chore: add protocol doc

Author: RitheeshBaradwaj

PROTOCOL

@@ -0,0 +1,109 @@
+# **CacheX Protocol: Request and Response Format**
+
+## **Request Format**
+CacheX follows a **binary protocol** for efficient parsing and communication. Each request consists of **multiple arguments** encoded in a structured format.
+
+### **Structure**
+| Field  | Type   | Description |
+|--------|--------|-------------|
+| `nstr` | `uint32_t` | Number of arguments (e.g., `SET key value` has 3 arguments) |
+| `len1` | `uint32_t` | Length of the first argument |
+| `str1` | `char[]` | First argument (e.g., `"SET"`) |
+| `len2` | `uint32_t` | Length of the second argument |
+| `str2` | `char[]` | Second argument (e.g., `"key"`) |
+| `lenN` | `uint32_t` | Length of the Nth argument |
+| `strN` | `char[]` | Nth argument |
+
+### **Binary Layout**
+```
++------+-----+------+-----+------+-----+-----+------+
+| nstr | len | str1 | len | str2 | ... | len | strN |
++------+-----+------+-----+------+-----+-----+------+
+   4B     4B   ...
+```
+
+### **Example**
+#### **SET Request**
+**Command:** `SET key value`  
+**Binary Format (Network Order)**
+```
+[ 0x00000003 ]  // Number of arguments (3)
+[ 0x00000003 ]  // Length of "SET"
+[ "SET" ]       // Command
+[ 0x00000003 ]  // Length of "key"
+[ "key" ]       // Key
+[ 0x00000005 ]  // Length of "value"
+[ "value" ]     // Value
+```
+
+#### **GET Request**
+**Command:** `GET key`  
+**Binary Format**
+```
+[ 0x00000002 ]  // Number of arguments (2)
+[ 0x00000003 ]  // Length of "GET"
+[ "GET" ]       // Command
+[ 0x00000003 ]  // Length of "key"
+[ "key" ]       // Key
+```
+
+---
+
+## **Response Format**
+The response contains a **status code** followed by optional **data**.
+
+### **Structure**
+| Field     | Type   | Description |
+|-----------|--------|-------------|
+| `length`  | `uint32_t` | Total response length (excluding itself) |
+| `status`  | `uint32_t` | Response status code |
+| `data`    | `char[]` | (Optional) Response data |
+
+### **Binary Layout**
+```
++--------+-----------+
+| length | status    |
++--------+-----------+
+|  data  |(optional) |
++--------------------+
+   4B       ...
+```
+
+### **Response Status Codes**
+| Code  | Meaning |
+|-------|---------|
+| `0` (`RES_OK`) | Success |
+| `1` (`RES_ERR`) | Error |
+| `2` (`RES_NX`) | Key not found |
+
+---
+
+### **Example Responses**
+#### **SET Response**
+```
+[ 0x00000004 ]  // Response length (4 bytes for status)
+[ 0x00000000 ]  // Status: RES_OK (0)
+```
+
+#### **GET Response (Key Found)**
+```
+[ 0x00000009 ]  // Response length (4 bytes for status + 5 bytes data)
+[ 0x00000000 ]  // Status: RES_OK (0)
+[ "value" ]     // Data: "value"
+```
+
+#### **GET Response (Key Not Found)**
+```
+[ 0x00000004 ]  // Response length (4 bytes for status)
+[ 0x00000002 ]  // Status: RES_NX (2)
+```
+
+#### **Invalid Command Response**
+```
+[ 0x00000004 ]  // Response length (4 bytes for status)
+[ 0x00000001 ]  // Status: RES_ERR (1)
+```
+
+---
+
+Handles large requests with up to **200,000 arguments** safely.

PROTOCOL.md

@@ -1,3 +1,7 @@
 # CacheX  
 
 CacheX is a high-performance cache server written in **C and C++**, designed to explore **low-level programming, data structures, and scalable network systems**. This project is a hands-on approach to learning **efficient memory management, high-throughput networking, and system-level optimizations** while building a fast and lightweight caching solution.
+
+## CacheX Protocol
+
+[PROTOCOL](./PROTOCOL.md)

README.md

@@ -10,6 +10,7 @@
 
 constexpr size_t kHeaderSize = 4;
 constexpr size_t kMaxPayloadSize = 32 * 1024 * 1024;  // 32 << 20 (32MB)
+constexpr size_t kMaxArgs = 200 * 1000;
 
 static inline int32_t read_all(int fd, uint8_t *buf, size_t n) {
     size_t total_read = 0;
@@ -40,7 +41,7 @@ static inline int32_t write_all(int fd, const uint8_t *buf, size_t n) {
 }
 
 // Append to the back
-static void buffer_append(std::vector<uint8_t> &buf, const uint8_t *data, size_t len) {
+static inline void buffer_append(std::vector<uint8_t> &buf, const uint8_t *data, size_t len) {
     buf.insert(buf.end(), data, data + len);
 }