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should use LLONG_MAX for INVALID_EXPIRE not LLONG_MIN and add better comments

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Former-commit-id: 1ab19b445f00a9ccdab13bf6b96363d068e2fa02
This commit is contained in:
malavan 2021-08-18 20:59:01 +00:00
parent 69f3e7c802
commit 67300040f7
1 changed files with 7 additions and 2 deletions
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9
src/expire.h
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@ -1,7 +1,11 @@
#pragma once
// eventually this number might actually end up being a valid expire time, this could cause bugs so at that time it might be a good idea to use a larger data type.
#define INVALID_EXPIRE (LLONG_MIN & ~((1LL) << (sizeof(long long)*CHAR_BIT - 1)))
/*
* INVALID_EXPIRE is the value we set the expireEntry's m_when value to when the main key is not expired and the value we return when we try to get the expire time of a key or subkey that is not expired
* Want this value to be LLONG_MAX however we use the most significant bit of m_when as a flag to see if the expireEntry is Fat or not so we want to ensure that it is unset hence the (& ~((1LL) << (sizeof(long long)*CHAR_BIT - 1)))
* Eventually this number might actually end up being a valid expire time, this could cause bugs so at that time it might be a good idea to use a larger data type.
*/
#define INVALID_EXPIRE (LLONG_MAX & ~((1LL) << (sizeof(long long)*CHAR_BIT - 1)))
class expireEntryFat
{
@ -56,6 +60,7 @@ class expireEntry {
} u;
long long m_when; // bit wise and with FFatMask means this is a fat entry and we should use the pointer
/* Mask to check if an entry is Fat, most significant bit of m_when being set means it is Fat otherwise it is not */
long long FFatMask() const noexcept {
return (1LL) << (sizeof(long long)*CHAR_BIT - 1);
}