From 4d62f01af159fddd56585b3dce19b8a0f47369c1 Mon Sep 17 00:00:00 2001
From: SangTran-127 <tranquangsang12.7@gmail.com>
Date: Sun, 9 Aug 2026 01:11:31 +0700
Subject: feat: implement memory state backend with key group assignment and
 value state interface

---
 core/hash.go            | 19 +++++++++++++++++++
 core/state.go           | 10 ++++++++++
 core/state_backend.go   | 13 +++++++++++++
 state/memory_backend.go | 41 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 83 insertions(+)
 create mode 100644 core/hash.go
 create mode 100644 core/state.go
 create mode 100644 core/state_backend.go
 create mode 100644 state/memory_backend.go

diff --git a/core/hash.go b/core/hash.go
new file mode 100644
index 0000000..af15546
--- /dev/null
+++ b/core/hash.go
@@ -0,0 +1,19 @@
+package core
+
+import "hash/fnv"
+
+const DefaultMaxParallelism = 128
+
+func AssignToKeyGroup(key string, maxParallelism int) int {
+
+	if maxParallelism <= 0 {
+		maxParallelism = DefaultMaxParallelism
+	}
+
+	// hash
+	h := fnv.New32a()
+	h.Write([]byte(key))
+	hash := h.Sum32()
+
+	return int(hash % uint32(maxParallelism))
+}
diff --git a/core/state.go b/core/state.go
new file mode 100644
index 0000000..d6d7847
--- /dev/null
+++ b/core/state.go
@@ -0,0 +1,10 @@
+package core
+
+import "context"
+
+// ValueState is for client side using to update state
+type ValueState[T any] interface {
+	Value(ctx context.Context) (T, error)
+	Update(ctx context.Context, newVal T) (T, error)
+	Clear(ctx context.Context) error
+}
diff --git a/core/state_backend.go b/core/state_backend.go
new file mode 100644
index 0000000..219bb63
--- /dev/null
+++ b/core/state_backend.go
@@ -0,0 +1,13 @@
+package core
+
+import "context"
+
+type StateBackend interface {
+	// SetCurrentKey will perform in Memory
+	SetCurrentKey(key string) error
+	// GetCurrentKey will perform in Memory
+	GetCurrentKey() string
+
+	// GetValueState will perform in disk
+	GetValueState(ctx context.Context, key string) (ValueState[any], error)
+}
diff --git a/state/memory_backend.go b/state/memory_backend.go
new file mode 100644
index 0000000..58e86e0
--- /dev/null
+++ b/state/memory_backend.go
@@ -0,0 +1,41 @@
+package state
+
+import (
+	"context"
+	"goflink/core"
+)
+
+// TODO: currently using Golang Map for go through the DAG pipline
+// This should be use index map index map[uint64]uint32  Hash(KeyGroup + StateName + Key) -> Offset
+// with 1GB of []byte allocation
+// This should be optimize with ZERO GC Scanning, Memory Alignment
+
+type MemoryStateBackend struct {
+	maxParallelism  int
+	currentKey      string
+	currentGroupKey int
+	// 3D structure StateName -> KeyGroup -> Key -> Value
+	states map[string]map[int]map[string]any
+}
+
+func NewMemoryStateBackend(maxParallelism int) *MemoryStateBackend {
+	return &MemoryStateBackend{
+		maxParallelism: maxParallelism,
+		states:         make(map[string]map[int]map[string]any),
+	}
+}
+
+func (ms *MemoryStateBackend) GetCurrentKey() string {
+	return ms.currentKey
+}
+
+func (ms *MemoryStateBackend) SetCurrentKey(key string) error {
+	ms.currentKey = key
+	ms.currentGroupKey = core.AssignToKeyGroup(key, ms.maxParallelism)
+	return nil
+}
+
+func (ms *MemoryStateBackend) GetValueState(ctx context.Context, key string) (core.ValueState[any], error) {
+	//TODO implement me
+	panic("implement me")
+}
-- 
cgit v1.2.3