1 files changed, 148 insertions, 0 deletions
diff --git a/test/tt3_checkpoint.c b/test/tt3_checkpoint.c
new file mode 100644
index 0000000..ec9d072
--- /dev/null
+++ b/test/tt3_checkpoint.c
@@ -0,0 +1,148 @@
+/*
+** 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);
+}