separated commands into their own files TODO: refactor all commands to work like this

6 files changed, 306 insertions, 0 deletions

diff --git a/pkg/commands/command-registry.go b/pkg/commands/command-registry.go
new file mode 100644
index 0000000..0193da1
--- /dev/null
+++ b/pkg/commands/command-registry.go
@@ -0,0 +1,58 @@
+package commands
+
+import (
+	"errors"
+	"redisClone/pkg/core"
+)
+func SingleKey(args []string) []string {
+    return []string{args[1]}
+}
+
+func AllSubsequentKeys(args []string) []string {
+    return args[1:]
+}
+
+func NoKeys(args []string) []string {
+    return nil
+}
+
+type CommandDef struct{
+	MinArgs int
+	ExtractKeys func(args []string)[]string
+	Execute func(args []string, getShard func(k string) *core.Shard) interface{}
+}
+
+func DispatchBaseCommand(db core.RedisDB ,commandName string, args []string) interface{} {
+    cmd, exists := Registry[commandName]
+    if !exists {
+        return nil
+    }
+
+    if len(args) < cmd.MinArgs {
+        return errors.New("wrong number of arguments")
+    }
+
+    keys := cmd.ExtractKeys(args)
+    
+    db.Lock(keys)
+    defer db.Unlock(keys)
+    return cmd.Execute(args, db.GetShard)
+}
+
+var Registry = map[string]CommandDef{
+    "GET": {
+        MinArgs:     2,
+        ExtractKeys: SingleKey,
+        Execute: Get,
+    },
+	"SET": {
+		MinArgs:	3,
+		ExtractKeys: SingleKey,
+		Execute: Set,
+	},
+    "DEL": {
+        MinArgs:     2,
+        ExtractKeys: AllSubsequentKeys,
+        Execute: Del,
+    },
+}
\ No newline at end of file
diff --git a/pkg/commands/del.go b/pkg/commands/del.go
new file mode 100644
index 0000000..bc7d3f9
--- /dev/null
+++ b/pkg/commands/del.go
@@ -0,0 +1,15 @@
+package commands
+
+import "redisClone/pkg/core"
+
+func Del(args []string, getShard func(k string) *core.Shard) interface{} {
+            count := 0
+            for _, key := range args[1:] {
+                shard := getShard(key)
+                if _, exists := shard.Data[key]; exists {
+                    delete(shard.Data, key)
+                    count++
+                }
+            }
+            return count
+        }
\ No newline at end of file
diff --git a/pkg/commands/get.go b/pkg/commands/get.go
new file mode 100644
index 0000000..9dc2bcd
--- /dev/null
+++ b/pkg/commands/get.go
@@ -0,0 +1,28 @@
+package commands
+
+import (
+	"errors"
+	"redisClone/pkg/core"
+	"time"
+)
+
+func Get(args []string, getShard func(k string) *core.Shard) interface{} {
+			key := args[1]
+			s := getShard(key)
+			item, exists := s.Data[key]
+			if !exists {
+				return nil
+			}
+
+			if item.ExpiresAt != nil && time.Now().After(*item.ExpiresAt) {
+				delete(s.Data, key)
+				return nil
+			}
+
+			strValue, ok := item.Value.(string)
+			if !ok {
+				err := errors.New("WRONGTYPE Operation against a key holding the wrong kind of value")
+				return err
+			}
+			return strValue
+        }
\ No newline at end of file
diff --git a/pkg/commands/set.go b/pkg/commands/set.go
new file mode 100644
index 0000000..19175f1
--- /dev/null
+++ b/pkg/commands/set.go
@@ -0,0 +1,10 @@
+package commands
+
+import "redisClone/pkg/core"
+
+func Set(args []string, getShard func(k string) *core.Shard) interface{} {
+			key := args[1]
+			item := core.Item{Value: args[2]}
+			getShard(key).Data[key] = item
+			return core.SimpleString("OK")
+		}
\ No newline at end of file
diff --git a/pkg/core/redisDB.go b/pkg/core/redisDB.go
new file mode 100644
index 0000000..cbd737c
--- /dev/null
+++ b/pkg/core/redisDB.go
@@ -0,0 +1,61 @@
+package core
+
+import (
+	"fmt"
+	"time"
+)
+
+
+type Item struct {
+	Value any
+	ExpiresAt *time.Time
+}
+
+type RedisDB struct {
+	Shards []*Shard
+}
+
+type SimpleString string
+
+func SerializeRESP(v any) []byte {
+    switch val := v.(type) {
+    case string:
+		bulkString := fmt.Sprintf("$%d\r\n%s\r\n", len(val), val)
+        return []byte(bulkString)
+    case int:
+		integerString := fmt.Sprintf(":%d\r\n",val)
+        return []byte(integerString)
+    case nil:
+		return []byte("$-1\r\n")
+    case error:
+        errorString := fmt.Sprintf("-ERR %s\r\n",val.Error())
+		return []byte(errorString)
+    case []string:
+        size := len(val)
+		result := []byte(fmt.Sprintf("*%d\r\n", size))
+		for i := 0; i < size; i++ {
+			result = append(result, SerializeRESP(val[i])...)
+		}
+		return result
+	case []any:
+		size := len(val)
+		result := []byte(fmt.Sprintf("*%d\r\n", size))
+		for i := 0; i < size; i++ {
+			result = append(result, SerializeRESP(val[i])...)
+		}
+		return result
+	case map[string]string:
+		size := len(val)
+		result := []byte(fmt.Sprintf("*%d\r\n", size*2))
+		for key, value := range val {
+			result = append(result, SerializeRESP(key)...)
+			result = append(result, SerializeRESP(value)...)
+		}
+		return result
+	case SimpleString:
+		simpleStr := fmt.Sprintf("+%s\r\n", val)
+		return []byte(simpleStr)
+    default:
+        return []byte("-ERR internal server error: unknown type\r\n")
+    }
+}
diff --git a/pkg/core/shards.go b/pkg/core/shards.go
new file mode 100644
index 0000000..5ede61c
--- /dev/null
+++ b/pkg/core/shards.go
@@ -0,0 +1,134 @@
+package core
+
+import (
+	"hash/fnv"
+	"sort"
+	"sync"
+)
+const NumShards = 16
+
+type Shard struct{
+	Mu sync.RWMutex
+	Id int
+	Data map[string]Item
+}
+
+func (db *RedisDB) GetShard(key string)*Shard{
+	hash := fnv.New64a()
+	hash.Write([]byte(key))
+	val := hash.Sum64()
+
+	return db.Shards[val%NumShards]
+}
+
+func (db *RedisDB) Execute(key string, fn func(*Shard) interface{}) interface{} {
+    shard := db.GetShard(key)
+    shard.Mu.Lock()
+    defer shard.Mu.Unlock()
+    return fn(shard)
+}
+func (db *RedisDB) ExecuteRead(key string, fn func(*Shard) interface{}) interface{} {
+    shard := db.GetShard(key)
+    shard.Mu.RLock()
+    defer shard.Mu.RUnlock()
+    return fn(shard)
+}
+func ( db *RedisDB) ExecuteMulti(keys []string, fn func([]*Shard) interface{})interface{}{
+	if len(keys) == 1{
+		shard := db.GetShard(keys[0])
+		shard.Mu.Lock()
+		defer shard.Mu.Unlock()
+		Shards := []*Shard{shard}
+		return fn(Shards)
+	}else{
+		shardMap := make(map[int]*Shard)
+		for _, k := range keys {
+			shard := db.GetShard(k)
+			shardMap[shard.Id] = shard
+		}
+		var sortedIDs []int
+		for Id := range shardMap {
+			sortedIDs = append(sortedIDs, Id)
+		}
+		sort.Ints(sortedIDs)
+		for _, Id := range sortedIDs{
+			shardMap[Id].Mu.Lock()
+		}
+		defer func(){
+			for i := len(sortedIDs)-1; i >= 0; i --{
+				shardMap[sortedIDs[i]].Mu.Unlock()
+			}
+		}()
+		
+		Shards := make([]*Shard, 0, len(shardMap))
+		for _, Id := range sortedIDs {
+			Shards = append(Shards, shardMap[Id])
+		}
+		return fn(Shards)
+	}
+}
+
+func ( db *RedisDB) ExecuteAll(fn func([]*Shard) interface{})interface{}{
+	for _, shard := range db.Shards {
+        shard.Mu.Lock()
+    }
+
+	defer func(){
+		for i := len(db.Shards)-1;i >= 0; i --{
+			db.Shards[i].Mu.Unlock()
+		}
+	}()
+
+	return fn(db.Shards)
+}
+
+func ( db *RedisDB) ExecuteReadAll(fn func([]*Shard) interface{})interface{}{
+	for _, shard := range db.Shards {
+        shard.Mu.RLock()
+    }
+
+	defer func(){
+		for i := len(db.Shards)-1;i >= 0; i --{
+			db.Shards[i].Mu.RUnlock()
+		}
+	}()
+
+	return fn(db.Shards)
+}
+
+func ( db *RedisDB) Lock(keys []string){
+		if len(keys) == 1{
+		shard := db.GetShard(keys[0])
+		shard.Mu.Lock()
+	}else{
+		shardMap := make(map[int]*Shard)
+		for _, k := range keys {
+			shard := db.GetShard(k)
+			shardMap[shard.Id] = shard
+		}
+		var sortedIDs []int
+		for Id := range shardMap {
+			sortedIDs = append(sortedIDs, Id)
+		}
+		sort.Ints(sortedIDs)
+		for _, Id := range sortedIDs{
+			shardMap[Id].Mu.Lock()
+		}
+	}
+}
+func ( db *RedisDB) Unlock(keys []string){
+	shardMap := make(map[int]*Shard)
+	for _, k := range keys {
+		shard := db.GetShard(k)
+		shardMap[shard.Id] = shard
+	}
+	var sortedIDs []int
+	for Id := range shardMap {
+		sortedIDs = append(sortedIDs, Id)
+	}
+	sort.Ints(sortedIDs)
+
+	for i := len(sortedIDs)-1; i >= 0; i --{
+		shardMap[sortedIDs[i]].Mu.Unlock()
+	}
+}
\ No newline at end of file