From 9bf3b53533cdc9b95c921b71da755401f223f765 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Sun, 22 Dec 2013 19:59:12 +0100
Subject: shared: switch our hash table implementation over to SipHash

SipHash appears to be the new gold standard for hashing smaller strings
for hashtables these days, so let's make use of it.
---
 src/journal/journald-rate-limit.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

(limited to 'src/journal/journald-rate-limit.c')

diff --git a/src/journal/journald-rate-limit.c b/src/journal/journald-rate-limit.c
index 4b76221527..6d779d2966 100644
--- a/src/journal/journald-rate-limit.c
+++ b/src/journal/journald-rate-limit.c
@@ -56,7 +56,7 @@ struct JournalRateLimitGroup {
 
         char *id;
         JournalRateLimitPool pools[POOLS_MAX];
-        unsigned hash;
+        unsigned long hash;
 
         LIST_FIELDS(JournalRateLimitGroup, bucket);
         LIST_FIELDS(JournalRateLimitGroup, lru);
@@ -70,6 +70,8 @@ struct JournalRateLimit {
         JournalRateLimitGroup *lru, *lru_tail;
 
         unsigned n_groups;
+
+        uint8_t hash_key[16];
 };
 
 JournalRateLimit *journal_rate_limit_new(usec_t interval, unsigned burst) {
@@ -84,6 +86,8 @@ JournalRateLimit *journal_rate_limit_new(usec_t interval, unsigned burst) {
         r->interval = interval;
         r->burst = burst;
 
+        random_bytes(r->hash_key, sizeof(r->hash_key));
+
         return r;
 }
 
@@ -152,7 +156,7 @@ static JournalRateLimitGroup* journal_rate_limit_group_new(JournalRateLimit *r,
         if (!g->id)
                 goto fail;
 
-        g->hash = string_hash_func(g->id);
+        g->hash = string_hash_func(g->id, r->hash_key);
 
         journal_rate_limit_vacuum(r, ts);
 
@@ -199,7 +203,7 @@ static unsigned burst_modulate(unsigned burst, uint64_t available) {
 }
 
 int journal_rate_limit_test(JournalRateLimit *r, const char *id, int priority, uint64_t available) {
-        unsigned h;
+        unsigned long h;
         JournalRateLimitGroup *g;
         JournalRateLimitPool *p;
         unsigned burst;
@@ -217,7 +221,7 @@ int journal_rate_limit_test(JournalRateLimit *r, const char *id, int priority, u
 
         ts = now(CLOCK_MONOTONIC);
 
-        h = string_hash_func(id);
+        h = string_hash_func(id, r->hash_key);
         g = r->buckets[h % BUCKETS_MAX];
 
         LIST_FOREACH(bucket, g, g)
-- 
cgit v1.2.3-54-g00ecf