feat: Copy async_http_client from B&A

Note that AsyncHttpClient is a subset of AsyncClient.
The AsyncClient interface in B&A actually contains
two methods - one for http and one for grpc.
No implementation overrides both, so it doesn't make much
sense to keep both methods in one interface.

Breaking out the http portion makes the clients
pure interfaces.

This is part of a series of CLs to copy
the KV BYOS clients from B&A to common repo.

Bug: 411430242
Change-Id: I1b246bfc43e2e4e1b98ed78ae2b4ff3b4701aea0
GitOrigin-RevId: eb8cc179741f446739a07b057e630b38f81c03ff

Author: Privacy Sandbox Team

src/clients/async_client/BUILD.bazel

@@ -0,0 +1,26 @@
+load("@rules_cc//cc:defs.bzl", "cc_library")
+
+cc_library(
+    name = "async_http_client",
+    hdrs = ["async_http_client.h"],
+    # header only library for interface
+    linkstatic = True,
+    visibility = ["//visibility:public"],
+    deps = [
+        "@com_google_absl//absl/functional:any_invocable",
+        "@com_google_absl//absl/status",
+        "@com_google_absl//absl/time",
+    ],
+)
+
+cc_library(
+    name = "mocks",
+    testonly = 1,
+    hdrs = ["mocks.h"],
+    deps = [
+        "@com_google_absl//absl/functional:any_invocable",
+        "@com_google_absl//absl/status",
+        "@com_google_absl//absl/time",
+        "@com_google_googletest//:gtest_main",
+    ],
+)

src/clients/async_client/async_http_client.h

@@ -0,0 +1,57 @@
+//  Copyright 2025 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 SRC_CLIENTS_ASYNC_CLIENT_ASYNC_HTTP_CLIENT_H_
+#define SRC_CLIENTS_ASYNC_CLIENT_ASYNC_HTTP_CLIENT_H_
+
+#include <memory>
+#include <string>
+
+#include "absl/container/flat_hash_map.h"
+#include "absl/functional/any_invocable.h"
+#include "absl/status/statusor.h"
+#include "absl/time/time.h"
+
+namespace privacy_sandbox::server_common::clients {
+
+// This provides access to the Metadata Object type
+using RequestMetadata = absl::flat_hash_map<std::string, std::string>;
+
+// Classes implementing this template and interface are able to execute
+// asynchronous requests.
+template <typename Request, typename Response, typename RawRequest = Request,
+          typename RawResponse = Response>
+class AsyncHttpClient {
+ public:
+  virtual ~AsyncHttpClient() = default;
+
+  // Executes the request asynchronously.
+  //
+  // request: the request object to execute.
+  // metadata: Metadata to be passed to the client.
+  // on_done: callback called when the request is finished executing.
+  // timeout: a timeout value for the request.
+  virtual absl::Status Execute(
+      std::unique_ptr<Request> request, const RequestMetadata& metadata,
+      absl::AnyInvocable<void(absl::StatusOr<std::unique_ptr<Response>>) &&>
+          on_done,
+      absl::Duration timeout,
+      privacy_sandbox::server_common::log::PSLogContext& log_context =
+          const_cast<privacy_sandbox::server_common::log::NoOpContext&>(
+              privacy_sandbox::server_common::log::kNoOpContext)) const = 0;
+};
+
+}  // namespace privacy_sandbox::server_common::clients
+
+#endif  // SRC_CLIENTS_ASYNC_CLIENT_ASYNC_HTTP_CLIENT_H_

src/clients/async_client/mocks.h

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2025 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 SRC_CLIENTS_ASYNC_CLIENT_MOCKS_H_
+#define SRC_CLIENTS_ASYNC_CLIENT_MOCKS_H_
+
+#include <gmock/gmock.h>
+
+#include <memory>
+
+#include "absl/container/flat_hash_map.h"
+#include "absl/functional/any_invocable.h"
+#include "absl/status/statusor.h"
+#include "absl/time/time.h"
+#include "src/clients/async_client/async_http_client.h"
+
+namespace privacy_sandbox::server_common::clients {
+
+template <typename Request, typename Response, typename RawRequest = Request,
+          typename RawResponse = Response>
+class AsyncClientMock
+    : public AsyncClient<Request, Response, RawRequest, RawResponse> {
+ public:
+  MOCK_METHOD(
+      absl::Status, Execute,
+      (std::unique_ptr<Request> request, const RequestMetadata& metadata,
+       absl::AnyInvocable<void(absl::StatusOr<std::unique_ptr<Response>>) &&>
+           on_done,
+       absl::Duration timeout, RequestContext context),
+      (const, override));
+
+  using OnDoneCallbackType =
+      absl::AnyInvocable<void(absl::StatusOr<std::unique_ptr<RawResponse>>,
+                              ResponseMetadata) &&>;
+  MOCK_METHOD(absl::Status, ExecuteInternal,
+              (std::unique_ptr<RawRequest> raw_request,
+               grpc::ClientContext* context, OnDoneCallbackType on_done,
+               absl::Duration timeout, RequestConfig request_config),
+              (override));
+};
+
+}  // namespace privacy_sandbox::server_common::clients
+
+#endif  // SRC_CLIENTS_ASYNC_CLIENT_MOCKS_H_

src/core/kv_client/BUILD.bazel

@@ -12,38 +12,24 @@ cc_library(
 
 cc_library(
     name = "buyer_key_value_async_http_client",
-    srcs = [
-    ],
     hdrs = [
         "buyer_key_value_async_http_client.h",
     ],
+    visibility = ["//visibility:public"],
     deps = [
         ":common",
-    ],
-)
-
-cc_library(
-    name = "byos_client",
-    srcs = [
-    ],
-    hdrs = [
-        "byos_client.h",
-    ],
-    deps = [
-        "@com_google_absl//absl/functional:any_invocable",
-        "@com_google_absl//absl/status",
-        "@com_google_absl//absl/time",
+        "//src/clients/async_client:async_http_client",
     ],
 )
 
 cc_library(
     name = "seller_key_value_async_http_client",
-    srcs = [
-    ],
     hdrs = [
         "seller_key_value_async_http_client.h",
     ],
+    visibility = ["//visibility:public"],
     deps = [
         ":common",
+        "//src/clients/async_client:async_http_client",
     ],
 )

src/core/kv_client/buyer_key_value_async_http_client.h

@@ -20,7 +20,7 @@
 #include <memory>
 #include <string>
 
-#include "src/core/kv_client/byos_client.h"
+#include "src/clients/async_client/async_http_client.h"
 #include "src/core/kv_client/common.h"
 
 namespace privacy_sandbox::server_common::kv_client {
@@ -72,7 +72,7 @@ struct GetBuyerValuesOutput {
 // TODO(b/411430242): Move actual implementation from B&A repo. This is
 // currently no-op
 class BuyerKeyValuesAsyncHttpClient
-    : public ByosClient<GetBuyerValuesInput, GetBuyerValuesOutput> {
+    : public AsyncHttpClient<GetBuyerValuesInput, GetBuyerValuesOutput> {
  public:
   explicit BuyerKeyValueAsyncHttpClient(std::string_view kv_server_base_address)
       : kv_server_base_address_(kv_server_base_address) {}

src/core/kv_client/byos_client.h

@@ -20,6 +20,7 @@
 #include <memory>
 #include <string>
 
+#include "src/clients/async_client/async_http_client.h"
 #include "src/core/kv_client/common.h"
 
 namespace privacy_sandbox::server_common::kv_client {
@@ -56,7 +57,7 @@ struct GetSellerValuesOutput {
 // TODO(b/411430242): Move actual implementation from B&A repo. This is
 // currently no-op
 class SellerKeyValuesAsyncHttpClient
-    : public ByosClient<GetSellerValuesInput, GetSellerValuesOutput> {
+    : public AsyncHttpClient<GetSellerValuesInput, GetSellerValuesOutput> {
  public:
   explicit SellerKeyValueAsyncHttpClient(
       std::string_view kv_server_base_address)