Get adds context cache feature (#1102)

* context

* add context cache feature

* remove global context cache

* remove global context cache

* reset statment

* fix bug

* remove unused params

* refactor ContextCache

* refactor ContextCache

* update README

* update README

* disable global cache on context cache test

README.md

@@ -34,6 +34,8 @@ Xorm is a simple and powerful ORM for Go.
 
 * Postgres schema support
 
+* Context Cache support
+
 ## Drivers Support
 
 Drivers for Go's sql package which currently support database/sql includes:
@@ -358,6 +360,56 @@ if _, err := session.Exec("delete from userinfo where username = ?", user2.Usern
 return session.Commit()
 ```
 
+* Or you can use `Transaction` to replace above codes.
+
+```Go
+res, err := engine.Transaction(func(sess *xorm.Session) (interface{}, error) {
+    user1 := Userinfo{Username: "xiaoxiao", Departname: "dev", Alias: "lunny", Created: time.Now()}
+    if _, err := session.Insert(&user1); err != nil {
+        return nil, err
+    }
+
+    user2 := Userinfo{Username: "yyy"}
+    if _, err := session.Where("id = ?", 2).Update(&user2); err != nil {
+        return nil, err
+    }
+
+    if _, err := session.Exec("delete from userinfo where username = ?", user2.Username); err != nil {
+        return nil, err
+    }
+    return nil, nil
+})
+```
+
+* Context Cache, if enabled, current query result will be cached on session and be used by next same statement on the same session.
+
+```Go
+	sess := engine.NewSession()
+	defer sess.Close()
+
+	var context = xorm.NewMemoryContextCache()
+
+	var c2 ContextGetStruct
+	has, err := sess.ID(1).ContextCache(context).Get(&c2)
+	assert.NoError(t, err)
+	assert.True(t, has)
+	assert.EqualValues(t, 1, c2.Id)
+	assert.EqualValues(t, "1", c2.Name)
+	sql, args := sess.LastSQL()
+	assert.True(t, len(sql) > 0)
+	assert.True(t, len(args) > 0)
+
+	var c3 ContextGetStruct
+	has, err = sess.ID(1).ContextCache(context).Get(&c3)
+	assert.NoError(t, err)
+	assert.True(t, has)
+	assert.EqualValues(t, 1, c3.Id)
+	assert.EqualValues(t, "1", c3.Name)
+	sql, args = sess.LastSQL()
+	assert.True(t, len(sql) == 0)
+	assert.True(t, len(args) == 0)
+```
+
 ## Contributing
 
 If you want to pull request, please see [CONTRIBUTING](https://github.com/go-xorm/xorm/blob/master/CONTRIBUTING.md). And we also provide [Xorm on Google Groups](https://groups.google.com/forum/#!forum/xorm) to discuss.

README_CN.md

@@ -32,6 +32,8 @@ xorm是一个简单而强大的Go语言ORM库. 通过它可以使数据库操作
 
 * 内置SQL Builder支持
 
+* 上下文缓存支持
+
 ## 驱动支持
 
 目前支持的Go数据库驱动和对应的数据库如下：
@@ -360,6 +362,56 @@ if _, err := session.Exec("delete from userinfo where username = ?", user2.Usern
 return session.Commit()
 ```
 
+* 事物的简写方法
+
+```Go
+res, err := engine.Transaction(func(sess *xorm.Session) (interface{}, error) {
+    user1 := Userinfo{Username: "xiaoxiao", Departname: "dev", Alias: "lunny", Created: time.Now()}
+    if _, err := session.Insert(&user1); err != nil {
+        return nil, err
+    }
+
+    user2 := Userinfo{Username: "yyy"}
+    if _, err := session.Where("id = ?", 2).Update(&user2); err != nil {
+        return nil, err
+    }
+
+    if _, err := session.Exec("delete from userinfo where username = ?", user2.Username); err != nil {
+        return nil, err
+    }
+    return nil, nil
+})
+```
+
+* Context Cache, if enabled, current query result will be cached on session and be used by next same statement on the same session.
+
+```Go
+	sess := engine.NewSession()
+	defer sess.Close()
+
+	var context = xorm.NewMemoryContextCache()
+
+	var c2 ContextGetStruct
+	has, err := sess.ID(1).ContextCache(context).Get(&c2)
+	assert.NoError(t, err)
+	assert.True(t, has)
+	assert.EqualValues(t, 1, c2.Id)
+	assert.EqualValues(t, "1", c2.Name)
+	sql, args := sess.LastSQL()
+	assert.True(t, len(sql) > 0)
+	assert.True(t, len(args) > 0)
+
+	var c3 ContextGetStruct
+	has, err = sess.ID(1).ContextCache(context).Get(&c3)
+	assert.NoError(t, err)
+	assert.True(t, has)
+	assert.EqualValues(t, 1, c3.Id)
+	assert.EqualValues(t, "1", c3.Name)
+	sql, args = sess.LastSQL()
+	assert.True(t, len(sql) == 0)
+	assert.True(t, len(args) == 0)
+```
+
 ## 贡献
 
 如果您也想为Xorm贡献您的力量，请查看 [CONTRIBUTING](https://github.com/go-xorm/xorm/blob/master/CONTRIBUTING.md)。您也可以加入QQ群  技术帮助和讨论。

context_cache.go

@@ -0,0 +1,30 @@
+// Copyright 2018 The Xorm Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package xorm
+
+// ContextCache is the interface that operates the cache data.
+type ContextCache interface {
+	// Put puts value into cache with key.
+	Put(key string, val interface{})
+	// Get gets cached value by given key.
+	Get(key string) interface{}
+}
+
+type memoryContextCache map[string]interface{}
+
+// NewMemoryContextCache return memoryContextCache
+func NewMemoryContextCache() memoryContextCache {
+	return make(map[string]interface{})
+}
+
+// Put puts value into cache with key.
+func (m memoryContextCache) Put(key string, val interface{}) {
+	m[key] = val
+}
+
+// Get gets cached value by given key.
+func (m memoryContextCache) Get(key string) interface{} {
+	return m[key]
+}

session.go

@@ -102,6 +102,12 @@ func (session *Session) Close() {
 	}
 }
 
+// ContextCache enable context cache or not
+func (session *Session) ContextCache(context ContextCache) *Session {
+	session.statement.context = context
+	return session
+}
+
 // IsClosed returns if session is closed
 func (session *Session) IsClosed() bool {
 	return session.db == nil

session_get.go

@@ -7,6 +7,7 @@ package xorm
 import (
 	"database/sql"
 	"errors"
+	"fmt"
 	"reflect"
 	"strconv"
 
@@ -66,7 +67,28 @@ func (session *Session) get(bean interface{}) (bool, error) {
 		}
 	}
 
-	return session.nocacheGet(beanValue.Elem().Kind(), table, bean, sqlStr, args...)
+	context := session.statement.context
+	if context != nil {
+		res := context.Get(fmt.Sprintf("%v-%v", sqlStr, args))
+		if res != nil {
+			structValue := reflect.Indirect(reflect.ValueOf(bean))
+			structValue.Set(reflect.Indirect(reflect.ValueOf(res)))
+			session.lastSQL = ""
+			session.lastSQLArgs = nil
+			return true, nil
+		}
+	}
+
+	has, err := session.nocacheGet(beanValue.Elem().Kind(), table, bean, sqlStr, args...)
+	if err != nil || !has {
+		return has, err
+	}
+
+	if context != nil {
+		context.Put(fmt.Sprintf("%v-%v", sqlStr, args), bean)
+	}
+
+	return true, nil
 }
 
 func (session *Session) nocacheGet(beanKind reflect.Kind, table *core.Table, bean interface{}, sqlStr string, args ...interface{}) (bool, error) {

session_get_test.go

@@ -319,3 +319,70 @@ func TestGetStructId(t *testing.T) {
 	assert.True(t, has)
 	assert.EqualValues(t, 2, maxid.Id)
 }
+
+func TestContextGet(t *testing.T) {
+	type ContextGetStruct struct {
+		Id   int64
+		Name string
+	}
+
+	assert.NoError(t, prepareEngine())
+	assertSync(t, new(ContextGetStruct))
+
+	_, err := testEngine.Insert(&ContextGetStruct{Name: "1"})
+	assert.NoError(t, err)
+
+	sess := testEngine.NewSession()
+	defer sess.Close()
+
+	context := NewMemoryContextCache()
+
+	var c2 ContextGetStruct
+	has, err := sess.ID(1).NoCache().ContextCache(context).Get(&c2)
+	assert.NoError(t, err)
+	assert.True(t, has)
+	assert.EqualValues(t, 1, c2.Id)
+	assert.EqualValues(t, "1", c2.Name)
+	sql, args := sess.LastSQL()
+	assert.True(t, len(sql) > 0)
+	assert.True(t, len(args) > 0)
+
+	var c3 ContextGetStruct
+	has, err = sess.ID(1).NoCache().ContextCache(context).Get(&c3)
+	assert.NoError(t, err)
+	assert.True(t, has)
+	assert.EqualValues(t, 1, c3.Id)
+	assert.EqualValues(t, "1", c3.Name)
+	sql, args = sess.LastSQL()
+	assert.True(t, len(sql) == 0)
+	assert.True(t, len(args) == 0)
+}
+
+func TestContextGet2(t *testing.T) {
+	type ContextGetStruct2 struct {
+		Id   int64
+		Name string
+	}
+
+	assert.NoError(t, prepareEngine())
+	assertSync(t, new(ContextGetStruct2))
+
+	_, err := testEngine.Insert(&ContextGetStruct2{Name: "1"})
+	assert.NoError(t, err)
+
+	context := NewMemoryContextCache()
+
+	var c2 ContextGetStruct2
+	has, err := testEngine.ID(1).NoCache().ContextCache(context).Get(&c2)
+	assert.NoError(t, err)
+	assert.True(t, has)
+	assert.EqualValues(t, 1, c2.Id)
+	assert.EqualValues(t, "1", c2.Name)
+
+	var c3 ContextGetStruct2
+	has, err = testEngine.ID(1).NoCache().ContextCache(context).Get(&c3)
+	assert.NoError(t, err)
+	assert.True(t, has)
+	assert.EqualValues(t, 1, c3.Id)
+	assert.EqualValues(t, "1", c3.Name)
+}

statement.go

@@ -59,6 +59,7 @@ type Statement struct {
 	exprColumns     map[string]exprParam
 	cond            builder.Cond
 	bufferSize      int
+	context         ContextCache
 }
 
 // Init reset all the statement's fields
@@ -99,6 +100,7 @@ func (statement *Statement) Init() {
 	statement.exprColumns = make(map[string]exprParam)
 	statement.cond = builder.NewCond()
 	statement.bufferSize = 0
+	statement.context = nil
 }
 
 // NoAutoCondition if you do not want convert bean's field as query condition, then use this function