Move packages to proejct/pkg to follow go project folder structure convention (#1190)

pkg/cache/cache.go

@@ -0,0 +1,202 @@
+/*
+Copyright 2016 The Fission Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package cache
+
+import (
+	"fmt"
+	"time"
+
+	ferror "github.com/fission/fission/pkg/error"
+)
+
+type requestType int
+
+const (
+	GET requestType = iota
+	SET
+	DELETE
+	EXPIRE
+	COPY
+)
+
+type (
+	Value struct {
+		ctime time.Time
+		atime time.Time
+		value interface{}
+	}
+	Cache struct {
+		cache          map[interface{}]*Value
+		ctimeExpiry    time.Duration
+		atimeExpiry    time.Duration
+		requestChannel chan *request
+	}
+
+	request struct {
+		requestType
+		key             interface{}
+		value           interface{}
+		responseChannel chan *response
+	}
+	response struct {
+		error
+		existingValue interface{}
+		mapCopy       map[interface{}]interface{}
+		value         interface{}
+	}
+)
+
+func (c *Cache) IsOld(v *Value) bool {
+	if (c.ctimeExpiry != time.Duration(0)) && (time.Since(v.ctime) > c.ctimeExpiry) {
+		return true
+	}
+
+	if (c.atimeExpiry != time.Duration(0)) && (time.Since(v.atime) > c.atimeExpiry) {
+		return true
+	}
+
+	return false
+}
+
+func MakeCache(ctimeExpiry, atimeExpiry time.Duration) *Cache {
+	c := &Cache{
+		cache:          make(map[interface{}]*Value),
+		ctimeExpiry:    ctimeExpiry,
+		atimeExpiry:    atimeExpiry,
+		requestChannel: make(chan *request),
+	}
+	go c.service()
+	if ctimeExpiry != time.Duration(0) || atimeExpiry != time.Duration(0) {
+		go c.expiryService()
+	}
+	return c
+}
+
+func (c *Cache) service() {
+	for {
+		req := <-c.requestChannel
+		resp := &response{}
+		switch req.requestType {
+		case GET:
+			val, ok := c.cache[req.key]
+			if !ok {
+				resp.error = ferror.MakeError(ferror.ErrorNotFound,
+					fmt.Sprintf("key '%v' not found", req.key))
+			} else if c.IsOld(val) {
+				resp.error = ferror.MakeError(ferror.ErrorNotFound,
+					fmt.Sprintf("key '%v' expired (atime %v)", req.key, val.atime))
+				delete(c.cache, req.key)
+			} else {
+				// update atime
+				val.atime = time.Now()
+				c.cache[req.key] = val
+				resp.value = val.value
+			}
+			req.responseChannel <- resp
+		case SET:
+			now := time.Now()
+			if _, ok := c.cache[req.key]; ok {
+				val := c.cache[req.key]
+				val.atime = time.Now()
+				resp.existingValue = val.value
+				resp.error = ferror.MakeError(ferror.ErrorNameExists, "key already exists")
+			} else {
+				c.cache[req.key] = &Value{
+					value: req.value,
+					ctime: now,
+					atime: now,
+				}
+			}
+			req.responseChannel <- resp
+		case DELETE:
+			delete(c.cache, req.key)
+			req.responseChannel <- resp
+		case EXPIRE:
+			for k, v := range c.cache {
+				if c.IsOld(v) {
+					delete(c.cache, k)
+				}
+			}
+			// no response
+		case COPY:
+			resp.mapCopy = make(map[interface{}]interface{})
+			for k, v := range c.cache {
+				resp.mapCopy[k] = v.value
+			}
+			req.responseChannel <- resp
+		default:
+			resp.error = ferror.MakeError(ferror.ErrorInvalidArgument,
+				fmt.Sprintf("invalid request type: %v", req.requestType))
+			req.responseChannel <- resp
+		}
+	}
+}
+
+func (c *Cache) Get(key interface{}) (interface{}, error) {
+	respChannel := make(chan *response)
+	c.requestChannel <- &request{
+		requestType:     GET,
+		key:             key,
+		responseChannel: respChannel,
+	}
+	resp := <-respChannel
+	return resp.value, resp.error
+}
+
+// if key exists in the cache, the new value is NOT set; instead an
+// error and the old value are returned
+func (c *Cache) Set(key interface{}, value interface{}) (error, interface{}) {
+	respChannel := make(chan *response)
+	c.requestChannel <- &request{
+		requestType:     SET,
+		key:             key,
+		value:           value,
+		responseChannel: respChannel,
+	}
+	resp := <-respChannel
+	return resp.error, resp.existingValue
+}
+
+func (c *Cache) Delete(key interface{}) error {
+	respChannel := make(chan *response)
+	c.requestChannel <- &request{
+		requestType:     DELETE,
+		key:             key,
+		responseChannel: respChannel,
+	}
+	resp := <-respChannel
+	return resp.error
+}
+
+func (c *Cache) Copy() map[interface{}]interface{} {
+	respChannel := make(chan *response)
+	c.requestChannel <- &request{
+		requestType:     COPY,
+		responseChannel: respChannel,
+	}
+	resp := <-respChannel
+	return resp.mapCopy
+}
+
+func (c *Cache) expiryService() {
+	for {
+		time.Sleep(time.Minute)
+		c.requestChannel <- &request{
+			requestType: EXPIRE,
+		}
+	}
+}