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Commit d8cc161

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tglsfdctglsfdc
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Minor additional improvements for ecpglib/prepare.c.
Avoid allocating never-used entries in stmtCacheEntries[], other than the intentionally-unused zero'th entry. Tie the array size directly to the bucket count and size, rather than having undocumented dependencies between three magic constants. Fix the hash calculation to be platform-independent --- notably, it was sensitive to the signed'ness of "char" before, not to mention having an unnecessary hard-wired dependency on the existence and size of type "long long". (The lack of complaints says it's been a long time since anybody tried to build PG on a compiler without "long long", and certainly with the requirement for C99 this isn't a live bug anymore. But it's still not per project coding style.) Fix ecpg_auto_prepare's new-cache-entry path so that it increments the exec count for the new cache entry not the dummy zero'th entry. The last of those is an actual bug, though one of little consequence; the rest is mostly future-proofing and neatnik-ism. Doesn't seem necessary to back-patch.
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‎src/interfaces/ecpg/ecpglib/prepare.c

Copy file name to clipboardExpand all lines: src/interfaces/ecpg/ecpglib/prepare.c
+22-11Lines changed: 22 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -13,7 +13,17 @@
1313

1414
#define STMTID_SIZE 32
1515

16-
#define N_STMTCACHE_ENTRIES 16384
16+
/*
17+
* The statement cache contains stmtCacheNBuckets hash buckets, each
18+
* having stmtCacheEntPerBucket entries, which we recycle as needed,
19+
* giving up the least-executed entry in the bucket.
20+
* stmtCacheEntries[0] is never used, so that zero can be a "not found"
21+
* indicator.
22+
*/
23+
#define stmtCacheNBuckets 2039 /* should be a prime number */
24+
#define stmtCacheEntPerBucket 8
25+
26+
#define stmtCacheArraySize (stmtCacheNBuckets * stmtCacheEntPerBucket + 1)
1727

1828
typedef struct
1929
{
@@ -25,8 +35,6 @@ typedef struct
2535
} stmtCacheEntry;
2636

2737
static int nextStmtID = 1;
28-
static const int stmtCacheNBuckets = 2039; /* # buckets - a prime # */
29-
static const int stmtCacheEntPerBucket = 8; /* # entries/bucket */
3038
static stmtCacheEntry *stmtCacheEntries = NULL;
3139

3240
static bool deallocate_one(int lineno, enum COMPAT_MODE c, struct connection *con,
@@ -330,7 +338,7 @@ HashStmt(const char *ecpgQuery)
330338
bucketNo,
331339
hashLeng,
332340
stmtLeng;
333-
long long hashVal,
341+
uint64 hashVal,
334342
rotVal;
335343

336344
stmtLeng = strlen(ecpgQuery);
@@ -341,16 +349,17 @@ HashStmt(const char *ecpgQuery)
341349
hashVal = 0;
342350
for (stmtIx = 0; stmtIx < hashLeng; ++stmtIx)
343351
{
344-
hashVal = hashVal + (int) ecpgQuery[stmtIx];
352+
hashVal = hashVal + (unsigned char) ecpgQuery[stmtIx];
353+
/* rotate 32-bit hash value left 13 bits */
345354
hashVal = hashVal << 13;
346-
rotVal = (hashVal & 0x1fff00000000LL) >> 32;
347-
hashVal = (hashVal & 0xffffffffLL) | rotVal;
355+
rotVal = (hashVal & UINT64CONST(0x1fff00000000)) >> 32;
356+
hashVal = (hashVal & UINT64CONST(0xffffffff)) | rotVal;
348357
}
349358

350359
bucketNo = hashVal % stmtCacheNBuckets;
351-
bucketNo += 1; /* don't use bucket # 0 */
352360

353-
return (bucketNo * stmtCacheEntPerBucket);
361+
/* Add 1 so that array entry 0 is never used */
362+
return bucketNo * stmtCacheEntPerBucket + 1;
354363
}
355364

356365
/*
@@ -451,7 +460,7 @@ AddStmtToCache(int lineno, /* line # of statement */
451460
if (stmtCacheEntries == NULL)
452461
{
453462
stmtCacheEntries = (stmtCacheEntry *)
454-
ecpg_alloc(sizeof(stmtCacheEntry) * N_STMTCACHE_ENTRIES, lineno);
463+
ecpg_alloc(sizeof(stmtCacheEntry) * stmtCacheArraySize, lineno);
455464
if (stmtCacheEntries == NULL)
456465
return -1;
457466
}
@@ -534,7 +543,9 @@ ecpg_auto_prepare(int lineno, const char *connection_name, const int compat, cha
534543

535544
if (!ECPGprepare(lineno, connection_name, 0, stmtID, query))
536545
return false;
537-
if (AddStmtToCache(lineno, stmtID, connection_name, compat, query) < 0)
546+
547+
entNo = AddStmtToCache(lineno, stmtID, connection_name, compat, query);
548+
if (entNo < 0)
538549
return false;
539550

540551
*name = ecpg_strdup(stmtID, lineno);

‎src/interfaces/ecpg/test/expected/preproc-autoprep.stderr

Copy file name to clipboardExpand all lines: src/interfaces/ecpg/test/expected/preproc-autoprep.stderr
+5-5Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -30,7 +30,7 @@
3030
[NO_PID]: sqlca: code: 0, state: 00000
3131
[NO_PID]: ecpg_process_output on line 24: OK: INSERT 0 1
3232
[NO_PID]: sqlca: code: 0, state: 00000
33-
[NO_PID]: ecpg_auto_prepare on line 26: statement found in cache; entry 1640
33+
[NO_PID]: ecpg_auto_prepare on line 26: statement found in cache; entry 1633
3434
[NO_PID]: sqlca: code: 0, state: 00000
3535
[NO_PID]: ecpg_execute on line 26: query: insert into T values ( 1 , $1 ); with 1 parameter(s) on connection ecpg1_regression
3636
[NO_PID]: sqlca: code: 0, state: 00000
@@ -168,7 +168,7 @@
168168
[NO_PID]: sqlca: code: 0, state: 00000
169169
[NO_PID]: ecpg_process_output on line 21: OK: CREATE TABLE
170170
[NO_PID]: sqlca: code: 0, state: 00000
171-
[NO_PID]: ecpg_auto_prepare on line 23: statement found in cache; entry 15328
171+
[NO_PID]: ecpg_auto_prepare on line 23: statement found in cache; entry 15321
172172
[NO_PID]: sqlca: code: 0, state: 00000
173173
[NO_PID]: prepare_common on line 23: name ecpg1; query: "insert into T values ( 1 , null )"
174174
[NO_PID]: sqlca: code: 0, state: 00000
@@ -178,7 +178,7 @@
178178
[NO_PID]: sqlca: code: 0, state: 00000
179179
[NO_PID]: ecpg_process_output on line 23: OK: INSERT 0 1
180180
[NO_PID]: sqlca: code: 0, state: 00000
181-
[NO_PID]: ecpg_auto_prepare on line 24: statement found in cache; entry 1640
181+
[NO_PID]: ecpg_auto_prepare on line 24: statement found in cache; entry 1633
182182
[NO_PID]: sqlca: code: 0, state: 00000
183183
[NO_PID]: prepare_common on line 24: name ecpg2; query: "insert into T values ( 1 , $1 )"
184184
[NO_PID]: sqlca: code: 0, state: 00000
@@ -190,7 +190,7 @@
190190
[NO_PID]: sqlca: code: 0, state: 00000
191191
[NO_PID]: ecpg_process_output on line 24: OK: INSERT 0 1
192192
[NO_PID]: sqlca: code: 0, state: 00000
193-
[NO_PID]: ecpg_auto_prepare on line 26: statement found in cache; entry 1640
193+
[NO_PID]: ecpg_auto_prepare on line 26: statement found in cache; entry 1633
194194
[NO_PID]: sqlca: code: 0, state: 00000
195195
[NO_PID]: ecpg_execute on line 26: query: insert into T values ( 1 , $1 ); with 1 parameter(s) on connection ecpg1_regression
196196
[NO_PID]: sqlca: code: 0, state: 00000
@@ -208,7 +208,7 @@
208208
[NO_PID]: sqlca: code: 0, state: 00000
209209
[NO_PID]: ecpg_process_output on line 28: OK: INSERT 0 1
210210
[NO_PID]: sqlca: code: 0, state: 00000
211-
[NO_PID]: ecpg_auto_prepare on line 30: statement found in cache; entry 13056
211+
[NO_PID]: ecpg_auto_prepare on line 30: statement found in cache; entry 13049
212212
[NO_PID]: sqlca: code: 0, state: 00000
213213
[NO_PID]: prepare_common on line 30: name ecpg3; query: "select Item2 from T order by Item2 nulls last"
214214
[NO_PID]: sqlca: code: 0, state: 00000

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