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/*
** 2011-02-02
**
** 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 is part of the test program "threadtest3". Despite being a C
** file it is not compiled separately, but included by threadtest3.c using
** the #include directive normally used with header files.
**
** This file contains the implementation of test cases:
**
** checkpoint_starvation_1
** checkpoint_starvation_2
*/
/*
** Both test cases involve 1 writer/checkpointer thread and N reader threads.
**
** Each reader thread performs a series of read transactions, one after
** another. Each read transaction lasts for 100 ms.
**
** The writer writes transactions as fast as possible. It uses a callback
** registered with sqlite3_wal_hook() to try to keep the WAL-size limited to
** around 50 pages.
**
** In test case checkpoint_starvation_1, the auto-checkpoint uses
** SQLITE_CHECKPOINT_PASSIVE. In checkpoint_starvation_2, it uses RESTART.
** The expectation is that in the first case the WAL file will grow very
** large, and in the second will be limited to the 50 pages or thereabouts.
** However, the overall transaction throughput will be lower for
** checkpoint_starvation_2, as every checkpoint will block for up to 200 ms
** waiting for readers to clear.
*/
/* Frame limit used by the WAL hook for these tests. */
#define CHECKPOINT_STARVATION_FRAMELIMIT 50
/* Duration in ms of each read transaction */
#define CHECKPOINT_STARVATION_READMS 100
struct CheckpointStarvationCtx {
int eMode;
int nMaxFrame;
};
typedef struct CheckpointStarvationCtx CheckpointStarvationCtx;
static int checkpoint_starvation_walhook(
void *pCtx,
sqlite3 *db,
const char *zDb,
int nFrame
){
CheckpointStarvationCtx *p = (CheckpointStarvationCtx *)pCtx;
if( nFrame>p->nMaxFrame ){
p->nMaxFrame = nFrame;
}
if( nFrame>=CHECKPOINT_STARVATION_FRAMELIMIT ){
sqlite3_wal_checkpoint_v2(db, zDb, p->eMode, 0, 0);
}
return SQLITE_OK;
}
static char *checkpoint_starvation_reader(int iTid, void *pArg){
Error err = {0};
Sqlite db = {0};
opendb(&err, &db, "test.db", 0);
while( !timetostop(&err) ){
i64 iCount1, iCount2;
sql_script(&err, &db, "BEGIN");
iCount1 = execsql_i64(&err, &db, "SELECT count(x) FROM t1");
sqlite3_sleep(CHECKPOINT_STARVATION_READMS);
iCount2 = execsql_i64(&err, &db, "SELECT count(x) FROM t1");
sql_script(&err, &db, "COMMIT");
if( iCount1!=iCount2 ){
test_error(&err, "Isolation failure - %lld %lld", iCount1, iCount2);
}
}
closedb(&err, &db);
print_and_free_err(&err);
return 0;
}
static void checkpoint_starvation_main(int nMs, CheckpointStarvationCtx *p){
Error err = {0};
Sqlite db = {0};
Threadset threads = {0};
int nInsert = 0;
int i;
opendb(&err, &db, "test.db", 1);
sql_script(&err, &db,
"PRAGMA page_size = 1024;"
"PRAGMA journal_mode = WAL;"
"CREATE TABLE t1(x);"
);
setstoptime(&err, nMs);
for(i=0; i<4; i++){
launch_thread(&err, &threads, checkpoint_starvation_reader, 0);
sqlite3_sleep(CHECKPOINT_STARVATION_READMS/4);
}
sqlite3_wal_hook(db.db, checkpoint_starvation_walhook, (void *)p);
while( !timetostop(&err) ){
sql_script(&err, &db, "INSERT INTO t1 VALUES(randomblob(1200))");
nInsert++;
}
printf(" Checkpoint mode : %s\n",
p->eMode==SQLITE_CHECKPOINT_PASSIVE ? "PASSIVE" : "RESTART"
);
printf(" Peak WAL : %d frames\n", p->nMaxFrame);
printf(" Transaction count: %d transactions\n", nInsert);
join_all_threads(&err, &threads);
closedb(&err, &db);
print_and_free_err(&err);
}
static void checkpoint_starvation_1(int nMs){
Error err = {0};
CheckpointStarvationCtx ctx = { SQLITE_CHECKPOINT_PASSIVE, 0 };
checkpoint_starvation_main(nMs, &ctx);
if( ctx.nMaxFrame<(CHECKPOINT_STARVATION_FRAMELIMIT*10) ){
test_error(&err, "WAL failed to grow - %d frames", ctx.nMaxFrame);
}
print_and_free_err(&err);
}
static void checkpoint_starvation_2(int nMs){
Error err = {0};
CheckpointStarvationCtx ctx = { SQLITE_CHECKPOINT_RESTART, 0 };
checkpoint_starvation_main(nMs, &ctx);
if( ctx.nMaxFrame>CHECKPOINT_STARVATION_FRAMELIMIT+10 ){
test_error(&err, "WAL grew too large - %d frames", ctx.nMaxFrame);
}
print_and_free_err(&err);
}
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