forked from github-mirrorer/taskchampion-sync-server
47ce4c1e3b
This will make it easier to build variations on the server, or embed it into larger projects.
97 lines
3.2 KiB
Rust
97 lines
3.2 KiB
Rust
use chrono::{DateTime, Utc};
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use uuid::Uuid;
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/// A representation of stored metadata about a client.
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#[derive(Clone, PartialEq, Eq, Debug)]
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pub struct Client {
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/// The latest version for this client (may be the nil version)
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pub latest_version_id: Uuid,
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/// Data about the latest snapshot for this client
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pub snapshot: Option<Snapshot>,
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}
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/// Metadata about a snapshot, not including the snapshot data itself.
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#[derive(Clone, PartialEq, Eq, Debug)]
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pub struct Snapshot {
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/// ID of the version at which this snapshot was made
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pub version_id: Uuid,
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/// Timestamp at which this snapshot was set
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pub timestamp: DateTime<Utc>,
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/// Number of versions since this snapshot was made
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pub versions_since: u32,
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}
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#[derive(Clone, PartialEq, Eq, Debug)]
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pub struct Version {
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/// The uuid identifying this version.
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pub version_id: Uuid,
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/// The uuid identifying this version's parent.
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pub parent_version_id: Uuid,
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/// The data carried in this version.
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pub history_segment: Vec<u8>,
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}
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/// A transaction in the storage backend.
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///
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/// Transactions must be sequentially consistent. That is, the results of transactions performed
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/// in storage must be as if each were executed sequentially in some order. In particular, the
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/// `Client.latest_version` must not change between a call to `get_client` and `add_version`.
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pub trait StorageTxn {
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/// Get information about the given client
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fn get_client(&mut self, client_id: Uuid) -> anyhow::Result<Option<Client>>;
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/// Create a new client with the given latest_version_id
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fn new_client(&mut self, client_id: Uuid, latest_version_id: Uuid) -> anyhow::Result<()>;
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/// Set the client's most recent snapshot.
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fn set_snapshot(
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&mut self,
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client_id: Uuid,
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snapshot: Snapshot,
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data: Vec<u8>,
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) -> anyhow::Result<()>;
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/// Get the data for the most recent snapshot. The version_id
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/// is used to verify that the snapshot is for the correct version.
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fn get_snapshot_data(
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&mut self,
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client_id: Uuid,
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version_id: Uuid,
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) -> anyhow::Result<Option<Vec<u8>>>;
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/// Get a version, indexed by parent version id
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fn get_version_by_parent(
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&mut self,
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client_id: Uuid,
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parent_version_id: Uuid,
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) -> anyhow::Result<Option<Version>>;
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/// Get a version, indexed by its own version id
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fn get_version(&mut self, client_id: Uuid, version_id: Uuid)
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-> anyhow::Result<Option<Version>>;
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/// Add a version (that must not already exist), and
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/// - update latest_version_id
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/// - increment snapshot.versions_since
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fn add_version(
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&mut self,
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client_id: Uuid,
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version_id: Uuid,
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parent_version_id: Uuid,
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history_segment: Vec<u8>,
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) -> anyhow::Result<()>;
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/// Commit any changes made in the transaction. It is an error to call this more than
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/// once. It is safe to skip this call for read-only operations.
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fn commit(&mut self) -> anyhow::Result<()>;
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}
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/// A trait for objects able to act as storage. Most of the interesting behavior is in the
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/// [`crate::storage::StorageTxn`] trait.
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pub trait Storage: Send + Sync {
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/// Begin a transaction
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fn txn<'a>(&'a self) -> anyhow::Result<Box<dyn StorageTxn + 'a>>;
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}
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