. - # However, benchmarking (https://gist.github.com/3552829) showed that #fetch is - # significantly slower than #[]. So in the nil case, no caching will take place, - # but that's ok since the nil case is not the common one that we wish to optimise - # for. + # However, benchmarking (https://gist.github.com/jonleighton/3552829) showed that + # #fetch is significantly slower than #[]. So in the nil case, no caching will + # take place, but that's ok since the nil case is not the common one that we wish + # to optimise for. def retrieve_connection_pool(klass) class_to_pool[klass.name] ||= begin until pool = pool_for(klass) @@ -620,7 +640,7 @@ module ActiveRecord end def call(env) - testing = env.key?('rack.test') + testing = env['rack.test'] response = @app.call(env) response[2] = ::Rack::BodyProxy.new(response[2]) do @@ -628,7 +648,7 @@ module ActiveRecord end response - rescue + rescue Exception ActiveRecord::Base.clear_active_connections! unless testing raise end |