add a Map::contains suite to db

Signed-off-by: Jason Volk <jason@zemos.net>

src/database/map.rs

@@ -1,3 +1,4 @@
+mod contains;
 mod count;
 mod get;
 mod insert;

src/database/map/contains.rs

@@ -0,0 +1,88 @@
+use std::{convert::AsRef, fmt::Debug, future::Future, io::Write};
+
+use arrayvec::ArrayVec;
+use conduit::{implement, utils::TryFutureExtExt, Err, Result};
+use futures::future::ready;
+use serde::Serialize;
+
+use crate::{ser, util};
+
+/// Returns true if the map contains the key.
+/// - key is serialized into allocated buffer
+/// - harder errors may not be reported
+#[implement(super::Map)]
+pub fn contains<K>(&self, key: &K) -> impl Future<Output = bool> + Send
+where
+	K: Serialize + ?Sized + Debug,
+{
+	let mut buf = Vec::<u8>::with_capacity(64);
+	self.bcontains(key, &mut buf)
+}
+
+/// Returns true if the map contains the key.
+/// - key is serialized into stack-buffer
+/// - harder errors will panic
+#[implement(super::Map)]
+pub fn acontains<const MAX: usize, K>(&self, key: &K) -> impl Future<Output = bool> + Send
+where
+	K: Serialize + ?Sized + Debug,
+{
+	let mut buf = ArrayVec::<u8, MAX>::new();
+	self.bcontains(key, &mut buf)
+}
+
+/// Returns true if the map contains the key.
+/// - key is serialized into provided buffer
+/// - harder errors will panic
+#[implement(super::Map)]
+#[tracing::instrument(skip(self, buf), fields(%self), level = "trace")]
+pub fn bcontains<K, B>(&self, key: &K, buf: &mut B) -> impl Future<Output = bool> + Send
+where
+	K: Serialize + ?Sized + Debug,
+	B: Write + AsRef<[u8]>,
+{
+	let key = ser::serialize(buf, key).expect("failed to serialize query key");
+	self.exists(key).is_ok()
+}
+
+/// Returns Ok if the map contains the key.
+/// - key is raw
+#[implement(super::Map)]
+pub fn exists<K>(&self, key: &K) -> impl Future<Output = Result<()>> + Send
+where
+	K: AsRef<[u8]> + ?Sized + Debug,
+{
+	ready(self.exists_blocking(key))
+}
+
+/// Returns Ok if the map contains the key; NotFound otherwise. Harder errors
+/// may not always be reported properly.
+#[implement(super::Map)]
+#[tracing::instrument(skip(self, key), fields(%self), level = "trace")]
+pub fn exists_blocking<K>(&self, key: &K) -> Result<()>
+where
+	K: AsRef<[u8]> + ?Sized + Debug,
+{
+	if self.maybe_exists_blocking(key)
+		&& self
+			.db
+			.db
+			.get_pinned_cf_opt(&self.cf(), key, &self.read_options)
+			.map_err(util::map_err)?
+			.is_some()
+	{
+		Ok(())
+	} else {
+		Err!(Request(NotFound("Not found in database")))
+	}
+}
+
+#[implement(super::Map)]
+fn maybe_exists_blocking<K>(&self, key: &K) -> bool
+where
+	K: AsRef<[u8]> + ?Sized,
+{
+	self.db
+		.db
+		.key_may_exist_cf_opt(&self.cf(), key, &self.read_options)
+}