feat: tellydb is now completely in-memory database

note: only supports for primitive types for now
feat(database): add DIRECT I/O for database file
perf: reduce system calls
feat(database): renew password saving to database file
feat(database): change password deriving algorithm to HKDF on SHA384
perf(database): change password structure
fix(database): missing configuration freeing on checking lock file
docs(file): change authorization file specification
perf(commands): replace where_password with get_password in AUTH command
feat(commands): add RENAME and DEL commands
refactor(utils): add length argument to hash method
refactor(database): change get_data argument to string_t
feat(commands): add DELETE command
feat(commands): add deleting empty data to HDEL, RPOP and LPOP commands
perf(database): remove null terminator from data keys

README.md

@@ -1,5 +1,5 @@
 # tellydb
-A key-value database project for educational purposes.
+An in-memory key-value database project for educational purposes.
 
 ## Features
 + Follows [RESP2/RESP3](https://redis.io/docs/latest/develop/reference/protocol-spec/) specification from redis, so all redis clients are compatible
@@ -9,7 +9,8 @@ A key-value database project for educational purposes.
 + Supports integer, string, null, boolean, list and hash table types
 + Provides atomicity when saving to the database file
 + Provides saving to the database file using a background thread
-+ Provides authorization system with permissions
++ Provides authorization system with permissions using passwords
++ Uses Direct I/O for logging and database files
 
 > Look at:  
 > [docs/SPECS.md](./docs/SPECS.md) for more technical information,  

docs/AUTH.md

@@ -5,7 +5,11 @@ This file defines authorization system concepts.
 If a client use a password defined in the server with `AUTH`, this client have all permissions of the password.  
 
 ## Limitations
-Server can have up to `2^6-1` passwords.
+* Server can have up to `2^6-1` passwords.
+
+## Notes
+* Password deriving algorithm is HKDF SHA384.
+* The length of derived passwords is 48.
 
 ## Permissions
 * `P_READ`, read a value from database, not included data type and data existence

docs/COMMANDS.md

@@ -517,6 +517,19 @@ APPEND user_name " Black"
 DECR user_age
 ```
 
+#### DEL
+**Syntax**: `DEL key [key ...]`  
+**Description**: Deletes the specified keys.  
+**Since**: `0.1.7`  
+**Time complexity**: `O(N) where N is key count`  
+**Permissions**: `P_WRITE`  
+**Returns**: Deleted key count  
+
+**Example**:
+```shell
+DEL user_name user_id
+```
+
 ---
 
 ### EXISTS
@@ -572,6 +585,23 @@ INCR user_age
 
 ---
 
+#### RENAME
+**Syntax**: `RENAME old new`  
+**Description**: Renames existing key to new key.  
+**Since**: `0.1.7`  
+**Time complexity**: `O(1)`  
+**Permissions**: `P_WRITE`  
+**Returns**: `OK` or null reply if key is ntot exist  
+**Behavior**:
+* If new key already exists, throws an error.
+
+**Example**:
+```shell
+RENAME name user_name
+```
+
+---
+
 ### SET
 **Syntax**: `SET key value [NX|XX] [GET]`  
 **Description**: Sets value.  

docs/FILE.md

@@ -28,7 +28,7 @@ Authorization part consists of passwords and their permissions and as follows:
 * `password count byte count (1 byte, n) + password count (n byte) + passwords`
 
 A password is as follows:
-* `string length specifier + hashed password + password salt (2 bytes) + password permissions (1 byte)`
+* `derived password (48 byte) + password permissions (1 byte)`
 
 For permissions, look at [AUTH.md](./AUTH.md).
 

headers/commands.h

@@ -62,9 +62,11 @@ extern const struct Command cmd_htype;
 /* KV COMMANDS */
 extern const struct Command cmd_append;
 extern const struct Command cmd_decr;
+extern const struct Command cmd_del;
 extern const struct Command cmd_get;
 extern const struct Command cmd_exists;
 extern const struct Command cmd_incr;
+extern const struct Command cmd_rename;
 extern const struct Command cmd_set;
 extern const struct Command cmd_type;
 /* /KV COMMANDS */

headers/database.h

@@ -15,33 +15,29 @@ struct KVPair {
   string_t key;
   void *value;
   enum TellyTypes type;
-
-  struct {
-    off_t start_at;
-    off_t end_at;
-  } pos;
 };
 
 struct BTree *create_cache();
 struct BTree *get_cache();
-struct KVPair *get_kv_from_cache(const char *key);
-struct BTreeValue **get_sorted_kvs_by_pos_as_values(uint32_t *size);
-bool delete_kv_from_cache(const char *key);
+struct KVPair *get_kv_from_cache(const char *key, const size_t length);
+bool delete_kv_from_cache(const char *key, const size_t length);
 void free_cache();
 
-void get_all_keys(off_t from);
-struct KVPair *get_data(const char *key);
+void get_all_data_from_file(const int fd, const off64_t file_size, char *block, const uint16_t block_size, const uint16_t filled_block_size);
+struct KVPair *get_data(const string_t key);
 struct KVPair *set_data(struct KVPair *data, const string_t key, void *value, const enum TellyTypes type);
+bool delete_data(const string_t key);
 void save_data(const uint64_t server_age);
 bool bg_save(uint64_t server_age);
 
-void set_kv(struct KVPair *kv, const string_t key, void *value, const enum TellyTypes type, const off_t start_at, const off_t end_at);
+void set_kv(struct KVPair *kv, const string_t key, void *value, const enum TellyTypes type);
 void free_kv(struct KVPair *kv);
 /* /DATABASE */
 
 
 /* DATABASE FILE */
 bool open_database_fd(const char *filename, uint64_t *server_age);
+uint16_t get_block_size();
 int get_database_fd();
 void close_database_fd();
 /* /DATABASE FILE */

headers/hashtable.h

@@ -28,7 +28,7 @@ struct HashTable {
 
 struct HashTable *create_hashtable(uint32_t default_size);
 void resize_hashtable(struct HashTable *table, const uint32_t size);
-struct FVPair *get_fv_from_hashtable(struct HashTable *table, char *name);
+struct FVPair *get_fv_from_hashtable(struct HashTable *table, const string_t name);
 void free_hashtable(struct HashTable *table);
 
 void free_fv(struct FVPair *fv);

headers/server.h

@@ -63,26 +63,28 @@ enum Permissions {
 };
 
 struct Password {
-  string_t data;
+  unsigned char data[48];
   uint8_t permissions;
-  char salt[3];
 };
 
 void create_constant_passwords();
 void free_constant_passwords();
 struct Password *get_full_password();
 struct Password *get_empty_password();
 
+bool initialize_kdf();
+void free_kdf();
+
 struct Password **get_passwords();
 uint32_t get_password_count();
-off_t get_authorization_from_file(const int fd);
+uint16_t get_authorization_from_file(const int fd, char *block, const uint16_t block_size);
 void free_passwords();
 
 void add_password(struct Client *client, const string_t data, const uint8_t permissions);
-bool remove_password(struct Client *executor, const char *value);
-int32_t where_password(const char *value);
-struct Password *get_password(const char *value);
-bool edit_password(const char *value, const uint32_t permissions);
+bool remove_password(struct Client *executor, char *value, const size_t value_len);
+int32_t where_password(char *value, const size_t value_len);
+struct Password *get_password(char *value, const size_t value_len);
+bool edit_password(char *value, const size_t value_len, const uint32_t permissions);
 /* /AUTH */
 
 

headers/utils.h

@@ -45,4 +45,4 @@ void generate_date_string(char *text, const time_t value);
 
 int open_file(const char *file, int flags);
 
-uint64_t hash(char *key);
+uint64_t hash(char *key, uint32_t length);

src/commands/generic/auth.c

@@ -13,10 +13,10 @@ static void run(struct Client *client, commanddata_t *command, struct Password *
       return;
     }
 
-    const char *value = command->args[0].value;
-    const int32_t at = where_password(value);
+    const string_t input = command->args[0];
+    struct Password *found = get_password(input.value, input.len);
 
-    if (at == -1) {
+    if (!found) {
       _write(client, "-This password does not exist\r\n", 31);
     } else {
       if (password && password != get_empty_password()) {
@@ -33,9 +33,7 @@ static void run(struct Client *client, commanddata_t *command, struct Password *
         }
       }
 
-      struct Password **passwords = get_passwords();
-      client->password = passwords[at];
-
+      client->password = found;
       WRITE_OK(client);
     }
   }

src/commands/generic/pwd.c

@@ -78,7 +78,7 @@ static void run(struct Client *client, commanddata_t *command, struct Password *
         return;
       }
 
-      if (where_password(data.value) == -1) {
+      if (where_password(data.value, data.len) == -1) {
         add_password(client, data, permissions);
         WRITE_OK(client);
       } else {
@@ -90,10 +90,10 @@ static void run(struct Client *client, commanddata_t *command, struct Password *
         return;
       }
 
-      const char *value = command->args[1].value;
+      const string_t input = command->args[1];
       char *permissions_value = command->args[2].value;
 
-      struct Password *target = get_password(value);
+      struct Password *target = get_password(input.value, input.len);
 
       if (target) {
         const uint8_t permissions = read_permissions_value(client, permissions_value);
@@ -115,9 +115,9 @@ static void run(struct Client *client, commanddata_t *command, struct Password *
         return;
       }
 
-      const char *value = command->args[1].value;
+      const string_t input = command->args[1];
 
-      if (remove_password(client, value)) WRITE_OK(client);
+      if (remove_password(client, input.value, input.len)) WRITE_OK(client);
       else {
         _write(client, "-This password cannot be found\r\n", 32);
       }

src/commands/hashtable/hdel.c

@@ -16,7 +16,7 @@ static void run(struct Client *client, commanddata_t *command, struct Password *
 
   if (password->permissions & P_WRITE) {
     const string_t key = command->args[0];
-    struct KVPair *kv = get_data(key.value);
+    struct KVPair *kv = get_data(key);
     struct HashTable *table;
 
     if (kv) {
@@ -39,6 +39,8 @@ static void run(struct Client *client, commanddata_t *command, struct Password *
           del_fv_to_hashtable(table, command->args[i]);
         }
 
+        if (table->size.all == 0) delete_data(key);
+
         char buf[14];
         const size_t nbytes = sprintf(buf, ":%d\r\n", old_size - table->size.all);
         _write(client, buf, nbytes);
@@ -49,6 +51,8 @@ static void run(struct Client *client, commanddata_t *command, struct Password *
       for (uint32_t i = 1; i < command->arg_count; ++i) {
         del_fv_to_hashtable(table, command->args[i]);
       }
+
+      if (table->size.all == 0) delete_data(key);
     }
   } else if (client) {
     _write(client, "-Not allowed to use this command, need P_WRITE\r\n", 48);

src/commands/hashtable/hget.c

@@ -14,12 +14,11 @@ static void run(struct Client *client, commanddata_t *command, struct Password *
     }
 
     if (password->permissions & P_READ) {
-      const struct KVPair *kv = get_data(command->args[0].value);
+      const struct KVPair *kv = get_data(command->args[0]);
 
       if (kv) {
         if (kv->type == TELLY_HASHTABLE) {
-          char *name = command->args[1].value;
-          const struct FVPair *field = get_fv_from_hashtable(kv->value, name);
+          const struct FVPair *field = get_fv_from_hashtable(kv->value, command->args[1]);
 
           if (field) {
             write_value(client, field->value, field->type);

src/commands/hashtable/hlen.c

@@ -15,7 +15,7 @@ static void run(struct Client *client, commanddata_t *command, struct Password *
     }
 
     if (password->permissions & P_READ) {
-      const struct KVPair *kv = get_data(command->args[0].value);
+      const struct KVPair *kv = get_data(command->args[0]);
 
       if (kv) {
         if (kv->type == TELLY_HASHTABLE) {

src/commands/hashtable/hset.c

@@ -18,7 +18,7 @@ static void run(struct Client *client, commanddata_t *command, struct Password *
     }
 
     const string_t key = command->args[0];
-    struct KVPair *kv = get_data(key.value);
+    struct KVPair *kv = get_data(key);
     struct HashTable *table;
 
     if (kv) {

src/commands/hashtable/htype.c

@@ -14,13 +14,11 @@ static void run(struct Client *client, commanddata_t *command, struct Password *
     }
 
     if (password->permissions & P_READ) {
-      const char *key = command->args[0].value;
-      const struct KVPair *kv = get_data(key);
+      const struct KVPair *kv = get_data(command->args[0]);
 
       if (kv) {
         if (kv->type == TELLY_HASHTABLE) {
-          char *name = command->args[1].value;
-          struct FVPair *fv = get_fv_from_hashtable(kv->value, name);
+          struct FVPair *fv = get_fv_from_hashtable(kv->value, command->args[1]);
 
           switch (fv->type) {
             case TELLY_NULL:

src/commands/kv/append.c

@@ -12,7 +12,7 @@ static void run(struct Client *client, commanddata_t *command, struct Password *
 
   if (password->permissions & (P_READ | P_WRITE)) {
     const string_t key = command->args[0];
-    const struct KVPair *kv = get_data(key.value);
+    const struct KVPair *kv = get_data(key);
 
     if (kv) {
       if (kv->type == TELLY_STR) {

src/commands/kv/decr.c

@@ -15,7 +15,7 @@ static void run(struct Client *client, commanddata_t *command, struct Password *
 
   if (password->permissions & (P_READ | P_WRITE)) {
     string_t key = command->args[0];
-    struct KVPair *result = get_data(key.value);
+    struct KVPair *result = get_data(key);
 
     if (!result) {
       long *number = calloc(1, sizeof(long));

src/commands/kv/del.c

@@ -0,0 +1,40 @@
+#include "../../../headers/server.h"
+#include "../../../headers/database.h"
+#include "../../../headers/commands.h"
+
+#include <stdio.h>
+#include <stdint.h>
+
+static void run(struct Client *client, commanddata_t *command, struct Password *password) {
+  if (command->arg_count == 0) {
+    if (client) WRONG_ARGUMENT_ERROR(client, "DEL", 3);
+    return;
+  }
+
+  if (password->permissions & P_WRITE) {
+    uint32_t deleted = 0;
+
+    for (uint32_t i = 0; i < command->arg_count; ++i) {
+      deleted += delete_data(command->args[i]);
+    }
+
+    if (client) {
+      char res[13];
+      const size_t res_len = sprintf(res, ":%d\r\n", deleted);
+
+      _write(client, res, res_len);
+    }
+  } else if (client) {
+    _write(client, "-Not allowed to use this command, need P_WRITE\r\n", 48);
+  }
+}
+
+const struct Command cmd_del = {
+  .name = "DEL",
+  .summary = "Deletes the specified keys.",
+  .since = "0.1.7",
+  .complexity = "O(N) where N is key count",
+  .subcommands = NULL,
+  .subcommand_count = 0,
+  .run = run
+};

src/commands/kv/exists.c

@@ -20,7 +20,7 @@ static void run(struct Client *client, commanddata_t *command, __attribute__((un
     buf[0] = '\0';
 
     for (uint32_t i = 0; i < command->arg_count; ++i) {
-      const char *key = command->args[i].value;
+      const string_t key = command->args[i];
 
       if (get_data(key)) {
         existed += 1;

src/commands/kv/get.c

@@ -12,8 +12,7 @@ static void run(struct Client *client, commanddata_t *command, struct Password *
     }
 
     if (password->permissions & P_READ) {
-      const char *key = command->args[0].value;
-      const struct KVPair *kv = get_data(key);
+      const struct KVPair *kv = get_data(command->args[0]);
 
       if (kv) {
         write_value(client, kv->value, kv->type);