primitives - channel - SpecValidators own Iter struct

- This removes additional `Vec` overhead

Author: elpiel

adapter/src/lib.rs

@@ -87,7 +87,7 @@ impl TryFrom<&Channel> for EthereumChannel {
         let validators = channel
             .spec
             .validators
-            .into_iter()
+            .iter()
             .map(|v| &v.id)
             .collect::<Vec<_>>();
 

adview-manager/src/lib.rs

@@ -234,7 +234,7 @@ pub fn get_html(
         }],
     };
 
-    let on_load: String = validators.into_iter().map(|validator| {
+    let on_load: String = validators.iter().map(|validator| {
         let fetch_opts = "{ method: 'POST', headers: { 'content-type': 'application/json' }, body: this.dataset.eventBody }";
         let fetch_url = format!("{}/channel/{}/events", validator.url, channel_id);
 

primitives/src/channel.rs

@@ -148,6 +148,10 @@ impl SpecValidators {
             SpecValidator::None
         }
     }
+
+    pub fn iter(&self) -> Iter<'_> {
+        Iter::new(&self)
+    }
 }
 
 impl From<(ValidatorDesc, ValidatorDesc)> for SpecValidators {
@@ -159,10 +163,44 @@ impl From<(ValidatorDesc, ValidatorDesc)> for SpecValidators {
 /// Fixed size iterator of 2, as we need an iterator in couple of occasions
 impl<'a> IntoIterator for &'a SpecValidators {
     type Item = &'a ValidatorDesc;
-    type IntoIter = ::std::vec::IntoIter<Self::Item>;
+    type IntoIter = Iter<'a>;
 
     fn into_iter(self) -> Self::IntoIter {
-        vec![self.leader(), self.follower()].into_iter()
+        self.iter()
+    }
+}
+
+pub struct Iter<'a> {
+    validators: &'a SpecValidators,
+    index: u8,
+}
+
+impl<'a> Iter<'a> {
+    fn new(validators: &'a SpecValidators) -> Self {
+        Self {
+            validators,
+            index: 0,
+        }
+    }
+}
+
+impl<'a> Iterator for Iter<'a> {
+    type Item = &'a ValidatorDesc;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match self.index {
+            0 => {
+                self.index += 1;
+
+                Some(self.validators.leader())
+            }
+            1 => {
+                self.index += 1;
+
+                Some(self.validators.follower())
+            }
+            _ => None,
+        }
     }
 }
 

validator_worker/src/core/fees.rs

@@ -10,7 +10,7 @@ pub fn get_balances_after_fees_tree(
 
     let total_distributed = balances.iter().map(|(_, balance)| balance).sum::<BigNum>();
 
-    let validators_iter = channel.spec.validators.into_iter();
+    let validators_iter = channel.spec.validators.iter();
     let total_validators_fee = validators_iter
         .map(|validator| &validator.fee)
         .sum::<BigNum>();
@@ -54,7 +54,7 @@ pub fn get_balances_after_fees_tree(
         balances_after_fees,
         rounding_error,
         fee_ratio,
-        channel.spec.validators.into_iter(),
+        channel.spec.validators.iter(),
     );
 
     Ok(balances_after_fees)

validator_worker/src/sentry_interface.rs

@@ -48,7 +48,7 @@ impl<T: Adapter + 'static> SentryApi<T> {
                 let propagate_to = channel
                     .spec
                     .validators
-                    .into_iter()
+                    .iter()
                     .map(|validator| {
                         adapter
                             .get_auth(&validator.id)