Custom Storage

ACOR does not support custom storage backends. Redis is the only backend, and Create() always builds it. This page explains why the interface you may have seen in older releases is gone, and what to do instead for the case it was usually reached for: testing.

What changed in v1.5.0

Through v1.4.0 the package exported a KVStorage interface, along with Pipeliner, Subscription, StringMapResult, PubSubMessage, and Z. They were exported in anticipation of pluggable backends.

They are unexported as of v1.5.0, for two reasons:

• Nothing could be plugged in. No public constructor accepted a KVStorage, and no public function returned one. You could name the interface and write an implementation, but there was no way to hand it to ACOR — so the capability the interface implied never existed.
• Freezing it would have blocked the feature it was for. The compatibility policy forbids adding a method to an exported interface inside v1. KVStorage has 23 methods; had v1.5.0 frozen it, a future backend needing one more operation would have had nowhere to put it for the rest of the v1 line.

Leaving the shape unfrozen is what keeps pluggable storage possible. Publishing an interface later is an addition, which v1 allows; growing a frozen one is not.

Testing without Redis

This is what the interface was most often reached for, and it has a better answer that works today: miniredis, an in-process Redis-compatible server. ACOR’s own test suite uses it, so the behavior you test against is the behavior ACOR is tested against.

package example

import (
    "testing"

    "github.com/alicebob/miniredis/v2"
    "github.com/skyoo2003/acor/pkg/acor"
)

func TestWithMiniredis(t *testing.T) {
    mr := miniredis.RunT(t)

    ac, err := acor.Create(&acor.AhoCorasickArgs{
        Addr: mr.Addr(),
        Name: "test-collection",
    })
    if err != nil {
        t.Fatal(err)
    }
    defer func() { _ = ac.Close() }()

    if _, err := ac.Add("hello"); err != nil {
        t.Fatal(err)
    }

    matches, err := ac.Find("hello world")
    if err != nil {
        t.Fatal(err)
    }
    if len(matches) != 1 || matches[0] != "hello" {
        t.Fatalf("Find() = %v, want [hello]", matches)
    }
}

miniredis covers the commands ACOR issues, including the Lua scripts the V2 schema uses for atomic writes. To exercise Pub/Sub-driven cache invalidation across instances, point two instances at the same miniredis address.

Reducing Redis traffic

If the reason for a custom backend was to avoid Redis round trips on reads rather than to replace Redis, that is already available without one:

• Preset serves reads from a local automaton and touches Redis only on writes and invalidations. See Presets.
• EnableCache caches trie data locally and invalidates over Pub/Sub.

CacheStats() reports whether either is working — hit rate, rebuild cost, and invalidation lag — without any Redis I/O of its own.

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