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+/*
+** 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"
+#if SQLITE_OS_WIN
+# include "os_win.h"
+#endif
+
+#if SQLITE_MAX_WORKER_THREADS>0
+
+/********************************* Unix Pthreads ****************************/
+#if SQLITE_OS_UNIX && defined(SQLITE_MUTEX_PTHREADS) && SQLITE_THREADSAFE>0
+
+#define SQLITE_THREADS_IMPLEMENTED 1 /* Prevent the single-thread code below */
+#include <pthread.h>
+
+/* A running thread */
+struct SQLiteThread {
+ pthread_t tid; /* Thread ID */
+ int done; /* Set to true when thread finishes */
+ void *pOut; /* Result returned by the thread */
+ void *(*xTask)(void*); /* The thread routine */
+ void *pIn; /* Argument to the thread */
+};
+
+/* 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;
+
+ assert( ppThread!=0 );
+ assert( xTask!=0 );
+ /* This routine is never used in single-threaded mode */
+ assert( sqlite3GlobalConfig.bCoreMutex!=0 );
+
+ *ppThread = 0;
+ p = sqlite3Malloc(sizeof(*p));
+ if( p==0 ) return SQLITE_NOMEM_BKPT;
+ memset(p, 0, sizeof(*p));
+ p->xTask = xTask;
+ p->pIn = pIn;
+ /* If the SQLITE_TESTCTRL_FAULT_INSTALL callback is registered to a
+ ** function that returns SQLITE_ERROR when passed the argument 200, that
+ ** forces worker threads to run sequentially and deterministically
+ ** for testing purposes. */
+ if( sqlite3FaultSim(200) ){
+ rc = 1;
+ }else{
+ rc = pthread_create(&p->tid, 0, xTask, pIn);
+ }
+ if( rc ){
+ p->done = 1;
+ p->pOut = xTask(pIn);
+ }
+ *ppThread = p;
+ return SQLITE_OK;
+}
+
+/* Get the results of the thread */
+int sqlite3ThreadJoin(SQLiteThread *p, void **ppOut){
+ int rc;
+
+ assert( ppOut!=0 );
+ if( NEVER(p==0) ) return SQLITE_NOMEM_BKPT;
+ if( p->done ){
+ *ppOut = p->pOut;
+ rc = SQLITE_OK;
+ }else{
+ rc = pthread_join(p->tid, ppOut) ? SQLITE_ERROR : SQLITE_OK;
+ }
+ sqlite3_free(p);
+ return rc;
+}
+
+#endif /* SQLITE_OS_UNIX && defined(SQLITE_MUTEX_PTHREADS) */
+/******************************** End Unix Pthreads *************************/
+
+
+/********************************* Win32 Threads ****************************/
+#if SQLITE_OS_WIN_THREADS
+
+#define SQLITE_THREADS_IMPLEMENTED 1 /* Prevent the single-thread code below */
+#include <process.h>
+
+/* A running thread */
+struct SQLiteThread {
+ void *tid; /* The thread handle */
+ unsigned id; /* The thread identifier */
+ void *(*xTask)(void*); /* The routine to run as a thread */
+ void *pIn; /* Argument to xTask */
+ void *pResult; /* Result of xTask */
+};
+
+/* Thread procedure Win32 compatibility shim */
+static unsigned __stdcall sqlite3ThreadProc(
+ void *pArg /* IN: Pointer to the SQLiteThread structure */
+){
+ SQLiteThread *p = (SQLiteThread *)pArg;
+
+ assert( p!=0 );
+#if 0
+ /*
+ ** This assert appears to trigger spuriously on certain
+ ** versions of Windows, possibly due to _beginthreadex()
+ ** and/or CreateThread() not fully setting their thread
+ ** ID parameter before starting the thread.
+ */
+ assert( p->id==GetCurrentThreadId() );
+#endif
+ assert( p->xTask!=0 );
+ p->pResult = p->xTask(p->pIn);
+
+ _endthreadex(0);
+ return 0; /* NOT REACHED */
+}
+
+/* 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;
+
+ assert( ppThread!=0 );
+ assert( xTask!=0 );
+ *ppThread = 0;
+ p = sqlite3Malloc(sizeof(*p));
+ if( p==0 ) return SQLITE_NOMEM_BKPT;
+ /* If the SQLITE_TESTCTRL_FAULT_INSTALL callback is registered to a
+ ** function that returns SQLITE_ERROR when passed the argument 200, that
+ ** forces worker threads to run sequentially and deterministically
+ ** (via the sqlite3FaultSim() term of the conditional) for testing
+ ** purposes. */
+ if( sqlite3GlobalConfig.bCoreMutex==0 || sqlite3FaultSim(200) ){
+ memset(p, 0, sizeof(*p));
+ }else{
+ p->xTask = xTask;
+ p->pIn = pIn;
+ p->tid = (void*)_beginthreadex(0, 0, sqlite3ThreadProc, p, 0, &p->id);
+ if( p->tid==0 ){
+ memset(p, 0, sizeof(*p));
+ }
+ }
+ if( p->xTask==0 ){
+ p->id = GetCurrentThreadId();
+ p->pResult = xTask(pIn);
+ }
+ *ppThread = p;
+ return SQLITE_OK;
+}
+
+DWORD sqlite3Win32Wait(HANDLE hObject); /* os_win.c */
+
+/* Get the results of the thread */
+int sqlite3ThreadJoin(SQLiteThread *p, void **ppOut){
+ DWORD rc;
+ BOOL bRc;
+
+ assert( ppOut!=0 );
+ if( NEVER(p==0) ) return SQLITE_NOMEM_BKPT;
+ if( p->xTask==0 ){
+ /* assert( p->id==GetCurrentThreadId() ); */
+ rc = WAIT_OBJECT_0;
+ assert( p->tid==0 );
+ }else{
+ assert( p->id!=0 && p->id!=GetCurrentThreadId() );
+ rc = sqlite3Win32Wait((HANDLE)p->tid);
+ assert( rc!=WAIT_IO_COMPLETION );
+ bRc = CloseHandle((HANDLE)p->tid);
+ assert( bRc );
+ }
+ if( rc==WAIT_OBJECT_0 ) *ppOut = p->pResult;
+ sqlite3_free(p);
+ return (rc==WAIT_OBJECT_0) ? SQLITE_OK : SQLITE_ERROR;
+}
+
+#endif /* SQLITE_OS_WIN_THREADS */
+/******************************** End Win32 Threads *************************/
+
+
+/********************************* 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;
+
+ assert( ppThread!=0 );
+ assert( xTask!=0 );
+ *ppThread = 0;
+ p = sqlite3Malloc(sizeof(*p));
+ if( p==0 ) return SQLITE_NOMEM_BKPT;
+ if( (SQLITE_PTR_TO_INT(p)/17)&1 ){
+ p->xTask = xTask;
+ p->pIn = pIn;
+ }else{
+ p->xTask = 0;
+ p->pResult = xTask(pIn);
+ }
+ *ppThread = p;
+ return SQLITE_OK;
+}
+
+/* Get the results of the thread */
+int sqlite3ThreadJoin(SQLiteThread *p, void **ppOut){
+
+ assert( ppOut!=0 );
+ if( NEVER(p==0) ) return SQLITE_NOMEM_BKPT;
+ if( p->xTask ){
+ *ppOut = p->xTask(p->pIn);
+ }else{
+ *ppOut = p->pResult;
+ }
+ sqlite3_free(p);
+
+#if defined(SQLITE_TEST)
+ {
+ void *pTstAlloc = sqlite3Malloc(10);
+ if (!pTstAlloc) return SQLITE_NOMEM_BKPT;
+ sqlite3_free(pTstAlloc);
+ }
+#endif
+
+ return SQLITE_OK;
+}
+
+#endif /* !defined(SQLITE_THREADS_IMPLEMENTED) */
+/****************************** End Single-Threaded *************************/
+#endif /* SQLITE_MAX_WORKER_THREADS>0 */
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