Add EWMA and load biasing crates for failure-aware P2C balancing

Cargo.lock

@@ -1687,6 +1687,13 @@ dependencies = [
  "pin-project",
 ]
 
+[[package]]
+name = "linkerd-ewma"
+version = "0.1.0"
+dependencies = [
+ "tokio",
+]
+
 [[package]]
 name = "linkerd-exp-backoff"
 version = "0.1.0"
@@ -1751,6 +1758,7 @@ dependencies = [
  "futures",
  "http",
  "http-body",
+ "httpdate",
  "linkerd-error",
  "linkerd-http-box",
  "linkerd-stack",
@@ -1979,6 +1987,27 @@ dependencies = [
  "tokio-util",
 ]
 
+[[package]]
+name = "linkerd-load-biaser"
+version = "0.1.0"
+dependencies = [
+ "bytes",
+ "futures",
+ "http",
+ "http-body",
+ "http-body-util",
+ "hyper-balance",
+ "linkerd-ewma",
+ "linkerd-http-classify",
+ "linkerd-stack",
+ "parking_lot",
+ "pin-project",
+ "tokio",
+ "tower",
+ "tower-service",
+ "tracing",
+]
+
 [[package]]
 name = "linkerd-meshtls"
 version = "0.1.0"

Cargo.toml

@@ -22,6 +22,7 @@ members = [
     "linkerd/error",
     "linkerd/errno",
     "linkerd/error-respond",
+    "linkerd/ewma",
     "linkerd/exp-backoff",
     "linkerd/http/access-log",
     "linkerd/http/body-eos",
@@ -42,6 +43,7 @@ members = [
     "linkerd/identity",
     "linkerd/idle-cache",
     "linkerd/io",
+    "linkerd/load-biaser",
     "linkerd/meshtls",
     "linkerd/meshtls/verifier",
     "linkerd/metrics",
@@ -105,6 +107,7 @@ drain = { version = "0.2", default-features = false }
 h2 = { version = "0.4" }
 http = { version = "1" }
 http-body = { version = "1" }
+httpdate = { version = "1.0" }
 hyper = { version = "1", default-features = false }
 prometheus-client = { version = "0.23" }
 prost = { version = "0.14" }

linkerd/ewma/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "linkerd-ewma"
+version = { workspace = true }
+authors = { workspace = true }
+license = { workspace = true }
+edition = { workspace = true }
+publish = { workspace = true }
+
+[dependencies]
+tokio = { version = "1", default-features = false, features = ["time"] }
+
+[dev-dependencies]
+tokio = { version = "1", features = ["macros", "rt", "test-util"] }