/*
** 2012 July 21
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file presents a simple cross-platform threading interface for
** use internally by SQLite.
**
** A "thread" can be created using sqlite3ThreadCreate(). This thread
** runs independently of its creator until it is joined using
** sqlite3ThreadJoin(), at which point it terminates.
**
** Threads do not have to be real. It could be that the work of the
** "thread" is done by the main thread at either the sqlite3ThreadCreate()
** or sqlite3ThreadJoin() call. This is, in fact, what happens in
** single threaded systems. Nothing in SQLite requires multiple threads.
** This interface exists so that applications that want to take advantage
** of multiple cores can do so, while also allowing applications to stay
** single-threaded if desired.
*/
#include "sqliteInt.h"
/********************************* Unix Pthreads ****************************/
#if SQLITE_OS_UNIX && defined(SQLITE_MUTEX_PTHREADS)
#define SQLITE_THREADS_IMPLEMENTED 1 /* Prevent the single-thread code below */
#include <pthread.h>
/* A running thread */
struct SQLiteThread {
pthread_t tid;
};
/* Create a new thread */
int sqlite3ThreadCreate(
SQLiteThread **ppThread, /* OUT: Write the thread object here */
void *(*xTask)(void*), /* Routine to run in a separate thread */
void *pIn /* Argument passed into xTask() */
){
SQLiteThread *p;
int rc;
*ppThread = p = sqlite3Malloc(sizeof(*p));
if( p==0 ) return SQLITE_OK;
rc = pthread_create(&p->tid, 0, xTask, pIn);
if( rc ){
sqlite3_free(p);
return SQLITE_ERROR;
}
return SQLITE_OK;
}
/* Get the results of the thread */
int sqlite3ThreadJoin(SQLiteThread *p, void **ppOut){
int rc;
if( p==0 ) return SQLITE_NOMEM;
rc = pthread_join(p->tid, ppOut);
sqlite3_free(p);
return rc ? SQLITE_ERROR : SQLITE_OK;
}
#endif /* SQLITE_OS_UNIX && defined(SQLITE_MUTEX_PTHREADS) */
/******************************** End Unix Pthreads *************************/
/********************************* Single-Threaded **************************/
#ifndef SQLITE_THREADS_IMPLEMENTED
/*
** This implementation does not actually create a new thread. It does the
** work of the thread in the main thread, when either the thread is created
** or when it is joined
*/
/* A running thread */
struct SQLiteThread {
void *(*xTask)(void*); /* The routine to run as a thread */
void *pIn; /* Argument to xTask */
void *pResult; /* Result of xTask */
};
/* Create a new thread */
int sqlite3ThreadCreate(
SQLiteThread **ppThread, /* OUT: Write the thread object here */
void *(*xTask)(void*), /* Routine to run in a separate thread */
void *pIn /* Argument passed into xTask() */
){
SQLiteThread *p;
*ppThread = p = sqlite3Malloc(sizeof(*p));
if( p==0 ) return SQLITE_NOMEM;
if( (SQLITE_PTR_TO_INT(p)/17)&1 ){
p->xTask = xTask;
p->pIn = pIn;
}else{
p->xTask = 0;
p->pResult = xTask(pIn);
}
return p;
}
/* Get the results of the thread */
int sqlite3ThreadJoin(SQLiteThread *p, void **ppOut){
if( p==0 ) return SQLITE_NOMEM;
if( p->xTask ){
*ppOut = = p->xTask(p->pIn);
}else{
*ppOut = p->pResult;
}
sqlite3_free(p);
return SQLITE_OK;
}
#endif /* !defined(SQLITE_THREADS_IMPLEMENTED) */
/****************************** End Single-Threaded *************************/