add new service dirs

aqua-examples/decentralized-blockchain-gateway/wasm-modules/simple-quorum/src/main.rs

@@ -0,0 +1,117 @@
+/*
+ * Copyright 2022 Fluence Labs Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+use marine_rs_sdk::{marine, module_manifest};
+use std::collections::HashMap;
+
+module_manifest!();
+
+fn main() {}
+
+// very simple mode calculator with much room for improvement
+// see https://github.com/BurntSushi/rust-stats for inspiration
+fn mode<'a>(data: impl ExactSizeIterator<Item = &'a EVMResult>) -> (u32, u64) {
+    let frequencies = data
+        .into_iter()
+        .fold(HashMap::<u64, u32>::new(), |mut freqs, value| {
+            *freqs
+                .entry(
+                    match serde_json::from_str::<serde_json::Value>(&value.stdout) {
+                        Ok(r) => r["block-height"].as_u64().unwrap(),
+                        Err(_e) => 0 as u64,
+                    },
+                )
+                .or_insert(0) += 1;
+            freqs
+        });
+
+    let mode = frequencies
+        .iter()
+        .max_by_key(|&(_, count)| count)
+        .map(|(value, _)| value)
+        .unwrap();
+
+    (*frequencies.get(&mode).unwrap(), *mode)
+}
+
+fn mean<'a>(data: impl ExactSizeIterator<Item = &'a u64>) -> Option<f64> {
+    let n = data.len() as u64;
+    if n < 1 {
+        return None;
+    }
+    let res = (data.sum::<u64>() / n) as f64;
+    Some(res)
+}
+
+#[marine]
+pub struct EVMResult {
+    pub provider: String,
+    pub stdout: String,
+    pub stderr: String,
+}
+
+#[marine]
+#[derive(Default, Debug)]
+pub struct Quorum {
+    pub n: u32,
+    pub mode: u64,
+    pub freq: u32,
+    pub err_str: String,
+}
+
+#[marine]
+pub fn point_estimate(data: Vec<EVMResult>, min_points: u32) -> Quorum {
+    if data.len() < min_points as usize {
+        return Quorum {
+            err_str: format!(
+                "Expected at least {} points but only got {}.",
+                min_points,
+                data.len()
+            ),
+            ..<_>::default()
+        };
+    }
+
+    if data.len() < 1 {
+        return Quorum {
+            err_str: format!("Expected at least one timestamp."),
+            ..<_>::default()
+        };
+    }
+
+    let (freq, mode) = mode(data.iter());
+
+    Quorum {
+        n: data.len() as u32,
+        mode,
+        freq,
+        ..<_>::default()
+    }
+}
+
+#[marine]
+pub fn int_div(nom: u64, denom: u64) -> f64 {
+    nom as f64 / denom as f64
+}
+
+#[marine]
+pub fn is_quorum(nom: u64, denom: u64, threshold: f64) -> bool {
+    let div = nom as f64 / denom as f64;
+    if div >= threshold {
+        return true;
+    }
+    false
+}