Hello,
Here follows, my Async IO implementation (at the moment, I just have tested the
Win32 part. I will test soon the pthreads part).
The main thread creates a worker thread (in charge of running the
sqlite3async_run function).
In "Build options/compiler/defines", it seems that the following is working:
SQLITE_THREADSAFE=0
--------------------------------------------------------------------------------
#include <stdio.h>
#include <stdlib.h>
#include "sqlite3.h"
#include "sqlite3async.h"
#if SQLITE_OS_WIN || defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) ||
defined(__MINGW32__) || defined(__BORLANDC__)
#include <windows.h>
#else
#include <pthread.h>
#endif
static int callback(void *NotUsed, int argc, char **argv, char **azColName){
NotUsed=0;
int i;
for(i=0; i<argc; i++){
printf("%s = %s\n", azColName[i], argv[i] ? argv[i]: "NULL");
}
printf("\n");
return 0;
}
struct s_async_sqlite3 {
sqlite3 *pdb;
#if SQLITE_OS_WIN || defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) ||
defined(__MINGW32__) || defined(__BORLANDC__)
HANDLE hThread;
#else
pthread_t th;
#endif
};
typedef struct s_async_sqlite3 async_sqlite3;
int initSQLite(char *sDatabaseFile, int lock, async_sqlite3 *pasyncsql){
/* Initialize async IO for sqlite
- The current default VFS is used for IO
- the asynchronous IO VFS is registered as the default VFS for all
SQLite database connections within the process.
*/
if(sqlite3async_initialize(NULL, 1) != SQLITE_OK){
/* display some error */
return 0;
}
/* The sqlite3async_run will never stop
*/
if(sqlite3async_control(SQLITEASYNC_HALT, SQLITEASYNC_HALT_NEVER) !=
SQLITE_OK){
/* display some error */
return 0;
}
/* Lock are used (resp. not used)
- locks allow multiple accesses from several processes without
corrupting the database but may impact the throughput
*/
if(sqlite3async_control(SQLITEASYNC_LOCKFILES, lock) != SQLITE_OK){
/* display some error */
return 0;
}
if(sqlite3_threadsafe()){
printf("Thread Safe\n");
} else {
printf("Not Thread Safe\n");
}
#if SQLITE_OS_WIN || defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) ||
defined(__MINGW32__) || defined(__BORLANDC__)
/* Create a thread using Windows API */
if(! (pasyncsql->hThread = CreateThread(
NULL, // default security attributes
0, // use default stack size
(LPTHREAD_START_ROUTINE)sqlite3async_run, // thread function
name
NULL, // argument to thread function
0, // use default creation flags
NULL))){ // returns the thread identifier
return 0;
}
#else
/* Create a thread using pthreads API - Not tested at the moment */
if(pthread_create(&pasyncsql->th, NULL, sqlite3async_run, NULL)){
return 0;
}
#endif
/* Database must exist */
if(sqlite3_open_v2(sDatabaseFile, &pasyncsql->pdb, SQLITE_OPEN_EXCLUSIVE |
SQLITE_OPEN_READWRITE, NULL) != SQLITE_OK){
/* display some error */
fprintf(stderr, "Can't open database: %s\n",
sqlite3_errmsg(pasyncsql->pdb));
sqlite3_close(pasyncsql->pdb);
return 0;
}
return 1;
}
void shutdownSQLite(async_sqlite3 *pasyncsql, int force){
/* force <> 0 : HALT SQLITE NOW
force = 0 : HALT WHEN IDLE */
sqlite3async_control(SQLITEASYNC_HALT, force ? SQLITEASYNC_HALT_NOW :
SQLITEASYNC_HALT_IDLE);
#if SQLITE_OS_WIN || defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) ||
defined(__MINGW32__) || defined(__BORLANDC__)
/* Wait for the sqlite3async_run thread completion using Windows API */
if(pasyncsql->hThread){
WaitForSingleObject(pasyncsql->hThread, INFINITE);
CloseHandle(pasyncsql->hThread);
pasyncsql->hThread = NULL;
}
#else
/* Wait for the sqlite3async_run thread completion using pthreads API */
if(pasyncsql->th){
pthread_join(pasyncsql->th, NULL);
pasyncsql->th = NULL;
}
#endif
/* close sqlite database */
if(pasyncsql->pdb){
sqlite3_close(pasyncsql->pdb);
pasyncsql->pdb = NULL;
}
/* shutdown async IO */
sqlite3async_shutdown();
}
int main(int argc, char **argv){
async_sqlite3 asyncsql;
char *zErrMsg = 0;
int rc;
if( argc!=3 ){
fprintf(stderr, "Usage: %s DATABASE SQL-STATEMENT\n", argv[0]);
exit(1);
}
if(!initSQLite(argv[1], 1, &asyncsql)){
exit(1);
}
rc = sqlite3_exec(asyncsql.pdb, argv[2], callback, 0, &zErrMsg);
if( rc != SQLITE_OK ){
fprintf(stderr, "SQL error: %s\n", zErrMsg);
/* This will free zErrMsg if assigned */
if (zErrMsg)
free(zErrMsg);
} else {
printf("ok\n");
}
shutdownSQLite(&asyncsql, 0);
return 0;
}
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