extmod/modbtree: Initial implementation of "btree" module based on BerkeleyDB.

This implements basic wrapping of native get/put/seq API, and then dictionary
access protocol. Native API is intended to be superceded going forward.

extmod/modbtree.c

+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Paul Sokolovsky
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+
+#include "py/nlr.h"
+#include "py/runtime.h"
+
+#if MICROPY_PY_BTREE
+
+#include <db.h>
+#include <../../btree/btree.h>
+
+typedef struct _mp_obj_btree_t {
+    mp_obj_base_t base;
+    DB *db;
+    mp_obj_t start_key;
+    mp_obj_t end_key;
+    bool end_key_inclusive;
+} mp_obj_btree_t;
+
+STATIC const mp_obj_type_t btree_type;
+
+#define CHECK_ERROR(res) \
+        if (res == RET_ERROR) { \
+            nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(errno))); \
+        }
+
+void __dbpanic(DB *db) {
+    printf("__dbpanic(%p)\n", db);
+}
+
+STATIC mp_obj_btree_t *btree_new(DB *db) {
+    mp_obj_btree_t *o = m_new_obj(mp_obj_btree_t);
+    o->base.type = &btree_type;
+    o->db = db;
+    o->start_key = MP_OBJ_NULL;
+    o->end_key = MP_OBJ_NULL;
+    return o;
+}
+
+STATIC void btree_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    (void)kind;
+    mp_obj_btree_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_printf(print, "<btree %p>", self->db);
+}
+
+STATIC mp_obj_t btree_close(mp_obj_t self_in) {
+    mp_obj_btree_t *self = MP_OBJ_TO_PTR(self_in);
+    return MP_OBJ_NEW_SMALL_INT(__bt_close(self->db));
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(btree_close_obj, btree_close);
+
+STATIC mp_obj_t btree_put(size_t n_args, const mp_obj_t *args) {
+    mp_obj_btree_t *self = MP_OBJ_TO_PTR(args[0]);
+    DBT key, val;
+    key.data = (void*)mp_obj_str_get_data(args[1], &key.size);
+    val.data = (void*)mp_obj_str_get_data(args[2], &val.size);
+    return MP_OBJ_NEW_SMALL_INT(__bt_put(self->db, &key, &val, 0));
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(btree_put_obj, 3, 4, btree_put);
+
+STATIC mp_obj_t btree_get(size_t n_args, const mp_obj_t *args) {
+    mp_obj_btree_t *self = MP_OBJ_TO_PTR(args[0]);
+    DBT key, val;
+    key.data = (void*)mp_obj_str_get_data(args[1], &key.size);
+    int res = __bt_get(self->db, &key, &val, 0);
+    if (res == RET_SPECIAL) {
+        return mp_const_none;
+    }
+    return mp_obj_new_bytes(val.data, val.size);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(btree_get_obj, 2, 3, btree_get);
+
+STATIC mp_obj_t btree_seq(size_t n_args, const mp_obj_t *args) {
+    mp_obj_btree_t *self = MP_OBJ_TO_PTR(args[0]);
+    int flags = MP_OBJ_SMALL_INT_VALUE(args[1]);
+    DBT key, val;
+    if (n_args > 2) {
+        key.data = (void*)mp_obj_str_get_data(args[2], &key.size);
+    }
+
+    int res = __bt_seq(self->db, &key, &val, flags);
+    if (res == RET_SPECIAL) {
+        return mp_const_none;
+    }
+
+    mp_obj_tuple_t *pair = mp_obj_new_tuple(2, NULL);
+    pair->items[0] = mp_obj_new_bytes(key.data, key.size);
+    pair->items[1] = mp_obj_new_bytes(val.data, val.size);
+    return pair;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(btree_seq_obj, 2, 4, btree_seq);
+
+STATIC mp_obj_t btree_range(size_t n_args, const mp_obj_t *args) {
+    mp_obj_btree_t *self = MP_OBJ_TO_PTR(args[0]);
+    self->start_key = args[1];
+    self->end_key = args[2];
+    self->end_key_inclusive = false;
+    return args[0];
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(btree_range_obj, 3, 4, btree_range);
+
+STATIC mp_obj_t btree_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
+    mp_obj_btree_t *self = MP_OBJ_TO_PTR(self_in);
+    if (value == MP_OBJ_NULL) {
+        // delete
+        DBT key;
+        key.data = (void*)mp_obj_str_get_data(index, &key.size);
+        int res = __bt_delete(self->db, &key, 0);
+        if (res == RET_SPECIAL) {
+            nlr_raise(mp_obj_new_exception(&mp_type_KeyError));
+        }
+        CHECK_ERROR(res);
+        return mp_const_none;
+    } else if (value == MP_OBJ_SENTINEL) {
+        // load
+        DBT key, val;
+        key.data = (void*)mp_obj_str_get_data(index, &key.size);
+        int res = __bt_get(self->db, &key, &val, 0);
+        if (res == RET_SPECIAL) {
+            return mp_const_none;
+        }
+        CHECK_ERROR(res);
+        return mp_obj_new_bytes(val.data, val.size);
+    } else {
+        // store
+        DBT key, val;
+        key.data = (void*)mp_obj_str_get_data(index, &key.size);
+        val.data = (void*)mp_obj_str_get_data(value, &val.size);
+        int res = __bt_put(self->db, &key, &val, 0);
+        CHECK_ERROR(res);
+        return mp_const_none;
+    }
+}
+
+STATIC const mp_rom_map_elem_t btree_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_close), MP_ROM_PTR(&btree_close_obj) },
+    { MP_ROM_QSTR(MP_QSTR_get), MP_ROM_PTR(&btree_get_obj) },
+    { MP_ROM_QSTR(MP_QSTR_put), MP_ROM_PTR(&btree_put_obj) },
+    { MP_ROM_QSTR(MP_QSTR_seq), MP_ROM_PTR(&btree_seq_obj) },
+    { MP_ROM_QSTR(MP_QSTR_range), MP_ROM_PTR(&btree_range_obj) },
+};
+
+STATIC MP_DEFINE_CONST_DICT(btree_locals_dict, btree_locals_dict_table);
+
+STATIC const mp_obj_type_t btree_type = {
+    { &mp_type_type },
+    // Save on qstr's, reuse same as for module
+    .name = MP_QSTR_btree,
+    .print = btree_print,
+    .getiter = NULL,
+    .iternext = NULL,
+    .subscr = btree_subscr,
+    .locals_dict = (void*)&btree_locals_dict,
+};
+
+STATIC mp_obj_t mod_btree_open(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_server_side, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
+    };
+
+    const char *fname = mp_obj_str_get_str(pos_args[0]);
+
+    struct {
+        mp_arg_val_t server_side;
+    } args;
+    mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args,
+        MP_ARRAY_SIZE(allowed_args), allowed_args, (mp_arg_val_t*)&args);
+
+    DB *db = __bt_open(fname, /*flags*/O_CREAT | O_RDWR, /*mode*/0770, /*openinfo*/NULL, /*dflags*/0);
+    return MP_OBJ_FROM_PTR(btree_new(db));
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(mod_btree_open_obj, 1, mod_btree_open);
+
+STATIC const mp_rom_map_elem_t mp_module_btree_globals_table[] = {
+    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_btree) },
+    { MP_ROM_QSTR(MP_QSTR_open), MP_ROM_PTR(&mod_btree_open_obj) },
+};
+
+STATIC MP_DEFINE_CONST_DICT(mp_module_btree_globals, mp_module_btree_globals_table);
+
+const mp_obj_module_t mp_module_btree = {
+    .base = { &mp_type_module },
+    .name = MP_QSTR_btree,
+    .globals = (mp_obj_dict_t*)&mp_module_btree_globals,
+};
+
+#endif // MICROPY_PY_BTREE