Introduce RESET request

Signed-off-by: Cole Miller <cole.miller@canonical.com>

src/gateway.c

@@ -1268,6 +1268,45 @@ static int handle_weight(struct handle *req)
 	return 0;
 }
 
+static void resetCb(struct exec *exec, int status)
+{
+	tracef("reset cb status:%d", status);
+	struct gateway *g = exec->data;
+	struct handle *req = g->req;
+	struct response_empty response = {0};
+	g->req = NULL;
+	if (status != 0) {
+		failure(req, status, "database reset failed");
+		return;
+	}
+	/* status and exec->status should always match. */
+	assert(exec->status == 0);
+	SUCCESS(empty, EMPTY);
+}
+
+static int handle_reset(struct handle *req)
+{
+	tracef("handle reset");
+	struct cursor *cursor = &req->cursor;
+	struct gateway *g = req->gateway;
+	int rc;
+
+	START_V0(reset, empty);
+	(void)response;
+	CHECK_LEADER(req);
+	LOOKUP_DB(request.db_id);
+	FAIL_IF_CHECKPOINTING;
+
+	g->req = req;
+	rc = leader__reset(g->leader, &g->exec, resetCb);
+	if (rc != 0) {
+		tracef("leader reset failed %d");
+		g->req = NULL;
+		return rc;
+	}
+	return 0;
+}
+
 int gateway__handle(struct gateway *g,
 		    struct handle *req,
 		    int type,

src/leader.c

@@ -450,3 +450,105 @@ int leader__barrier(struct leader *l, struct barrier *barrier, barrier_cb cb)
 	}
 	return 0;
 }
+
+static void resetBarrierCb(struct barrier *barrier, int status)
+{
+	tracef("reset barrier cb status:%d", status);
+	struct exec *exec = barrier->data;
+	struct leader *l = exec->leader;
+	sqlite3_vfs *vfs;
+	dqlite_vfs_frame *frames;
+	struct vfs_database_memory_usage usage;
+	unsigned n, i;
+	int rv;
+
+	if (status != 0) {
+		rv = status;
+		goto finish;
+	}
+
+#if SQLITE_VERSION_NUMBER >= 302400
+	vfs = sqlite3_vfs_find(l->db->config->name);
+	assert(vfs != NULL);
+	usage = VfsDatabaseMemoryUsage(vfs, l->db->filename);
+	tracef("reset barrier usage before database_n_pages=%u wal_n_frames=%u wal_n_tx=%u shm_n_regions=%u",
+	       usage.database_n_pages,
+	       usage.wal_n_frames,
+	       usage.wal_n_tx,
+	       usage.shm_n_regions);
+
+	rv = sqlite3_db_config(l->conn, SQLITE_DBCONFIG_RESET_DATABASE, 1, 0);
+	assert(rv == 0);
+	exec->status = sqlite3_exec(l->conn, "VACUUM", NULL, NULL, NULL);
+	rv = sqlite3_db_config(l->conn, SQLITE_DBCONFIG_RESET_DATABASE, 0, 0);
+	assert(rv == 0);
+
+	rv = VfsPoll(vfs, l->db->filename, &frames, &n);
+	if (rv != 0 || n == 0) {
+		goto finish;
+	}
+
+	rv = leaderApplyFrames(exec, frames, n);
+	for (i = 0; i < n; i++) {
+		sqlite3_free(frames[i].data);
+	}
+	sqlite3_free(frames);
+	if (rv != 0) {
+		VfsAbort(vfs, l->db->filename);
+		goto finish;
+	}
+
+	usage = VfsDatabaseMemoryUsage(vfs, l->db->filename);
+	tracef("reset barrier usage after database_n_pages=%u wal_n_frames=%u wal_n_tx=%u shm_n_regions=%u",
+	       usage.database_n_pages,
+	       usage.wal_n_frames,
+	       usage.wal_n_tx,
+	       usage.shm_n_regions);
+	return;
+#else
+	tracef("reset barrier cb not supported");
+	(void)vfs;
+	(void)frames;
+	(void)n;
+	(void)i;
+	rv = DQLITE_ERROR;
+#endif
+
+finish:
+	if (rv != 0) {
+		l->exec->status = rv;
+	}
+	leaderExecDone(l->exec);
+}
+
+int leader__reset(struct leader *l, struct exec *exec, exec_cb cb)
+{
+	tracef("leader reset");
+	int version = sqlite3_libversion_number();
+	int rv;
+
+	if (version < 302400) {
+		tracef("leader reset not supported");
+		return DQLITE_ERROR;
+	}
+
+	exec->leader = l;
+	exec->barrier.data = exec;
+	exec->barrier.cb = NULL;
+	exec->stmt = NULL;
+	exec->cb = cb;
+
+	if (l->exec != NULL) {
+		tracef("leader reset busy");
+		return SQLITE_BUSY;
+	}
+	l->exec = exec;
+
+	rv = leader__barrier(l, &exec->barrier, resetBarrierCb);
+	if (rv != 0) {
+                tracef("raft barrier failed %d", rv);
+		l->exec = NULL;
+		return rv;
+	}
+	return 0;
+}

src/leader.h

@@ -108,4 +108,6 @@ int leader__exec(struct leader *l,
  */
 int leader__barrier(struct leader *l, struct barrier *barrier, barrier_cb cb);
 
+int leader__reset(struct leader *l, struct exec *exec, exec_cb cb);
+
 #endif /* LEADER_H_*/

src/protocol.h

@@ -48,7 +48,8 @@ enum {
     DQLITE_REQUEST_CLUSTER,
     DQLITE_REQUEST_TRANSFER,
     DQLITE_REQUEST_DESCRIBE,
-    DQLITE_REQUEST_WEIGHT
+    DQLITE_REQUEST_WEIGHT,
+    DQLITE_REQUEST_RESET
 };
 
 #define DQLITE_REQUEST_CLUSTER_FORMAT_V0 0 /* ID and address */

src/request.h

@@ -42,6 +42,7 @@
 #define REQUEST_TRANSFER(X, ...) X(uint64, id, ##__VA_ARGS__)
 #define REQUEST_DESCRIBE(X, ...) X(uint64, format, ##__VA_ARGS__)
 #define REQUEST_WEIGHT(X, ...) X(uint64, weight, ##__VA_ARGS__)
+#define REQUEST_RESET(X, ...) X(uint64, db_id, ##__VA_ARGS__)
 
 #define REQUEST__DEFINE(LOWER, UPPER, _) \
 	SERIALIZE__DEFINE(request_##LOWER, REQUEST_##UPPER);
@@ -64,7 +65,8 @@
 	X(cluster, CLUSTER, __VA_ARGS__)     \
 	X(transfer, TRANSFER, __VA_ARGS__)   \
 	X(describe, DESCRIBE, __VA_ARGS__)   \
-	X(weight, WEIGHT, __VA_ARGS__)
+	X(weight, WEIGHT, __VA_ARGS__)       \
+	X(reset, RESET, __VA_ARGS__)
 
 REQUEST__TYPES(REQUEST__DEFINE);
 

src/vfs.c

@@ -2702,3 +2702,19 @@ int VfsRestore(sqlite3_vfs *vfs,
 
 	return 0;
 }
+
+struct vfs_database_memory_usage VfsDatabaseMemoryUsage(sqlite3_vfs *vfs, const char *filename)
+{
+	struct vfs *v;
+	struct vfsDatabase *d;
+	struct vfs_database_memory_usage usage = {0};
+
+	v = (struct vfs *)(vfs->pAppData);
+	d = vfsDatabaseLookup(v, filename);
+	assert(d != NULL);
+	usage.database_n_pages = d->n_pages;
+	usage.wal_n_frames = d->wal.n_frames;
+	usage.wal_n_tx = d->wal.n_tx;
+	usage.shm_n_regions = d->shm.n_regions;
+	return usage;
+}

src/vfs.h

@@ -54,4 +54,15 @@ int VfsDatabaseNumPages(sqlite3_vfs *vfs,
 			const char* filename,
 			uint32_t *n);
 
+struct vfs_database_memory_usage
+{
+	unsigned database_n_pages;
+	unsigned wal_n_frames;
+	unsigned wal_n_tx;
+	unsigned shm_n_regions;
+};
+
+struct vfs_database_memory_usage VfsDatabaseMemoryUsage(sqlite3_vfs *vfs,
+							const char *filename);
+
 #endif /* VFS_H_ */

test/unit/test_gateway.c

@@ -2077,6 +2077,64 @@ TEST_CASE(request_cluster, unrecognizedFormat, NULL)
 	return MUNIT_OK;
 }
 
+#if SQLITE_VERSION_NUMBER >= 302400
+
+/******************************************************************************
+ *
+ * reset
+ *
+ ******************************************************************************/
+
+struct reset_fixture
+{
+	FIXTURE;
+	struct request_reset request;
+	struct response_empty response;
+};
+
+TEST_SUITE(reset);
+TEST_SETUP(reset)
+{
+	struct reset_fixture *f = munit_malloc(sizeof *f);
+	SETUP;
+	CLUSTER_ELECT(0);
+	OPEN;
+	return f;
+}
+TEST_TEAR_DOWN(reset)
+{
+	struct reset_fixture *f = data;
+	TEAR_DOWN;
+	free(f);
+}
+
+TEST_CASE(reset, simple, NULL)
+{
+	struct reset_fixture *f = data;
+	char buf[100];
+	int i;
+	(void)params;
+	EXEC("CREATE TABLE test (n INT)");
+	for (i = 0; i < 100; i += 1) {
+		snprintf(buf, 100, "INSERT INTO test VALUES (%d)", i);
+		EXEC(buf);
+	}
+	f->request.db_id = 0;
+	ENCODE(&f->request, reset);
+	HANDLE(RESET);
+	WAIT;
+	ASSERT_CALLBACK(0, EMPTY);
+
+	CLUSTER_DEPOSE;
+	SELECT(1);
+	CLUSTER_ELECT(1);
+	OPEN;
+	EXEC("CREATE TABLE test (n INT)");
+	return MUNIT_OK;
+}
+
+#endif /* SQLITE_VERSION_NUMBER >= 302400 */
+
 /******************************************************************************
  *
  * invalid