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Commitd7694fc

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Consolidate the function pointer types used by dshash.c.
Commit8c0d7ba introduced dshash with hashand compare functions like DynaHash's, and also variants that take a userdata pointer instead of size. Simplify the interface by merging them intoa single pair of function pointer types that take both size and a user datapointer.Since it is anticipated that memcmp and tag_hash behavior will be a commonrequirement, provide wrapper functions dshash_memcmp and dshash_memhash thatconform to the new function types.Author: Thomas MunroReviewed-By: Andres FreundDiscussion:https://postgr.es/m/20170823054644.efuzftxjpfi6wwqs%40alap3.anarazel.de
1 parent4569715 commitd7694fc

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2 files changed

+39
-63
lines changed

2 files changed

+39
-63
lines changed

‎src/backend/lib/dshash.c‎

Lines changed: 29 additions & 36 deletions
Original file line numberDiff line numberDiff line change
@@ -35,6 +35,7 @@
3535
#include"storage/ipc.h"
3636
#include"storage/lwlock.h"
3737
#include"utils/dsa.h"
38+
#include"utils/hsearch.h"
3839
#include"utils/memutils.h"
3940

4041
/*
@@ -188,24 +189,15 @@ static inline bool equal_keys(dshash_table *hash_table,
188189
/*
189190
* Create a new hash table backed by the given dynamic shared area, with the
190191
* given parameters. The returned object is allocated in backend-local memory
191-
* using the current MemoryContext. If 'arg' is non-null, the arg variants of
192-
* hash and compare functions must be provided in 'params' and 'arg' will be
193-
* passed down to them.
192+
* using the current MemoryContext. 'arg' will be passed through to the
193+
* compare and hash functions.
194194
*/
195195
dshash_table*
196196
dshash_create(dsa_area*area,constdshash_parameters*params,void*arg)
197197
{
198198
dshash_table*hash_table;
199199
dsa_pointercontrol;
200200

201-
/* Sanity checks on the set of supplied functions. */
202-
Assert((params->compare_function!=NULL) ^
203-
(params->compare_arg_function!=NULL));
204-
Assert((params->hash_function!=NULL) ^
205-
(params->hash_arg_function!=NULL));
206-
Assert(arg==NULL|| (params->compare_arg_function!=NULL));
207-
Assert(arg==NULL|| (params->hash_arg_function!=NULL));
208-
209201
/* Allocate the backend-local object representing the hash table. */
210202
hash_table=palloc(sizeof(dshash_table));
211203

@@ -263,9 +255,8 @@ dshash_create(dsa_area *area, const dshash_parameters *params, void *arg)
263255

264256
/*
265257
* Attach to an existing hash table using a handle. The returned object is
266-
* allocated in backend-local memory using the current MemoryContext. If
267-
* 'arg' is non-null, the arg variants of hash and compare functions must be
268-
* provided in 'params' and 'arg' will be passed down to them.
258+
* allocated in backend-local memory using the current MemoryContext. 'arg'
259+
* will be passed through to the compare and hash functions.
269260
*/
270261
dshash_table*
271262
dshash_attach(dsa_area*area,constdshash_parameters*params,
@@ -274,14 +265,6 @@ dshash_attach(dsa_area *area, const dshash_parameters *params,
274265
dshash_table*hash_table;
275266
dsa_pointercontrol;
276267

277-
/* Sanity checks on the set of supplied functions. */
278-
Assert((params->compare_function!=NULL) ^
279-
(params->compare_arg_function!=NULL));
280-
Assert((params->hash_function!=NULL) ^
281-
(params->hash_arg_function!=NULL));
282-
Assert(arg==NULL|| (params->compare_arg_function!=NULL));
283-
Assert(arg==NULL|| (params->hash_arg_function!=NULL));
284-
285268
/* Allocate the backend-local object representing the hash table. */
286269
hash_table=palloc(sizeof(dshash_table));
287270

@@ -582,6 +565,24 @@ dshash_release_lock(dshash_table *hash_table, void *entry)
582565
LWLockRelease(PARTITION_LOCK(hash_table,partition_index));
583566
}
584567

568+
/*
569+
* A compare function that forwards to memcmp.
570+
*/
571+
int
572+
dshash_memcmp(constvoid*a,constvoid*b,size_tsize,void*arg)
573+
{
574+
returnmemcmp(a,b,size);
575+
}
576+
577+
/*
578+
* A hash function that forwards to tag_hash.
579+
*/
580+
dshash_hash
581+
dshash_memhash(constvoid*v,size_tsize,void*arg)
582+
{
583+
returntag_hash(v,size);
584+
}
585+
585586
/*
586587
* Print debugging information about the internal state of the hash table to
587588
* stderr. The caller must hold no partition locks.
@@ -874,11 +875,9 @@ delete_item_from_bucket(dshash_table *hash_table,
874875
staticinlinedshash_hash
875876
hash_key(dshash_table*hash_table,constvoid*key)
876877
{
877-
if (hash_table->params.hash_arg_function!=NULL)
878-
returnhash_table->params.hash_arg_function(key,hash_table->arg);
879-
else
880-
returnhash_table->params.hash_function(key,
881-
hash_table->params.key_size);
878+
returnhash_table->params.hash_function(key,
879+
hash_table->params.key_size,
880+
hash_table->arg);
882881
}
883882

884883
/*
@@ -887,13 +886,7 @@ hash_key(dshash_table *hash_table, const void *key)
887886
staticinlinebool
888887
equal_keys(dshash_table*hash_table,constvoid*a,constvoid*b)
889888
{
890-
intr;
891-
892-
if (hash_table->params.compare_arg_function!=NULL)
893-
r=hash_table->params.compare_arg_function(a,b,hash_table->arg);
894-
else
895-
r=hash_table->params.compare_function(a,b,
896-
hash_table->params.key_size);
897-
898-
returnr==0;
889+
returnhash_table->params.compare_function(a,b,
890+
hash_table->params.key_size,
891+
hash_table->arg)==0;
899892
}

‎src/include/lib/dshash.h‎

Lines changed: 10 additions & 27 deletions
Original file line numberDiff line numberDiff line change
@@ -26,32 +26,13 @@ typedef dsa_pointer dshash_table_handle;
2626
/* The type for hash values. */
2727
typedefuint32dshash_hash;
2828

29-
/*
30-
* A function used for comparing keys. This version is compatible with
31-
* HashCompareFunction in hsearch.h and memcmp.
32-
*/
33-
typedefint (*dshash_compare_function) (constvoid*a,constvoid*b,size_tsize);
29+
/* A function type for comparing keys. */
30+
typedefint (*dshash_compare_function) (constvoid*a,constvoid*b,
31+
size_tsize,void*arg);
3432

35-
/*
36-
* A function type used for comparing keys. This version allows compare
37-
* functions to receive a pointer to arbitrary user data that was given to the
38-
* create or attach function. Similar to qsort_arg_comparator.
39-
*/
40-
typedefint (*dshash_compare_arg_function) (constvoid*a,constvoid*b,void*arg);
41-
42-
/*
43-
* A function type for computing hash values for keys. This version is
44-
* compatible with HashValueFunc in hsearch.h and hash functions like
45-
* tag_hash.
46-
*/
47-
typedefdshash_hash (*dshash_hash_function) (constvoid*v,size_tsize);
48-
49-
/*
50-
* A function type for computing hash values for keys. This version allows
51-
* hash functions to receive a pointer to arbitrary user data that was given
52-
* to the create or attach function.
53-
*/
54-
typedefdshash_hash (*dshash_hash_arg_function) (constvoid*v,void*arg);
33+
/* A function type for computing hash values for keys. */
34+
typedefdshash_hash (*dshash_hash_function) (constvoid*v,size_tsize,
35+
void*arg);
5536

5637
/*
5738
* The set of parameters needed to create or attach to a hash table. The
@@ -70,9 +51,7 @@ typedef struct dshash_parameters
7051
size_tkey_size;/* Size of the key (initial bytes of entry) */
7152
size_tentry_size;/* Total size of entry */
7253
dshash_compare_functioncompare_function;/* Compare function */
73-
dshash_compare_arg_functioncompare_arg_function;/* Arg version */
7454
dshash_hash_functionhash_function;/* Hash function */
75-
dshash_hash_arg_functionhash_arg_function;/* Arg version */
7655
inttranche_id;/* The tranche ID to use for locks */
7756
}dshash_parameters;
7857

@@ -101,6 +80,10 @@ extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
10180
externvoiddshash_delete_entry(dshash_table*hash_table,void*entry);
10281
externvoiddshash_release_lock(dshash_table*hash_table,void*entry);
10382

83+
/* Convenience hash and compare functions wrapping memcmp and tag_hash. */
84+
externintdshash_memcmp(constvoid*a,constvoid*b,size_tsize,void*arg);
85+
externdshash_hashdshash_memhash(constvoid*v,size_tsize,void*arg);
86+
10487
/* Debugging support. */
10588
externvoiddshash_dump(dshash_table*hash_table);
10689

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