From 00ac50e3e98f751f43268338fda250c3df08cfa3 Mon Sep 17 00:00:00 2001
From: Yoni Fogel <yoni@tokutek.com>
Date: Wed, 17 Apr 2013 00:01:23 -0400
Subject: [PATCH] refs #5802 Fix calculations for probabilistic clock, take
into account things could be negative (so use int64_ts instead of uint_64)
and set appropriate max for size_current
git-svn-id: file:///svn/toku/tokudb@51207 c7de825b-a66e-492c-adef-691d508d4ae1
---
ft/cachetable.cc | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/ft/cachetable.cc b/ft/cachetable.cc
index c8b2d347d47..9b4a2e6ae79 100644
--- a/ft/cachetable.cc
+++ b/ft/cachetable.cc
@@ -3771,9 +3771,9 @@ bool evictor::run_eviction_on_pair(PAIR curr_in_clock) {
curr_in_clock->count--;
} else {
// generate a random number between 0 and 2^16
- assert(size_current < (1LL<<48)); // to protect against possible overflows
+ assert(size_current <= (INT64_MAX / ((1<<16)-1))); // to protect against possible overflows
int32_t rnd = myrandom_r(&m_random_data) % (1<<16);
- // The if-statement below will be true with probability of
+ // The if-statement below will be true with probability of
// curr_size/(average size of PAIR in cachetable)
// Here is how the math is done:
// average_size = size_current/n_in_table
@@ -3785,10 +3785,10 @@ bool evictor::run_eviction_on_pair(PAIR curr_in_clock) {
// if (2^16*curr_size*n_in_table/size_current > rnd)
// by multiplying each side of the equation by size_current, we get
// if (2^16*curr_size*n_in_table > rnd*size_current)
- // and dividing each side by 2^16,
+ // and dividing each side by 2^16,
// we get the if-clause below
- //
- if ((((uint64_t)curr_size) * n_in_table) >= (((uint64_t)rnd) * size_current)>>16) {
+ //
+ if ((((int64_t)curr_size) * n_in_table) >= (((int64_t)rnd) * size_current)>>16) {
curr_in_clock->count--;
}
}