K2V client improvements (#307)v0.7.2

- [x] Better distinguish error types
- [x] Parse error messages received from server
- [x] Remove `src/` folder layer, we don't have that for other crates

Co-authored-by: Alex Auvolat <alex@adnab.me>
Reviewed-on: https://git.deuxfleurs.fr/Deuxfleurs/garage/pulls/307
Co-authored-by: Alex <alex@adnab.me>
Co-committed-by: Alex <alex@adnab.me>

1 files changed, 611 insertions, 0 deletions

diff --git a/src/k2v-client/lib.rs b/src/k2v-client/lib.rs
new file mode 100644
index 00000000..95974d7a
--- /dev/null
+++ b/src/k2v-client/lib.rs
@@ -0,0 +1,611 @@
+use std::collections::BTreeMap;
+use std::time::Duration;
+
+use http::header::{ACCEPT, CONTENT_LENGTH, CONTENT_TYPE};
+use http::status::StatusCode;
+use http::HeaderMap;
+use log::{debug, error};
+
+use rusoto_core::{ByteStream, DispatchSignedRequest, HttpClient};
+use rusoto_credential::AwsCredentials;
+use rusoto_signature::region::Region;
+use rusoto_signature::signature::SignedRequest;
+use serde::de::Error as DeError;
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
+
+use tokio::io::AsyncReadExt;
+
+mod error;
+
+pub use error::Error;
+
+const DEFAULT_TIMEOUT: Duration = Duration::from_secs(5);
+const DEFAULT_POLL_TIMEOUT: Duration = Duration::from_secs(300);
+const SERVICE: &str = "k2v";
+const GARAGE_CAUSALITY_TOKEN: &str = "X-Garage-Causality-Token";
+
+/// Client used to query a K2V server.
+pub struct K2vClient {
+	region: Region,
+	bucket: String,
+	creds: AwsCredentials,
+	client: HttpClient,
+}
+
+impl K2vClient {
+	/// Create a new K2V client.
+	pub fn new(
+		region: Region,
+		bucket: String,
+		creds: AwsCredentials,
+		user_agent: Option<String>,
+	) -> Result<Self, Error> {
+		let mut client = HttpClient::new()?;
+		if let Some(ua) = user_agent {
+			client.local_agent_prepend(ua);
+		} else {
+			client.local_agent_prepend(format!("k2v/{}", env!("CARGO_PKG_VERSION")));
+		}
+		Ok(K2vClient {
+			region,
+			bucket,
+			creds,
+			client,
+		})
+	}
+
+	/// Perform a ReadItem request, reading the value(s) stored for a single pk+sk.
+	pub async fn read_item(
+		&self,
+		partition_key: &str,
+		sort_key: &str,
+	) -> Result<CausalValue, Error> {
+		let mut req = SignedRequest::new(
+			"GET",
+			SERVICE,
+			&self.region,
+			&format!("/{}/{}", self.bucket, partition_key),
+		);
+		req.add_param("sort_key", sort_key);
+		req.add_header(ACCEPT, "application/octet-stream, application/json");
+
+		let res = self.dispatch(req, None).await?;
+
+		let causality = res
+			.causality_token
+			.ok_or_else(|| Error::InvalidResponse("missing causality token".into()))?;
+
+		if res.status == StatusCode::NO_CONTENT {
+			return Ok(CausalValue {
+				causality,
+				value: vec![K2vValue::Tombstone],
+			});
+		}
+
+		match res.content_type.as_deref() {
+			Some("application/octet-stream") => Ok(CausalValue {
+				causality,
+				value: vec![K2vValue::Value(res.body)],
+			}),
+			Some("application/json") => {
+				let value = serde_json::from_slice(&res.body)?;
+				Ok(CausalValue { causality, value })
+			}
+			Some(ct) => Err(Error::InvalidResponse(
+				format!("invalid content type: {}", ct).into(),
+			)),
+			None => Err(Error::InvalidResponse("missing content type".into())),
+		}
+	}
+
+	/// Perform a PollItem request, waiting for the value(s) stored for a single pk+sk to be
+	/// updated.
+	pub async fn poll_item(
+		&self,
+		partition_key: &str,
+		sort_key: &str,
+		causality: CausalityToken,
+		timeout: Option<Duration>,
+	) -> Result<Option<CausalValue>, Error> {
+		let timeout = timeout.unwrap_or(DEFAULT_POLL_TIMEOUT);
+
+		let mut req = SignedRequest::new(
+			"GET",
+			SERVICE,
+			&self.region,
+			&format!("/{}/{}", self.bucket, partition_key),
+		);
+		req.add_param("sort_key", sort_key);
+		req.add_param("causality_token", &causality.0);
+		req.add_param("timeout", &timeout.as_secs().to_string());
+		req.add_header(ACCEPT, "application/octet-stream, application/json");
+
+		let res = self.dispatch(req, Some(timeout + DEFAULT_TIMEOUT)).await?;
+
+		let causality = res
+			.causality_token
+			.ok_or_else(|| Error::InvalidResponse("missing causality token".into()))?;
+
+		if res.status == StatusCode::NOT_MODIFIED {
+			return Ok(None);
+		}
+
+		if res.status == StatusCode::NO_CONTENT {
+			return Ok(Some(CausalValue {
+				causality,
+				value: vec![K2vValue::Tombstone],
+			}));
+		}
+
+		match res.content_type.as_deref() {
+			Some("application/octet-stream") => Ok(Some(CausalValue {
+				causality,
+				value: vec![K2vValue::Value(res.body)],
+			})),
+			Some("application/json") => {
+				let value = serde_json::from_slice(&res.body)?;
+				Ok(Some(CausalValue { causality, value }))
+			}
+			Some(ct) => Err(Error::InvalidResponse(
+				format!("invalid content type: {}", ct).into(),
+			)),
+			None => Err(Error::InvalidResponse("missing content type".into())),
+		}
+	}
+
+	/// Perform an InsertItem request, inserting a value for a single pk+sk.
+	pub async fn insert_item(
+		&self,
+		partition_key: &str,
+		sort_key: &str,
+		value: Vec<u8>,
+		causality: Option<CausalityToken>,
+	) -> Result<(), Error> {
+		let mut req = SignedRequest::new(
+			"PUT",
+			SERVICE,
+			&self.region,
+			&format!("/{}/{}", self.bucket, partition_key),
+		);
+		req.add_param("sort_key", sort_key);
+		req.set_payload(Some(value));
+
+		if let Some(causality) = causality {
+			req.add_header(GARAGE_CAUSALITY_TOKEN, &causality.0);
+		}
+
+		self.dispatch(req, None).await?;
+		Ok(())
+	}
+
+	/// Perform a DeleteItem request, deleting the value(s) stored for a single pk+sk.
+	pub async fn delete_item(
+		&self,
+		partition_key: &str,
+		sort_key: &str,
+		causality: CausalityToken,
+	) -> Result<(), Error> {
+		let mut req = SignedRequest::new(
+			"DELETE",
+			SERVICE,
+			&self.region,
+			&format!("/{}/{}", self.bucket, partition_key),
+		);
+		req.add_param("sort_key", sort_key);
+		req.add_header(GARAGE_CAUSALITY_TOKEN, &causality.0);
+
+		self.dispatch(req, None).await?;
+		Ok(())
+	}
+
+	/// Perform a ReadIndex request, listing partition key which have at least one associated
+	/// sort key, and which matches the filter.
+	pub async fn read_index(
+		&self,
+		filter: Filter<'_>,
+	) -> Result<PaginatedRange<PartitionInfo>, Error> {
+		let mut req =
+			SignedRequest::new("GET", SERVICE, &self.region, &format!("/{}", self.bucket));
+		filter.insert_params(&mut req);
+
+		let res = self.dispatch(req, None).await?;
+
+		let resp: ReadIndexResponse = serde_json::from_slice(&res.body)?;
+
+		let items = resp
+			.partition_keys
+			.into_iter()
+			.map(|ReadIndexItem { pk, info }| (pk, info))
+			.collect();
+
+		Ok(PaginatedRange {
+			items,
+			next_start: resp.next_start,
+		})
+	}
+
+	/// Perform an InsertBatch request, inserting multiple values at once. Note: this operation is
+	/// *not* atomic: it is possible for some sub-operations to fails and others to success. In
+	/// that case, failure is reported.
+	pub async fn insert_batch(&self, operations: &[BatchInsertOp<'_>]) -> Result<(), Error> {
+		let mut req =
+			SignedRequest::new("POST", SERVICE, &self.region, &format!("/{}", self.bucket));
+
+		let payload = serde_json::to_vec(operations)?;
+		req.set_payload(Some(payload));
+		self.dispatch(req, None).await?;
+		Ok(())
+	}
+
+	/// Perform a ReadBatch request, reading multiple values or range of values at once.
+	pub async fn read_batch(
+		&self,
+		operations: &[BatchReadOp<'_>],
+	) -> Result<Vec<PaginatedRange<CausalValue>>, Error> {
+		let mut req =
+			SignedRequest::new("POST", SERVICE, &self.region, &format!("/{}", self.bucket));
+		req.add_param("search", "");
+
+		let payload = serde_json::to_vec(operations)?;
+		req.set_payload(Some(payload));
+		let res = self.dispatch(req, None).await?;
+
+		let resp: Vec<BatchReadResponse> = serde_json::from_slice(&res.body)?;
+
+		Ok(resp
+			.into_iter()
+			.map(|e| PaginatedRange {
+				items: e
+					.items
+					.into_iter()
+					.map(|BatchReadItem { sk, ct, v }| {
+						(
+							sk,
+							CausalValue {
+								causality: ct,
+								value: v,
+							},
+						)
+					})
+					.collect(),
+				next_start: e.next_start,
+			})
+			.collect())
+	}
+
+	/// Perform a DeleteBatch request, deleting mutiple values or range of values at once, without
+	/// providing causality information.
+	pub async fn delete_batch(&self, operations: &[BatchDeleteOp<'_>]) -> Result<Vec<u64>, Error> {
+		let mut req =
+			SignedRequest::new("POST", SERVICE, &self.region, &format!("/{}", self.bucket));
+		req.add_param("delete", "");
+
+		let payload = serde_json::to_vec(operations)?;
+		req.set_payload(Some(payload));
+		let res = self.dispatch(req, None).await?;
+
+		let resp: Vec<BatchDeleteResponse> = serde_json::from_slice(&res.body)?;
+
+		Ok(resp.into_iter().map(|r| r.deleted_items).collect())
+	}
+
+	async fn dispatch(
+		&self,
+		mut req: SignedRequest,
+		timeout: Option<Duration>,
+	) -> Result<Response, Error> {
+		req.sign(&self.creds);
+		let mut res = self
+			.client
+			.dispatch(req, Some(timeout.unwrap_or(DEFAULT_TIMEOUT)))
+			.await?;
+
+		let causality_token = res
+			.headers
+			.remove(GARAGE_CAUSALITY_TOKEN)
+			.map(CausalityToken);
+		let content_type = res.headers.remove(CONTENT_TYPE);
+
+		let body = match res.status {
+			StatusCode::OK => read_body(&mut res.headers, res.body).await?,
+			StatusCode::NO_CONTENT => Vec::new(),
+			StatusCode::NOT_FOUND => return Err(Error::NotFound),
+			StatusCode::NOT_MODIFIED => Vec::new(),
+			s => {
+				let err_body = read_body(&mut res.headers, res.body)
+					.await
+					.unwrap_or_default();
+				let err_body_str = std::str::from_utf8(&err_body)
+					.map(String::from)
+					.unwrap_or_else(|_| base64::encode(&err_body));
+
+				if s.is_client_error() || s.is_server_error() {
+					error!("Error response {}: {}", res.status, err_body_str);
+					let err = match serde_json::from_slice::<ErrorResponse>(&err_body) {
+						Ok(err) => Error::Remote(
+							res.status,
+							err.code.into(),
+							err.message.into(),
+							err.path.into(),
+						),
+						Err(_) => Error::Remote(
+							res.status,
+							"unknown".into(),
+							err_body_str.into(),
+							"?".into(),
+						),
+					};
+					return Err(err);
+				} else {
+					let msg = format!(
+						"Unexpected response code {}. Response body: {}",
+						res.status, err_body_str
+					);
+					error!("{}", msg);
+					return Err(Error::InvalidResponse(msg.into()));
+				}
+			}
+		};
+		debug!(
+			"Response body: {}",
+			std::str::from_utf8(&body)
+				.map(String::from)
+				.unwrap_or_else(|_| base64::encode(&body))
+		);
+
+		Ok(Response {
+			body,
+			status: res.status,
+			causality_token,
+			content_type,
+		})
+	}
+}
+
+async fn read_body(headers: &mut HeaderMap<String>, body: ByteStream) -> Result<Vec<u8>, Error> {
+	let body_len = headers
+		.get(CONTENT_LENGTH)
+		.and_then(|h| h.parse().ok())
+		.unwrap_or(0);
+	let mut res = Vec::with_capacity(body_len);
+	body.into_async_read().read_to_end(&mut res).await?;
+	Ok(res)
+}
+
+/// An opaque token used to convey causality between operations.
+#[derive(Debug, Clone, PartialEq, Eq, Deserialize, Serialize)]
+#[serde(transparent)]
+pub struct CausalityToken(String);
+
+impl From<String> for CausalityToken {
+	fn from(v: String) -> Self {
+		CausalityToken(v)
+	}
+}
+
+impl From<CausalityToken> for String {
+	fn from(v: CausalityToken) -> Self {
+		v.0
+	}
+}
+
+/// A value in K2V. can be either a binary value, or a tombstone.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum K2vValue {
+	Tombstone,
+	Value(Vec<u8>),
+}
+
+impl From<Vec<u8>> for K2vValue {
+	fn from(v: Vec<u8>) -> Self {
+		K2vValue::Value(v)
+	}
+}
+
+impl From<Option<Vec<u8>>> for K2vValue {
+	fn from(v: Option<Vec<u8>>) -> Self {
+		match v {
+			Some(v) => K2vValue::Value(v),
+			None => K2vValue::Tombstone,
+		}
+	}
+}
+
+impl<'de> Deserialize<'de> for K2vValue {
+	fn deserialize<D>(d: D) -> Result<Self, D::Error>
+	where
+		D: Deserializer<'de>,
+	{
+		let val: Option<&str> = Option::deserialize(d)?;
+		Ok(match val {
+			Some(s) => {
+				K2vValue::Value(base64::decode(s).map_err(|_| DeError::custom("invalid base64"))?)
+			}
+			None => K2vValue::Tombstone,
+		})
+	}
+}
+
+impl Serialize for K2vValue {
+	fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+	where
+		S: Serializer,
+	{
+		match self {
+			K2vValue::Tombstone => serializer.serialize_none(),
+			K2vValue::Value(v) => {
+				let b64 = base64::encode(v);
+				serializer.serialize_str(&b64)
+			}
+		}
+	}
+}
+
+/// A set of K2vValue and associated causality information.
+#[derive(Debug, Clone, Serialize)]
+pub struct CausalValue {
+	pub causality: CausalityToken,
+	pub value: Vec<K2vValue>,
+}
+
+/// Result of paginated requests.
+#[derive(Debug, Clone)]
+pub struct PaginatedRange<V> {
+	pub items: BTreeMap<String, V>,
+	pub next_start: Option<String>,
+}
+
+/// Filter for batch operations.
+#[derive(Debug, Default, Clone, Deserialize, Serialize)]
+pub struct Filter<'a> {
+	pub start: Option<&'a str>,
+	pub end: Option<&'a str>,
+	pub prefix: Option<&'a str>,
+	pub limit: Option<u64>,
+	#[serde(default)]
+	pub reverse: bool,
+}
+
+impl<'a> Filter<'a> {
+	fn insert_params(&self, req: &mut SignedRequest) {
+		if let Some(start) = &self.start {
+			req.add_param("start", start);
+		}
+		if let Some(end) = &self.end {
+			req.add_param("end", end);
+		}
+		if let Some(prefix) = &self.prefix {
+			req.add_param("prefix", prefix);
+		}
+		if let Some(limit) = &self.limit {
+			req.add_param("limit", &limit.to_string());
+		}
+		if self.reverse {
+			req.add_param("reverse", "true");
+		}
+	}
+}
+
+#[derive(Debug, Clone, Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct ReadIndexResponse<'a> {
+	#[serde(flatten, borrow)]
+	#[allow(dead_code)]
+	filter: Filter<'a>,
+	partition_keys: Vec<ReadIndexItem>,
+	#[allow(dead_code)]
+	more: bool,
+	next_start: Option<String>,
+}
+
+#[derive(Debug, Clone, Deserialize)]
+struct ReadIndexItem {
+	pk: String,
+	#[serde(flatten)]
+	info: PartitionInfo,
+}
+
+/// Information about data stored with a given partition key.
+#[derive(Debug, Clone, Deserialize, Serialize)]
+pub struct PartitionInfo {
+	pub entries: u64,
+	pub conflicts: u64,
+	pub values: u64,
+	pub bytes: u64,
+}
+
+/// Single sub-operation of an InsertBatch.
+#[derive(Debug, Clone, Serialize)]
+pub struct BatchInsertOp<'a> {
+	#[serde(rename = "pk")]
+	pub partition_key: &'a str,
+	#[serde(rename = "sk")]
+	pub sort_key: &'a str,
+	#[serde(rename = "ct")]
+	pub causality: Option<CausalityToken>,
+	#[serde(rename = "v")]
+	pub value: K2vValue,
+}
+
+/// Single sub-operation of a ReadBatch.
+#[derive(Debug, Default, Clone, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct BatchReadOp<'a> {
+	pub partition_key: &'a str,
+	#[serde(flatten, borrow)]
+	pub filter: Filter<'a>,
+	#[serde(default)]
+	pub single_item: bool,
+	#[serde(default)]
+	pub conflicts_only: bool,
+	#[serde(default)]
+	pub tombstones: bool,
+}
+
+#[derive(Debug, Clone, Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct BatchReadResponse<'a> {
+	#[serde(flatten, borrow)]
+	#[allow(dead_code)]
+	op: BatchReadOp<'a>,
+	items: Vec<BatchReadItem>,
+	#[allow(dead_code)]
+	more: bool,
+	next_start: Option<String>,
+}
+
+#[derive(Debug, Clone, Deserialize)]
+struct BatchReadItem {
+	sk: String,
+	ct: CausalityToken,
+	v: Vec<K2vValue>,
+}
+
+/// Single sub-operation of a DeleteBatch
+#[derive(Debug, Clone, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct BatchDeleteOp<'a> {
+	pub partition_key: &'a str,
+	pub prefix: Option<&'a str>,
+	pub start: Option<&'a str>,
+	pub end: Option<&'a str>,
+	#[serde(default)]
+	pub single_item: bool,
+}
+
+impl<'a> BatchDeleteOp<'a> {
+	pub fn new(partition_key: &'a str) -> Self {
+		BatchDeleteOp {
+			partition_key,
+			prefix: None,
+			start: None,
+			end: None,
+			single_item: false,
+		}
+	}
+}
+
+#[derive(Debug, Clone, Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct BatchDeleteResponse<'a> {
+	#[serde(flatten, borrow)]
+	#[allow(dead_code)]
+	filter: BatchDeleteOp<'a>,
+	deleted_items: u64,
+}
+
+#[derive(Deserialize)]
+struct ErrorResponse {
+	code: String,
+	message: String,
+	#[allow(dead_code)]
+	region: String,
+	path: String,
+}
+
+struct Response {
+	body: Vec<u8>,
+	status: StatusCode,
+	causality_token: Option<CausalityToken>,
+	content_type: Option<String>,
+}