taskwarrior/taskchampion/src/taskstorage/mod.rs
2020-11-24 11:53:11 -05:00

101 lines
4 KiB
Rust

use failure::Fallible;
use std::collections::HashMap;
use uuid::Uuid;
mod inmemory;
mod kv;
mod operation;
pub use self::kv::KVStorage;
pub use inmemory::InMemoryStorage;
pub use operation::Operation;
/// An in-memory representation of a task as a simple hashmap
pub type TaskMap = HashMap<String, String>;
#[cfg(test)]
fn taskmap_with(mut properties: Vec<(String, String)>) -> TaskMap {
let mut rv = TaskMap::new();
for (p, v) in properties.drain(..) {
rv.insert(p, v);
}
rv
}
/// A TaskStorage transaction, in which storage operations are performed.
///
/// # Concurrency
///
/// Serializable consistency must be maintained. Concurrent access is unusual
/// and some implementations may simply apply a mutex to limit access to
/// one transaction at a time.
///
/// # Commiting and Aborting
///
/// A transaction is not visible to other readers until it is committed with
/// [`crate::taskstorage::TaskStorageTxn::commit`]. Transactions are aborted if they are dropped.
/// It is safe and performant to drop transactions that did not modify any data without committing.
pub trait TaskStorageTxn {
/// Get an (immutable) task, if it is in the storage
fn get_task(&mut self, uuid: &Uuid) -> Fallible<Option<TaskMap>>;
/// Create an (empty) task, only if it does not already exist. Returns true if
/// the task was created (did not already exist).
fn create_task(&mut self, uuid: Uuid) -> Fallible<bool>;
/// Set a task, overwriting any existing task. If the task does not exist, this implicitly
/// creates it (use `get_task` to check first, if necessary).
fn set_task(&mut self, uuid: Uuid, task: TaskMap) -> Fallible<()>;
/// Delete a task, if it exists. Returns true if the task was deleted (already existed)
fn delete_task(&mut self, uuid: &Uuid) -> Fallible<bool>;
/// Get the uuids and bodies of all tasks in the storage, in undefined order.
fn all_tasks<'a>(&mut self) -> Fallible<Vec<(Uuid, TaskMap)>>;
/// Get the uuids of all tasks in the storage, in undefined order.
fn all_task_uuids<'a>(&mut self) -> Fallible<Vec<Uuid>>;
/// Get the current base_version for this storage -- the last version synced from the server.
fn base_version(&mut self) -> Fallible<u64>;
/// Set the current base_version for this storage.
fn set_base_version(&mut self, version: u64) -> Fallible<()>;
/// Get the current set of outstanding operations (operations that have not been sync'd to the
/// server yet)
fn operations<'a>(&mut self) -> Fallible<Vec<Operation>>;
/// Add an operation to the end of the list of operations in the storage. Note that this
/// merely *stores* the operation; it is up to the TaskDB to apply it.
fn add_operation(&mut self, op: Operation) -> Fallible<()>;
/// Replace the current list of operations with a new list.
fn set_operations(&mut self, ops: Vec<Operation>) -> Fallible<()>;
/// Get the entire working set, with each task UUID at its appropriate (1-based) index.
/// Element 0 is always None.
fn get_working_set(&mut self) -> Fallible<Vec<Option<Uuid>>>;
/// Add a task to the working set and return its (one-based) index. This index will be one greater
/// than the highest used index.
fn add_to_working_set(&mut self, uuid: &Uuid) -> Fallible<usize>;
/// Remove a task from the working set. Other tasks' indexes are not affected.
fn remove_from_working_set(&mut self, index: usize) -> Fallible<()>;
/// Clear all tasks from the working set in preparation for a garbage-collection operation.
fn clear_working_set(&mut self) -> Fallible<()>;
/// Commit any changes made in the transaction. It is an error to call this more than
/// once.
fn commit(&mut self) -> Fallible<()>;
}
/// A trait for objects able to act as task storage. Most of the interesting behavior is in the
/// [`crate::taskstorage::TaskStorageTxn`] trait.
pub trait TaskStorage {
/// Begin a transaction
fn txn<'a>(&'a mut self) -> Fallible<Box<dyn TaskStorageTxn + 'a>>;
}