tdb: test exponential recovery expansion problem.

ccan/tdb/test/run-transaction-expand.c

+/* We need this otherwise fcntl locking fails. */
+#define _FILE_OFFSET_BITS 64
+#define _XOPEN_SOURCE 500
+#include <ccan/tdb/tdb_private.h>
+
+/* Speed up the tests: setting TDB_NOSYNC removed recovery altogether. */
+static inline int fake_fsync(int fd)
+{
+	return 0;
+}
+#define fsync fake_fsync
+
+#ifdef MS_SYNC
+static inline int fake_msync(void *addr, size_t length, int flags)
+{
+	return 0;
+}
+#define msync fake_msync
+#endif
+
+#include <ccan/tdb/tdb.h>
+#include <ccan/tdb/io.c>
+#include <ccan/tdb/tdb.c>
+#include <ccan/tdb/lock.c>
+#include <ccan/tdb/freelist.c>
+#include <ccan/tdb/traverse.c>
+#include <ccan/tdb/transaction.c>
+#include <ccan/tdb/error.c>
+#include <ccan/tdb/open.c>
+#include <ccan/tdb/check.c>
+#include <ccan/tdb/hash.c>
+#include <ccan/tap/tap.h>
+#include <stdlib.h>
+#include <err.h>
+#include "logging.h"
+
+static void write_record(struct tdb_context *tdb, size_t extra_len,
+			 TDB_DATA *data)
+{
+	TDB_DATA key;
+	key.dsize = strlen("hi");
+	key.dptr = (void *)"hi";
+
+	data->dptr = realloc(data->dptr, data->dsize + extra_len);
+	memset(data->dptr + data->dsize, 'x', extra_len);
+	data->dsize += extra_len;
+	tdb_transaction_start(tdb);
+	tdb_store(tdb, key, *data, TDB_REPLACE);
+	tdb_transaction_commit(tdb);
+	diag("TDB size = %zu", (size_t)tdb->map_size);
+}
+
+int main(int argc, char *argv[])
+{
+	struct tdb_context *tdb;
+	size_t i;
+	TDB_DATA data;
+
+	plan_tests(2);
+	tdb = tdb_open_ex("run-transaction-expand.tdb",
+			  1024, TDB_CLEAR_IF_FIRST,
+			  O_CREAT|O_TRUNC|O_RDWR, 0600, &taplogctx, NULL);
+	ok1(tdb);
+
+	data.dsize = 0;
+	data.dptr = NULL;
+
+	/* Simulate a slowly growing record. */
+	for (i = 0; i < 1000; i++)
+		write_record(tdb, getpagesize(), &data);
+
+	/* We should only be about 3 times larger than largest record. */
+	ok1(tdb->map_size < 3 * i * getpagesize());
+	tdb_close(tdb);
+	free(data.dptr);
+
+	return exit_status();
+}