Count user variables on a per-room basis.

This commit is contained in:
projectmoon 2020-10-20 20:54:20 +00:00 committed by ProjectMoon
parent ebfd230f31
commit 114c879c6f
1 changed files with 256 additions and 16 deletions

272
src/db.rs
View File

@ -1,5 +1,7 @@
use byteorder::LittleEndian;
use sled::{Db, IVec, Tree};
use sled::transaction::abort;
use sled::transaction::{TransactionError, TransactionalTree, UnabortableTransactionError};
use sled::{Db, Tree};
use std::collections::HashMap;
use thiserror::Error;
use zerocopy::byteorder::I32;
@ -10,6 +12,8 @@ use zerocopy::{AsBytes, LayoutVerified};
/// read.
type LittleEndianI32Layout<'a> = LayoutVerified<&'a [u8], I32<LittleEndian>>;
const VARIABLE_COUNT_KEY: &'static str = "variable_count";
#[derive(Clone)]
pub struct Database {
db: Db,
@ -32,6 +36,23 @@ pub enum DataError {
#[error("internal database error: {0}")]
InternalError(#[from] sled::Error),
#[error("transaction error: {0}")]
TransactionError(#[from] sled::transaction::TransactionError),
#[error("unabortable transaction error: {0}")]
UnabortableTransactionError(#[from] UnabortableTransactionError),
}
impl From<TransactionError<DataError>> for DataError {
fn from(error: TransactionError<DataError>) -> Self {
match error {
TransactionError::Abort(data_err) => data_err,
TransactionError::Storage(storage_err) => {
DataError::TransactionError(TransactionError::Storage(storage_err))
}
}
}
}
fn to_key(room_id: &str, username: &str, variable_name: &str) -> Vec<u8> {
@ -42,6 +63,10 @@ fn to_key(room_id: &str, username: &str, variable_name: &str) -> Vec<u8> {
key
}
fn room_variable_count_key(room_id: &str, username: &str) -> Vec<u8> {
to_key(room_id, username, VARIABLE_COUNT_KEY)
}
fn to_prefix(room_id: &str, username: &str) -> Vec<u8> {
let mut prefix = vec![];
prefix.extend_from_slice(room_id.as_bytes());
@ -49,7 +74,9 @@ fn to_prefix(room_id: &str, username: &str) -> Vec<u8> {
prefix
}
fn convert(raw_value: &[u8]) -> Result<i32, DataError> {
/// Convert bytes to an i32 with zero-copy deserialization. An error
/// is returned if the bytes do not represent an i32.
fn convert_i32(raw_value: &[u8]) -> Result<i32, DataError> {
let layout = LittleEndianI32Layout::new_unaligned(raw_value.as_ref());
if let Some(layout) = layout {
@ -60,6 +87,29 @@ fn convert(raw_value: &[u8]) -> Result<i32, DataError> {
}
}
/// Atomically alter the count of variables in the database, by the
/// given amount. Count cannot go below 0.
fn alter_room_variable_count(
variables: &TransactionalTree,
room_id: &str,
username: &str,
amount: i32,
) -> Result<i32, DataError> {
let key = room_variable_count_key(room_id, username);
let mut new_count = match variables.get(&key)? {
Some(bytes) => convert_i32(&bytes)? + amount,
None => amount,
};
if new_count < 0 {
new_count = 0;
}
let db_value: I32<LittleEndian> = I32::new(new_count);
variables.insert(key, db_value.as_bytes())?;
Ok(new_count)
}
impl Database {
pub fn new<P: AsRef<std::path::Path>>(path: P) -> Result<Database, DataError> {
let db = sled::open(path)?;
@ -89,17 +139,30 @@ impl Database {
//Strips room and username from key, leaving
//behind name.
let variable_name = std::str::from_utf8(&key[prefix_len..])?;
Ok((variable_name.to_owned(), convert(&raw_value)?))
Ok((variable_name.to_owned(), convert_i32(&raw_value)?))
}
Err(e) => Err(e.into()),
})
.collect();
//Convert to hash map. Can we do this in the first mapping
//step instead?
//Convert_I32 to hash map. Can we do this in the first mapping
//step instead? For some reason this is faster.
variables.map(|entries| entries.into_iter().collect())
}
pub async fn get_variable_count(
&self,
room_id: &str,
username: &str,
) -> Result<i32, DataError> {
let key = room_variable_count_key(room_id, username);
if let Some(raw_value) = self.variables.get(&key)? {
convert_i32(&raw_value)
} else {
Ok(0)
}
}
pub async fn get_user_variable(
&self,
room_id: &str,
@ -109,7 +172,7 @@ impl Database {
let key = to_key(room_id, username, variable_name);
if let Some(raw_value) = self.variables.get(&key)? {
convert(&raw_value)
convert_i32(&raw_value)
} else {
Err(DataError::KeyDoesNotExist(String::from_utf8(key).unwrap()))
}
@ -122,11 +185,23 @@ impl Database {
variable_name: &str,
value: i32,
) -> Result<(), DataError> {
let key = to_key(room_id, username, variable_name);
let db_value: I32<LittleEndian> = I32::new(value);
self.variables
.insert(&key, IVec::from(db_value.as_bytes()))?;
Ok(())
.transaction(|tx| {
let key = to_key(room_id, username, variable_name);
let db_value: I32<LittleEndian> = I32::new(value);
let old_value = tx.insert(key, db_value.as_bytes())?;
//Only increment variable count on new keys.
if let None = old_value {
match alter_room_variable_count(&tx, room_id, username, 1) {
Err(e) => abort(e),
_ => Ok(()),
}
} else {
Ok(())
}
})
.map_err(|e| e.into())
}
pub async fn delete_user_variable(
@ -135,11 +210,176 @@ impl Database {
username: &str,
variable_name: &str,
) -> Result<(), DataError> {
let key = to_key(room_id, username, variable_name);
if let Some(_) = self.variables.remove(&key)? {
Ok(())
} else {
Err(DataError::KeyDoesNotExist(String::from_utf8(key).unwrap()))
}
self.variables
.transaction(|tx| {
let key = to_key(room_id, username, variable_name);
if let Some(_) = tx.remove(key.clone())? {
match alter_room_variable_count(&tx, room_id, username, -1) {
Err(e) => abort(e),
_ => Ok(()),
}
} else {
abort(DataError::KeyDoesNotExist(String::from_utf8(key).unwrap()))
}
})
.map_err(|e| e.into())
}
}
#[cfg(test)]
mod tests {
use super::*;
use tempfile::tempdir;
//Room Variable count tests
#[tokio::test]
async fn alter_room_variable_count_test() {
let db = Database::new(&tempdir().unwrap()).unwrap();
let alter_count = |amount: i32| {
db.variables
.transaction(|tx| {
match alter_room_variable_count(&tx, "room", "username", amount) {
Err(e) => abort(e),
_ => Ok(()),
}
})
.expect("got transaction failure");
};
async fn get_count(db: &Database) -> i32 {
db.get_variable_count("room", "username")
.await
.expect("could not get variable count")
}
//addition
alter_count(5);
assert_eq!(5, get_count(&db).await);
//subtraction
alter_count(-3);
assert_eq!(2, get_count(&db).await);
}
#[tokio::test]
async fn alter_room_variable_count_cannot_go_below_0_test() {
let db = Database::new(&tempdir().unwrap()).unwrap();
db.variables
.transaction(
|tx| match alter_room_variable_count(&tx, "room", "username", -1000) {
Err(e) => abort(e),
_ => Ok(()),
},
)
.expect("got transaction failure");
let count = db
.get_variable_count("room", "username")
.await
.expect("could not get variable count");
assert_eq!(0, count);
}
#[tokio::test]
async fn empty_db_reports_0_room_variable_count_test() {
let db = Database::new(&tempdir().unwrap()).unwrap();
let count = db
.get_variable_count("room", "username")
.await
.expect("could not get variable count");
assert_eq!(0, count);
}
#[tokio::test]
async fn set_user_variable_increments_count() {
let db = Database::new(&tempdir().unwrap()).unwrap();
db.set_user_variable("room", "username", "myvariable", 5)
.await
.expect("could not insert variable");
let count = db
.get_variable_count("room", "username")
.await
.expect("could not get variable count");
assert_eq!(1, count);
}
#[tokio::test]
async fn update_user_variable_does_not_increment_count() {
let db = Database::new(&tempdir().unwrap()).unwrap();
db.set_user_variable("room", "username", "myvariable", 5)
.await
.expect("could not insert variable");
db.set_user_variable("room", "username", "myvariable", 10)
.await
.expect("could not update variable");
let count = db
.get_variable_count("room", "username")
.await
.expect("could not get variable count");
assert_eq!(1, count);
}
// Set/get/delete variable tests
#[tokio::test]
async fn set_and_get_variable_test() {
let db = Database::new(&tempdir().unwrap()).unwrap();
db.set_user_variable("room", "username", "myvariable", 5)
.await
.expect("could not insert variable");
let value = db
.get_user_variable("room", "username", "myvariable")
.await
.expect("could not get value");
assert_eq!(5, value);
}
#[tokio::test]
async fn delete_variable_test() {
let db = Database::new(&tempdir().unwrap()).unwrap();
db.set_user_variable("room", "username", "myvariable", 5)
.await
.expect("could not insert variable");
db.delete_user_variable("room", "username", "myvariable")
.await
.expect("could not delete value");
let result = db.get_user_variable("room", "username", "myvariable").await;
assert!(result.is_err());
assert!(matches!(result, Err(DataError::KeyDoesNotExist(_))));
}
#[tokio::test]
async fn get_missing_variable_returns_key_does_not_exist() {
let db = Database::new(&tempdir().unwrap()).unwrap();
let result = db.get_user_variable("room", "username", "myvariable").await;
assert!(result.is_err());
assert!(matches!(result, Err(DataError::KeyDoesNotExist(_))));
}
#[tokio::test]
async fn remove_missing_variable_returns_key_does_not_exist() {
let db = Database::new(&tempdir().unwrap()).unwrap();
let result = db
.delete_user_variable("room", "username", "myvariable")
.await;
assert!(result.is_err());
assert!(matches!(result, Err(DataError::KeyDoesNotExist(_))));
}
}