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Introduce an enum for flag types in LRUHandle (#5024)

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Summary:
Replace the integers used for setting and querying the various
flags in LRUHandle with enum values to improve readability.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5024

Differential Revision: D14263429

Pulled By: ltamasi

fbshipit-source-id: b1b9ba95635265f122c2b40da73850eaac18227a
This commit is contained in:
Levi Tamasi 2019-02-28 11:48:45 -08:00 committed by Facebook Github Bot
parent 5e298f865b
commit f83eecff99
1 changed files with 23 additions and 15 deletions
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38
cache/lru_cache.h vendored
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@ -55,10 +55,18 @@ struct LRUHandle {
// cache itself is counted as 1 // cache itself is counted as 1
// Include the following flags: // Include the following flags:
// in_cache: whether this entry is referenced by the hash table. // IN_CACHE: whether this entry is referenced by the hash table.
// is_high_pri: whether this entry is high priority entry. // IS_HIGH_PRI: whether this entry is high priority entry.
// in_high_pri_pool: whether this entry is in high-pri pool. // IN_HIGH_PRI_POOL: whether this entry is in high-pri pool.
char flags; // HAS_HIT: whether this entry has had any lookups (hits).
enum Flags : uint8_t {
IN_CACHE = (1 << 0),
IS_HIGH_PRI = (1 << 1),
IN_HIGH_PRI_POOL = (1 << 2),
HAS_HIT = (1 << 3),
};
uint8_t flags;
uint32_t hash; // Hash of key(); used for fast sharding and comparisons uint32_t hash; // Hash of key(); used for fast sharding and comparisons
@ -74,36 +82,36 @@ struct LRUHandle {
} }
} }
bool InCache() { return flags & 1; } bool InCache() const { return flags & IN_CACHE; }
bool IsHighPri() { return flags & 2; } bool IsHighPri() const { return flags & IS_HIGH_PRI; }
bool InHighPriPool() { return flags & 4; } bool InHighPriPool() const { return flags & IN_HIGH_PRI_POOL; }
bool HasHit() { return flags & 8; } bool HasHit() const { return flags & HAS_HIT; }
void SetInCache(bool in_cache) { void SetInCache(bool in_cache) {
if (in_cache) { if (in_cache) {
flags |= 1; flags |= IN_CACHE;
} else { } else {
flags &= ~1; flags &= ~IN_CACHE;
} }
} }
void SetPriority(Cache::Priority priority) { void SetPriority(Cache::Priority priority) {
if (priority == Cache::Priority::HIGH) { if (priority == Cache::Priority::HIGH) {
flags |= 2; flags |= IS_HIGH_PRI;
} else { } else {
flags &= ~2; flags &= ~IS_HIGH_PRI;
} }
} }
void SetInHighPriPool(bool in_high_pri_pool) { void SetInHighPriPool(bool in_high_pri_pool) {
if (in_high_pri_pool) { if (in_high_pri_pool) {
flags |= 4; flags |= IN_HIGH_PRI_POOL;
} else { } else {
flags &= ~4; flags &= ~IN_HIGH_PRI_POOL;
} }
} }
void SetHit() { flags |= 8; } void SetHit() { flags |= HAS_HIT; }
void Free() { void Free() {
assert((refs == 1 && InCache()) || (refs == 0 && !InCache())); assert((refs == 1 && InCache()) || (refs == 0 && !InCache()));