New Query Cache Feature (part deux)

shard.yml

@@ -34,6 +34,9 @@ dependencies:
   pulsar:
     github: luckyframework/pulsar
     version: ~> 0.2.2
+  lucky_cache:
+    github: luckyframework/lucky_cache
+    branch: master
 
 development_dependencies:
   ameba:

spec/queryable_spec.cr

@@ -32,7 +32,20 @@ end
 class PostQuery < Post::BaseQuery
 end
 
+class UserQuery
+  class_property query_counter : Int32 = 0
+
+  private def exec_query
+    @@query_counter += 1
+    super
+  end
+end
+
 describe Avram::Queryable do
+  Spec.before_each do
+    UserQuery.query_counter = 0
+  end
+
   it "can chain scope methods" do
     ChainedQuery.new.young.named("Paul")
   end
@@ -1358,7 +1371,7 @@ describe Avram::Queryable do
 
       users = UserQuery.new.group(&.age).group(&.id)
       users.query.statement.should eq "SELECT #{User::COLUMN_SQL} FROM users GROUP BY users.age, users.id"
-      users.map(&.name).should eq ["Dwight", "Michael", "Jim"]
+      users.map(&.name).sort!.should eq ["Dwight", "Jim", "Michael"]
     end
 
     it "raises an error when grouped incorrectly" do
@@ -1471,4 +1484,22 @@ describe Avram::Queryable do
       query.to_sql.should eq original_query_sql
     end
   end
+
+  describe "with query cache" do
+    it "only runs the query once" do
+      # We're testing the actual caching
+      Fiber.current.query_cache = LuckyCache::MemoryStore.new
+      Avram.temp_config(query_cache_enabled: true) do
+        UserFactory.create &.name("Amy")
+        UserQuery.query_counter.should eq(0)
+
+        UserQuery.new.name("Amy").first
+        UserQuery.new.name("Amy").first
+        user = UserQuery.new.name("Amy").first
+
+        UserQuery.query_counter.should eq(1)
+        user.name.should eq("Amy")
+      end
+    end
+  end
 end

spec/spec_helper.cr

@@ -21,6 +21,10 @@ Db::VerifyConnection.new(quiet: true).run_task
 
 Spec.before_each do
   TestDatabase.truncate
+  # All specs seem to run on the same Fiber,
+  # so we set back to NullStore before each spec
+  # to ensure queries aren't randomly cached
+  Fiber.current.query_cache = LuckyCache::NullStore.new
 end
 
 class SampleBackupDatabase < Avram::Database

src/avram.cr

@@ -2,6 +2,7 @@ require "dexter"
 require "wordsmith"
 require "habitat"
 require "pulsar"
+require "lucky_cache"
 require "db"
 require "pg"
 require "uuid"
@@ -22,6 +23,7 @@ module Avram
     setting database_to_migrate : Avram::Database.class, example: "AppDatabase"
     setting time_formats : Array(String) = [] of String
     setting i18n_backend : Avram::I18nBackend = Avram::I18n.new, example: "Avram::I18n.new"
+    setting query_cache_enabled : Bool = false
   end
 
   Log            = ::Log.for(Avram)

src/avram/charms/fiber.cr

@@ -0,0 +1,12 @@
+# https://crystal-lang.org/api/latest/Fiber.html
+class Fiber
+  # This is stored on Fiber so it's released after each
+  # HTTP Request.
+  property query_cache : LuckyCache::BaseStore do
+    if Avram.settings.query_cache_enabled
+      LuckyCache::MemoryStore.new
+    else
+      LuckyCache::NullStore.new
+    end
+  end
+end

src/avram/model.cr

@@ -18,6 +18,7 @@ abstract class Avram::Model
   macro inherited
     COLUMNS = [] of Nil # types are not checked in macros
     ASSOCIATIONS = [] of Nil # types are not checked in macros
+    include LuckyCache::Cachable
   end
 
   def self.primary_key_name : Symbol?

src/avram/queryable.cr

@@ -245,9 +245,19 @@ module Avram::Queryable(T)
     @preloads << block
   end
 
+  def cache_store
+    Fiber.current.query_cache
+  end
+
+  private def cache_key : String
+    [query.statement, query.args].join(':')
+  end
+
   def results : Array(T)
-    exec_query.tap do |records|
-      preloads.each(&.call(records))
+    cache_store.fetch(cache_key, as: Array(T)) do
+      exec_query.tap do |records|
+        preloads.each(&.call(records))
+      end
     end
   end