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pool_query_cache.c
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pool_query_cache.c
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/* -*-pgsql-c-*- */
/*
* $Header$
*
* pgpool: a language independent connection pool server for PostgreSQL
* written by Tatsuo Ishii
*
* Copyright (c) 2003-2010 PgPool Global Development Group
*
* Permission to use, copy, modify, and distribute this software and
* its documentation for any purpose and without fee is hereby
* granted, provided that the above copyright notice appear in all
* copies and that both that copyright notice and this permission
* notice appear in supporting documentation, and that the name of the
* author not be used in advertising or publicity pertaining to
* distribution of the software without specific, written prior
* permission. The author makes no representations about the
* suitability of this software for any purpose. It is provided "as
* is" without express or implied warranty.
*
* pool_query_cache.c: query cache
*
*/
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <time.h>
#include <sys/time.h>
#include <unistd.h>
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
#include "pool.h"
#include "md5.h"
#include "pool_stream.h"
#include "pool_config.h"
#include "pool_proto_modules.h"
#include "parser/parsenodes.h"
#define QUERY_CACHE_TABLE_NAME "query_cache"
#define CACHE_REGISTER_PREPARED_STMT "register_prepared_stmt"
#define DEFAULT_CACHE_SIZE 8192
#define SYSDB_CON (SYSDB_CONNECTION->con)
#define SYSDB_MAJOR (SYSDB_CONNECTION->sp->major)
#define CACHE_TABLE_INFO (SYSDB_INFO->query_cache_table_info)
/* data structure to store RowDescription and DataRow cache */
typedef struct
{
char *md5_query; /* query in md5 hushed format*/
char *query; /* query string */
char *cache; /* cached data */
int cache_size; /* cached data size */
int cache_offset; /* points the end of cache */
char *db_name; /* database name */
char *create_time; /* cache create timestamp in ISO format */
} QueryCacheInfo;
typedef enum
{
CACHE_FOUND, CACHE_NOT_FOUND, CACHE_ERROR
} CACHE_STATUS;
static QueryCacheInfo *query_cache_info;
static CACHE_STATUS search_system_db_for_cache(POOL_CONNECTION *frontend, char *sql, int sql_len, struct timeval *t, char tstate);
static int ForwardCacheToFrontend(POOL_CONNECTION *frontend, char *cache, char tstate);
static int init_query_cache_info(POOL_CONNECTION *pc, char *database, char *query);
static void free_query_cache_info(void);
static int malloc_failed(void *p);
static int write_cache(void *buf, int len);
static char *pq_time_to_str(time_t t);
static int system_db_connection_exists(void);
static void define_prepared_statements(void);
/* --------------------------------
* pool_clear_cache - clears cache data from the SystemDB
*
* return 0 on success, -1 otherwise
* --------------------------------
*/
int
pool_clear_cache_by_time(Interval *interval, int size)
{
PGresult *pg_result = NULL;
long interval_in_days = 0;
long interval_in_seconds = 0;
time_t query_delete_timepoint;
char *query_delete_timepoint_in_str = NULL;
int sql_len;
char *sql = NULL;
int i;
if (! system_db_connection_exists())
return -1;
for (i = 0; i < size; i++)
{
int q = interval[i].quantity;
switch (interval[i].unit)
{
case millennium:
case millenniums:
q *= 10;
case century:
case centuries:
q *= 10;
case decade:
case decades:
q *= 10;
case year:
case years:
q *= 12;
case month:
case months:
q *= 31; /* should I change this according to the month? */
interval_in_days += q;
break;
case week:
case weeks:
q *= 7;
case day:
case days:
q *= 24;
case hour:
case hours:
q *= 60;
case minute:
case minutes:
q *= 60;
case second:
case seconds:
interval_in_seconds += q;
break;
}
}
interval_in_seconds = (interval_in_days * 86400) + interval_in_seconds;
query_delete_timepoint = time(NULL) - interval_in_seconds;
query_delete_timepoint_in_str = pq_time_to_str(query_delete_timepoint);
if (malloc_failed(query_delete_timepoint_in_str))
return -1;
sql_len =
strlen(pool_config->system_db_schema) +
strlen(QUERY_CACHE_TABLE_NAME) +
strlen(query_delete_timepoint_in_str) +
64;
sql = (char *)malloc(sql_len);
if (malloc_failed(sql))
{
free(query_delete_timepoint_in_str);
return -1;
}
snprintf(sql, sql_len,
"DELETE FROM %s.%s WHERE create_time <= '%s'",
pool_config->system_db_schema,
QUERY_CACHE_TABLE_NAME,
query_delete_timepoint_in_str);
pool_debug("pool_clear_cache: delete all query cache created before '%s'", query_delete_timepoint_in_str);
pg_result = PQexec(system_db_info->pgconn, sql);
if (!pg_result || PQresultStatus(pg_result) != PGRES_COMMAND_OK)
{
pool_error("pool_clear_cache: PQexec() failed. reason: %s",
PQerrorMessage(system_db_info->pgconn));
PQclear(pg_result);
free(query_delete_timepoint_in_str);
free(sql);
return -1;
}
PQclear(pg_result);
free(query_delete_timepoint_in_str);
free(sql);
return 0;
}
/* --------------------------------
* pool_query_cache_table_exists - checks if query_cache table exists in the SystemDB
*
* This function is called once and only once from the pgpool parent process.
* return 1 if query_cache table exists, 0 otherwise.
* --------------------------------
*/
int
pool_query_cache_table_exists(void)
{
PGresult *pg_result = NULL;
char *sql = NULL;
int sql_len = strlen(pool_config->system_db_schema) + strlen(QUERY_CACHE_TABLE_NAME) + 64;
if (! system_db_connection_exists())
return 0;
sql = (char *)malloc(sql_len);
if (malloc_failed(sql))
return 0;
snprintf(sql, sql_len,
"SELECT hash, query, value, dbname, create_time FROM %s.%s LIMIT 1",
pool_config->system_db_schema,
QUERY_CACHE_TABLE_NAME);
pg_result = PQexec(system_db_info->pgconn, sql);
if (!pg_result || PQresultStatus(pg_result) != PGRES_TUPLES_OK)
{
pool_error("pool_query_cache_table_exists: PQexec() failed. reason: %s",
PQerrorMessage(system_db_info->pgconn));
PQclear(pg_result);
free(sql);
return 0;
}
PQclear(pg_result);
pool_close_libpq_connection();
free(sql);
return 1;
}
/* --------------------------------
* pool_query_cache_lookup - retrieve query cache from the SystemDB
*
* creates a SQL query string for searching a cache from the SystemDB.
*
* returns POOL_CONTINUE if cache is found. returns POOL_END if cache was
* not found. returns POOL_ERROR if an error has been encountered while
* searching.
*
* Note that POOL_END and POOL_ERROR are treated the same by the caller
* (pool_process_query.c).
* POOL_END and POOL_ERROR both indicates to the caller that the search
* query must be forwarded to the backends in order to retrieve data and
* the result be cached.
* Only difference is that POOL_ERROR indicates that some fatal error has
* occured; query cache function, however, should be seemless to the user
* whether cache was not found or error has occured during cache retrieve.
* --------------------------------
*/
POOL_STATUS
pool_query_cache_lookup(POOL_CONNECTION *frontend, char *query, char *database, char tstate)
{
char *sql = NULL;
int sql_len;
char md5_query[33];
struct timeval timeout;
int status;
if (! system_db_connection_exists())
return POOL_ERROR; /* same as POOL_END ... at least for now */
sql_len =
strlen(pool_config->system_db_schema) +
strlen(QUERY_CACHE_TABLE_NAME) +
sizeof(md5_query) +
strlen(database) +
64;
sql = (char *)malloc(sql_len);
if (malloc_failed(sql))
return POOL_ERROR; /* should I exit here rather than returning an error? */
/* cached data lookup */
pool_md5_hash(query, strlen(query), md5_query);
snprintf(sql, sql_len, "SELECT value FROM %s.%s WHERE hash = '%s' AND dbname = '%s'",
pool_config->system_db_schema,
QUERY_CACHE_TABLE_NAME,
md5_query,
database);
/* set timeout value for select */
timeout.tv_sec = pool_config->child_life_time;
timeout.tv_usec = 0;
pool_debug("pool_query_cache_lookup: searching cache for query: \"%s\"", query);
status = search_system_db_for_cache(frontend, sql, strlen(sql)+1, &timeout, tstate);
/* make sure that the remaining data is discarded */
SYSDB_CON->po = 0;
SYSDB_CON->len = 0;
free(sql);
/* cache found, and no backend communication needed */
if (status == CACHE_FOUND)
{
return POOL_CONTINUE;
}
/* cache not found */
if (status == CACHE_ERROR)
{
pool_error("pool_query_cache_lookup: query cache lookup failed");
/* reset the SystemDB connection */
if (system_db_info->pgconn)
pool_close_libpq_connection();
return POOL_ERROR; /* same as POOL_END ... at least for now */
}
pool_debug("pool_query_cache_lookup: query cache not found");
return POOL_END;
}
/* --------------------------------
* search_system_db_for_cache - search for query cache in libpq protocol level
*
* sends a cache searching query string using libpq protocol to the SystemDB.
* if the SystemDB returns cache, forward the data to the frontend, and return
* CACHE_FOUND. if cache was not found, silently discards the remaining data
* returned by the SystemDB, and return CACHE_NOT_FOUND. returns CACHE_ERROR
* if an error was encountered.
* --------------------------------
*/
static CACHE_STATUS
search_system_db_for_cache(POOL_CONNECTION *frontend, char *sql, int sql_len, struct timeval *t, char tstate)
{
fd_set readmask;
int fds;
int num_fds;
struct timeval *timeout = NULL;
char kind;
int readlen;
char *data = NULL;
CACHE_STATUS return_value = CACHE_ERROR;
int cache_found = 0;
pool_debug("pool_query_cache_lookup: executing query: \"%s\"", sql);
pool_write(SYSDB_CON, "Q", 1);
if (SYSDB_MAJOR == PROTO_MAJOR_V3)
{
int sendlen = htonl(sql_len + 4);
pool_write(SYSDB_CON, &sendlen, sizeof(sendlen));
}
if (pool_write_and_flush(SYSDB_CON, sql, sql_len) < 0)
{
pool_error("pool_query_cache_lookup: error while sending data to the SystemDB");
return CACHE_ERROR;
}
if ((t->tv_sec + t->tv_usec) == 0)
timeout = NULL;
else
timeout = t;
/* don't really need select() or for(;;) here, but we may need it someday... or not */
for (;;)
{
FD_ZERO(&readmask);
num_fds = 0;
num_fds = SYSDB_CON->fd + 1;
FD_SET(SYSDB_CON->fd, &readmask);
fds = select(num_fds, &readmask, NULL, NULL, timeout);
if (fds == -1)
{
if (errno == EINTR)
continue;
pool_error("pool_query_cache_lookup: select() failed. reason: %s", strerror(errno));
return CACHE_ERROR;
}
/* select() timeout */
if (fds == 0)
return CACHE_ERROR;
for (;;)
{
if (! FD_ISSET(SYSDB_CON->fd, &readmask))
{
pool_error("pool_query_cache_lookup: select() failed");
return CACHE_ERROR;
}
/* read kind */
if (pool_read(SYSDB_CON, &kind, sizeof(kind)) < 0)
{
pool_error("pool_query_cache_lookup: error while reading message kind");
return CACHE_ERROR;
}
pool_debug("pool_query_cache_lookup: received %c from systemdb", kind);
/* just do the routine work of reading data in. data won't be used */
if (kind == 'T')
{
if (SYSDB_MAJOR == PROTO_MAJOR_V3)
{
if (pool_read(SYSDB_CON, &readlen, sizeof(int)) < 0)
{
pool_error("pool_query_cache_lookup: error while reading message length");
return CACHE_ERROR;
}
readlen = ntohl(readlen) - sizeof(int);
data = pool_read2(SYSDB_CON, readlen);
}
else
{
data = pool_read_string(SYSDB_CON, &readlen, 0);
}
}
else if (kind == 'D') /* cache found! forward it to the frontend */
{
char *cache;
int status;
cache_found = 1;
if (SYSDB_MAJOR == PROTO_MAJOR_V3)
{
if (pool_read(SYSDB_CON, &readlen, sizeof(readlen)) < 0)
{
pool_error("pool_query_cache_lookup: error while reading message length");
return CACHE_ERROR;
}
readlen = ntohl(readlen) - sizeof(int);
cache = pool_read2(SYSDB_CON, readlen);
}
else
{
cache = pool_read_string(SYSDB_CON, &readlen, 0);
}
if (cache == NULL)
{
pool_error("pool_query_cache_lookup: error while reading message body");
return CACHE_ERROR;
}
cache[readlen] = '\0';
cache += sizeof(short); /* number of columns in 'D' (we know it's always going to be 1, so skip) */
cache += sizeof(int); /* length of escaped bytea cache in string format. don't need the length */
status = ForwardCacheToFrontend(frontend, cache, tstate);
if (status < 0)
{
/* fatal error has occured while forwarding cache */
pool_error("pool_query_cache_lookup: query cache forwarding failed");
return_value = CACHE_ERROR;
}
}
else if (kind == 'C') /* see if 'D' was received */
{
if (cache_found)
return_value = CACHE_FOUND;
else
return_value = CACHE_NOT_FOUND;
/* must discard the remaining data */
if (SYSDB_MAJOR == PROTO_MAJOR_V3)
{
if (pool_read(SYSDB_CON, &readlen, sizeof(int)) < 0)
{
pool_error("pool_query_cache_lookup: error while reading message length");
return CACHE_ERROR;
}
readlen = ntohl(readlen) - sizeof(int);
data = pool_read2(SYSDB_CON, readlen);
}
else
{
data = pool_read_string(SYSDB_CON, &readlen, 0);
}
}
else if (kind == 'Z')
{
/* must discard the remaining data */
if (SYSDB_MAJOR == PROTO_MAJOR_V3)
{
if (pool_read(SYSDB_CON, &readlen, sizeof(int)) < 0)
{
pool_error("pool_query_cache_lookup: error while reading message length");
return CACHE_ERROR;
}
readlen = ntohl(readlen) - sizeof(int);
data = pool_read2(SYSDB_CON, readlen);
}
else
{
data = pool_read_string(SYSDB_CON, &readlen, 0);
}
break;
}
else if (kind == 'E')
{
/* must discard the remaining data */
if (SYSDB_MAJOR == PROTO_MAJOR_V3)
{
if (pool_read(SYSDB_CON, &readlen, sizeof(int)) < 0)
{
pool_error("pool_query_cache_lookup: error while reading message length");
return CACHE_ERROR;
}
readlen = ntohl(readlen) - sizeof(int);
data = pool_read2(SYSDB_CON, readlen);
}
else
{
data = pool_read_string(SYSDB_CON, &readlen, 0);
}
return_value = CACHE_ERROR;
}
else
{
/* shouldn't get here, but just in case */
return CACHE_ERROR;
}
}
break;
}
return return_value;
}
/* --------------------------------
* ForwardCacheToFrontend - simply forwards cached data to the frontend
*
* since the cached data passed from the caller is in escaped binary string
* format, unescape it and send it to the frontend appending 'Z' at the end.
* returns 0 on success, -1 otherwise.
* --------------------------------
*/
static int ForwardCacheToFrontend(POOL_CONNECTION *frontend, char *cache, char tstate)
{
int sendlen;
size_t sz;
char *binary_cache = NULL;
binary_cache = (char *)PQunescapeBytea((unsigned char *)cache, &sz);
sendlen = (int) sz;
if (malloc_failed(binary_cache))
return -1;
pool_debug("ForwardCacheToFrontend: query cache found (%d bytes)", sendlen);
/* forward cache to the frontend */
pool_write(frontend, binary_cache, sendlen);
/* send ReadyForQuery to the frontend*/
pool_write(frontend, "Z", 1);
sendlen = htonl(5);
pool_write(frontend, &sendlen, sizeof(int));
if (pool_write_and_flush(frontend, &tstate, 1) < 0)
{
pool_error("pool_query_cache_lookup: error while writing data to the frontend");
PQfreemem(binary_cache);
return -1;
}
PQfreemem(binary_cache);
return 0;
}
/* --------------------------------
* pool_query_cache_register() - register query cache to the SystemDB
*
* returns 0 on sucess, -1 otherwise
* --------------------------------
*/
int
pool_query_cache_register(char kind,
POOL_CONNECTION *frontend,
char *database,
char *data,
int data_len,
char *query)
{
int ret;
int send_len;
if (! system_db_connection_exists())
return -1;
if (! CACHE_TABLE_INFO.has_prepared_statement)
define_prepared_statements();
switch (kind)
{
case 'T': /* RowDescription */
{
/* for all SELECT result data from the backend, 'T' must come first */
if (query_cache_info != NULL)
{
pool_error("pool_query_cache_register: received RowDescription in the wrong order");
free_query_cache_info();
return -1;
}
pool_debug("pool_query_cache_register: saving cache for query: \"%s\"", query);
/* initialize query_cache_info and save the query */
ret = init_query_cache_info(frontend, database, query);
if (ret)
return ret;
/* store data into the cache */
write_cache(&kind, 1);
send_len = htonl(data_len + sizeof(int));
write_cache(&send_len, sizeof(int));
write_cache(data, data_len);
break;
}
case 'D': /* DataRow */
{
/* for all SELECT result data from the backend, 'T' must come first */
if (query_cache_info == NULL)
{
pool_error("pool_query_cache_register: received DataRow in the wrong order");
return -1;
}
write_cache(&kind, 1);
send_len = htonl(data_len + sizeof(int));
write_cache(&send_len, sizeof(int));
write_cache(data, data_len);
break;
}
case 'C': /* CommandComplete */
{
PGresult *pg_result = NULL;
char *escaped_query = NULL;
size_t escaped_query_len;
time_t now = time(NULL);
char *values[5];
int values_len[5];
int values_format[5];
int i;
/* for all SELECT result data from the backend, 'T' must come first */
if (query_cache_info == NULL)
{
pool_error("pool_query_cache_register: received CommandComplete in the wrong order");
return -1;
}
/* pack CommandComplete data into the cache */
write_cache(&kind, 1);
send_len = htonl(data_len + sizeof(int));
write_cache(&send_len, sizeof(int));
write_cache(data, data_len);
query_cache_info->create_time = pq_time_to_str(now);
if (malloc_failed(query_cache_info->create_time))
{
free_query_cache_info();
return -1;
}
escaped_query = (char *)malloc(strlen(query_cache_info->query) * 2 + 1);
if (malloc_failed(escaped_query))
{
free_query_cache_info();
return -1;
}
/* escaped_query_len = PQescapeStringConn(system_db_info->pgconn, */
/* escaped_query, */
/* query_cache_info->query, */
/* strlen(query_cache_info->query))); */
escaped_query_len = PQescapeString(escaped_query, query_cache_info->query, strlen(query_cache_info->query));
/* all the result data have been received. store into the SystemDB */
values[0] = strdup(query_cache_info->md5_query);
values[1] = strdup(escaped_query);
values[2] = (char *)malloc(query_cache_info->cache_offset);
memcpy(values[2], query_cache_info->cache, query_cache_info->cache_offset);
values[3] = strdup(query_cache_info->db_name);
values[4] = strdup(query_cache_info->create_time);
for (i = 0; i < 5; i++)
{
if (malloc_failed(values[i]))
{
pool_error("pool_query_cache_register: malloc() failed");
free_query_cache_info();
{
int j;
for (j = 0; j < i; j++)
free(values[j]);
}
return -1;
}
values_len[i] = strlen(values[i]);
}
values_format[0] = values_format[1] = values_format[3] = values_format[4] = 0;
values_format[2] = 1;
values_len[2] = query_cache_info->cache_offset;
pg_result = PQexecPrepared(system_db_info->pgconn,
CACHE_TABLE_INFO.register_prepared_statement,
5,
(const char * const *)values,
values_len,
values_format,
0);
if (!pg_result || PQresultStatus(pg_result) != PGRES_COMMAND_OK)
{
pool_error("pool_query_cache_register: PQexecPrepared() failed. reason: %s",
PQerrorMessage(system_db_info->pgconn));
PQclear(pg_result);
PQfreemem(escaped_query);
free_query_cache_info();
for (i = 0; i < 5; i++)
free(values[i]);
return -1;
}
PQclear(pg_result);
PQfreemem(escaped_query);
for (i = 0; i < 5; i++)
free(values[i]);
free_query_cache_info();
break;
}
case 'E':
{
pool_debug("pool_query_cache_register: received 'E': free query cache buffer");
pool_close_libpq_connection();
free_query_cache_info();
break;
}
}
return 0;
}
/* --------------------------------
* init_query_cache_info() - allocate memory for query_cache_info and stores query
*
* returns 0 on success, -1 otherwise
`* --------------------------------
*/
static int
init_query_cache_info(POOL_CONNECTION *pc, char *database, char *query)
{
int query_len; /* length of the SELECT query to be cached */
query_cache_info = (QueryCacheInfo *)malloc(sizeof(QueryCacheInfo));
if (malloc_failed(query_cache_info))
return -1;
/* query */
query_len = strlen(query);
query_cache_info->query = (char *)malloc(query_len + 1);
if (malloc_failed(query_cache_info->query))
return -1;
memcpy(query_cache_info->query, query, query_len + 1);
/* md5_query */
query_cache_info->md5_query = (char *)malloc(33); /* md5sum is always 33 bytes (including the '\0') */
if (malloc_failed(query_cache_info->md5_query))
return -1;
pool_md5_hash(query_cache_info->query, query_len, query_cache_info->md5_query);
/* malloc DEFAULT_CACHE_SIZE for query_cache_info->cache */
query_cache_info->cache = (char *)malloc(DEFAULT_CACHE_SIZE);
if (malloc_failed(query_cache_info->cache))
return -1;
query_cache_info->cache_size = DEFAULT_CACHE_SIZE;
query_cache_info->cache_offset = 0;
/* save database name */
query_cache_info->db_name = (char *)malloc(strlen(database)+1);
if (malloc_failed(query_cache_info->db_name))
return -1;
strcpy(query_cache_info->db_name, database);
/* initialize create_timestamp */
query_cache_info->create_time = NULL;
return 0;
}
/* --------------------------------
* free_query_cache_info() - free query_cache_info and its members
* --------------------------------
*/
static void
free_query_cache_info(void)
{
if (query_cache_info == NULL)
return;
free(query_cache_info->md5_query);
free(query_cache_info->query);
free(query_cache_info->cache);
free(query_cache_info->db_name);
if (query_cache_info->create_time)
free(query_cache_info->create_time);
free(query_cache_info);
query_cache_info = NULL;
}
/* --------------------------------
* malloc_failed() - checks if the caller's most recent malloc() has succeeded
*
* returns 0 if malloc() was a success, -1 otherwise
`* --------------------------------
*/
static int
malloc_failed(void *p)
{
if (p != NULL)
return 0;
pool_error("pool_query_cache: malloc() failed");
free_query_cache_info();
return -1;
}
/* --------------------------------
* write_cache() - append result data to buffer
*
* returns 0 on success, -1 otherwise
* --------------------------------
*/
static int
write_cache(void *buf, int len)
{
int required_len;
if (len < 0)
return -1;
required_len = query_cache_info->cache_offset + len;
if (required_len > query_cache_info->cache_size)
{
char *ptr;
required_len = query_cache_info->cache_size * 2;
ptr = (char *)realloc(query_cache_info->cache, required_len);
if (malloc_failed(ptr))
return -1;
query_cache_info->cache = ptr;
query_cache_info->cache_size = required_len;
pool_debug("pool_query_cache: extended cache buffer size to %d", query_cache_info->cache_size);
}
memcpy(query_cache_info->cache + query_cache_info->cache_offset, buf, len);
query_cache_info->cache_offset += len;
return 0;
}
/* --------------------------------
* pq_time_to_str() - convert time_t to ISO standard time output string
*
* returns a pointer to newly allocated string, NULL if malloc fails
* --------------------------------
*/
static char *
pq_time_to_str(time_t t)
{
char *time_p;
char iso_time[32];
struct tm *tm;
tm = localtime(&t);
strftime(iso_time, sizeof(iso_time), "%Y-%m-%d %H:%M:%S%z", tm);
time_p = strdup(iso_time);
return time_p;
}
/* --------------------------------
* system_db_connection_exists() - checks and if a connection to the SystemDB exists
*
* if not connected, it makes an attempt to connect to the SystemDB. If a connection
* exists, returns 1, returns 0 otherwise.
* --------------------------------
*/
static int
system_db_connection_exists(void)
{
if (!system_db_info->pgconn ||
(PQstatus(system_db_info->pgconn) != CONNECTION_OK))
{
if (system_db_connect())
return 0;
}
return 1;
}
/* --------------------------------
* define_prepared_statements() - defines prepared statements for the current session
* --------------------------------
*/
static void
define_prepared_statements(void)
{
PGresult *pg_result;
char *sql = NULL;
int sql_len;
sql_len =
strlen(pool_config->system_db_schema) +
strlen(QUERY_CACHE_TABLE_NAME) +
1024;
sql = (char *)malloc(sql_len);
if (malloc_failed(sql))
{
pool_error("pool_query_cache: malloc() failed");
return;
}
free(CACHE_TABLE_INFO.register_prepared_statement);
CACHE_TABLE_INFO.register_prepared_statement
= strdup(CACHE_REGISTER_PREPARED_STMT);
if (malloc_failed(CACHE_TABLE_INFO.register_prepared_statement))
{
pool_error("pool_query_cache: malloc() failed");
free(sql);
return;
}
#ifdef HAVE_PQPREPARE
snprintf(sql, sql_len,
"INSERT INTO %s.%s VALUES ( $1, $2, $3, $4, $5 )",
pool_config->system_db_schema,
QUERY_CACHE_TABLE_NAME);
pg_result = PQprepare(system_db_info->pgconn,
CACHE_TABLE_INFO.register_prepared_statement,
sql,
5,
NULL);
#else
snprintf(sql, sql_len,
"PREPARE %s (TEXT, TEXT, BYTEA, TEXT, TIMESTAMP WITH TIME ZONE) AS INSERT INTO %s.%s VALUES ( $1, $2, $3, $4, $5 )",
CACHE_TABLE_INFO.register_prepared_statement,
pool_config->system_db_schema,
QUERY_CACHE_TABLE_NAME);
pg_result = PQexec(system_db_info->pgconn, sql);
#endif
if (!pg_result || PQresultStatus(pg_result) != PGRES_COMMAND_OK)
{
pool_error("pool_query_cache: PQprepare() failed: %s", PQerrorMessage(system_db_info->pgconn));
free(CACHE_TABLE_INFO.register_prepared_statement);
free(sql);
return;
}
pool_debug("pool_query_cache: prepared statements created");
CACHE_TABLE_INFO.has_prepared_statement = 1;
free(sql);
PQclear(pg_result);
}
/* --------------------------------
* Execute query cache look up
* --------------------------------
*/
POOL_STATUS pool_execute_query_cache_lookup(POOL_CONNECTION *frontend, POOL_CONNECTION_POOL *backend, Node *node)
{
SelectStmt *select = (SelectStmt *)node;
POOL_STATUS status = POOL_END; /* cache not found */