tutorials/sqlite-clone
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cd4c6002c6
sqlite-clone/db.c
Timothy Warren cd4c6002c6 Step 10
2019-04-30 16:07:37 -04:00

795 lines
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#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
struct InputBuffer_t {
char* buffer;
size_t buffer_length;
ssize_t input_length;
};
typedef struct InputBuffer_t InputBuffer;
enum ExecuteResult_t {
EXECUTE_SUCCESS,
EXECUTE_DUPLICATE_KEY,
EXECUTE_TABLE_FULL
};
typedef enum ExecuteResult_t ExecuteResult;
enum MetaCommandResult_t {
META_COMMAND_SUCCESS,
META_COMMAND_UNRECOGNIZED_COMMAND
};
typedef enum MetaCommandResult_t MetaCommandResult;
enum PrepareResult_t {
PREPARE_SUCCESS,
PREPARE_NEGATIVE_ID,
PREPARE_STRING_TOO_LONG,
PREPARE_SYNTAX_ERROR,
PREPARE_UNRECOGNIZED_STATEMENT
};
typedef enum PrepareResult_t PrepareResult;
enum StatementType_t {
STATEMENT_INSERT,
STATEMENT_SELECT
};
typedef enum StatementType_t StatementType;
const uint32_t COLUMN_USERNAME_SIZE = 32;
const uint32_t COLUMN_EMAIL_SIZE = 255;
struct Row_t {
uint32_t id;
char username[COLUMN_USERNAME_SIZE + 1];
char email[COLUMN_EMAIL_SIZE + 1];
};
typedef struct Row_t Row;
struct Statement_t {
StatementType type;
Row row_to_insert; // only used by insert statement
};
typedef struct Statement_t Statement;
#define size_of_attribute(Struct, Attribute) sizeof(((Struct*)0)->Attribute)
const uint32_t ID_SIZE = size_of_attribute(Row, id);
const uint32_t USERNAME_SIZE = size_of_attribute(Row, username);
const uint32_t EMAIL_SIZE = size_of_attribute(Row, email);
const uint32_t ID_OFFSET = 0;
const uint32_t USERNAME_OFFSET = ID_OFFSET + ID_SIZE;
const uint32_t EMAIL_OFFSET = USERNAME_OFFSET + USERNAME_SIZE;
const uint32_t ROW_SIZE = ID_SIZE + USERNAME_SIZE + EMAIL_SIZE;
const uint32_t PAGE_SIZE = 4096;
const uint32_t TABLE_MAX_PAGES = 100;
struct Pager_t {
int file_descriptor;
uint32_t file_length;
uint32_t num_pages;
void* pages[TABLE_MAX_PAGES];
};
typedef struct Pager_t Pager;
struct Table_t {
Pager* pager;
uint32_t root_page_num;
};
typedef struct Table_t Table;
struct Cursor_t {
Table* table;
uint32_t page_num;
uint32_t cell_num;
bool end_of_table; // Indicates a position one past the last element
};
typedef struct Cursor_t Cursor;
void print_row(Row* row) {
printf("(%d, %s, %s)\n", row->id, row->username, row->email);
}
enum NodeType_t { NODE_INTERNAL, NODE_LEAF };
typedef enum NodeType_t NodeType;
/*
* Common Node Header Layout
*/
const uint32_t NODE_TYPE_SIZE = sizeof(uint8_t);
const uint32_t NODE_TYPE_OFFSET = 0;
const uint32_t IS_ROOT_SIZE = sizeof(uint8_t);
const uint32_t IS_ROOT_OFFSET = NODE_TYPE_SIZE;
const uint32_t PARENT_POINTER_SIZE = sizeof(uint32_t);
const uint32_t PARENT_POINTER_OFFSET = IS_ROOT_OFFSET + IS_ROOT_SIZE;
const uint32_t COMMON_NODE_HEADER_SIZE = NODE_TYPE_SIZE + IS_ROOT_SIZE + PARENT_POINTER_SIZE;
/*
* Internal Node Header Layout
*/
const uint32_t INTERNAL_NODE_NUM_KEYS_SIZE = sizeof(uint32_t);
const uint32_t INTERNAL_NODE_NUM_KEYS_OFFSET = COMMON_NODE_HEADER_SIZE;
const uint32_t INTERNAL_NODE_RIGHT_CHILD_SIZE = sizeof(uint32_t);
const uint32_t INTERNAL_NODE_RIGHT_CHILD_OFFSET = INTERNAL_NODE_NUM_KEYS_OFFSET + INTERNAL_NODE_NUM_KEYS_SIZE;
const uint32_t INTERNAL_NODE_HEADER_SIZE = COMMON_NODE_HEADER_SIZE + INTERNAL_NODE_NUM_KEYS_SIZE + INTERNAL_NODE_RIGHT_CHILD_SIZE;
/*
* Internal Node Body Layout
*/
const uint32_t INTERNAL_NODE_KEY_SIZE = sizeof(uint32_t);
const uint32_t INTERNAL_NODE_CHILD_SIZE = sizeof(uint32_t);
const uint32_t INTERNAL_NODE_CELL_SIZE = INTERNAL_NODE_CHILD_SIZE + INTERNAL_NODE_KEY_SIZE;
/*
* Leaf Node Header Layout
*/
const uint32_t LEAF_NODE_NUM_CELLS_SIZE = sizeof(uint32_t);
const uint32_t LEAF_NODE_NUM_CELLS_OFFSET = COMMON_NODE_HEADER_SIZE;
const uint32_t LEAF_NODE_HEADER_SIZE = COMMON_NODE_HEADER_SIZE + LEAF_NODE_NUM_CELLS_SIZE;
/*
* Leaf Node Body Layout
*/
const uint32_t LEAF_NODE_KEY_SIZE = sizeof(uint32_t);
const uint32_t LEAF_NODE_KEY_OFFSET = 0;
const uint32_t LEAF_NODE_VALUE_SIZE = ROW_SIZE;
const uint32_t LEAF_NODE_VALUE_OFFSET = LEAF_NODE_KEY_OFFSET + LEAF_NODE_KEY_SIZE;
const uint32_t LEAF_NODE_CELL_SIZE = LEAF_NODE_KEY_SIZE + LEAF_NODE_VALUE_SIZE;
const uint32_t LEAF_NODE_SPACE_FOR_CELLS = PAGE_SIZE - LEAF_NODE_HEADER_SIZE;
const uint32_t LEAF_NODE_MAX_CELLS = LEAF_NODE_SPACE_FOR_CELLS / LEAF_NODE_CELL_SIZE;
const uint32_t LEAF_NODE_RIGHT_SPLIT_COUNT = (LEAF_NODE_MAX_CELLS + 1) / 2;
const uint32_t LEAF_NODE_LEFT_SPLIT_COUNT = (LEAF_NODE_MAX_CELLS + 1) - LEAF_NODE_RIGHT_SPLIT_COUNT;
NodeType get_node_type(void* node) {
uint8_t value = *((uint8_t*)(node + NODE_TYPE_OFFSET));
return (NodeType)value;
}
void set_node_type(void* node, NodeType type) {
uint8_t value = type;
*((uint8_t*)(node + NODE_TYPE_OFFSET)) = value;
}
bool is_node_root(void* node) {
uint8_t value = *((uint8_t*)(node + IS_ROOT_OFFSET));
return (bool)value;
}
void set_node_root(void* node, bool is_root) {
uint8_t value = is_root;
*((uint8_t*)(node + IS_ROOT_OFFSET)) = value;
}
uint32_t* internal_node_num_keys(void* node) {
return node + INTERNAL_NODE_NUM_KEYS_OFFSET;
}
uint32_t* internal_node_right_child(void* node) {
return node + INTERNAL_NODE_RIGHT_CHILD_OFFSET;
}
uint32_t* internal_node_cell(void* node, uint32_t cell_num) {
return node + INTERNAL_NODE_HEADER_SIZE + cell_num * INTERNAL_NODE_CELL_SIZE;
}
uint32_t* internal_node_child(void* node, uint32_t child_num) {
uint32_t num_keys = *internal_node_num_keys(node);
if (child_num > num_keys) {
printf("Tried to access child_num %d > num_keys %d\n", child_num, num_keys);
exit(EXIT_FAILURE);
} else if (child_num == num_keys) {
return internal_node_right_child(node);
} else {
return internal_node_cell(node, child_num);
}
}
uint32_t* internal_node_key(void* node, uint32_t key_num) {
return internal_node_cell(node, key_num) + INTERNAL_NODE_CHILD_SIZE;
}
uint32_t* leaf_node_num_cells(void* node) {
return (char *)node + LEAF_NODE_NUM_CELLS_OFFSET;
}
void* leaf_node_cell(void* node, uint32_t cell_num) {
return (char *)node + LEAF_NODE_HEADER_SIZE + cell_num;
}
uint32_t* leaf_node_key(void* node, uint32_t cell_num) {
return leaf_node_cell(node, cell_num);
}
void* leaf_node_value(void* node, uint32_t cell_num) {
return leaf_node_cell(node, cell_num) + LEAF_NODE_KEY_SIZE;
}
uint32_t get_node_max_key(void* node) {
switch (get_node_type(node)) {
case NODE_INTERNAL:
return *internal_node_key(node, *internal_node_num_keys(node) - 1);
case NODE_LEAF:
return *leaf_node_key(node, *leaf_node_num_cells(node) - 1);
}
}
void print_constants() {
printf("ROW_SIZE: %d\n", ROW_SIZE);
printf("COMMON_NODE_HEADER_SIZE: %d\n", COMMON_NODE_HEADER_SIZE);
printf("LEAF_NODE_HEADER_SIZE: %d\n", LEAF_NODE_HEADER_SIZE);
printf("LEAF_NODE_CELL_SIZE: %d\n", LEAF_NODE_CELL_SIZE);
printf("LEAF_NODE_SPACE_FOR_CELLS: %d\n", LEAF_NODE_SPACE_FOR_CELLS);
printf("LEAF_NODE_MAX_CELLS: %d\n", LEAF_NODE_MAX_CELLS);
}
void* get_page(Pager* pager, uint32_t page_num) {
if (page_num > TABLE_MAX_PAGES) {
printf("Tried to fetch page number out of bounds. %d > %d\n", page_num, TABLE_MAX_PAGES);
exit(EXIT_FAILURE);
}
if (pager->pages[page_num] == NULL) {
// Cache miss. Allocate memory and load from file.
void* page = malloc(PAGE_SIZE);
uint32_t num_pages = pager->file_length / PAGE_SIZE;
// We might save a partial page at the end of the file
if (pager->file_length % PAGE_SIZE) {
num_pages += 1;
}
if (page_num <= num_pages) {
lseek(pager->file_descriptor, page_num * PAGE_SIZE, SEEK_SET);
ssize_t bytes_read = read(pager->file_descriptor, page, PAGE_SIZE);
if (bytes_read == -1) {
printf("Error reading file: %d\n", errno);
exit(EXIT_FAILURE);
}
}
pager->pages[page_num] = page;
if (page_num >= pager->num_pages) {
pager->num_pages = page_num + 1;
}
}
return pager->pages[page_num];
}
void indent(uint32_t level) {
for (uint32_t i = 0; i < level; i++) {
printf(" ");
}
}
void print_tree(Pager* pager, uint32_t page_num, uint32_t indentation_level) {
void* node = get_page(pager, page_num);
uint32_t num_keys, child;
switch(get_node_type(node)) {
case (NODE_LEAF):
num_keys = *leaf_node_num_cells(node);
indent(indentation_level);
printf("- leaf (size %d\n", num_keys);
for (uint32_t i = 0; i < num_keys; i++) {
indent(indentation_level + 1);
printf("- %d\n", *leaf_node_key(node, i));
}
break;
case (NODE_INTERNAL):
num_keys = *internal_node_num_keys(node);
indent(indentation_level);
printf("- internal (size %d)\n", num_keys);
for (uint32_t i = 0; i < num_keys; i++) {
child = *internal_node_child(node, i);
print_tree(pager, child, indentation_level + 1);
indent(indentation_level + 1);
printf("- key %d\n", *internal_node_key(node, i));
}
child = *internal_node_right_child(node);
print_tree(pager, child, indentation_level + 1);
break;
}
}
void serialize_row(Row* source, void* destination) {
memcpy(destination + ID_OFFSET, &(source->id), ID_SIZE);
memcpy(destination + USERNAME_OFFSET, &(source->username), USERNAME_SIZE);
memcpy(destination + EMAIL_OFFSET, &(source->email), EMAIL_SIZE);
}
void deserialize_row(void* source, Row* destination) {
memcpy(&(destination->id), source + ID_OFFSET, ID_SIZE);
memcpy(&(destination->username), source + USERNAME_OFFSET, USERNAME_SIZE);
memcpy(&(destination->email), source + EMAIL_OFFSET, EMAIL_SIZE);
}
void initialize_leaf_node(void* node) {
set_node_type(node, NODE_LEAF);
set_node_root(node, false);
*leaf_node_num_cells(node) = 0;
}
void initialize_internal_node(void* node) {
set_node_type(node, NODE_INTERNAL);
set_node_root(node, false);
*internal_node_num_keys(node) = 0;
}
Cursor* leaf_node_find(Table* table, uint32_t page_num, uint32_t key) {
void* node = get_page(table->pager, page_num);
uint32_t num_cells = *leaf_node_num_cells(node);
Cursor* cursor = malloc(sizeof(Cursor));
cursor->table = table;
cursor->page_num = page_num;
// Binary search
uint32_t min_index = 0;
uint32_t one_past_max_index = num_cells;
while (one_past_max_index != min_index) {
uint32_t index = (min_index + one_past_max_index) / 2;
uint32_t key_at_index = *leaf_node_key(node, index);
if (key == key_at_index) {
cursor->cell_num = index;
return cursor;
}
if (key < key_at_index) {
one_past_max_index = index;
} else {
min_index = index + 1;
}
}
cursor->cell_num = min_index;
return cursor;
}
/*
* Return the position of the given key.
* If the key is not present, return the position
* where it should be inserted
*/
Cursor* table_find(Table* table, uint32_t key) {
uint32_t root_page_num = table->root_page_num;
void* root_node = get_page(table->pager, root_page_num);
if (get_node_type(root_node) == NODE_LEAF) {
return leaf_node_find(table, root_page_num, key);
} else {
printf("Need to implement searching an internal node\n");
exit(EXIT_FAILURE);
}
}
Cursor* table_start(Table* table) {
Cursor* cursor = malloc(sizeof(Cursor));
cursor->table = table;
cursor->page_num = table->root_page_num;
cursor->cell_num = 0;
void* root_node = get_page(table->pager, table->root_page_num);
uint32_t num_cells = *leaf_node_num_cells(root_node);
cursor->end_of_table = (num_cells == 0);
return cursor;
}
void* cursor_value(Cursor* cursor) {
uint32_t page_num = cursor->page_num;
void* page = get_page(cursor->table->pager, page_num);
return leaf_node_value(page, cursor->cell_num);
}
void cursor_advance(Cursor* cursor) {
uint32_t page_num = cursor->page_num;
void* node = get_page(cursor->table->pager, page_num);
cursor->cell_num += 1;
if (cursor->cell_num >= (*leaf_node_num_cells(node))) {
cursor->end_of_table = true;
}
}
Pager* pager_open(const char* filename) {
// Read/Write mode, Create non-existent file, user read and write permission
int fd = open(filename, O_RDWR | O_CREAT, S_IWUSR | S_IRUSR);
if (fd == -1) {
printf("Unable to open file\n");
exit(EXIT_FAILURE);
}
off_t file_length = lseek(fd, 0, SEEK_END);
Pager* pager = malloc(sizeof(Pager));
pager->file_descriptor = fd;
pager->file_length = file_length;
pager->num_pages = (file_length / PAGE_SIZE);
if (file_length % PAGE_SIZE != 0) {
printf("Db file is not a whole number of pages. Corrupt file.\n");
exit(EXIT_FAILURE);
}
for (uint32_t i = 0; i < TABLE_MAX_PAGES; i++) {
pager->pages[i] = NULL;
}
return pager;
}
Table* db_open(const char* filename) {
Pager* pager = pager_open(filename);
Table* table = malloc(sizeof(Table));
table->pager = pager;
table->root_page_num = 0;
if (pager->num_pages == 0) {
// New database file. Initialize page 0 as leaf node.
void* root_node = get_page(pager, 0);
initialize_leaf_node(root_node);
set_node_root(root_node, true);
}
return table;
}
InputBuffer* new_input_buffer() {
InputBuffer* input_buffer = malloc(sizeof(InputBuffer));
input_buffer->buffer = NULL;
input_buffer->buffer_length = 0;
input_buffer->input_length = 0;
return input_buffer;
}
void print_prompt() {
printf("db > ");
}
void read_input(InputBuffer* input_buffer) {
ssize_t bytes_read = getline(
&(input_buffer->buffer),
&(input_buffer->buffer_length),
stdin
);
if (bytes_read <= 0) {
printf("Error reading input\n");
exit(EXIT_FAILURE);
}
// Ignore trailing newline
input_buffer->input_length = bytes_read -1;
input_buffer->buffer[bytes_read - 1] = 0;
}
void pager_flush(Pager* pager, uint32_t page_num) {
if (pager->pages[page_num] == NULL) {
printf("Tried to flush null page\n");
exit(EXIT_FAILURE);
}
off_t offset = lseek(pager->file_descriptor, page_num * PAGE_SIZE, SEEK_SET);
if (offset == -1) {
printf("Error seeking: %d\n", errno);
exit(EXIT_FAILURE);
}
ssize_t bytes_written = write(pager->file_descriptor, pager->pages[page_num], PAGE_SIZE);
if (bytes_written == -1) {
printf("Error writing: %d\n", errno);
exit(EXIT_FAILURE);
}
}
void db_close(Table* table) {
Pager* pager = table->pager;
for (uint32_t i = 0; i < pager->num_pages; i++) {
if (pager->pages[i] == NULL) {
continue;
}
pager_flush(pager, i);
free(pager->pages[i]);
pager->pages[i] = NULL;
}
int result = close(pager->file_descriptor);
if (result == -1) {
printf("Error closing db file.\n");
exit(EXIT_FAILURE);
}
for(uint32_t i = 0; i < TABLE_MAX_PAGES; i++) {
void* page = pager->pages[i];
if (page) {
free(page);
pager->pages[i] = NULL;
}
}
free(pager);
}
MetaCommandResult do_meta_command(InputBuffer* input_buffer, Table* table) {
if (strcmp(input_buffer->buffer, ".exit") == 0) {
db_close(table);
exit(EXIT_SUCCESS);
} else if (strcmp(input_buffer->buffer, ".btree") == 0){
printf("Tree:\n");
print_tree(table->pager, 0, 0);
return META_COMMAND_SUCCESS;
} else if (strcmp(input_buffer->buffer, ".constants") == 0) {
printf("Constants:\n");
print_constants();
return META_COMMAND_SUCCESS;
} else {
return META_COMMAND_UNRECOGNIZED_COMMAND;
}
}
PrepareResult prepare_insert(InputBuffer* input_buffer, Statement* statement) {
statement->type = STATEMENT_INSERT;
char* keyword = strtok(input_buffer->buffer, " ");
char* id_string = strtok(NULL, " ");
char* username = strtok(NULL, " ");
char* email = strtok(NULL, " ");
if (id_string == NULL || username == NULL || email == NULL) {
return PREPARE_SYNTAX_ERROR;
}
int id = atoi(id_string);
if (id < 0) {
return PREPARE_NEGATIVE_ID;
}
if (strlen(username) > COLUMN_USERNAME_SIZE) {
return PREPARE_STRING_TOO_LONG;
}
if (strlen(email) > COLUMN_EMAIL_SIZE) {
return PREPARE_STRING_TOO_LONG;
}
statement->row_to_insert.id = id;
strcpy(statement->row_to_insert.username, username);
strcpy(statement->row_to_insert.email, email);
return PREPARE_SUCCESS;
}
PrepareResult prepare_statement(InputBuffer* input_buffer, Statement* statement) {
if (strncmp(input_buffer->buffer, "insert", 6) == 0) {
return prepare_insert(input_buffer, statement);
}
if (strncmp(input_buffer->buffer, "select", 6) == 0) {
statement->type = STATEMENT_SELECT;
return PREPARE_SUCCESS;
}
return PREPARE_UNRECOGNIZED_STATEMENT;
}
/*
* Until we start recycling free pages, new pages will always
* go onto the end of the database file
*/
uint32_t get_unused_page_num(Pager * pager) {
return pager->num_pages;
}
void create_new_root(Table* table, uint32_t right_child_page_num) {
/*
* Handle splitting the root.
* Old root copied to new page, becomes left child.
* Address of right child passed in.
* Re-initialize root page to contain the new root node.
* New root points to two children.
*/
void* root = get_page(table->pager, table->root_page_num);
void* right_child = get_page(table->pager, right_child_page_num);
uint32_t left_child_page_num = get_unused_page_num(table->pager);
void* left_child = get_page(table->pager, left_child_page_num);
/* Left child has data copied from old root */
memcpy(left_child, root, PAGE_SIZE);
set_node_root(left_child, false);
/* Root node is a new internal node with one key and two children */
initialize_internal_node(root);
set_node_root(root, true);
*internal_node_num_keys(root) = 1;
*internal_node_child(root, 0) = left_child_page_num;
uint32_t left_child_max_key = get_node_max_key(left_child);
*internal_node_key(root, 0) = left_child_max_key;
*internal_node_right_child(root) = right_child_page_num;
}
void leaf_node_split_and_insert(Cursor* cursor, uint32_t key, Row* value) {
/*
* Create a new node and move half the cells over.
* Insert the new value in one of the two nodes.
* Update parent or create a new parent.
*/
void* old_node = get_page(cursor->table->pager, cursor->page_num);
uint32_t new_page_num = get_unused_page_num(cursor->table->pager);
void* new_node = get_page(cursor->table->pager, new_page_num);
initialize_leaf_node(new_node);
/*
* All existing keys plus new key should be divided
* evenly between old (left) and new (right) nodes.
* Starting from the right, move each key to correct position.
*/
for (int32_t i = LEAF_NODE_MAX_CELLS; i >= 0; i--) {
void* destination_node;
if (i >+ LEAF_NODE_LEFT_SPLIT_COUNT) {
destination_node = new_node;
} else {
destination_node = old_node;
}
uint32_t index_within_node = i % LEAF_NODE_LEFT_SPLIT_COUNT;
void* destination = leaf_node_cell(destination_node, index_within_node);
if (i == cursor->cell_num) {
serialize_row(value, destination);
} else if (i > cursor->cell_num) {
memcpy(destination, leaf_node_cell(old_node, i - 1), LEAF_NODE_CELL_SIZE);
} else {
memcpy(destination, leaf_node_cell(old_node, i), LEAF_NODE_CELL_SIZE);
}
}
/* Update cell count on both leaf nodes */
*(leaf_node_num_cells(old_node)) = LEAF_NODE_LEFT_SPLIT_COUNT;
*(leaf_node_num_cells(new_node)) = LEAF_NODE_RIGHT_SPLIT_COUNT;
if (is_node_root(old_node)) {
return create_new_root(cursor->table, new_page_num);
} else {
printf("Need to implement updating parent after split\n");
exit(EXIT_FAILURE);
}
}
void leaf_node_insert(Cursor* cursor, uint32_t key, Row* value) {
void* node = get_page(cursor->table->pager, cursor->page_num);
uint32_t num_cells = *leaf_node_num_cells(node);
if (num_cells >= LEAF_NODE_MAX_CELLS) {
// Node full
leaf_node_split_and_insert(cursor, key, value);
return;
}
if (cursor->cell_num < num_cells) {
// Make room for new cell
for (uint32_t i = num_cells; i > cursor->cell_num; i--) {
memcpy(leaf_node_cell(node, i), leaf_node_cell(node, i - 1),
LEAF_NODE_CELL_SIZE);
}
*(leaf_node_num_cells(node)) += 1;
*(leaf_node_key(node, cursor->cell_num)) = key;
serialize_row(value, leaf_node_value(node, cursor->cell_num));
}
}
ExecuteResult execute_insert(Statement* statement, Table* table) {
void* node = get_page(table->pager, table->root_page_num);
uint32_t num_cells = (*leaf_node_num_cells(node));
Row* row_to_insert = &(statement->row_to_insert);
uint32_t key_to_insert = row_to_insert->id;
Cursor* cursor = table_find(table, key_to_insert);
if (cursor->cell_num < num_cells) {
uint32_t key_at_index = *leaf_node_key(node, cursor->cell_num);
if (key_at_index == key_to_insert) {
return EXECUTE_DUPLICATE_KEY;
}
}
leaf_node_insert(cursor, row_to_insert->id, row_to_insert);
free(cursor);
return EXECUTE_SUCCESS;
}
ExecuteResult execute_select(Statement* statement, Table* table) {
Cursor* cursor = table_start(table);
Row row;
while (!(cursor->end_of_table)) {
deserialize_row(cursor_value(cursor), &row);
print_row(&row);
cursor_advance(cursor);
}
free(cursor);
return EXECUTE_SUCCESS;
}
ExecuteResult execute_statement(Statement* statement, Table* table) {
switch(statement->type) {
case (STATEMENT_INSERT):
return execute_insert(statement, table);
case (STATEMENT_SELECT):
return execute_select(statement, table);
}
}
int main(int argc, char* argv[]) {
if (argc < 2) {
printf("Must supply a database filename\n");
exit(EXIT_FAILURE);
}
char* filename = argv[1];
Table* table = db_open(filename);
InputBuffer* input_buffer = new_input_buffer();
while (true) {
print_prompt();
read_input(input_buffer);
if (input_buffer->buffer[0] == '.') {
switch (do_meta_command(input_buffer, table)) {
case (META_COMMAND_SUCCESS):
continue;
case (META_COMMAND_UNRECOGNIZED_COMMAND):
printf("Unrecognized command '%s'\n", input_buffer->buffer);
continue;
}
}
Statement statement;
switch(prepare_statement(input_buffer, &statement)) {
case (PREPARE_SUCCESS):
break;
case (PREPARE_NEGATIVE_ID):
printf("ID must be positive.\n");
continue;
case (PREPARE_STRING_TOO_LONG):
printf("String is too long.\n");
continue;
case (PREPARE_SYNTAX_ERROR):
printf("Syntax error. Could not parse statement.\n");
continue;
case (PREPARE_UNRECOGNIZED_STATEMENT):
printf("Unrecognized keyword at start of '%s'.\n", input_buffer->buffer);
continue;
}
switch(execute_statement(&statement, table)) {
case (EXECUTE_SUCCESS):
printf("Executed.\n");
break;
case (EXECUTE_DUPLICATE_KEY):
printf("Error: Duplicate key.\n");
break;
case (EXECUTE_TABLE_FULL):
printf("Error: Table full.\n");
break;
}
}
}
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