From 0529fd1dde97494f63c78584cd70910c959fea87 Mon Sep 17 00:00:00 2001
From: hippoz <10706925-hippoz@users.noreply.gitlab.com>
Date: Sun, 22 Jan 2023 20:26:46 +0200
Subject: [PATCH] optimize name lookup

---
 server.c | 30 ++++++++++++++++++++++--------
 server.h |  2 ++
 2 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/server.c b/server.c
index 6a11171..b8f05c0 100644
--- a/server.c
+++ b/server.c
@@ -19,12 +19,12 @@
 
 
 // https://en.wikipedia.org/wiki/Fowler-Noll-Vo_hash_function#FNV-1a_hash
-uint64_t hashmap_hash(const char *bytes, size_t map_len)
+static inline uint32_t hashmap_hash(const char *bytes, int map_len)
 {
-    uint64_t hash = 0xcbf29ce484222325;
+    uint32_t hash = 0x811c9dc5;
 
     while (*bytes++) {
-        hash *= 0x100000001b3;
+        hash *= 0x01000193;
         hash ^= *bytes;
     }
 
@@ -105,6 +105,8 @@ Bus *bus_create(const char *socket_path)
     for (int i = 0; i < BUS_MAX_NAMES; i++) {
         s->names[i].client = NULL;
         s->names[i].name = NULL;
+        s->names[i].root_index = i;
+        s->names[i].chain_count = 0;
     }
     s->names_count = 0;
     s->clients_count = 0;
@@ -139,11 +141,15 @@ int bus_client_add(Bus *s, int fd)
     return -1;
 }
 
-int bus_name_find(Bus *s, char *name)
+static inline int bus_name_find(Bus *s, char *name)
 {
     int bucket = hashmap_hash(name, BUS_MAX_NAMES);
 
-    for (int i = bucket; i < bucket + 12 && i < BUS_MAX_NAMES; i++) {
+    if (s->names[bucket].name && s->names[bucket].chain_count == 0) {
+        return bucket;
+    }
+
+    for (int i = bucket + 1; i < bucket + 12 && i < BUS_MAX_NAMES; i++) {
         if (s->names[i].name && strcmp(s->names[i].name, name) == 0) {
             return i;
         }
@@ -158,12 +164,12 @@ BusClient *bus_name_find_client(Bus *s, char *name)
     if (name_index < 0) {
         return NULL;
     }
-    
-    if (!s->names[name_index].client) {
+
+    if (unlikely(!s->names[name_index].client)) {
         return NULL;
     }
 
-    if (s->names[name_index].client->state != BUS_CLIENT_STATE_READY) {
+    if (unlikely(s->names[name_index].client->state != BUS_CLIENT_STATE_READY)) {
         return NULL;
     }
 
@@ -182,6 +188,10 @@ BusName *bus_name_add(Bus *s, char *name, BusClient *client)
         if (!s->names[i].client) {
             for (int j = 0; j < BUS_NAMES_PER_CLIENT; j++) {
                 if (!client->owned_names[j]) {
+                    if (i != bucket) {
+                        s->names[bucket].chain_count++;
+                    }
+                    s->names[i].root_index = bucket;
                     client->owned_names[j] = &s->names[i];
                     s->names[i].client = client;
                     s->names[i].name = name;
@@ -266,6 +276,9 @@ void bus_name_remove(Bus *s, BusName *name)
     name->client = NULL;
 
     s->names_count--;
+    if (&s->names[name->root_index] != name) {
+        s->names[name->root_index].chain_count--;
+    }
 }
 
 void bus_client_remove(Bus *s, BusClient *c)
@@ -284,6 +297,7 @@ void bus_client_remove(Bus *s, BusClient *c)
         c->owned_names[j] = NULL;
     }
 
+    bus_name_remove(s, c->unique_name);
     c->unique_name = NULL;
     c->match_count = 0;
     c->fd = -1;
diff --git a/server.h b/server.h
index 5d6503d..1f700bf 100644
--- a/server.h
+++ b/server.h
@@ -33,6 +33,8 @@ enum {
 typedef struct bus_name {
     char *name;
     struct bus_client *client;
+    uint16_t chain_count;
+    uint16_t root_index;
 } BusName;
 
 typedef struct bus_client {