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Avoid statically allocating statement cache in ecpglib/prepare.c.

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This removes a megabyte of storage that isn't used at all in ecpglib's
default operating mode --- you have to enable auto-prepare to get any
use out of it.  Seems well worth the trouble to allocate on demand.

Discussion: https://postgr.es/m/20181015200754.7y7zfuzsoux2c4ya@alap3.anarazel.de
This commit is contained in:
Tom Lane 2018-10-17 00:04:48 -04:00
parent 92dff34116
commit e15aae829e
1 changed files with 20 additions and 1 deletions
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21
src/interfaces/ecpg/ecpglib/prepare.c
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@ -13,6 +13,8 @@
#define STMTID_SIZE 32
#define N_STMTCACHE_ENTRIES 16384
typedef struct
{
int lineno;
@ -25,7 +27,7 @@ typedef struct
static int nextStmtID = 1;
static const int stmtCacheNBuckets = 2039; /* # buckets - a prime # */
static const int stmtCacheEntPerBucket = 8; /* # entries/bucket */
static stmtCacheEntry stmtCacheEntries[16384] = {{0, {0}, 0, 0, 0}};
static stmtCacheEntry *stmtCacheEntries = NULL;
static bool deallocate_one(int lineno, enum COMPAT_MODE c, struct connection *con,
struct prepared_statement *prev, struct prepared_statement *this);
@ -362,6 +364,10 @@ SearchStmtCache(const char *ecpgQuery)
int entNo,
entIx;
/* quick failure if cache not set up */
if (stmtCacheEntries == NULL)
return 0;
/* hash the statement */
entNo = HashStmt(ecpgQuery);
@ -397,6 +403,10 @@ ecpg_freeStmtCacheEntry(int lineno, int compat,
struct prepared_statement *this,
*prev;
/* fail if cache isn't set up */
if (stmtCacheEntries == NULL)
return -1;
entry = &stmtCacheEntries[entNo];
if (!entry->stmtID[0]) /* return if the entry isn't in use */
return 0;
@ -437,6 +447,15 @@ AddStmtToCache(int lineno, /* line # of statement */
entNo;
stmtCacheEntry *entry;
/* allocate and zero cache array if we haven't already */
if (stmtCacheEntries == NULL)
{
stmtCacheEntries = (stmtCacheEntry *)
ecpg_alloc(sizeof(stmtCacheEntry) * N_STMTCACHE_ENTRIES, lineno);
if (stmtCacheEntries == NULL)
return -1;
}
/* hash the statement */
initEntNo = HashStmt(ecpgQuery);