X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=vendor%2Frails%2Factiverecord%2Flib%2Factive_record%2Fconnection_adapters%2Fabstract%2Fconnection_pool.rb;fp=vendor%2Frails%2Factiverecord%2Flib%2Factive_record%2Fconnection_adapters%2Fabstract%2Fconnection_pool.rb;h=aac84cc5f4996e101ea39e63c4a14d4fc3d73a2f;hb=437aa336c44c74a30aeea16a06743c32747ed661;hp=0000000000000000000000000000000000000000;hpb=97a0772b06264134cfe38e7494f9427efe0840a0;p=feedcatcher.git

diff --git a/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb b/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
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+++ b/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
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+require 'monitor'
+require 'set'
+
+module ActiveRecord
+  # Raised when a connection could not be obtained within the connection
+  # acquisition timeout period.
+  class ConnectionTimeoutError < ConnectionNotEstablished
+  end
+
+  module ConnectionAdapters
+    # Connection pool base class for managing ActiveRecord database
+    # connections.
+    #
+    # == Introduction
+    #
+    # A connection pool synchronizes thread access to a limited number of
+    # database connections. The basic idea is that each thread checks out a
+    # database connection from the pool, uses that connection, and checks the
+    # connection back in. ConnectionPool is completely thread-safe, and will
+    # ensure that a connection cannot be used by two threads at the same time,
+    # as long as ConnectionPool's contract is correctly followed. It will also
+    # handle cases in which there are more threads than connections: if all
+    # connections have been checked out, and a thread tries to checkout a
+    # connection anyway, then ConnectionPool will wait until some other thread
+    # has checked in a connection.
+    #
+    # == Obtaining (checking out) a connection
+    #
+    # Connections can be obtained and used from a connection pool in several
+    # ways:
+    #
+    # 1. Simply use ActiveRecord::Base.connection as with ActiveRecord 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!. This will be the
+    #    default behavior for ActiveRecord when used in conjunction with
+    #    ActionPack's request handling cycle.
+    # 2. 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).
+    # 3. 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 two connection-pooling-related options that you can add to
+    # your database connection configuration:
+    #
+    # * +pool+: number indicating size of connection pool (default 5)
+    # * +wait_timeout+: number of seconds to block and wait for a connection
+    #   before giving up and raising a timeout error (default 5 seconds).
+    class ConnectionPool
+      attr_reader :spec
+
+      # 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.
+      def initialize(spec)
+        @spec = spec
+
+        # The cache of reserved connections mapped to threads
+        @reserved_connections = {}
+
+        # The mutex used to synchronize pool access
+        @connection_mutex = Monitor.new
+        @queue = @connection_mutex.new_cond
+
+        # default 5 second timeout unless on ruby 1.9
+        @timeout =
+          if RUBY_VERSION < '1.9'
+            spec.config[:wait_timeout] || 5
+          end
+
+        # default max pool size to 5
+        @size = (spec.config[:pool] && spec.config[:pool].to_i) || 5
+
+        @connections = []
+        @checked_out = []
+      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
+        if conn = @reserved_connections[current_connection_id]
+          conn
+        else
+          @reserved_connections[current_connection_id] = checkout
+        end
+      end
+
+      # Signal that the thread is finished with the current connection.
+      # #release_connection releases the connection-thread association
+      # and returns the connection to the pool.
+      def release_connection
+        conn = @reserved_connections.delete(current_connection_id)
+        checkin conn if conn
+      end
+
+      # Reserve a connection, and yield it to a block. Ensure the connection is
+      # checked back in when finished.
+      def with_connection
+        conn = checkout
+        yield conn
+      ensure
+        checkin conn
+      end
+
+      # Returns true if a connection has already been opened.
+      def connected?
+        !@connections.empty?
+      end
+
+      # Disconnects all connections in the pool, and clears the pool.
+      def disconnect!
+        @reserved_connections.each do |name,conn|
+          checkin conn
+        end
+        @reserved_connections = {}
+        @connections.each do |conn|
+          conn.disconnect!
+        end
+        @connections = []
+      end
+
+      # Clears the cache which maps classes
+      def clear_reloadable_connections!
+        @reserved_connections.each do |name, conn|
+          checkin conn
+        end
+        @reserved_connections = {}
+        @connections.each do |conn|
+          conn.disconnect! if conn.requires_reloading?
+        end
+        @connections = []
+      end
+
+      # Verify active connections and remove and disconnect connections
+      # associated with stale threads.
+      def verify_active_connections! #:nodoc:
+        clear_stale_cached_connections!
+        @connections.each do |connection|
+          connection.verify!
+        end
+      end
+
+      # Return any checked-out connections back to the pool by threads that
+      # are no longer alive.
+      def clear_stale_cached_connections!
+        remove_stale_cached_threads!(@reserved_connections) do |name, conn|
+          checkin conn
+        end
+      end
+
+      # 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.
+      #
+      # This is done by either returning an existing connection, or by creating
+      # a new connection. If the maximum number of connections for this pool has
+      # already been reached, but the pool is empty (i.e. they're all being used),
+      # then this method will wait until a thread has checked in a connection.
+      # The wait time is bounded however: if no connection can be checked out
+      # within the timeout specified for this pool, then a ConnectionTimeoutError
+      # exception will be raised.
+      #
+      # Returns: an AbstractAdapter object.
+      #
+      # Raises:
+      # - ConnectionTimeoutError: no connection can be obtained from the pool
+      #   within the timeout period.
+      def checkout
+        # Checkout an available connection
+        @connection_mutex.synchronize do
+          loop do
+            conn = if @checked_out.size < @connections.size
+                     checkout_existing_connection
+                   elsif @connections.size < @size
+                     checkout_new_connection
+                   end
+            return conn if conn
+            # No connections available; wait for one
+            if @queue.wait(@timeout)
+              next
+            else
+              # try looting dead threads
+              clear_stale_cached_connections!
+              if @size == @checked_out.size
+                raise ConnectionTimeoutError, "could not obtain a database connection#{" within #{@timeout} seconds" if @timeout}.  The max pool size is currently #{@size}; consider increasing it."
+              end
+            end
+          end
+        end
+      end
+
+      # Check-in a database connection back into the pool, indicating that you
+      # no longer need this connection.
+      #
+      # +conn+: an AbstractAdapter object, which was obtained by earlier by
+      # calling +checkout+ on this pool.
+      def checkin(conn)
+        @connection_mutex.synchronize do
+          conn.run_callbacks :checkin
+          @checked_out.delete conn
+          @queue.signal
+        end
+      end
+
+      synchronize :clear_reloadable_connections!, :verify_active_connections!,
+        :connected?, :disconnect!, :with => :@connection_mutex
+
+      private
+      def new_connection
+        ActiveRecord::Base.send(spec.adapter_method, spec.config)
+      end
+
+      def current_connection_id #:nodoc:
+        Thread.current.object_id
+      end
+
+      # Remove stale threads from the cache.
+      def remove_stale_cached_threads!(cache, &block)
+        keys = Set.new(cache.keys)
+
+        Thread.list.each do |thread|
+          keys.delete(thread.object_id) if thread.alive?
+        end
+        keys.each do |key|
+          next unless cache.has_key?(key)
+          block.call(key, cache[key])
+          cache.delete(key)
+        end
+      end
+
+      def checkout_new_connection
+        c = new_connection
+        @connections << c
+        checkout_and_verify(c)
+      end
+
+      def checkout_existing_connection
+        c = (@connections - @checked_out).first
+        checkout_and_verify(c)
+      end
+
+      def checkout_and_verify(c)
+        c.verify!
+        c.run_callbacks :checkout
+        @checked_out << c
+        c
+      end
+    end
+
+    # ConnectionHandler is a collection of ConnectionPool objects. It is used
+    # for keeping separate connection pools for ActiveRecord models that connect
+    # to different databases.
+    #
+    # For example, suppose that you have 5 models, with the following hierarchy:
+    #
+    #  |
+    #  +-- Book
+    #  |    |
+    #  |    +-- ScaryBook
+    #  |    +-- GoodBook
+    #  +-- Author
+    #  +-- BankAccount
+    #
+    # 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.
+    #
+    # Normally there is only a single ConnectionHandler instance, accessible via
+    # ActiveRecord::Base.connection_handler. ActiveRecord models use this to
+    # determine that connection pool that they should use.
+    class ConnectionHandler
+      def initialize(pools = {})
+        @connection_pools = pools
+      end
+
+      def connection_pools
+        @connection_pools ||= {}
+      end
+
+      def establish_connection(name, spec)
+        @connection_pools[name] = ConnectionAdapters::ConnectionPool.new(spec)
+      end
+
+      # Returns any connections in use by the current thread back to the pool,
+      # and also returns connections to the pool cached by threads that are no
+      # longer alive.
+      def clear_active_connections!
+        @connection_pools.each_value {|pool| pool.release_connection }
+      end
+
+      # Clears the cache which maps classes
+      def clear_reloadable_connections!
+        @connection_pools.each_value {|pool| pool.clear_reloadable_connections! }
+      end
+
+      def clear_all_connections!
+        @connection_pools.each_value {|pool| pool.disconnect! }
+      end
+
+      # Verify active connections.
+      def verify_active_connections! #:nodoc:
+        @connection_pools.each_value {|pool| pool.verify_active_connections! }
+      end
+
+      # Locate the connection of the nearest super class. This can be an
+      # active or defined connection: if it is the latter, it will be
+      # opened and set as the active connection for the class it was defined
+      # for (not necessarily the current class).
+      def retrieve_connection(klass) #:nodoc:
+        pool = retrieve_connection_pool(klass)
+        (pool && pool.connection) or raise ConnectionNotEstablished
+      end
+
+      # Returns true if a connection that's accessible to this class has
+      # already been opened.
+      def connected?(klass)
+        conn = retrieve_connection_pool(klass)
+        conn ? conn.connected? : false
+      end
+
+      # Remove the connection for this class. This will close the active
+      # connection and the defined connection (if they exist). The result
+      # can be used as an argument for establish_connection, for easily
+      # re-establishing the connection.
+      def remove_connection(klass)
+        pool = @connection_pools[klass.name]
+        @connection_pools.delete_if { |key, value| value == pool }
+        pool.disconnect! if pool
+        pool.spec.config if pool
+      end
+
+      def retrieve_connection_pool(klass)
+        pool = @connection_pools[klass.name]
+        return pool if pool
+        return nil if ActiveRecord::Base == klass
+        retrieve_connection_pool klass.superclass
+      end
+    end
+
+    class ConnectionManagement
+      def initialize(app)
+        @app = app
+      end
+
+      def call(env)
+        @app.call(env)
+      ensure
+        # Don't return connection (and peform implicit rollback) if
+        # this request is a part of integration test
+        unless env.key?("rack.test")
+          ActiveRecord::Base.clear_active_connections!
+        end
+      end
+    end
+  end
+end