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Comment:Add the threadtest4.c test program. Not yet working.
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SHA1:ec3a74469ca2f0f3fb7d82a05fdac7500354e78f
User & Date: drh 2014-12-11 19:29:42
Context
2014-12-12
00:20
Fix a bug in the threadtest4.c program. Remove the keyinfo cache as it provides minimal performance improvements, and then only at SQL preparation time, not at runtime, and it has problems with data races in shared-cache mode. We might later add the keyinfo cache back but only enable it when shared-cache mode is off. check-in: b7489f94 user: drh tags: threadtest4
2014-12-11
19:29
Add the threadtest4.c test program. Not yet working. check-in: ec3a7446 user: drh tags: threadtest4
15:27
Fix a typo in the documentation for sqlite3_threadsafe(). check-in: 258e747b user: drh tags: trunk
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/*
** 2014-12-11
**
** 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 implements a simple standalone program used to stress the
** SQLite library when accessing the same set of databases simultaneously
** from multiple threads in shared-cache mode.
**
** This test program runs on unix-like systems only.  It uses pthreads.
** To compile:
**
**     gcc -o tt4 -I. threadtest4.c sqlite3.c -ldl -lpthread
**
** To run:
**
**     ./tt4 10
**
** The argument is the number of threads.
*/
#include "sqlite3.h"
#include <pthread.h>
#include <sched.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdarg.h>

/*
** An instance of the following structure is passed into each worker
** thread.
*/
typedef struct WorkerInfo WorkerInfo;
struct WorkerInfo {
  int tid;                    /* Thread ID */
  unsigned wkrFlags;          /* Flags */
  sqlite3 *mainDb;            /* Database connection of the main thread */
  sqlite3 *db;                /* Database connection of this thread */
  int nErr;                   /* Number of errors seen by this thread */
  int nTest;                  /* Number of tests run by this thread */
  char *zMsg;                 /* Message returned by this thread */
  pthread_t id;               /* Thread id */
  pthread_mutex_t *pWrMutex;  /* Hold this mutex while writing */
};

/*
** Allowed values for WorkerInfo.wkrFlags
*/
#define TT4_SERIALIZED    0x0000001   /* The --serialized option is used */
#define TT4_WAL           0x0000002   /* WAL mode in use */
#define TT4_TRACE         0x0000004   /* Trace activity */


/*
** Report an OOM error and die if the argument is NULL
*/
static void check_oom(void *x){
  if( x==0 ){
    fprintf(stderr, "out of memory\n");
    exit(1);
  }
}

/*
** Allocate memory.  If the allocation fails, print an error message and
** kill the process.
*/
static void *safe_malloc(int sz){
  void *x = sqlite3_malloc(sz>0?sz:1);
  check_oom(x);
  return x;
}

/*
** Print a trace message for a worker
*/
static void worker_trace(WorkerInfo *p, const char *zFormat, ...){
  va_list ap;
  char *zMsg;
  if( (p->wkrFlags & TT4_TRACE)==0 ) return;
  va_start(ap, zFormat);
  zMsg = sqlite3_vmprintf(zFormat, ap);
  check_oom(zMsg);
  va_end(ap);
  fprintf(stderr, "TRACE(%02d): %s\n", p->tid, zMsg);
  sqlite3_free(zMsg);
}

/*
** Prepare a single SQL query
*/
static sqlite3_stmt *prep_sql(sqlite3 *db, const char *zFormat, ...){
  va_list ap;
  char *zSql;
  int rc;
  sqlite3_stmt *pStmt = 0;

  va_start(ap, zFormat);
  zSql = sqlite3_vmprintf(zFormat, ap);
  va_end(ap);
  check_oom(zSql);
  rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);
  if( rc!=SQLITE_OK ){
    fprintf(stderr, "SQL error (%d,%d): %s\nWhile preparing: [%s]\n",
            rc, sqlite3_extended_errcode(db), sqlite3_errmsg(db), zSql);
    exit(1);
  }
  sqlite3_free(zSql);
  return pStmt;
}

/*
** Run a SQL statements.  Panic if unable.
*/
static void run_sql(WorkerInfo *p, const char *zFormat, ...){
  va_list ap;
  char *zSql;
  int rc;
  sqlite3_stmt *pStmt = 0;
  int nRetry = 0;

  va_start(ap, zFormat);
  zSql = sqlite3_vmprintf(zFormat, ap);
  va_end(ap);
  check_oom(zSql);
  rc = sqlite3_prepare_v2(p->db, zSql, -1, &pStmt, 0);
  if( rc!=SQLITE_OK ){
    fprintf(stderr, "SQL error (%d,%d): %s\nWhile preparing: [%s]\n",
            rc, sqlite3_extended_errcode(p->db), sqlite3_errmsg(p->db), zSql);
    exit(1);
  }
  worker_trace(p, "running [%s]", zSql);
  while( (rc = sqlite3_step(pStmt))!=SQLITE_DONE ){
    if( (rc&0xff)==SQLITE_BUSY || (rc&0xff)==SQLITE_LOCKED ){
      sqlite3_reset(pStmt);
      nRetry++;
      if( nRetry<10 ){
        worker_trace(p, "retry %d for [%s]", nRetry, zSql);
        sched_yield();
        continue;
      }else{
        fprintf(stderr, "Deadlock in thread %d while running [%s]\n",
                p->tid, zSql);
        exit(1);
      }
    }
    if( rc!=SQLITE_ROW ){
      fprintf(stderr, "SQL error (%d,%d): %s\nWhile running [%s]\n",
              rc, sqlite3_extended_errcode(p->db), sqlite3_errmsg(p->db), zSql);
      exit(1);
    }
  }
  sqlite3_free(zSql);
  sqlite3_finalize(pStmt);
}


/*
** Open the database connection for WorkerInfo.  The order in which
** the files are opened is a function of the tid value.
*/
static void worker_open_connection(WorkerInfo *p, int iCnt){
  char *zFile;
  int x;
  int rc;
  static const unsigned char aOrder[6][3] = {
    { 1, 2, 3},
    { 1, 3, 2},
    { 2, 1, 3},
    { 2, 3, 1},
    { 3, 1, 2},
    { 3, 2, 1}
  };
  x = (p->tid + iCnt) % 6;
  zFile = sqlite3_mprintf("tt4-test%d.db", aOrder[x][0]);
  check_oom(zFile);
  worker_trace(p, "open %s", zFile);
  rc = sqlite3_open_v2(zFile, &p->db,
                       SQLITE_OPEN_READWRITE|SQLITE_OPEN_SHAREDCACHE, 0);
  if( rc!=SQLITE_OK ){
    fprintf(stderr, "sqlite_open_v2(%s) failed on thread %d\n",
            zFile, p->tid);
    exit(1);
  }
  sqlite3_free(zFile);
  run_sql(p, "PRAGMA read_uncommitted=ON;");
  sqlite3_busy_timeout(p->db, 10000);
  run_sql(p, "PRAGMA synchronous=OFF;");
  run_sql(p, "ATTACH 'tt4-test%d.db' AS aux1", aOrder[x][1]);
  run_sql(p, "ATTACH 'tt4-test%d.db' AS aux2", aOrder[x][2]);
}

/*
** Close the worker database connection
*/
static void worker_close_connection(WorkerInfo *p){
  if( p->db ){
    worker_trace(p, "close");
    sqlite3_close(p->db);
    p->db = 0;
  }
}

/*
** Delete all content in the three databases associated with a
** single thread.  Make this happen all in a single transaction if
** inTrans is true, or separately for each database if inTrans is
** false.
*/
static void worker_delete_all_content(WorkerInfo *p, int inTrans){
  if( inTrans ){
    pthread_mutex_lock(p->pWrMutex);
    run_sql(p, "BEGIN");
    run_sql(p, "DELETE FROM t1 WHERE tid=%d", p->tid);
    run_sql(p, "DELETE FROM t2 WHERE tid=%d", p->tid);
    run_sql(p, "DELETE FROM t3 WHERE tid=%d", p->tid);
    run_sql(p, "COMMIT");
    pthread_mutex_unlock(p->pWrMutex);
    p->nTest++;
  }else{
    pthread_mutex_lock(p->pWrMutex);
    run_sql(p, "DELETE FROM t1 WHERE tid=%d", p->tid);
    pthread_mutex_unlock(p->pWrMutex);
    p->nTest++;
    pthread_mutex_lock(p->pWrMutex);
    run_sql(p, "DELETE FROM t2 WHERE tid=%d", p->tid);
    pthread_mutex_unlock(p->pWrMutex);
    p->nTest++;
    pthread_mutex_lock(p->pWrMutex);
    run_sql(p, "DELETE FROM t3 WHERE tid=%d", p->tid);
    pthread_mutex_unlock(p->pWrMutex);
    p->nTest++;
  }
}

/*
** Create rows mn through mx in table iTab for the given worker
*/
static void worker_add_content(WorkerInfo *p, int mn, int mx, int iTab){
  char *zTabDef;
  switch( iTab ){
    case 1:  zTabDef = "t1(tid,sp,a,b,c)";  break;
    case 2:  zTabDef = "t2(tid,sp,d,e,f)";  break;
    case 3:  zTabDef = "t3(tid,sp,x,y,z)";  break;
  }
  pthread_mutex_lock(p->pWrMutex);
  run_sql(p, 
     "WITH RECURSIVE\n"
     " c(i) AS (VALUES(%d) UNION ALL SELECT i+1 FROM c WHERE i<%d)\n"
     "INSERT INTO %s SELECT %d, zeroblob(3000), i, printf('%%d',i), i FROM c;",
     mn, mx, zTabDef, p->tid
  );
  pthread_mutex_unlock(p->pWrMutex);
  p->nTest++;
}

/*
** Set an error message on a worker
*/
static void worker_error(WorkerInfo *p, const char *zFormat, ...){
  va_list ap;
  p->nErr++;
  sqlite3_free(p->zMsg);
  va_start(ap, zFormat);
  p->zMsg = sqlite3_vmprintf(zFormat, ap);
  va_end(ap);
}

/*
** Each thread runs the following function.
*/
static void *worker_thread(void *pArg){
  WorkerInfo *p = (WorkerInfo*)pArg;
  int iOuter;
  int i;
  int rc;
  sqlite3_stmt *pStmt;

  printf("worker %d startup\n", p->tid);  fflush(stdout);
  for(iOuter=1; iOuter<=4; iOuter++){
    worker_open_connection(p, iOuter);
    for(i=0; i<4; i++){
      worker_add_content(p, i*100+1, (i+1)*100, (p->tid+iOuter)%3 + 1);
      worker_add_content(p, i*100+1, (i+1)*100, (p->tid+iOuter+1)%3 + 1);
      worker_add_content(p, i*100+1, (i+1)*100, (p->tid+iOuter+2)%3 + 1);
    }

    pStmt = prep_sql(p->db, "SELECT count(a) FROM t1 WHERE tid=%d", p->tid);
    worker_trace(p, "query [%s]", sqlite3_sql(pStmt));
    rc = sqlite3_step(pStmt);
    if( rc!=SQLITE_ROW ){
      worker_error(p, "Failed to step: %s", sqlite3_sql(pStmt));
    }else if( sqlite3_column_int(pStmt, 0)!=400 ){
      worker_error(p, "Wrong result: %d", sqlite3_column_int(pStmt,0));
    }
    if( p->nErr ) break;

    worker_delete_all_content(p, (p->tid+iOuter)%2);
    worker_close_connection(p);
    p->db = 0;
  }
  worker_close_connection(p);
  printf("worker %d finished\n", p->tid); fflush(stdout);
  return 0;
}

int main(int argc, char **argv){
  int nWorker = 0;         /* Number of worker threads */
  int i;                   /* Loop counter */
  WorkerInfo *aInfo;       /* Information for each worker */
  unsigned wkrFlags = 0;   /* Default worker flags */
  int nErr = 0;            /* Number of errors */
  int nTest = 0;           /* Number of tests */
  int rc;                  /* Return code */
  sqlite3 *db = 0;         /* Main database connection */
  pthread_mutex_t wrMutex; /* The write serialization mutex */
  WorkerInfo infoTop;      /* WorkerInfo for the main thread */
  WorkerInfo *p;           /* Pointer to infoTop */

  sqlite3_config(SQLITE_CONFIG_MULTITHREAD);
  for(i=1; i<argc; i++){
    const char *z = argv[i];
    if( z[0]=='-' ){
      if( z[1]=='-' && z[2]!=0 ) z++;
      if( strcmp(z,"-multithread")==0 ){
        sqlite3_config(SQLITE_CONFIG_MULTITHREAD);
        wkrFlags &= ~TT4_SERIALIZED;
      }else if( strcmp(z,"-serialized")==0 ){
        sqlite3_config(SQLITE_CONFIG_SERIALIZED);
        wkrFlags |= TT4_SERIALIZED;
      }else if( strcmp(z,"-wal")==0 ){
        wkrFlags |= TT4_WAL;
      }else if( strcmp(z,"-trace")==0 ){
        wkrFlags |= TT4_TRACE;
      }else{
        fprintf(stderr, "unknown command-line option: %s\n", argv[i]);
        exit(1);
      }
    }else if( z[0]>='1' && z[0]<='9' && nWorker==0 ){
      nWorker = atoi(z);
      if( nWorker<2 ){
        fprintf(stderr, "minimum of 2 threads\n");
        exit(1);
      }
    }else{
      fprintf(stderr, "extra command-line argument: \"%s\"\n", argv[i]);
      exit(1);
    }
  }
  if( nWorker==0 ){ 
    fprintf(stderr,
       "usage:  %s ?OPTIONS? N\n"
       "N is the number of threads and must be at least 2.\n"
       "Options:\n"
       "  --serialized\n"
       "  --multithread\n"
       ,argv[0]
    );
    exit(1);
  }
  if( !sqlite3_threadsafe() ){
    fprintf(stderr, "requires a threadsafe build of SQLite\n");
    exit(1);
  }
  sqlite3_initialize();
  sqlite3_enable_shared_cache(1);
  pthread_mutex_init(&wrMutex, 0);

  /* Initialize the test database files */
  (void)unlink("tt4-test1.db");
  (void)unlink("tt4-test2.db");
  (void)unlink("tt4-test3.db");
  rc = sqlite3_open("tt4-test1.db", &db);
  if( rc!=SQLITE_OK ){
    fprintf(stderr, "Unable to open test database: tt4-test2.db\n");
    exit(1);
  }
  memset(&infoTop, 0, sizeof(infoTop));
  infoTop.db = db;
  infoTop.wkrFlags = wkrFlags;
  p = &infoTop;
  if( wkrFlags & TT4_WAL ){
    run_sql(p, "PRAGMA journal_mode=WAL");
  }
  run_sql(p, "PRAGMA synchronous=OFF");
  run_sql(p, "CREATE TABLE IF NOT EXISTS t1(tid INTEGER, sp, a, b, c)");
  run_sql(p, "CREATE INDEX t1tid ON t1(tid)");
  run_sql(p, "CREATE INDEX t1ab ON t1(a,b)");
  run_sql(p, "ATTACH 'tt4-test2.db' AS 'test2'");
  run_sql(p, "CREATE TABLE IF NOT EXISTS test2.t2(tid INTEGER, sp, d, e, f)");
  run_sql(p, "CREATE INDEX test2.t2tid ON t2(tid)");
  run_sql(p, "CREATE INDEX test2.t2de ON t2(d,e)");
  run_sql(p, "ATTACH 'tt4-test3.db' AS 'test3'");
  run_sql(p, "CREATE TABLE IF NOT EXISTS test3.t3(tid INTEGER, sp, x, y, z)");
  run_sql(p, "CREATE INDEX test3.t3tid ON t3(tid)");
  run_sql(p, "CREATE INDEX test3.t3xy ON t3(x,y)");
  aInfo = safe_malloc( sizeof(*aInfo)*nWorker );
  memset(aInfo, 0, sizeof(*aInfo)*nWorker);
  for(i=0; i<nWorker; i++){
    aInfo[i].tid = i+1;
    aInfo[i].wkrFlags = wkrFlags;
    aInfo[i].mainDb = db;
    aInfo[i].pWrMutex = &wrMutex;
    rc = pthread_create(&aInfo[i].id, 0, worker_thread, &aInfo[i]);
    if( rc!=0 ){
      fprintf(stderr, "thread creation failed for thread %d\n", i+1);
      exit(1);
    }
    sched_yield();
  }
  for(i=0; i<nWorker; i++){
    pthread_join(aInfo[i].id, 0);
    printf("Joined thread %d: %d errors in %d tests",
           aInfo[i].tid, aInfo[i].nErr, aInfo[i].nTest);
    if( aInfo[i].zMsg ){
      printf(": %s\n", aInfo[i].zMsg);
    }else{
      printf("\n");
    }
    nErr += aInfo[i].nErr;
    nTest += aInfo[i].nTest;
    fflush(stdout);
  }
  sqlite3_close(db);
  sqlite3_free(aInfo);
  printf("Total %d errors in %d tests\n", nErr, nTest);
  return nErr;
}