initial commit

Author: jftuga

README.md

@@ -1,2 +1,63 @@
-# ttlmap
-A map in which entries expire after given time period
+# ttlMap
+
+`ttlMap` is golang package that implements a *time-to-live* map such that after a given amount of time, items in the map are deleted.
+* The default map key uses a type of `string`, but this can be modified be changing `CustomKeyType` in [ttlMap.go](ttlMap.go).
+* Any data type can be used as a map value. Internally, `interface{}` is used for this.
+
+## Example
+
+[Full example using many data types](example/example.go)
+
+Small example:
+
+```go
+package main
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/jftuga/ttlMap"
+)
+
+func main() {
+	maxTTL := 4                    // a key's time to live in seconds
+	startSize := 3                 // initial number of items in map
+	pruneInterval := 1             // search for expired items every 'pruneInterval' seconds
+	refreshLastAccessOnGet := true // update item's 'lastAccessTime' on a .Get()
+	t := ttlMap.New(maxTTL, startSize, pruneInterval, refreshLastAccessOnGet)
+
+	// populate the ttlMap
+	t.Put("myString", "a b c")
+	t.Put("int_array", []int{1, 2, 3})
+	fmt.Println("ttlMap length:", t.Len())
+
+	// display all items in ttlMap
+	all := t.All()
+	for k, v := range all {
+		fmt.Printf("[%9s] %v\n", k, v.Value)
+	}
+	fmt.Println()
+
+	sleepTime := maxTTL + pruneInterval
+	fmt.Printf("Sleeping %v seconds, items should be 'nil' after this time\n", sleepTime)
+	time.Sleep(time.Second * time.Duration(sleepTime))
+	fmt.Printf("[%9s] %v\n", "myString", t.Get("myString"))
+	fmt.Printf("[%9s] %v\n", "int_array", t.Get("int_array"))
+	fmt.Println("ttlMap length:", t.Len())
+}
+```
+
+## Performance
+* Searching for expired items runs in O(n) time, where n = number of items in the `ttlMap`.
+* * This inefficiency can be somewhat mitigated by increasing the value of the `pruneInterval` time.
+* In most cases you want `pruneInterval > maxTTL`; otherwise expired items will stay in the map longer than expected.
+
+## Acknowledgments
+* Adopted from: [Map with TTL option in Go](https://stackoverflow.com/a/25487392/452281)
+* * Answer created by: [OneOfOne](https://stackoverflow.com/users/145587/oneofone)
+* [/u/skeeto](https://old.reddit.com/user/skeeto): suggestions for the `New` function
+
+## Disclosure Notification
+
+This program was completely developed on my own personal time, for my own personal benefit, and on my personally owned equipment.

example/example.go

@@ -0,0 +1,98 @@
+/*
+example.go
+-John Taylor
+2023-10-21
+
+This is an example on how to use the ttlMap package.  Notice the variety of data types used.
+*/
+
+package main
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/jftuga/ttlMap"
+)
+
+type User struct {
+	Name  string
+	Level uint
+}
+
+func main() {
+	maxTTL := 4                    // time in seconds
+	startSize := 3                 // initial number of items in map
+	pruneInterval := 1             // search for expired items every 'pruneInterval' seconds
+	refreshLastAccessOnGet := true // update item's lastAccessTime on a .Get()
+	t := ttlMap.New(maxTTL, startSize, pruneInterval, refreshLastAccessOnGet)
+
+	// populate the ttlMap
+	t.Put("string", "a b c")
+	t.Put("int", 3)
+	t.Put("float", 4.4)
+	t.Put("int_array", []int{1, 2, 3})
+	t.Put("bool", false)
+	t.Put("rune", '{')
+	t.Put("byte", 0x7b)
+	var u = uint64(123456789)
+	t.Put("uint64", u)
+	var c = complex(3.14, -4.321)
+	t.Put("complex", c)
+
+	allUsers := []User{{Name: "abc", Level: 123}, {Name: "def", Level: 456}}
+	t.Put("all_users", allUsers)
+
+	fmt.Println()
+	fmt.Println("ttlMap length:", t.Len())
+
+	// extract entry from struct array
+	a := t.Get("all_users").([]User)
+	fmt.Printf("second user: %v, %v\n", a[1].Name, a[1].Level)
+
+	// display all items in ttlMap
+	fmt.Println()
+	fmt.Println("vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv")
+	all := t.All()
+	for k, v := range all {
+		fmt.Printf("[%9s] %v\n", k, v.Value)
+	}
+	fmt.Println("^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^")
+	fmt.Println()
+
+	// by executing Get(), the 'dontExpireKey' lastAccessTime will be updated
+	// therefore, this item will not expire
+	dontExpireKey := "float"
+	go func() {
+		for range time.Tick(time.Second) {
+			t.Get(ttlMap.CustomKeyType(dontExpireKey))
+		}
+	}()
+
+	// ttlMap has an expiration time, wait until this amount of time passes
+	sleepTime := maxTTL + pruneInterval
+	fmt.Println()
+	fmt.Printf("Sleeping %v seconds, items should be removed after this time, except for the '%v' key\n", sleepTime, dontExpireKey)
+	fmt.Println()
+	time.Sleep(time.Second * time.Duration(sleepTime))
+
+	// these items have expired and therefore should be nil, except for 'dontExpireKey'
+	fmt.Printf("[%9s] %v\n", "string", t.Get("string"))
+	fmt.Printf("[%9s] %v\n", "int", t.Get("int"))
+	fmt.Printf("[%9s] %v\n", "float", t.Get("float"))
+	fmt.Printf("[%9s] %v\n", "int_array", t.Get("int_array"))
+	fmt.Printf("[%9s] %v\n", "bool", t.Get("bool"))
+	fmt.Printf("[%9s] %v\n", "rune", t.Get("rune"))
+	fmt.Printf("[%9s] %v\n", "byte", t.Get("byte"))
+	fmt.Printf("[%9s] %v\n", "uint64", t.Get("uint64"))
+	fmt.Printf("[%9s] %v\n", "complex", t.Get("complex"))
+	fmt.Printf("[%9s] %v\n", "all_users", t.Get("all_users"))
+
+	// sanity check, this comparison should be true
+	fmt.Println()
+	if t.Get("int") == nil {
+		fmt.Println("[int] is nil")
+	}
+	fmt.Println("ttlMap length:", t.Len())
+	fmt.Println()
+}

example/small/small.go

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+package main
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/jftuga/ttlMap"
+)
+
+func main() {
+	maxTTL := 4                    // time in seconds
+	startSize := 3                 // initial number of items in map
+	pruneInterval := 1             // search for expired items every 'pruneInterval' seconds
+	refreshLastAccessOnGet := true // update item's lastAccessTime on a .Get()
+	t := ttlMap.New(maxTTL, startSize, pruneInterval, refreshLastAccessOnGet)
+
+	// populate the ttlMap
+	t.Put("myString", "a b c")
+	t.Put("int_array", []int{1, 2, 3})
+	fmt.Println("ttlMap length:", t.Len())
+
+	// display all items in ttlMap
+	all := t.All()
+	for k, v := range all {
+		fmt.Printf("[%9s] %v\n", k, v.Value)
+	}
+	fmt.Println()
+
+	sleepTime := maxTTL + pruneInterval
+	fmt.Printf("Sleeping %v seconds, items should be 'nil' after this time\n", sleepTime)
+	time.Sleep(time.Second * time.Duration(sleepTime))
+	fmt.Printf("[%9s] %v\n", "myString", t.Get("myString"))
+	fmt.Printf("[%9s] %v\n", "int_array", t.Get("int_array"))
+	fmt.Println("ttlMap length:", t.Len())
+}

go.mod

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+module github.com/jftuga/ttlMap
+
+go 1.21.3

ttlMap.go

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+/*
+ttlMap.go
+-John Taylor
+2023-10-21
+
+ttlMap is a "time-to-live" map such that after a given amount of time, items
+in the map are deleted.
+
+When a Put() occurs, the lastAccess time is set to time.Now().Unix()
+When a Get() occurs, the lastAccess time is updated to time.Now().Unix()
+Therefore, only items that are not called by Get() will be deleted after the TTL occurs.
+
+Adopted from: https://stackoverflow.com/a/25487392/452281
+
+Changes from the referenced implementation
+==========================================
+1) the may key is user definable by setting CustomKeyType (defaults to string)
+2) use interface{} instead of string as the map value so that any data type can be used
+3) added All() function
+4) use item.Value instead of item.value so that it can be externally referenced
+5) added user configurable prune interval - search for expired items every 'pruneInterval' seconds
+6) toggle for refreshLastAccessOnGet - update item's lastAccessTime on a .Get() when set to true
+
+*/
+
+package ttlMap
+
+import (
+	"sync"
+	"time"
+)
+
+const version string = "1.0.0"
+
+type CustomKeyType string
+
+type item struct {
+	Value      interface{}
+	lastAccess int64
+}
+
+type ttlMap struct {
+	m       map[CustomKeyType]*item
+	l       sync.Mutex
+	refresh bool
+}
+
+func New(maxTTL int, ln int, pruneInterval int, refreshLastAccessOnGet bool) (m *ttlMap) {
+	// if pruneInterval > maxTTL {
+	// 	print("WARNING: ttlMap: pruneInterval > maxTTL\n")
+	// }
+	m = &ttlMap{m: make(map[CustomKeyType]*item, ln)}
+	m.refresh = refreshLastAccessOnGet
+	go func() {
+		for now := range time.Tick(time.Second * time.Duration(pruneInterval)) {
+			currentTime := now.Unix()
+			m.l.Lock()
+			for k, v := range m.m {
+				// print("TICK:", currentTime, "  ", v.lastAccess, "  ", (currentTime - v.lastAccess), "  ", maxTTL, "  ", k, "\n")
+				if currentTime-v.lastAccess >= int64(maxTTL) {
+					delete(m.m, k)
+					// print("deleting: ", k, "\n")
+				}
+			}
+			// print("\n")
+			m.l.Unlock()
+		}
+	}()
+	return
+}
+
+func (m *ttlMap) Len() int {
+	return len(m.m)
+}
+
+func (m *ttlMap) Put(k CustomKeyType, v interface{}) {
+	m.l.Lock()
+	it, ok := m.m[k]
+	if !ok {
+		it = &item{Value: v}
+		m.m[k] = it
+	}
+	it.lastAccess = time.Now().Unix()
+	m.l.Unlock()
+}
+
+func (m *ttlMap) Get(k CustomKeyType) (v interface{}) {
+	m.l.Lock()
+	if it, ok := m.m[k]; ok {
+		v = it.Value
+		if m.refresh {
+			m.m[k].lastAccess = time.Now().Unix()
+		}
+	}
+	m.l.Unlock()
+	return
+}
+
+func (m *ttlMap) All() map[CustomKeyType]*item {
+	return m.m
+}