wip: implemented backend

rpxy-lib/src/backend/load_balance/load_balance_sticky.rs

@@ -0,0 +1,137 @@
+use super::{
+  load_balance_main::{LoadBalanceContext, LoadBalanceWithPointer, PointerToUpstream},
+  sticky_cookie::StickyCookieConfig,
+  Upstream,
+};
+use crate::{constants::STICKY_COOKIE_NAME, log::*};
+use derive_builder::Builder;
+use rustc_hash::FxHashMap as HashMap;
+use std::{
+  borrow::Cow,
+  sync::{
+    atomic::{AtomicUsize, Ordering},
+    Arc,
+  },
+};
+
+#[derive(Debug, Clone, Builder)]
+/// Round Robin LB object in the sticky cookie manner
+pub struct LoadBalanceSticky {
+  #[builder(default)]
+  /// Pointer to the index of the last served upstream destination
+  ptr: Arc<AtomicUsize>,
+  #[builder(setter(custom), default)]
+  /// Number of upstream destinations
+  num_upstreams: usize,
+  #[builder(setter(custom))]
+  /// Information to build the cookie to stick clients to specific backends
+  pub sticky_config: StickyCookieConfig,
+  #[builder(setter(custom))]
+  /// Hashmaps:
+  /// - Hashmap that maps server indices to server id (string)
+  /// - Hashmap that maps server ids (string) to server indices, for fast reverse lookup
+  upstream_maps: UpstreamMap,
+}
+#[derive(Debug, Clone)]
+pub struct UpstreamMap {
+  /// Hashmap that maps server indices to server id (string)
+  upstream_index_map: Vec<String>,
+  /// Hashmap that maps server ids (string) to server indices, for fast reverse lookup
+  upstream_id_map: HashMap<String, usize>,
+}
+impl LoadBalanceStickyBuilder {
+  /// Set the number of upstream destinations
+  pub fn num_upstreams(&mut self, v: &usize) -> &mut Self {
+    self.num_upstreams = Some(*v);
+    self
+  }
+  /// Set the information to build the cookie to stick clients to specific backends
+  pub fn sticky_config(&mut self, server_name: &str, path_opt: &Option<String>) -> &mut Self {
+    self.sticky_config = Some(StickyCookieConfig {
+      name: STICKY_COOKIE_NAME.to_string(), // TODO: config等で変更できるように
+      domain: server_name.to_ascii_lowercase(),
+      path: if let Some(v) = path_opt {
+        v.to_ascii_lowercase()
+      } else {
+        "/".to_string()
+      },
+      duration: 300, // TODO: config等で変更できるように
+    });
+    self
+  }
+  /// Set the hashmaps: upstream_index_map and upstream_id_map
+  pub fn upstream_maps(&mut self, upstream_vec: &[Upstream]) -> &mut Self {
+    let upstream_index_map: Vec<String> = upstream_vec
+      .iter()
+      .enumerate()
+      .map(|(i, v)| v.calculate_id_with_index(i))
+      .collect();
+    let mut upstream_id_map = HashMap::default();
+    for (i, v) in upstream_index_map.iter().enumerate() {
+      upstream_id_map.insert(v.to_string(), i);
+    }
+    self.upstream_maps = Some(UpstreamMap {
+      upstream_index_map,
+      upstream_id_map,
+    });
+    self
+  }
+}
+impl<'a> LoadBalanceSticky {
+  /// Increment the count of upstream served up to the max value
+  fn simple_increment_ptr(&self) -> usize {
+    // Get a current count of upstream served
+    let current_ptr = self.ptr.load(Ordering::Relaxed);
+
+    if current_ptr < self.num_upstreams - 1 {
+      self.ptr.fetch_add(1, Ordering::Relaxed)
+    } else {
+      // Clear the counter
+      self.ptr.fetch_and(0, Ordering::Relaxed)
+    }
+  }
+  /// This is always called only internally. So 'unwrap()' is executed.
+  fn get_server_id_from_index(&self, index: usize) -> String {
+    self.upstream_maps.upstream_index_map.get(index).unwrap().to_owned()
+  }
+  /// This function takes value passed from outside. So 'result' is used.
+  fn get_server_index_from_id(&self, id: impl Into<Cow<'a, str>>) -> Option<usize> {
+    let id_str = id.into().to_string();
+    self.upstream_maps.upstream_id_map.get(&id_str).map(|v| v.to_owned())
+  }
+}
+impl LoadBalanceWithPointer for LoadBalanceSticky {
+  /// Get the pointer to the upstream server to serve the incoming request.
+  fn get_ptr(&self, req_info: Option<&LoadBalanceContext>) -> PointerToUpstream {
+    // If given context is None or invalid (not contained), get_ptr() is invoked to increment the pointer.
+    // Otherwise, get the server index indicated by the server_id inside the cookie
+    let ptr = match req_info {
+      None => {
+        debug!("No sticky cookie");
+        self.simple_increment_ptr()
+      }
+      Some(context) => {
+        let server_id = &context.sticky_cookie.value.value;
+        if let Some(server_index) = self.get_server_index_from_id(server_id) {
+          debug!("Valid sticky cookie: id={}, index={}", server_id, server_index);
+          server_index
+        } else {
+          debug!("Invalid sticky cookie: id={}", server_id);
+          self.simple_increment_ptr()
+        }
+      }
+    };
+
+    // Get the server id from the ptr.
+    // TODO: This should be simplified and optimized if ptr is not changed (id value exists in cookie).
+    let upstream_id = self.get_server_id_from_index(ptr);
+    let new_cookie = self.sticky_config.build_sticky_cookie(upstream_id).unwrap();
+    let new_context = Some(LoadBalanceContext {
+      sticky_cookie: new_cookie,
+    });
+    PointerToUpstream {
+      ptr,
+      context: new_context,
+    }
+  }
+}