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

2018年10月17日 04:04:48 +0000 (00:04 -0400)

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

src/interfaces/ecpg/ecpglib/prepare.c patch | blob | blame | history

diff --git a/src/interfaces/ecpg/ecpglib/prepare.c b/src/interfaces/ecpg/ecpglib/prepare.c

index bc0ac4afadbda3444a5febb3e94fce765cbe5e1c..f904d326e48c293f4bd4968a619c459e1e82c888 100644 (file)

--- a/src/interfaces/ecpg/ecpglib/prepare.c

+++ b/src/interfaces/ecpg/ecpglib/prepare.c

@@ -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);

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