PragmaTwice commented on code in PR #1342:
URL:
https://github.com/apache/incubator-kvrocks/pull/1342#discussion_r1144621512
##########
src/storage/redis_metadata.h:
##########
@@ -97,22 +97,45 @@ class InternalKey {
bool slot_id_encoded_;
};
+constexpr uint8_t METADATA_64BIT_ENCODING_MASK = 0x80;
+constexpr uint8_t METADATA_TYPE_MASK = 0x0f;
+
class Metadata {
public:
+ // metadata flags
+ // <(1-bit) 64bit-common-field-indicator> 0 0 0 <(4-bit) redis-type>
+ // 64bit-common-field-indicator: make `expire` and `size` 64bit instead of
32bit
+ // NOTE: `expire` is stored in milliseconds for 64bit, seconds for 32bit
+ // redis-type: RedisType for the key-value
uint8_t flags;
- int expire;
+
+ // expire timestamp, in milliseconds
+ uint64_t expire;
+
+ // the current version: 53bit timestamp + 11bit counter
uint64_t version;
- uint32_t size;
- public:
- explicit Metadata(RedisType type, bool generate_version = true);
+ // element size of the key-value
+ uint64_t size;
+
+ explicit Metadata(RedisType type, bool generate_version = true, bool
use_64bit_common_field = true);
Review Comment:
Yes, you are right.
##########
src/storage/redis_metadata.h:
##########
@@ -97,22 +97,45 @@ class InternalKey {
bool slot_id_encoded_;
};
+constexpr uint8_t METADATA_64BIT_ENCODING_MASK = 0x80;
+constexpr uint8_t METADATA_TYPE_MASK = 0x0f;
+
class Metadata {
public:
+ // metadata flags
+ // <(1-bit) 64bit-common-field-indicator> 0 0 0 <(4-bit) redis-type>
+ // 64bit-common-field-indicator: make `expire` and `size` 64bit instead of
32bit
+ // NOTE: `expire` is stored in milliseconds for 64bit, seconds for 32bit
+ // redis-type: RedisType for the key-value
uint8_t flags;
- int expire;
+
+ // expire timestamp, in milliseconds
+ uint64_t expire;
+
+ // the current version: 53bit timestamp + 11bit counter
uint64_t version;
- uint32_t size;
- public:
- explicit Metadata(RedisType type, bool generate_version = true);
+ // element size of the key-value
+ uint64_t size;
+
+ explicit Metadata(RedisType type, bool generate_version = true, bool
use_64bit_common_field = true);
Review Comment:
> maybe we can set 64-bit encoding in the constructor by default, and it
will be overwritten by the Decode method in case of decoding from the 'old'
format?
Yes, you are right.
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