Add rolling total and allow control over bytes per second allowed from node connections

backend/common/src/byte_size.rs

@@ -0,0 +1,94 @@
+use anyhow::{ anyhow, Error };
+
+#[derive(Copy,Clone,Debug)]
+pub struct ByteSize(usize);
+
+impl ByteSize {
+    pub fn new(bytes: usize) -> ByteSize {
+        ByteSize(bytes)
+    }
+    pub fn into_bytes(self) -> usize {
+        self.0
+    }
+}
+
+impl From<ByteSize> for usize {
+    fn from(b: ByteSize) -> Self {
+        b.0
+    }
+}
+
+impl std::str::FromStr for ByteSize {
+    type Err = Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let s = s.trim();
+        match s.find(|c| !char::is_ascii_digit(&c)) {
+            // No non-numeric chars; assume bytes then
+            None => Ok(ByteSize(s.parse().expect("all ascii digits"))),
+            // First non-numeric char
+            Some(idx) => {
+                let n = s[..idx].parse().expect("all ascii digits");
+                let suffix = s[idx..].trim();
+                let n = match suffix {
+                    "B" | "b" => n,
+                    "kB" | "K" | "k" => n * 1000,
+                    "MB" | "M" | "m" => n * 1000 * 1000,
+                    "GB" | "G" | "g" => n * 1000 * 1000 * 1000,
+                    "KiB" | "Ki" => n * 1024,
+                    "MiB" | "Mi" => n * 1024 * 1024,
+                    "GiB" | "Gi" => n * 1024 * 1024 * 1024,
+                    _ => return Err(anyhow!("\
+                        Cannot parse into bytes; suffix is '{}', but expecting one of \
+                        B,b, kB,K,k, MB,M,m, GB,G,g, KiB,Ki, MiB,Mi, GiB,Gi", suffix))
+                };
+                Ok(ByteSize(n))
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::byte_size::ByteSize;
+
+
+    #[test]
+    fn can_parse_valid_strings() {
+        let cases = vec![
+            ("100", 100),
+            ("100B", 100),
+            ("100b", 100),
+
+            ("20kB", 20 * 1000),
+            ("20 kB", 20 * 1000),
+            ("20K", 20 * 1000),
+            (" 20k", 20 * 1000),
+
+            ("1MB", 1 * 1000 * 1000),
+            ("1M", 1 * 1000 * 1000),
+            ("1m", 1 * 1000 * 1000),
+            ("1 m", 1 * 1000 * 1000),
+
+            ("1GB", 1 * 1000 * 1000 * 1000),
+            ("1G", 1 * 1000 * 1000 * 1000),
+            ("1g", 1 * 1000 * 1000 * 1000),
+
+            ("1KiB", 1 * 1024),
+            ("1Ki", 1 * 1024),
+
+            ("1MiB", 1 * 1024 * 1024),
+            ("1Mi", 1 * 1024 * 1024),
+
+            ("1GiB", 1 * 1024 * 1024 * 1024),
+            ("1Gi", 1 * 1024 * 1024 * 1024),
+            (" 1 Gi ", 1 * 1024 * 1024 * 1024),
+        ];
+
+        for (s, expected) in cases {
+            let b: ByteSize = s.parse().unwrap();
+            assert_eq!(b.into_bytes(), expected);
+        }
+    }
+
+}