[ISSUE #1288]⚡️Add doc for MessageSysFlag and optimize code (#1289)

Author: mxsm

rocketmq-common/src/common/sys_flag/message_sys_flag.rs

@@ -1,42 +1,62 @@
 use crate::common::compression::compression_type::CompressionType;
 
+// Meaning of each bit in the system flag
+///
+/// | bit    | 7 | 6 | 5         | 4        | 3           | 2                | 1                | 0                |
+/// |--------|---|---|-----------|----------|-------------|------------------|------------------|------------------|
+/// | byte 1 |   |   | STOREHOST | BORNHOST | TRANSACTION | TRANSACTION      | MULTI_TAGS       | COMPRESSED       |
+/// | byte 2 |   |   |           |          |             | COMPRESSION_TYPE | COMPRESSION_TYPE | COMPRESSION_TYPE |
+/// | byte 3 |   |   |           |          |             |                  |                  |                  |
+/// | byte 4 |   |   |           |          |             |                  |                  |
 pub struct MessageSysFlag;
 
 impl MessageSysFlag {
-    pub const BORNHOST_V6_FLAG: i32 = 0x1 << 4;
     pub const COMPRESSED_FLAG: i32 = 0x1;
-    // COMPRESSION_TYPE
-    pub const COMPRESSION_LZ4_TYPE: i32 = 0x1 << 8;
-    pub const COMPRESSION_TYPE_COMPARATOR: i32 = 0x7 << 8;
-    pub const COMPRESSION_ZLIB_TYPE: i32 = 0x3 << 8;
-    pub const COMPRESSION_ZSTD_TYPE: i32 = 0x2 << 8;
-    pub const INNER_BATCH_FLAG: i32 = 0x1 << 7;
     pub const MULTI_TAGS_FLAG: i32 = 0x1 << 1;
-    pub const NEED_UNWRAP_FLAG: i32 = 0x1 << 6;
-    pub const STOREHOSTADDRESS_V6_FLAG: i32 = 0x1 << 5;
-    pub const TRANSACTION_COMMIT_TYPE: i32 = 0x2 << 2;
+
+    //Transaction related flag
     pub const TRANSACTION_NOT_TYPE: i32 = 0;
     pub const TRANSACTION_PREPARED_TYPE: i32 = 0x1 << 2;
+    pub const TRANSACTION_COMMIT_TYPE: i32 = 0x2 << 2;
     pub const TRANSACTION_ROLLBACK_TYPE: i32 = 0x3 << 2;
 
-    pub fn get_transaction_value(flag: i32) -> i32 {
+    //Flag of the message properties
+    pub const BORNHOST_V6_FLAG: i32 = 0x1 << 4;
+    pub const STOREHOSTADDRESS_V6_FLAG: i32 = 0x1 << 5;
+
+    //Mark the flag for batch to avoid conflict
+    pub const NEED_UNWRAP_FLAG: i32 = 0x1 << 6;
+    pub const INNER_BATCH_FLAG: i32 = 0x1 << 7;
+
+    // COMPRESSION_TYPE
+    pub const COMPRESSION_LZ4_TYPE: i32 = 0x1 << 8;
+    pub const COMPRESSION_ZSTD_TYPE: i32 = 0x2 << 8;
+    pub const COMPRESSION_ZLIB_TYPE: i32 = 0x3 << 8;
+    pub const COMPRESSION_TYPE_COMPARATOR: i32 = 0x7 << 8;
+
+    #[inline]
+    pub const fn get_transaction_value(flag: i32) -> i32 {
         flag & Self::TRANSACTION_ROLLBACK_TYPE
     }
 
-    pub fn reset_transaction_value(flag: i32, transaction_type: i32) -> i32 {
+    #[inline]
+    pub const fn reset_transaction_value(flag: i32, transaction_type: i32) -> i32 {
         (flag & !Self::TRANSACTION_ROLLBACK_TYPE) | transaction_type
     }
 
-    pub fn clear_compressed_flag(flag: i32) -> i32 {
+    #[inline]
+    pub const fn clear_compressed_flag(flag: i32) -> i32 {
         flag & !Self::COMPRESSED_FLAG
     }
 
+    #[inline]
     pub fn get_compression_type(flag: i32) -> CompressionType {
         let compression_type_value = (flag & Self::COMPRESSION_TYPE_COMPARATOR) >> 8;
         CompressionType::find_by_value(compression_type_value)
     }
 
-    pub fn check(flag: i32, expected_flag: i32) -> bool {
+    #[inline]
+    pub const fn check(flag: i32, expected_flag: i32) -> bool {
         (flag & expected_flag) != 0
     }
 }