Initial add of simple stats collector

1 files changed, 282 insertions, 0 deletions

diff --git a/src/stats/mod.rs b/src/stats/mod.rs
new file mode 100644
index 0000000..126b88b
--- /dev/null
+++ b/src/stats/mod.rs
@@ -0,0 +1,282 @@
+// Copyright 2017-2019 int08h LLC
+//
+// 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 hashbrown::HashMap;
+use std::net::IpAddr;
+
+/// Maximum number of stats entries to maintain.
+const MAX_CLIENTS: usize = 1_000_000;
+
+/// Track number and sizes of requests and responses per client.
+pub trait ClientStats {
+    fn add_valid_request(&mut self, addr: &IpAddr);
+
+    fn add_invalid_request(&mut self, addr: &IpAddr);
+
+    fn add_health_check(&mut self, addr: &IpAddr);
+
+    fn add_response(&mut self, addr: &IpAddr, bytes_sent: usize);
+
+    fn total_valid_requests(&self) -> u64;
+
+    fn total_invalid_requests(&self) -> u64;
+
+    fn total_health_checks(&self) -> u64;
+
+    fn total_responses_sent(&self) -> u64;
+
+    fn total_bytes_sent(&self) -> usize;
+
+    fn total_unique_clients(&self) -> u64;
+
+    fn get_stats(&self, addr: &IpAddr) -> Option<&StatEntry>;
+
+    fn clear(&mut self);
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct StatEntry {
+    pub valid_requests: u64,
+    pub invalid_requests: u64,
+    pub health_checks: u64,
+    pub responses_sent: u64,
+    pub bytes_sent: usize,
+}
+
+impl StatEntry {
+    fn new() -> Self {
+        StatEntry {
+            valid_requests: 0,
+            invalid_requests: 0,
+            health_checks: 0,
+            responses_sent: 0,
+            bytes_sent: 0,
+        }
+    }
+}
+
+///
+/// Straight forward implementation of `ClientStats` backed by a hashmap.
+///
+/// Maintains a maximum of `MAX_CLIENTS` unique entries to bound memory use. Excess entries
+/// beyond `MAX_CLIENTS` are ignored and `num_overflows` is incremented.
+///
+pub struct SimpleStats {
+    clients: HashMap<IpAddr, StatEntry>,
+    num_overflows: u64,
+    max_clients: usize,
+}
+
+impl SimpleStats {
+    pub fn new() -> Self {
+        SimpleStats {
+            clients: HashMap::with_capacity(128),
+            num_overflows: 0,
+            max_clients: MAX_CLIENTS
+        }
+    }
+
+    // visible for testing
+    #[cfg(test)]
+    fn with_limits(limit: usize) -> Self {
+        SimpleStats {
+            clients: HashMap::with_capacity(128),
+            num_overflows: 0,
+            max_clients: limit
+        }
+    }
+
+    #[inline]
+    fn too_many_entries(&mut self) -> bool {
+        let too_big = self.clients.len() >= self.max_clients;
+
+        if too_big {
+            self.num_overflows += 1;
+        }
+
+        return too_big;
+    }
+
+    pub fn num_overflows(&self) -> u64 {
+        self.num_overflows
+    }
+}
+
+impl ClientStats for SimpleStats {
+    fn add_valid_request(&mut self, addr: &IpAddr) {
+        if self.too_many_entries() {
+            return;
+        }
+        self.clients
+            .entry(*addr)
+            .or_insert_with(StatEntry::new)
+            .valid_requests += 1;
+    }
+
+    fn add_invalid_request(&mut self, addr: &IpAddr) {
+        if self.too_many_entries() {
+            return;
+        }
+        self.clients
+            .entry(*addr)
+            .or_insert_with(StatEntry::new)
+            .invalid_requests += 1;
+    }
+
+    fn add_health_check(&mut self, addr: &IpAddr) {
+        if self.too_many_entries() {
+            return;
+        }
+        self.clients
+            .entry(*addr)
+            .or_insert_with(StatEntry::new)
+            .health_checks += 1;
+    }
+
+    fn add_response(&mut self, addr: &IpAddr, bytes_sent: usize) {
+        if self.too_many_entries() {
+            return;
+        }
+        let entry = self.clients
+            .entry(*addr)
+            .or_insert_with(StatEntry::new);
+
+        entry.responses_sent += 1;
+        entry.bytes_sent += bytes_sent;
+    }
+
+    fn total_valid_requests(&self) -> u64 {
+        self.clients
+            .values()
+            .map(|&v| v.valid_requests)
+            .sum()
+    }
+
+    fn total_invalid_requests(&self) -> u64 {
+        self.clients
+            .values()
+            .map(|&v| v.invalid_requests)
+            .sum()
+    }
+
+    fn total_health_checks(&self) -> u64 {
+        self.clients
+            .values()
+            .map(|&v| v.health_checks)
+            .sum()
+    }
+
+    fn total_responses_sent(&self) -> u64 {
+        self.clients
+            .values()
+            .map(|&v| v.responses_sent)
+            .sum()
+    }
+
+    fn total_bytes_sent(&self) -> usize {
+        self.clients
+            .values()
+            .map(|&v| v.bytes_sent)
+            .sum()
+    }
+
+    fn total_unique_clients(&self) -> u64 {
+        self.clients.len() as u64
+    }
+
+    fn get_stats(&self, addr: &IpAddr) -> Option<&StatEntry> {
+        self.clients.iter()
+
+        self.clients.get(addr)
+    }
+
+    fn clear(&mut self) {
+        self.clients.clear();
+        self.num_overflows = 0;
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::stats::{ClientStats, SimpleStats};
+    use std::net::{IpAddr, Ipv4Addr};
+
+    #[test]
+    fn simple_stats_starts_empty() {
+        let stats = SimpleStats::new();
+
+        assert_eq!(stats.total_valid_requests(), 0);
+        assert_eq!(stats.total_invalid_requests(), 0);
+        assert_eq!(stats.total_health_checks(), 0);
+        assert_eq!(stats.total_responses_sent(), 0);
+        assert_eq!(stats.total_bytes_sent(), 0);
+        assert_eq!(stats.total_unique_clients(), 0);
+        assert_eq!(stats.num_overflows(), 0);
+    }
+
+    #[test]
+    fn client_requests_are_tracked() {
+        let mut stats = SimpleStats::new();
+
+        let ip1 = "127.0.0.1".parse().unwrap();
+        let ip2 = "127.0.0.2".parse().unwrap();
+        let ip3 = "127.0.0.3".parse().unwrap();
+
+        stats.add_valid_request(&ip1);
+        stats.add_valid_request(&ip2);
+        stats.add_valid_request(&ip3);
+        assert_eq!(stats.total_valid_requests(), 3);
+
+        stats.add_invalid_request(&ip2);
+        assert_eq!(stats.total_invalid_requests(), 1);
+
+        stats.add_response(&ip2, 8192);
+        assert_eq!(stats.total_bytes_sent(), 8192);
+
+        assert_eq!(stats.total_unique_clients(), 3);
+    }
+
+    #[test]
+    fn per_client_stats() {
+        let mut stats = SimpleStats::new();
+        let ip = "127.0.0.3".parse().unwrap();
+
+        stats.add_valid_request(&ip);
+        stats.add_response(&ip, 2048);
+        stats.add_response(&ip, 1024);
+
+        let entry = stats.get_stats(&ip).unwrap();
+        assert_eq!(entry.valid_requests, 1);
+        assert_eq!(entry.invalid_requests, 0);
+        assert_eq!(entry.responses_sent, 2);
+        assert_eq!(entry.bytes_sent, 3072);
+    }
+
+    #[test]
+    fn overflow_max_entries() {
+        let mut stats = SimpleStats::with_limits(100);
+        
+        for i in 0..201 {
+            let ipv4 = Ipv4Addr::from(i as u32);
+            let addr = IpAddr::from(ipv4);
+
+            stats.add_valid_request(&addr);
+        };
+
+        assert_eq!(stats.total_unique_clients(), 100);
+        assert_eq!(stats.num_overflows(), 101);
+    }
+}
+
+