Add peregrine TransportMetrics and TransportAdapter::GetTransportMetrics().

tpu_sync/transport/lib/BUILD

@@ -34,6 +34,7 @@ cc_library(
     name = "transport_adapter",
     hdrs = ["transport_adapter.h"],
     deps = [
+        "//tpu_sync/transport/peregrine/src/api:transport_metrics",
         "@com_google_absl//absl/functional:any_invocable",
         "@com_google_absl//absl/status",
         "@com_google_absl//absl/status:statusor",

tpu_sync/transport/lib/transport_adapter.h

@@ -25,6 +25,7 @@
 #include "absl/status/status.h"
 #include "absl/status/statusor.h"
 #include "absl/types/span.h"
+#include "tpu_sync/transport/peregrine/src/api/transport_metrics.h"
 
 namespace tpu_raiden {
 namespace transport {
@@ -86,6 +87,10 @@ class TransportAdapter {
       CompletionCallback on_complete = nullptr) = 0;
 
   virtual absl::StatusOr<Status> Poll(Handle handle) = 0;
+
+  virtual ::peregrine::TransportMetrics GetTransportMetrics() const {
+    return {};
+  }
 };
 
 }  // namespace lib

tpu_sync/transport/peregrine/src/api/BUILD

@@ -18,6 +18,15 @@ load("@rules_cc//cc:defs.bzl", "cc_library", "cc_test")
 
 package(default_visibility = ["//visibility:public"])
 
+cc_library(
+    name = "transport_metrics",
+    hdrs = ["transport_metrics.h"],
+    deps = [
+        "@com_google_absl//absl/strings",
+        "@com_google_absl//absl/strings:str_format",
+    ],
+)
+
 cc_library(
     name = "transport_types",
     hdrs = ["transport_types.h"],

tpu_sync/transport/peregrine/src/api/transport_metrics.h

@@ -0,0 +1,86 @@
+// Copyright 2026 Google 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.
+
+#ifndef THIRD_PARTY_PEREGRINE_SRC_API_TRANSPORT_METRICS_H_
+#define THIRD_PARTY_PEREGRINE_SRC_API_TRANSPORT_METRICS_H_
+
+#include <array>
+#include <cstdint>
+#include <numeric>
+#include <string>
+
+#include "absl/strings/str_format.h"
+#include "absl/strings/str_join.h"
+
+namespace peregrine {
+
+// A log2-spaced metric histogram.
+// Sample value vs bucket mapping (N = #buckets):
+//    Value Rrange      Bucket
+//    [0, 1)            0
+//    [1, 2)            1
+//    [2, 4)            2
+//    ...
+//    [2^(i-1), 2^i)    i
+//    ...
+//    [2^(N-2), inf)    N-1
+template <int N = 32>
+struct Log2Histogram final {
+  uint64_t sum = 0;
+  std::array<uint64_t, N> buckets{};
+
+  constexpr int NumBuckets() const { return N; }
+
+  constexpr uint64_t Count() const {
+    return std::accumulate(buckets.begin(), buckets.end(), uint64_t{0});
+  }
+
+  std::string ToString() const {
+    return absl::StrFormat("Log2Histogram(sum: %d, count: %d, buckets: [%s])",
+                           sum, Count(), absl::StrJoin(buckets, ", "));
+  }
+};
+
+// Per-operation (read or write) end-to-end metrics.
+struct OpMetrics final {
+  // End-to-end transfer duration in microseconds.
+  Log2Histogram<32> e2e_latency_us{};
+  // Request per-op size in bytes.
+  Log2Histogram<32> request_size_bytes{};
+  // Total payload bytes transferred across all data channels.
+  uint64_t bytes = 0;
+  // Total transfer failures.
+  uint64_t errors = 0;
+};
+
+// High-level end-to-end metrics for transport users.
+struct TransportMetrics final {
+  OpMetrics write{};
+  OpMetrics read{};
+
+  // Transport Pipeline Breakdown
+  // ---------------------------------------------------------------------------
+  // TODO(yyd): Add tier 2 metrics here
+
+  // Hardware & Subsystem Internals
+  // ---------------------------------------------------------------------------
+  // Number of failed TCP connection attempts to peers
+  uint64_t tcp_connect_failures = 0;
+  // Number of RPC requests received by the control plane
+  uint64_t rpc_requests_received = 0;
+};
+
+}  // namespace peregrine
+
+#endif  // THIRD_PARTY_PEREGRINE_SRC_API_TRANSPORT_METRICS_H_