vkutil

🧰 vkutil

A go library of Valkey utilities built on the redigo client library.

[!IMPORTANT] Because this library is built on redigo it doesn't support cluster mode. However care has been taken to ensure this is possible in future by 1) not dynamically constructing keys in LUA scripts and 2) using hashtags to ensure that keys that are accessed together would hash to the same hash slot.

Interval Based Structs

IntervalSet

Creating very large numbers of keys can hurt performance, but putting them all in a single set requires that they all have the same expiration. IntervalSet is a way to have multiple sets based on time intervals, accessible like a single set. You trade accuracy of expiry times for a significantly reduced key space. For example using 2 intervals of 24 hours:

set := vkutil.NewIntervalSet("foos", time.Hour*24, 2)
set.Add(ctx, vc, "A")  // time is 2021-12-02T09:00
...
set.Add(ctx, vc, "B")  // time is 2021-12-03T10:00
set.Add(ctx, vc, "C")  // time is 2021-12-03T11:00

Creates 2 sets as follows:

{foos}:2021-12-02 => {"A"}       // expires at 2021-12-04T09:00
{foos}:2021-12-03 => {"B", "C"}  // expires at 2021-12-05T11:00

But can be accessed like a single set:

set.IsMember(ctx, vc, "A")   // true
set.IsMember(ctx, vc, "B")   // true
set.IsMember(ctx, vc, "D")   // false

IntervalHash

Same idea as IntervalSet but for hashes, and works well for caching values. For example using 2 intervals of 1 hour:

hash := vkutil.NewIntervalHash("foos", time.Hour, 2)
hash.Set(ctx, vc, "A", "1")  // time is 2021-12-02T09:10
...
hash.Set(ctx, vc, "B", "2")  // time is 2021-12-02T10:15
hash.Set(ctx, vc, "C", "3")  // time is 2021-12-02T10:20

Creates 2 hashes like:

{foos}:2021-12-02T09:00 => {"A": "1"}            // expires at 2021-12-02T11:10
{foos}:2021-12-02T10:00 => {"B": "2", "C": "3"}  // expires at 2021-12-02T12:20

But can be accessed like a single hash:

hash.Get(ctx, vc, "A")   // "1"
hash.Get(ctx, vc, "B")   // "2"
hash.Get(ctx, vc, "D")   // ""

IntervalSeries

When getting a value from an IntervalHash you're getting the newest value by looking back through the intervals. IntervalSeries however lets you get an accumulated value from each interval.

For example using 3 intervals of 1 hour:

series := vkutil.NewIntervalSeries("foos", time.Hour, 3)
series.Record(ctx, vc, "A", 1)  // time is 2021-12-02T09:10
series.Record(ctx, vc, "A", 2)  // time is 2021-12-02T09:15
...
series.Record(ctx, vc, "A", 3)  // time is 2021-12-02T10:15
series.Record(ctx, vc, "A", 4)  // time is 2021-12-02T10:20
...
series.Record(ctx, vc, "A", 5)  // time is 2021-12-02T11:25
series.Record(ctx, vc, "B", 1)  // time is 2021-12-02T11:30

Creates 3 hashes like:

{foos}:2021-12-02T09:00 => {"A": "3"}            // expires at 2021-12-02T12:15
{foos}:2021-12-02T10:00 => {"A": "7"}            // expires at 2021-12-02T13:20
{foos}:2021-12-02T11:00 => {"A": "5", "B": "1"}  // expires at 2021-12-02T14:30

But lets us retrieve values across intervals:

series.Get(ctx, vc, "A")   // [5, 7, 3]
series.Get(ctx, vc, "B")   // [1, 0, 0]
series.Get(ctx, vc, "C")   // [0, 0, 0]

Queues

Fair

import "github.com/nyaruka/vkutil/queues"

queue := queues.NewFair("jobs", 10)
queue.Push(ctx, vc, "owner1", true, []byte(`{...}`))
queue.Push(ctx, vc, "owner2", false, []byte(`{...}`))
owner, task, err := queue.Pop(ctx, vc)
...
queue.Done(ctx, vc, owner)

Locks

Locker

import "github.com/nyaruka/vkutil/locks"

locker := locks.NewLocker("mylock", time.Minute)
lock, err := locker.Grab(ctx, vp, 10 * time.Second)
...
locker.Release(ctx, vc, lock)

Other

NewPool

Simplifies creating a new connection pool, with optional auth, and tests that the connection works:

vp, err := vkutil.NewPool(
    "valkey://username:password@localhost:6379/15", 
    vkutil.WithMaxActive(10), 
    vkutil.WithMaxIdle(3), 
    vkutil.WithIdleTimeout(time.Minute)
)

CappedZSet

The CappedZSet type is based on a sorted set but enforces a cap on size, by only retaining the highest ranked members.

cset := vkutil.NewCappedZSet("foos", 3, time.Hour*24)
cset.Add(ctx, vc, "A", 1) 
cset.Add(ctx, vc, "C", 3) 
cset.Add(ctx, vc, "D", 4)
cset.Add(ctx, vc, "B", 2) 
cset.Add(ctx, vc, "E", 5) 
cset.Members(ctx, vc)      // ["C", "D", "E"] / [3, 4, 5]

Testing

Asserts

The assertvk package contains several asserts useful for testing the state of a database.

vp := assertvk.TestDB()
vc := vp.Get()
defer vc.Close()

assertvk.Keys(t, vc, "*", []string{"foo", "bar"})
assertvk.Exists(t, vc, "foo")
assertvk.NotExists(t, vc, "bar")
assertvk.Get(t, vc, "foo", "123")
assertvk.SCard(t, vc, "foo_set", 2)
assertvk.SMembers(t, vc, "foo_set", []string{"123", "234"})