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M2.1: Batch WAL writes #9

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Merged
SantanuKar43 merged 2 commits into from
Apr 27, 2026
Merged

M2.1: Batch WAL writes #9

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73778f9
add batch commit at fixed time interval
SantanuKar43 Apr 27, 2026
2bc7769
signal flush instead of fixed time interval
SantanuKar43 Apr 27, 2026
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2 changes: 1 addition & 1 deletion cmd/server/main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,7 @@ import (

const port = ":9000" // TODO configs
const walFilePath = "bin/wal.log" // TODO configs
const fsyncStrategy = wal.EVERY_SEC // TODO configs
const fsyncStrategy = wal.ALWAYS // TODO configs
const maxWalEntryLength = 1 << 30 // TODO configs

func main() {
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26 changes: 18 additions & 8 deletions internal/handler/handler.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ package handler
import (
"fmt"
"log"

"com.github.SantanuKar43/simple-kv/internal/protocol"
"com.github.SantanuKar43/simple-kv/internal/store"
"com.github.SantanuKar43/simple-kv/internal/wal"
Expand All @@ -15,9 +16,7 @@ func Handle(input string, store *store.Store, wal *wal.Wal) string {
if len(cmd.Args) != 2 {
return "ERR wrong number of arguments"
}

_, err := wal.Append(cmd.Name, cmd.Args[0], cmd.Args[1])
if err != nil {
if err := appendToWal(cmd, wal); err != nil {
return fmt.Sprintf("ERR unable to write to WAL: %s", err.Error())
}

Expand All @@ -36,9 +35,7 @@ func Handle(input string, store *store.Store, wal *wal.Wal) string {
if len(cmd.Args) != 1 {
return "ERR wrong number of arguments"
}

_, err := wal.Append(cmd.Name, cmd.Args[0])
if err != nil {
if err := appendToWal(cmd, wal); err != nil {
return fmt.Sprintf("ERR unable to write to WAL: %s", err.Error())
}

Expand All @@ -49,6 +46,19 @@ func Handle(input string, store *store.Store, wal *wal.Wal) string {
}
}

func appendToWal(cmd protocol.Command, wal *wal.Wal) error {
lsn, err := wal.Append(cmd.Name, cmd.Args[0])
if err != nil {
return err
}
wal.CommitSignal.L.Lock()
for lsn > wal.CommittedLSN {
wal.CommitSignal.Wait()
}
wal.CommitSignal.L.Unlock()
return nil
}

func Replay(input string, store *store.Store) {
cmd := protocol.Parse(input)
switch cmd.Name {
Expand All @@ -57,6 +67,6 @@ func Replay(input string, store *store.Store) {
case "DEL":
store.Delete(cmd.Args[0])
default:
log.Printf("invalid command parsed %s\n", cmd.Name)
log.Printf("invalid command parsed %s\n", cmd.Name)
}
}
}
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