LRU cache in mysql and sqlite are now per-process caches.

5 files changed, 82 insertions, 22 deletions

diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index 700e11ff94..143de81925 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,4 +1,8 @@
-*Rails 3.2.0 (unreleased)*
+Wed Sep  7 15:25:02 2011  Aaron Patterson <aaron@tenderlovemaking.com>
+
+	* lib/active_record/connection_adapters/mysql_adapter.rb: LRU cache
+	  keys are per process id.
+	* lib/active_record/connection_adapters/sqlite_adapter.rb: ditto
 
 * Support bulk change_table in mysql2 adapter, as well as the mysql one. [Jon Leighton]
 
diff --git a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
index 73e3afe1d5..a1824fe396 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
@@ -94,27 +94,32 @@ module ActiveRecord
       class StatementPool < ConnectionAdapters::StatementPool
         def initialize(connection, max = 1000)
           super
-          @cache = {}
+          @cache = Hash.new { |h,pid| h[pid] = {} }
         end
 
-        def each(&block); @cache.each(&block); end
-        def key?(key);    @cache.key?(key); end
-        def [](key);      @cache[key]; end
-        def length;       @cache.length; end
-        def delete(key);  @cache.delete(key); end
+        def each(&block); cache.each(&block); end
+        def key?(key);    cache.key?(key); end
+        def [](key);      cache[key]; end
+        def length;       cache.length; end
+        def delete(key);  cache.delete(key); end
 
         def []=(sql, key)
-          while @max <= @cache.size
-            @cache.shift.last[:stmt].close
+          while @max <= cache.size
+            cache.shift.last[:stmt].close
           end
-          @cache[sql] = key
+          cache[sql] = key
         end
 
         def clear
-          @cache.values.each do |hash|
+          cache.values.each do |hash|
             hash[:stmt].close
           end
-          @cache.clear
+          cache.clear
+        end
+
+        private
+        def cache
+          @cache[$$]
         end
       end
 
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb
index 7c7e762c19..1932a849ee 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb
@@ -52,29 +52,33 @@ module ActiveRecord
       class StatementPool < ConnectionAdapters::StatementPool
         def initialize(connection, max)
           super
-          @cache = {}
+          @cache = Hash.new { |h,pid| h[pid] = {} }
         end
 
-        def each(&block); @cache.each(&block); end
-        def key?(key);    @cache.key?(key); end
-        def [](key);      @cache[key]; end
-        def length;       @cache.length; end
+        def each(&block); cache.each(&block); end
+        def key?(key);    cache.key?(key); end
+        def [](key);      cache[key]; end
+        def length;       cache.length; end
 
         def []=(sql, key)
-          while @max <= @cache.size
-            dealloc(@cache.shift.last[:stmt])
+          while @max <= cache.size
+            dealloc(cache.shift.last[:stmt])
           end
-          @cache[sql] = key
+          cache[sql] = key
         end
 
         def clear
-          @cache.values.each do |hash|
+          cache.values.each do |hash|
             dealloc hash[:stmt]
           end
-          @cache.clear
+          cache.clear
         end
 
         private
+        def cache
+          @cache[$$]
+        end
+
         def dealloc(stmt)
           stmt.close unless stmt.closed?
         end
diff --git a/activerecord/test/cases/adapters/mysql/statement_pool_test.rb b/activerecord/test/cases/adapters/mysql/statement_pool_test.rb
new file mode 100644
index 0000000000..83de90f179
--- /dev/null
+++ b/activerecord/test/cases/adapters/mysql/statement_pool_test.rb
@@ -0,0 +1,23 @@
+require 'cases/helper'
+
+module ActiveRecord::ConnectionAdapters
+  class MysqlAdapter
+    class StatementPoolTest < ActiveRecord::TestCase
+      def test_cache_is_per_pid
+        return skip('must support fork') unless Process.respond_to?(:fork)
+
+        cache = StatementPool.new nil, 10
+        cache['foo'] = 'bar'
+        assert_equal 'bar', cache['foo']
+
+        pid = fork {
+          lookup = cache['foo'];
+          exit!(!lookup)
+        }
+
+        Process.waitpid pid
+        assert $?.success?, 'process should exit successfully'
+      end
+    end
+  end
+end
diff --git a/activerecord/test/cases/adapters/sqlite3/statement_pool_test.rb b/activerecord/test/cases/adapters/sqlite3/statement_pool_test.rb
new file mode 100644
index 0000000000..ae272e2c4b
--- /dev/null
+++ b/activerecord/test/cases/adapters/sqlite3/statement_pool_test.rb
@@ -0,0 +1,24 @@
+require 'cases/helper'
+
+module ActiveRecord::ConnectionAdapters
+  class SQLiteAdapter
+    class StatementPoolTest < ActiveRecord::TestCase
+      def test_cache_is_per_pid
+        return skip('must support fork') unless Process.respond_to?(:fork)
+
+        cache = StatementPool.new nil, 10
+        cache['foo'] = 'bar'
+        assert_equal 'bar', cache['foo']
+
+        pid = fork {
+          lookup = cache['foo'];
+          exit!(!lookup)
+        }
+
+        Process.waitpid pid
+        assert $?.success?, 'process should exit successfully'
+      end
+    end
+  end
+end
+