[ltt-dev] [PATCH 3/7] rculfhash: make cds_lfht_lookup() more generic

[Lai Jiangshan]

On 11/03/2011 01:23 AM, Mathieu Desnoyers wrote:
> * Lai Jiangshan (laijs at cn.fujitsu.com) wrote:
>> We use hash value to determine the range of the object
>> and use cds_lfht_lookup_fct to lookup them.
>>
>> Signed-off-by: Lai Jiangshan <laijs at cn.fujitsu.com>
>> ---
>>  rculfhash.c            |    8 ++++----
>>  tests/test_urcu_hash.c |   25 ++++++++++++++++++++++---
>>  urcu/rculfhash.h       |    4 +++-
>>  3 files changed, 29 insertions(+), 8 deletions(-)
>>
>> diff --git a/rculfhash.c b/rculfhash.c
>> index d1a1766..29054cd 100644
>> --- a/rculfhash.c
>> +++ b/rculfhash.c
>> @@ -1391,14 +1391,14 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
>>  	return ht;
>>  }
>>  
>> -void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
>> +void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash,
>> +		cds_lfht_lookup_fct match, void *arg,
> 
> arg -> key ?
> 
> for "match", our approach is to provide this function as parameter to
> cds_lfht_new rather than pass it as parameter each time a lookup is
> performed. What is the reason why we should pass it here as a parameter?
> 

Allow the user define it.
In the test, I pass match = a function always returns true when need,
thus cds_lfht_lookup() returns the first node of same-hash-value-chain.

thanks,
lai


> 
>>  		struct cds_lfht_iter *iter)
>>  {
>>  	struct cds_lfht_node *node, *next, *dummy_node;
>>  	struct _cds_lfht_node *lookup;
>> -	unsigned long hash, reverse_hash, size;
>> +	unsigned long reverse_hash, size;
>>  
>> -	hash = ht->hash_fct(key, key_len, ht->hash_seed);
>>  	reverse_hash = bit_reverse_ulong(hash);
>>  
>>  	size = rcu_dereference(ht->t.size);
>> @@ -1421,7 +1421,7 @@ void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
>>  		if (caa_likely(!is_removed(next))
>>  		    && !is_dummy(next)
>>  		    && node->p.reverse_hash == reverse_hash
>> -		    && caa_likely(!ht->compare_fct(node->key, node->key_len, key, key_len))) {
>> +		    && caa_likely(match(node, arg))) {
>>  				break;
>>  		}
>>  		node = clear_flag(next);
>> diff --git a/tests/test_urcu_hash.c b/tests/test_urcu_hash.c
>> index e28c14a..4c45573 100644
>> --- a/tests/test_urcu_hash.c
>> +++ b/tests/test_urcu_hash.c
>> @@ -41,6 +41,8 @@
>>  #define DEFAULT_MIN_ALLOC_SIZE	1
>>  #define DEFAULT_RAND_POOL	1000000
>>  
>> +#define TEST_HASH_SEED	0x42UL
>> +
>>  /* Make this big enough to include the POWER5+ L3 cacheline size of 256B */
>>  #define CACHE_LINE_SIZE 4096
>>  
>> @@ -419,6 +421,23 @@ unsigned long test_compare(void *key1, size_t key1_len,
>>  		return 1;
>>  }
>>  
>> +static
>> +int test_match(struct cds_lfht_node *node, void *arg)
>> +{
>> +	return !test_compare(node->key, node->key_len,
>> +			arg, sizeof(unsigned long));
>> +}
>> +
>> +static
>> +void cds_lfht_test_lookup(struct cds_lfht *ht, void *key, size_t key_len,
>> +		struct cds_lfht_iter *iter)
>> +{
>> +	assert(key_len == sizeof(unsigned long));
>> +
>> +	cds_lfht_lookup(ht, test_hash(key, key_len, TEST_HASH_SEED),
>> +			test_match, key, iter);
>> +}
>> +
>>  void *thr_count(void *arg)
>>  {
>>  	printf_verbose("thread_begin %s, thread id : %lx, tid %lu\n",
>> @@ -479,7 +498,7 @@ void *thr_reader(void *_count)
>>  
>>  	for (;;) {
>>  		rcu_read_lock();
>> -		cds_lfht_lookup(test_ht,
>> +		cds_lfht_test_lookup(test_ht,
>>  			(void *)(((unsigned long) rand_r(&rand_lookup) % lookup_pool_size) + lookup_pool_offset),
>>  			sizeof(void *), &iter);
>>  		node = cds_lfht_iter_get_test_node(&iter);
>> @@ -574,7 +593,7 @@ void *thr_writer(void *_count)
>>  		} else {
>>  			/* May delete */
>>  			rcu_read_lock();
>> -			cds_lfht_lookup(test_ht,
>> +			cds_lfht_test_lookup(test_ht,
>>  				(void *)(((unsigned long) rand_r(&rand_lookup) % write_pool_size) + write_pool_offset),
>>  				sizeof(void *), &iter);
>>  			ret = cds_lfht_del(test_ht, &iter);
>> @@ -932,7 +951,7 @@ int main(int argc, char **argv)
>>  	 * thread from the point of view of resize.
>>  	 */
>>  	rcu_register_thread();
>> -	test_ht = cds_lfht_new(test_hash, test_compare, 0x42UL,
>> +	test_ht = cds_lfht_new(test_hash, test_compare, TEST_HASH_SEED,
>>  			init_hash_size, min_hash_alloc_size,
>>  			(opt_auto_resize ? CDS_LFHT_AUTO_RESIZE : 0) |
>>  			CDS_LFHT_ACCOUNTING, NULL);
>> diff --git a/urcu/rculfhash.h b/urcu/rculfhash.h
>> index f4f3373..b56fe56 100644
>> --- a/urcu/rculfhash.h
>> +++ b/urcu/rculfhash.h
>> @@ -86,6 +86,7 @@ typedef unsigned long (*cds_lfht_hash_fct)(void *key, size_t length,
>>  					unsigned long seed);
>>  typedef unsigned long (*cds_lfht_compare_fct)(void *key1, size_t key1_len,
>>  					void *key2, size_t key2_len);
>> +typedef int (*cds_lfht_lookup_fct)(struct cds_lfht_node *node, void *arg);
>>  
>>  /*
>>   * cds_lfht_node_init - initialize a hash table node
>> @@ -203,7 +204,8 @@ void cds_lfht_count_nodes(struct cds_lfht *ht,
>>   * Call with rcu_read_lock held.
>>   * Threads calling this API need to be registered RCU read-side threads.
>>   */
>> -void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
>> +void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash,
>> +		cds_lfht_lookup_fct match, void *arg,
>>  		struct cds_lfht_iter *iter);
>>  
>>  /*
>> -- 
>> 1.7.4.4
>>
>