expose database in connection

get/return from pool while result set is been used. still single connection pool

spec/std/db/db_spec.cr

@@ -13,20 +13,18 @@ describe DB do
 
   it "should instantiate driver with connection uri" do
     db = DB.open "dummy://localhost:1027"
-    db.driver_class.should eq(DummyDriver)
+    db.driver.should be_a(DummyDriver)
     db.uri.scheme.should eq("dummy")
     db.uri.host.should eq("localhost")
     db.uri.port.should eq(1027)
   end
 
   it "should create a connection and close it" do
-    cnn = nil
+    DummyDriver::DummyConnection.clear_connections
     DB.open "dummy://localhost" do |db|
-      cnn = db.connection
     end
-
-    cnn.should be_a(DummyDriver::DummyConnection)
-    cnn.not_nil!.closed?.should be_true
+    connections.size.should eq(1)
+    connections.first.closed?.should be_true
   end
 
   it "query should close result_set" do
@@ -61,4 +59,14 @@ describe DB do
     end
     connections.first.closed?.should be_true
   end
+
+  it "should raise if the sole connection is been used" do
+    with_dummy do |db|
+      db.query "1" do |rs|
+        expect_raises Exception, /DB Pool Exhausted/ do
+          db.scalar "2"
+        end
+      end
+    end
+  end
 end

spec/std/db/dummy_driver.cr

@@ -1,14 +1,13 @@
 require "spec"
 
 class DummyDriver < DB::Driver
-  def build_connection
-    DummyConnection.new(uri)
+  def build_connection(db : DB::Database) : DB::Connection
+    DummyConnection.new(db)
   end
 
   class DummyConnection < DB::Connection
-    getter uri
-
-    def initialize(@uri)
+    def initialize(db)
+      super(db)
       @@connections ||= [] of DummyConnection
       @@connections.not_nil! << self
     end
@@ -60,6 +59,7 @@ class DummyDriver < DB::Driver
     end
 
     protected def do_close
+      super
     end
   end
 
@@ -74,6 +74,7 @@ class DummyDriver < DB::Driver
     end
 
     protected def do_close
+      super
     end
 
     def self.last_result_set

src/db/connection.cr

@@ -17,8 +17,14 @@ module DB
   abstract class Connection
     include Disposable
     include QueryMethods
+
+    # :nodoc:
+    getter database
     @statements_cache = {} of String => Statement
 
+    def initialize(@database : Database)
+    end
+
     # :nodoc:
     def prepare(query) : Statement
       stmt = @statements_cache.fetch(query, nil)

src/db/database.cr

@@ -8,30 +8,37 @@ module DB
   # Refer to `QueryMethods` for documentation about querying the database.
   class Database
     # :nodoc:
-    getter driver_class
+    getter driver
 
-    # Connection configuration to the database.
+    # Returns the uri with the connection settings to the database
     getter uri
 
     # :nodoc:
-    def initialize(@driver_class, @uri)
-      @driver = @driver_class.new(@uri)
-      @connection = @driver.build_connection
+    def initialize(@driver, @uri)
+      @in_pool = true
+      @connection = @driver.build_connection(self)
     end
 
     # Closes all connection to the database.
     def close
-      @connection.close
-    end
-
-    # :nodoc:
-    def connection
-      @connection
+      @connection.try &.close
     end
 
     # :nodoc:
     def prepare(query)
-      connection.prepare(query)
+      get_from_pool.prepare(query)
+    end
+
+    # :nodoc:
+    def get_from_pool
+      raise "DB Pool Exhausted" unless @in_pool
+      @in_pool = false
+      @connection.not_nil!
+    end
+
+    # :nodoc:
+    def return_to_pool(connection)
+      @in_pool = true
     end
 
     include QueryMethods

src/db/db.cr

@@ -105,7 +105,7 @@ module DB
   end
 
   private def self.build_database(uri : URI)
-    Database.new(driver_class(uri.scheme), uri)
+    Database.new(driver_class(uri.scheme).new, uri)
   end
 end
 

src/db/driver.cr

@@ -7,8 +7,8 @@ module DB
   # require "db"
   #
   # class FakeDriver < Driver
-  #   def build_connection
-  #     FakeConnection.new uri
+  #   def build_connection(db)
+  #     FakeConnection.new db
   #   end
   # end
   #
@@ -18,7 +18,7 @@ module DB
   # Access to this fake datbase will be available with
   #
   # ```
-  # DB.open "fake", "..." do |db|
+  # DB.open "fake://..." do |db|
   #   # ... use db ...
   # end
   # ```
@@ -26,11 +26,9 @@ module DB
   # Refer to `Connection`, `Statement` and `ResultSet` for further
   # driver implementation instructions.
   abstract class Driver
-    getter uri
-
-    def initialize(@uri : URI)
+    def initialize
     end
 
-    abstract def build_connection : Connection
+    abstract def build_connection(db : Database) : Connection
   end
 end

src/db/result_set.cr

@@ -21,6 +21,11 @@ module DB
     def initialize(@statement : Statement)
     end
 
+    protected def do_close
+      cnn = statement.connection
+      cnn.database.return_to_pool(cnn)
+    end
+
     # TODO add_next_result_set : Bool
 
     # Iterates over all the rows

src/db/statement.cr

@@ -18,6 +18,9 @@ module DB
     def initialize(@connection)
     end
 
+    protected def do_close
+    end
+
     # See `QueryMethods#exec`
     def exec
       perform_exec(Slice(Any).new(0)) # no overload matches ... with types Slice(NoReturn)