Make pool statement a struct

spec/database_spec.cr

@@ -57,14 +57,6 @@ describe DB::Database do
     end
   end
 
-  it "should close pool statements when closing db" do
-    stmt = uninitialized DB::PoolStatement
-    with_dummy do |db|
-      stmt = db.build("query1")
-    end
-    stmt.closed?.should be_true
-  end
-
   it "should not reconnect if connection is lost and retry_attempts=0" do
     DummyDriver::DummyConnection.clear_connections
     DB.open "dummy://localhost:1027?initial_pool_size=1&max_pool_size=1&retry_attempts=0" do |db|
@@ -239,24 +231,6 @@ describe DB::Database do
     end
   end
 
-  describe "prepared_statements_cache connection option" do
-    it "should reuse prepared statements if true" do
-      with_dummy "dummy://localhost:1027?prepared_statements=true&prepared_statements_cache=true" do |db|
-        stmt1 = db.build("the query")
-        stmt2 = db.build("the query")
-        stmt1.object_id.should eq(stmt2.object_id)
-      end
-    end
-
-    it "should not reuse prepared statements if false" do
-      with_dummy "dummy://localhost:1027?prepared_statements=true&prepared_statements_cache=false" do |db|
-        stmt1 = db.build("the query")
-        stmt2 = db.build("the query")
-        stmt1.object_id.should_not eq(stmt2.object_id)
-      end
-    end
-  end
-
   describe "unprepared statements in pool" do
     it "creating statements should not create new connections" do
       with_dummy "dummy://localhost:1027?initial_pool_size=1" do |db|

src/db/database.cr

@@ -38,7 +38,6 @@ module DB
     @connection_options : Connection::Options
     @pool : Pool(Connection)
     @setup_connection : Connection -> Nil
-    @statements_cache = StringKeyCache(PoolPreparedStatement).new
 
     # Initialize a database with the specified options and connection factory.
     # This covers more advanced use cases that might not be supported by an URI connection string such as tunneling connection.
@@ -81,9 +80,6 @@ module DB
 
     # Closes all connection to the database.
     def close
-      @statements_cache.each_value &.close
-      @statements_cache.clear
-
       @pool.close
     end
 
@@ -99,15 +95,6 @@ module DB
 
     # :nodoc:
     def fetch_or_build_prepared_statement(query) : PoolStatement
-      if @connection_options.prepared_statements_cache
-        @statements_cache.fetch(query) { build_prepared_statement(query) }
-      else
-        build_prepared_statement(query)
-      end
-    end
-
-    # :nodoc:
-    def build_prepared_statement(query) : PoolStatement
       PoolPreparedStatement.new(self, query)
     end
 

src/db/pool_prepared_statement.cr

@@ -4,7 +4,7 @@ module DB
   # The execution of the statement is retried according to the pool configuration.
   #
   # See `PoolStatement`
-  class PoolPreparedStatement < PoolStatement
+  struct PoolPreparedStatement < PoolStatement
     def initialize(db : Database, query : String)
       super
     end

src/db/pool_statement.cr

@@ -3,7 +3,7 @@ module DB
   # a statement from the DB needs to be able to represent a statement in any
   # of the connections of the pool. Otherwise the user will need to deal with
   # actual connections in some point.
-  abstract class PoolStatement
+  abstract struct PoolStatement
     include StatementMethods
 
     def initialize(@db : Database, @query : String)

src/db/pool_unprepared_statement.cr

@@ -4,7 +4,7 @@ module DB
   # The execution of the statement is retried according to the pool configuration.
   #
   # See `PoolStatement`
-  class PoolUnpreparedStatement < PoolStatement
+  struct PoolUnpreparedStatement < PoolStatement
     def initialize(db : Database, query : String)
       super
     end

src/db/statement.cr

@@ -2,11 +2,6 @@ module DB
   # Common interface for connection based statements
   # and for connection pool statements.
   module StatementMethods
-    include Disposable
-
-    protected def do_close
-    end
-
     # See `QueryMethods#scalar`
     def scalar(*args_, args : Array? = nil)
       query(*args_, args: args) do |rs|
@@ -47,6 +42,10 @@ module DB
   # 6. `#do_close` is called to release the statement resources.
   abstract class Statement
     include StatementMethods
+    include Disposable
+
+    protected def do_close
+    end
 
     # :nodoc:
     getter connection