Clean up migration to make it more readable

This commit is contained in:
projectmoon 2020-10-30 20:16:08 +00:00 committed by ProjectMoon
parent a53ce85f38
commit 3cec676b2f
2 changed files with 58 additions and 31 deletions

View File

@ -1,11 +1,12 @@
use crate::db::errors::{DataError, MigrationError};
use crate::db::variables;
use crate::db::Database;
use phf::phf_map;
pub(super) type DataMigration = fn(&Database) -> Result<(), DataError>;
static MIGRATIONS: phf::Map<u32, DataMigration> = phf_map! {
1u32 => super::variables::migrations::migration1,
1u32 => variables::migrations::add_room_user_variable_count,
};
pub fn get_migrations(versions: &[u32]) -> Result<Vec<DataMigration>, MigrationError> {

View File

@ -3,19 +3,29 @@ use crate::db::errors::{DataError, MigrationError};
use crate::db::Database;
use byteorder::LittleEndian;
use sled::transaction::TransactionError;
use sled::Batch;
use sled::{Batch, IVec};
use zerocopy::byteorder::U32;
use zerocopy::AsBytes;
//TODO we will make this set variable count properly.
pub(in crate::db) fn migration1(db: &Database) -> Result<(), DataError> {
let tree = &db.variables.0;
let prefix = variables_space_prefix("");
//Not to be confused with the super::RoomAndUser delineator.
#[derive(PartialEq, Eq, std::hash::Hash)]
struct RoomAndUser {
room_id: String,
username: String,
}
//Extract a vec of tuples, consisting of room id + username.
let results: Vec<(String, String)> = tree
.scan_prefix(prefix)
.map(|entry| {
/// Create a version 0 user variable key.
fn v0_variable_key(info: &RoomAndUser, variable_name: &str) -> Vec<u8> {
let mut key = vec![];
key.extend_from_slice(info.room_id.as_bytes());
key.extend_from_slice(info.username.as_bytes());
key.extend_from_slice(variable_name.as_bytes());
key
}
fn map_value_to_room_and_user(
entry: sled::Result<(IVec, IVec)>,
) -> Result<RoomAndUser, MigrationError> {
if let Ok((key, _)) = entry {
let keys: Vec<Result<&str, _>> = key
.split(|&b| b == 0xff)
@ -23,7 +33,10 @@ pub(in crate::db) fn migration1(db: &Database) -> Result<(), DataError> {
.collect();
if let &[_, Ok(room_id), Ok(username), Ok(_variable)] = keys.as_slice() {
Ok((room_id.to_owned(), username.to_owned()))
Ok(RoomAndUser {
room_id: room_id.to_owned(),
username: username.to_owned(),
})
} else {
Err(MigrationError::MigrationFailed(
"a key violates utf8 schema".to_string(),
@ -34,10 +47,19 @@ pub(in crate::db) fn migration1(db: &Database) -> Result<(), DataError> {
"encountered unexpected key".to_string(),
))
}
})
}
pub(in crate::db) fn add_room_user_variable_count(db: &Database) -> Result<(), DataError> {
let tree = &db.variables.0;
let prefix = variables_space_prefix("");
//Extract a vec of tuples, consisting of room id + username.
let results: Vec<RoomAndUser> = tree
.scan_prefix(prefix)
.map(map_value_to_room_and_user)
.collect::<Result<Vec<_>, MigrationError>>()?;
let counts: HashMap<(String, String), u32> =
let counts: HashMap<RoomAndUser, u32> =
results
.into_iter()
.fold(HashMap::new(), |mut count_map, room_and_user| {
@ -47,15 +69,19 @@ pub(in crate::db) fn migration1(db: &Database) -> Result<(), DataError> {
});
//Start a transaction on the variables tree.
//Delete the old variable_count variable if exists.
//Add variable count according to new schema.
let tx_result: Result<_, TransactionError<DataError>> = db.variables.0.transaction(|tx_vars| {
let batch = counts.iter().fold(Batch::default(), |mut batch, entry| {
let key =
variables_space_key(RoomAndUser(&(entry.0).0, &(entry.0).1), VARIABLE_COUNT_KEY);
let (info, count) = entry;
let db_value: U32<LittleEndian> = U32::new(*entry.1);
//Add variable count according to new schema.
let delineator = super::RoomAndUser(&info.room_id, &info.username);
let key = variables_space_key(delineator, VARIABLE_COUNT_KEY);
let db_value: U32<LittleEndian> = U32::new(*count);
batch.insert(key, db_value.as_bytes());
//Delete the old variable_count variable if exists.
let old_key = v0_variable_key(&info, "variable_count");
batch.remove(old_key);
batch
});