Remove some dependencies

Cargo.toml

@@ -19,7 +19,9 @@ build = "build.rs"
 default = ["atomic64", "quanta"]
 
 # Enable this feature to use `moka::future::Cache`.
-future = ["async-io", "async-lock", "futures-util"]
+future = ["async-io", "async-lock", "futures-util", "crossbeam-epoch", "thiserror", "uuid"]
+
+sync = ["crossbeam-epoch", "thiserror", "uuid"]
 
 # Enable this feature to use **experimental** `moka::dash::Cache`.
 # Please note that the APIs for this feature will be frequently changed in next
@@ -39,16 +41,16 @@ unstable-debug-counters = ["future"]
 
 [dependencies]
 crossbeam-channel = "0.5.4"
-crossbeam-epoch = "0.8.2"
+crossbeam-epoch = { version = "0.8.2", optional = true }
 crossbeam-utils = "0.8"
 num_cpus = "1.13"
 once_cell = "1.7"
 parking_lot = "0.12"
-scheduled-thread-pool = "0.2.5"
+scheduled-thread-pool = "0.2.6"
 smallvec = "1.8"
 tagptr = "0.2"
-thiserror = "1.0"
-uuid = { version = "0.8", features = ["v4"] }
+thiserror = { version = "1.0", optional = true }
+uuid = { version = "0.8", features = ["v4"], optional = true }
 
 # Opt-out serde and stable_deref_trait features
 # https://github.com/Manishearth/triomphe/pull/5

src/common/error.rs

@@ -2,6 +2,7 @@
 /// [`Cache#invalidate_entries_if`][invalidate-if] method.
 ///
 /// [invalidate-if]: ./sync/struct.Cache.html#method.invalidate_entries_if
+#[cfg(any(feature="sync", feature="future"))]
 #[derive(thiserror::Error, Debug)]
 pub enum PredicateError {
     /// This cache does not have a necessary configuration enabled to support

src/lib.rs

@@ -165,14 +165,14 @@ pub mod dash;
 #[cfg(feature = "future")]
 #[cfg_attr(docsrs, doc(cfg(feature = "future")))]
 pub mod future;
-
+#[cfg(any(feature="sync", feature="future"))]
 pub mod sync;
 pub mod unsync;
-
+#[cfg(any(feature="sync", feature="future"))]
 pub(crate) mod cht;
 pub(crate) mod common;
 pub(crate) mod policy;
-
+#[cfg(any(feature="sync", feature="future"))]
 pub use common::error::PredicateError;
 pub use policy::Policy;
 

src/sync/builder.rs

@@ -41,6 +41,7 @@ use std::{
 /// // after 30 minutes (TTL) from the insert().
 /// ```
 ///
+#[cfg(feature="sync")]
 #[must_use]
 pub struct CacheBuilder<K, V, C> {
     max_capacity: Option<u64>,

src/sync/cache.rs

@@ -227,6 +227,7 @@ use std::{
 /// [build-with-hasher-method]: ./struct.CacheBuilder.html#method.build_with_hasher
 /// [ahash-crate]: https://crates.io/crates/ahash
 ///
+#[cfg(feature="sync")]
 pub struct Cache<K, V, S = RandomState> {
     base: BaseCache<K, V, S>,
     value_initializer: Arc<ValueInitializer<K, V, S>>,

src/sync/segment.rs

@@ -24,6 +24,7 @@ use std::{
 ///
 /// [cache-struct]: ./struct.Cache.html
 ///
+#[cfg(feature="sync")]
 pub struct SegmentedCache<K, V, S = RandomState> {
     inner: Arc<Inner<K, V, S>>,
 }

src/sync/value_initializer.rs

@@ -17,7 +17,7 @@ pub(crate) enum InitResult<V, E> {
     ReadExisting(V),
     InitErr(Arc<E>),
 }
-
+#[cfg(feature="sync")]
 pub(crate) struct ValueInitializer<K, V, S> {
     // TypeId is the type ID of the concrete error type of generic type E in
     // try_init_or_read(). We use the type ID as a part of the key to ensure that