factor taskdb into multiple modules
This commit is contained in:
Dustin J. Mitchell
606
taskchampion/src/taskdb/mod.rs
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606
taskchampion/src/taskdb/mod.rs
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@@ -0,0 +1,606 @@
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use crate::server::Server;
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use crate::storage::{Operation, Storage, TaskMap};
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use std::collections::HashSet;
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use uuid::Uuid;
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mod ops;
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mod sync;
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/// A TaskDb is the backend for a replica. It manages the storage, operations, synchronization,
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/// and so on, and all the invariants that come with it. It leaves the meaning of particular task
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/// properties to the replica and task implementations.
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pub struct TaskDb {
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storage: Box<dyn Storage>,
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}
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impl TaskDb {
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/// Create a new TaskDb with the given backend storage
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pub fn new(storage: Box<dyn Storage>) -> TaskDb {
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TaskDb { storage }
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}
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#[cfg(test)]
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pub fn new_inmemory() -> TaskDb {
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TaskDb::new(Box::new(crate::storage::InMemoryStorage::new()))
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}
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/// Apply an operation to the TaskDb. Aside from synchronization operations, this is the only way
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/// to modify the TaskDb. In cases where an operation does not make sense, this function will do
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/// nothing and return an error (but leave the TaskDb in a consistent state).
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pub fn apply(&mut self, op: Operation) -> anyhow::Result<()> {
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// TODO: differentiate error types here?
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let mut txn = self.storage.txn()?;
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if let err @ Err(_) = ops::apply_op(txn.as_mut(), &op) {
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return err;
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}
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txn.add_operation(op)?;
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txn.commit()?;
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Ok(())
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}
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/// Get all tasks.
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pub fn all_tasks(&mut self) -> anyhow::Result<Vec<(Uuid, TaskMap)>> {
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let mut txn = self.storage.txn()?;
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txn.all_tasks()
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}
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/// Get the UUIDs of all tasks
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pub fn all_task_uuids(&mut self) -> anyhow::Result<Vec<Uuid>> {
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let mut txn = self.storage.txn()?;
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txn.all_task_uuids()
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}
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/// Get the working set
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pub fn working_set(&mut self) -> anyhow::Result<Vec<Option<Uuid>>> {
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let mut txn = self.storage.txn()?;
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txn.get_working_set()
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}
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/// Get a single task, by uuid.
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pub fn get_task(&mut self, uuid: Uuid) -> anyhow::Result<Option<TaskMap>> {
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let mut txn = self.storage.txn()?;
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txn.get_task(uuid)
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}
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/// Rebuild the working set using a function to identify tasks that should be in the set. This
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/// renumbers the existing working-set tasks to eliminate gaps, and also adds any tasks that
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/// are not already in the working set but should be. The rebuild occurs in a single
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/// trasnsaction against the storage backend.
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pub fn rebuild_working_set<F>(
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&mut self,
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in_working_set: F,
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renumber: bool,
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) -> anyhow::Result<()>
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where
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F: Fn(&TaskMap) -> bool,
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{
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let mut txn = self.storage.txn()?;
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let mut new_ws = vec![None]; // index 0 is always None
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let mut seen = HashSet::new();
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// The goal here is for existing working-set items to be "compressed' down to index 1, so
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// we begin by scanning the current working set and inserting any tasks that should still
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// be in the set into new_ws, implicitly dropping any tasks that are no longer in the
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// working set.
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for elt in txn.get_working_set()?.drain(1..) {
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if let Some(uuid) = elt {
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if let Some(task) = txn.get_task(uuid)? {
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if in_working_set(&task) {
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new_ws.push(Some(uuid));
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seen.insert(uuid);
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continue;
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}
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}
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}
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// if we are not renumbering, then insert a blank working-set entry here
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if !renumber {
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new_ws.push(None);
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}
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}
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// if renumbering, clear the working set and re-add
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if renumber {
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txn.clear_working_set()?;
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for elt in new_ws.drain(1..new_ws.len()).flatten() {
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txn.add_to_working_set(elt)?;
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}
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} else {
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// ..otherwise, just clear the None items determined above from the working set
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for (i, elt) in new_ws.iter().enumerate().skip(1) {
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if elt.is_none() {
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txn.set_working_set_item(i, None)?;
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}
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}
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}
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// Now go hunting for tasks that should be in this list but are not, adding them at the
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// end of the list, whether renumbering or not
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for (uuid, task) in txn.all_tasks()? {
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if !seen.contains(&uuid) && in_working_set(&task) {
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txn.add_to_working_set(uuid)?;
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}
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}
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txn.commit()?;
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Ok(())
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}
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/// Add the given uuid to the working set and return its index; if it is already in the working
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/// set, its index is returned. This does *not* renumber any existing tasks.
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pub fn add_to_working_set(&mut self, uuid: Uuid) -> anyhow::Result<usize> {
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let mut txn = self.storage.txn()?;
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// search for an existing entry for this task..
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for (i, elt) in txn.get_working_set()?.iter().enumerate() {
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if *elt == Some(uuid) {
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// (note that this drops the transaction with no changes made)
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return Ok(i);
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}
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}
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// and if not found, add one
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let i = txn.add_to_working_set(uuid)?;
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txn.commit()?;
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Ok(i)
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}
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/// Sync to the given server, pulling remote changes and pushing local changes.
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pub fn sync(&mut self, server: &mut Box<dyn Server>) -> anyhow::Result<()> {
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let mut txn = self.storage.txn()?;
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sync::sync(server, txn.as_mut())
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}
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// functions for supporting tests
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#[cfg(test)]
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pub(crate) fn sorted_tasks(&mut self) -> Vec<(Uuid, Vec<(String, String)>)> {
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let mut res: Vec<(Uuid, Vec<(String, String)>)> = self
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.all_tasks()
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.unwrap()
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.iter()
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.map(|(u, t)| {
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let mut t = t
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.iter()
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.map(|(p, v)| (p.clone(), v.clone()))
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.collect::<Vec<(String, String)>>();
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t.sort();
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(u.clone(), t)
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})
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.collect();
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res.sort();
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res
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}
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#[cfg(test)]
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pub(crate) fn operations(&mut self) -> Vec<Operation> {
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let mut txn = self.storage.txn().unwrap();
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txn.operations()
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.unwrap()
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.iter()
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.map(|o| o.clone())
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.collect()
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use crate::server::test::TestServer;
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use crate::storage::InMemoryStorage;
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use chrono::Utc;
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use pretty_assertions::assert_eq;
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use proptest::prelude::*;
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use std::collections::HashMap;
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use uuid::Uuid;
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#[test]
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fn test_apply_create() {
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let mut db = TaskDb::new_inmemory();
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let uuid = Uuid::new_v4();
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let op = Operation::Create { uuid };
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db.apply(op.clone()).unwrap();
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assert_eq!(db.sorted_tasks(), vec![(uuid, vec![]),]);
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assert_eq!(db.operations(), vec![op]);
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}
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#[test]
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fn test_apply_create_exists() {
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let mut db = TaskDb::new_inmemory();
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let uuid = Uuid::new_v4();
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let op = Operation::Create { uuid };
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db.apply(op.clone()).unwrap();
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assert_eq!(
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db.apply(op.clone()).err().unwrap().to_string(),
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format!("Task Database Error: Task {} already exists", uuid)
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);
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assert_eq!(db.sorted_tasks(), vec![(uuid, vec![])]);
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assert_eq!(db.operations(), vec![op]);
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}
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#[test]
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fn test_apply_create_update() {
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let mut db = TaskDb::new_inmemory();
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let uuid = Uuid::new_v4();
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let op1 = Operation::Create { uuid };
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db.apply(op1.clone()).unwrap();
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let op2 = Operation::Update {
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uuid,
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property: String::from("title"),
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value: Some("my task".into()),
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timestamp: Utc::now(),
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};
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db.apply(op2.clone()).unwrap();
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assert_eq!(
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db.sorted_tasks(),
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vec![(uuid, vec![("title".into(), "my task".into())])]
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);
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assert_eq!(db.operations(), vec![op1, op2]);
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}
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#[test]
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fn test_apply_create_update_delete_prop() {
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let mut db = TaskDb::new_inmemory();
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let uuid = Uuid::new_v4();
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let op1 = Operation::Create { uuid };
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db.apply(op1.clone()).unwrap();
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let op2 = Operation::Update {
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uuid,
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property: String::from("title"),
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value: Some("my task".into()),
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timestamp: Utc::now(),
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};
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db.apply(op2.clone()).unwrap();
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let op3 = Operation::Update {
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uuid,
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property: String::from("priority"),
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value: Some("H".into()),
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timestamp: Utc::now(),
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};
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db.apply(op3.clone()).unwrap();
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let op4 = Operation::Update {
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uuid,
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property: String::from("title"),
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value: None,
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timestamp: Utc::now(),
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};
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db.apply(op4.clone()).unwrap();
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let mut exp = HashMap::new();
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let mut task = HashMap::new();
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task.insert(String::from("priority"), String::from("H"));
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exp.insert(uuid, task);
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assert_eq!(
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db.sorted_tasks(),
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vec![(uuid, vec![("priority".into(), "H".into())])]
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);
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assert_eq!(db.operations(), vec![op1, op2, op3, op4]);
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}
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#[test]
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fn test_apply_update_does_not_exist() {
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let mut db = TaskDb::new_inmemory();
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let uuid = Uuid::new_v4();
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let op = Operation::Update {
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uuid,
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property: String::from("title"),
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value: Some("my task".into()),
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timestamp: Utc::now(),
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};
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assert_eq!(
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db.apply(op).err().unwrap().to_string(),
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format!("Task Database Error: Task {} does not exist", uuid)
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);
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assert_eq!(db.sorted_tasks(), vec![]);
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assert_eq!(db.operations(), vec![]);
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}
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#[test]
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fn test_apply_create_delete() {
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let mut db = TaskDb::new_inmemory();
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let uuid = Uuid::new_v4();
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let op1 = Operation::Create { uuid };
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db.apply(op1.clone()).unwrap();
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let op2 = Operation::Delete { uuid };
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db.apply(op2.clone()).unwrap();
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assert_eq!(db.sorted_tasks(), vec![]);
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assert_eq!(db.operations(), vec![op1, op2]);
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}
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#[test]
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fn test_apply_delete_not_present() {
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let mut db = TaskDb::new_inmemory();
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let uuid = Uuid::new_v4();
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let op1 = Operation::Delete { uuid };
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assert_eq!(
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db.apply(op1).err().unwrap().to_string(),
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format!("Task Database Error: Task {} does not exist", uuid)
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);
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assert_eq!(db.sorted_tasks(), vec![]);
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assert_eq!(db.operations(), vec![]);
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}
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#[test]
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fn rebuild_working_set_renumber() -> anyhow::Result<()> {
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rebuild_working_set(true)
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}
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#[test]
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fn rebuild_working_set_no_renumber() -> anyhow::Result<()> {
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rebuild_working_set(false)
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}
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fn rebuild_working_set(renumber: bool) -> anyhow::Result<()> {
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let mut db = TaskDb::new_inmemory();
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let mut uuids = vec![];
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uuids.push(Uuid::new_v4());
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println!("uuids[0]: {:?} - pending, not in working set", uuids[0]);
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uuids.push(Uuid::new_v4());
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println!("uuids[1]: {:?} - pending, in working set", uuids[1]);
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uuids.push(Uuid::new_v4());
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println!("uuids[2]: {:?} - not pending, not in working set", uuids[2]);
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uuids.push(Uuid::new_v4());
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println!("uuids[3]: {:?} - not pending, in working set", uuids[3]);
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uuids.push(Uuid::new_v4());
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println!("uuids[4]: {:?} - pending, in working set", uuids[4]);
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// add everything to the TaskDb
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for uuid in &uuids {
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db.apply(Operation::Create { uuid: *uuid })?;
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}
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for i in &[0usize, 1, 4] {
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db.apply(Operation::Update {
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uuid: uuids[*i].clone(),
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property: String::from("status"),
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value: Some("pending".into()),
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timestamp: Utc::now(),
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})?;
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}
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// set the existing working_set as we want it
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{
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let mut txn = db.storage.txn()?;
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txn.clear_working_set()?;
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for i in &[1usize, 3, 4] {
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txn.add_to_working_set(uuids[*i])?;
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}
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txn.commit()?;
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}
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assert_eq!(
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db.working_set()?,
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vec![
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None,
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Some(uuids[1].clone()),
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Some(uuids[3].clone()),
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Some(uuids[4].clone())
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]
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);
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db.rebuild_working_set(
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|t| {
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if let Some(status) = t.get("status") {
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status == "pending"
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} else {
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false
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}
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},
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renumber,
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)?;
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let exp = if renumber {
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// uuids[1] and uuids[4] are already in the working set, so are compressed
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// to the top, and then uuids[0] is added.
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vec![
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None,
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Some(uuids[1].clone()),
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Some(uuids[4].clone()),
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Some(uuids[0].clone()),
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]
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} else {
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// uuids[1] and uuids[4] are already in the working set, at indexes 1 and 3,
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// and then uuids[0] is added.
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vec![
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None,
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Some(uuids[1].clone()),
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None,
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Some(uuids[4].clone()),
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Some(uuids[0].clone()),
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]
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};
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assert_eq!(db.working_set()?, exp);
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Ok(())
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}
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fn newdb() -> TaskDb {
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TaskDb::new(Box::new(InMemoryStorage::new()))
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}
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#[test]
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fn test_sync() {
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let mut server: Box<dyn Server> = Box::new(TestServer::new());
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let mut db1 = newdb();
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db1.sync(&mut server).unwrap();
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let mut db2 = newdb();
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db2.sync(&mut server).unwrap();
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// make some changes in parallel to db1 and db2..
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let uuid1 = Uuid::new_v4();
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db1.apply(Operation::Create { uuid: uuid1 }).unwrap();
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db1.apply(Operation::Update {
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uuid: uuid1,
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property: "title".into(),
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value: Some("my first task".into()),
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timestamp: Utc::now(),
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})
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.unwrap();
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let uuid2 = Uuid::new_v4();
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db2.apply(Operation::Create { uuid: uuid2 }).unwrap();
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db2.apply(Operation::Update {
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uuid: uuid2,
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property: "title".into(),
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value: Some("my second task".into()),
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timestamp: Utc::now(),
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})
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.unwrap();
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// and synchronize those around
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db1.sync(&mut server).unwrap();
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db2.sync(&mut server).unwrap();
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db1.sync(&mut server).unwrap();
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assert_eq!(db1.sorted_tasks(), db2.sorted_tasks());
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// now make updates to the same task on both sides
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db1.apply(Operation::Update {
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uuid: uuid2,
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property: "priority".into(),
|
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value: Some("H".into()),
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timestamp: Utc::now(),
|
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})
|
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.unwrap();
|
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db2.apply(Operation::Update {
|
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uuid: uuid2,
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property: "project".into(),
|
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value: Some("personal".into()),
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timestamp: Utc::now(),
|
||||
})
|
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.unwrap();
|
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|
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// and synchronize those around
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db1.sync(&mut server).unwrap();
|
||||
db2.sync(&mut server).unwrap();
|
||||
db1.sync(&mut server).unwrap();
|
||||
assert_eq!(db1.sorted_tasks(), db2.sorted_tasks());
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_sync_create_delete() {
|
||||
let mut server: Box<dyn Server> = Box::new(TestServer::new());
|
||||
|
||||
let mut db1 = newdb();
|
||||
db1.sync(&mut server).unwrap();
|
||||
|
||||
let mut db2 = newdb();
|
||||
db2.sync(&mut server).unwrap();
|
||||
|
||||
// create and update a task..
|
||||
let uuid = Uuid::new_v4();
|
||||
db1.apply(Operation::Create { uuid }).unwrap();
|
||||
db1.apply(Operation::Update {
|
||||
uuid,
|
||||
property: "title".into(),
|
||||
value: Some("my first task".into()),
|
||||
timestamp: Utc::now(),
|
||||
})
|
||||
.unwrap();
|
||||
|
||||
// and synchronize those around
|
||||
db1.sync(&mut server).unwrap();
|
||||
db2.sync(&mut server).unwrap();
|
||||
db1.sync(&mut server).unwrap();
|
||||
assert_eq!(db1.sorted_tasks(), db2.sorted_tasks());
|
||||
|
||||
// delete and re-create the task on db1
|
||||
db1.apply(Operation::Delete { uuid }).unwrap();
|
||||
db1.apply(Operation::Create { uuid }).unwrap();
|
||||
db1.apply(Operation::Update {
|
||||
uuid,
|
||||
property: "title".into(),
|
||||
value: Some("my second task".into()),
|
||||
timestamp: Utc::now(),
|
||||
})
|
||||
.unwrap();
|
||||
|
||||
// and on db2, update a property of the task
|
||||
db2.apply(Operation::Update {
|
||||
uuid,
|
||||
property: "project".into(),
|
||||
value: Some("personal".into()),
|
||||
timestamp: Utc::now(),
|
||||
})
|
||||
.unwrap();
|
||||
|
||||
db1.sync(&mut server).unwrap();
|
||||
db2.sync(&mut server).unwrap();
|
||||
db1.sync(&mut server).unwrap();
|
||||
assert_eq!(db1.sorted_tasks(), db2.sorted_tasks());
|
||||
}
|
||||
|
||||
#[derive(Debug)]
|
||||
enum Action {
|
||||
Op(Operation),
|
||||
Sync,
|
||||
}
|
||||
|
||||
fn action_sequence_strategy() -> impl Strategy<Value = Vec<(Action, u8)>> {
|
||||
// Create, Update, Delete, or Sync on client 1, 2, .., followed by a round of syncs
|
||||
"([CUDS][123])*S1S2S3S1S2".prop_map(|seq| {
|
||||
let uuid = Uuid::parse_str("83a2f9ef-f455-4195-b92e-a54c161eebfc").unwrap();
|
||||
seq.as_bytes()
|
||||
.chunks(2)
|
||||
.map(|action_on| {
|
||||
let action = match action_on[0] {
|
||||
b'C' => Action::Op(Operation::Create { uuid }),
|
||||
b'U' => Action::Op(Operation::Update {
|
||||
uuid,
|
||||
property: "title".into(),
|
||||
value: Some("foo".into()),
|
||||
timestamp: Utc::now(),
|
||||
}),
|
||||
b'D' => Action::Op(Operation::Delete { uuid }),
|
||||
b'S' => Action::Sync,
|
||||
_ => unreachable!(),
|
||||
};
|
||||
let acton = action_on[1] - b'1';
|
||||
(action, acton)
|
||||
})
|
||||
.collect::<Vec<(Action, u8)>>()
|
||||
})
|
||||
}
|
||||
|
||||
proptest! {
|
||||
#[test]
|
||||
// check that various sequences of operations on mulitple db's do not get the db's into an
|
||||
// incompatible state. The main concern here is that there might be a sequence of create
|
||||
// and delete operations that results in a task existing in one TaskDb but not existing in
|
||||
// another. So, the generated sequences focus on a single task UUID.
|
||||
fn transform_sequences_of_operations(action_sequence in action_sequence_strategy()) {
|
||||
let mut server: Box<dyn Server> = Box::new(TestServer::new());
|
||||
let mut dbs = [newdb(), newdb(), newdb()];
|
||||
|
||||
for (action, db) in action_sequence {
|
||||
println!("{:?} on db {}", action, db);
|
||||
|
||||
let db = &mut dbs[db as usize];
|
||||
match action {
|
||||
Action::Op(op) => {
|
||||
if let Err(e) = db.apply(op) {
|
||||
println!(" {:?} (ignored)", e);
|
||||
}
|
||||
},
|
||||
Action::Sync => db.sync(&mut server).unwrap(),
|
||||
}
|
||||
}
|
||||
|
||||
assert_eq!(dbs[0].sorted_tasks(), dbs[0].sorted_tasks());
|
||||
assert_eq!(dbs[1].sorted_tasks(), dbs[2].sorted_tasks());
|
||||
}
|
||||
}
|
||||
}
|
||||
37
taskchampion/src/taskdb/ops.rs
Normal file
37
taskchampion/src/taskdb/ops.rs
Normal file
@@ -0,0 +1,37 @@
|
||||
use crate::errors::Error;
|
||||
use crate::storage::{Operation, StorageTxn};
|
||||
|
||||
pub(super) fn apply_op(txn: &mut dyn StorageTxn, op: &Operation) -> anyhow::Result<()> {
|
||||
match op {
|
||||
Operation::Create { uuid } => {
|
||||
// insert if the task does not already exist
|
||||
if !txn.create_task(*uuid)? {
|
||||
return Err(Error::Database(format!("Task {} already exists", uuid)).into());
|
||||
}
|
||||
}
|
||||
Operation::Delete { ref uuid } => {
|
||||
if !txn.delete_task(*uuid)? {
|
||||
return Err(Error::Database(format!("Task {} does not exist", uuid)).into());
|
||||
}
|
||||
}
|
||||
Operation::Update {
|
||||
ref uuid,
|
||||
ref property,
|
||||
ref value,
|
||||
timestamp: _,
|
||||
} => {
|
||||
// update if this task exists, otherwise ignore
|
||||
if let Some(mut task) = txn.get_task(*uuid)? {
|
||||
match value {
|
||||
Some(ref val) => task.insert(property.to_string(), val.clone()),
|
||||
None => task.remove(property),
|
||||
};
|
||||
txn.set_task(*uuid, task)?;
|
||||
} else {
|
||||
return Err(Error::Database(format!("Task {} does not exist", uuid)).into());
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
Ok(())
|
||||
}
|
||||
145
taskchampion/src/taskdb/sync.rs
Normal file
145
taskchampion/src/taskdb/sync.rs
Normal file
@@ -0,0 +1,145 @@
|
||||
use super::ops;
|
||||
use crate::server::{AddVersionResult, GetVersionResult, Server};
|
||||
use crate::storage::{Operation, StorageTxn};
|
||||
use log::{info, trace, warn};
|
||||
use serde::{Deserialize, Serialize};
|
||||
use std::str;
|
||||
|
||||
#[derive(Serialize, Deserialize, Debug)]
|
||||
struct Version {
|
||||
operations: Vec<Operation>,
|
||||
}
|
||||
|
||||
/// Sync to the given server, pulling remote changes and pushing local changes.
|
||||
pub(super) fn sync(server: &mut Box<dyn Server>, txn: &mut dyn StorageTxn) -> anyhow::Result<()> {
|
||||
// retry synchronizing until the server accepts our version (this allows for races between
|
||||
// replicas trying to sync to the same server). If the server insists on the same base
|
||||
// version twice, then we have diverged.
|
||||
let mut requested_parent_version_id = None;
|
||||
loop {
|
||||
trace!("beginning sync outer loop");
|
||||
let mut base_version_id = txn.base_version()?;
|
||||
|
||||
// first pull changes and "rebase" on top of them
|
||||
loop {
|
||||
trace!("beginning sync inner loop");
|
||||
if let GetVersionResult::Version {
|
||||
version_id,
|
||||
history_segment,
|
||||
..
|
||||
} = server.get_child_version(base_version_id)?
|
||||
{
|
||||
let version_str = str::from_utf8(&history_segment).unwrap();
|
||||
let version: Version = serde_json::from_str(version_str).unwrap();
|
||||
|
||||
// apply this verison and update base_version in storage
|
||||
info!("applying version {:?} from server", version_id);
|
||||
apply_version(txn, version)?;
|
||||
txn.set_base_version(version_id)?;
|
||||
base_version_id = version_id;
|
||||
} else {
|
||||
info!("no child versions of {:?}", base_version_id);
|
||||
// at the moment, no more child versions, so we can try adding our own
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
let operations: Vec<Operation> = txn.operations()?.to_vec();
|
||||
if operations.is_empty() {
|
||||
info!("no changes to push to server");
|
||||
// nothing to sync back to the server..
|
||||
break;
|
||||
}
|
||||
|
||||
trace!("sending {} operations to the server", operations.len());
|
||||
|
||||
// now make a version of our local changes and push those
|
||||
let new_version = Version { operations };
|
||||
let history_segment = serde_json::to_string(&new_version).unwrap().into();
|
||||
info!("sending new version to server");
|
||||
match server.add_version(base_version_id, history_segment)? {
|
||||
AddVersionResult::Ok(new_version_id) => {
|
||||
info!("version {:?} received by server", new_version_id);
|
||||
txn.set_base_version(new_version_id)?;
|
||||
txn.set_operations(vec![])?;
|
||||
break;
|
||||
}
|
||||
AddVersionResult::ExpectedParentVersion(parent_version_id) => {
|
||||
info!(
|
||||
"new version rejected; must be based on {:?}",
|
||||
parent_version_id
|
||||
);
|
||||
if let Some(requested) = requested_parent_version_id {
|
||||
if parent_version_id == requested {
|
||||
anyhow::bail!("Server's task history has diverged from this replica");
|
||||
}
|
||||
}
|
||||
requested_parent_version_id = Some(parent_version_id);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
txn.commit()?;
|
||||
Ok(())
|
||||
}
|
||||
|
||||
fn apply_version(txn: &mut dyn StorageTxn, mut version: Version) -> anyhow::Result<()> {
|
||||
// The situation here is that the server has already applied all server operations, and we
|
||||
// have already applied all local operations, so states have diverged by several
|
||||
// operations. We need to figure out what operations to apply locally and on the server in
|
||||
// order to return to the same state.
|
||||
//
|
||||
// Operational transforms provide this on an operation-by-operation basis. To break this
|
||||
// down, we treat each server operation individually, in order. For each such operation,
|
||||
// we start in this state:
|
||||
//
|
||||
//
|
||||
// base state-*
|
||||
// / \-server op
|
||||
// * *
|
||||
// local / \ /
|
||||
// ops * *
|
||||
// / \ / new
|
||||
// * * local
|
||||
// local / \ / ops
|
||||
// state-* *
|
||||
// new-\ /
|
||||
// server op *-new local state
|
||||
//
|
||||
// This is slightly complicated by the fact that the transform function can return None,
|
||||
// indicating no operation is required. If this happens for a local op, we can just omit
|
||||
// it. If it happens for server op, then we must copy the remaining local ops.
|
||||
let mut local_operations: Vec<Operation> = txn.operations()?;
|
||||
for server_op in version.operations.drain(..) {
|
||||
trace!(
|
||||
"rebasing local operations onto server operation {:?}",
|
||||
server_op
|
||||
);
|
||||
let mut new_local_ops = Vec::with_capacity(local_operations.len());
|
||||
let mut svr_op = Some(server_op);
|
||||
for local_op in local_operations.drain(..) {
|
||||
if let Some(o) = svr_op {
|
||||
let (new_server_op, new_local_op) = Operation::transform(o, local_op.clone());
|
||||
trace!("local operation {:?} -> {:?}", local_op, new_local_op);
|
||||
svr_op = new_server_op;
|
||||
if let Some(o) = new_local_op {
|
||||
new_local_ops.push(o);
|
||||
}
|
||||
} else {
|
||||
trace!(
|
||||
"local operation {:?} unchanged (server operation consumed)",
|
||||
local_op
|
||||
);
|
||||
new_local_ops.push(local_op);
|
||||
}
|
||||
}
|
||||
if let Some(o) = svr_op {
|
||||
if let Err(e) = ops::apply_op(txn, &o) {
|
||||
warn!("Invalid operation when syncing: {} (ignored)", e);
|
||||
}
|
||||
}
|
||||
local_operations = new_local_ops;
|
||||
}
|
||||
txn.set_operations(local_operations)?;
|
||||
Ok(())
|
||||
}
|
||||
Reference in New Issue
Block a user