introduce binderRpcBenchmark

VRRRRRRRRRRRRRRRRRMMMMMMM!!!

Some caveats:
- we are partially benchmarking the scheduler
- this is a microbenchmark

Results running on host (we'll want to watch and tune these on real
devices with core clamping and thermal throttling off):

-------------------------------------------------------------
Benchmark                   Time             CPU   Iterations
-------------------------------------------------------------
BM_getRootObject        45959 ns        39054 ns        18345
BM_pingTransaction      26128 ns        23360 ns        28705
BM_repeatString        394286 ns       200186 ns         3508
BM_repeatBinder         39357 ns        37437 ns        17705

Bug: 182940634
Test: run benchmark on host and on cuttlefish
Change-Id: I5084a00ddf207eaeb803da98587ca04df65add4d
diff --git a/libs/binder/RpcConnection.cpp b/libs/binder/RpcConnection.cpp
index 1bf3d88..c1ed93a 100644
--- a/libs/binder/RpcConnection.cpp
+++ b/libs/binder/RpcConnection.cpp
@@ -61,7 +61,8 @@
 public:
     explicit UnixSocketAddress(const char* path) : mAddr({.sun_family = AF_UNIX}) {
         unsigned int pathLen = strlen(path) + 1;
-        LOG_ALWAYS_FATAL_IF(pathLen > sizeof(mAddr.sun_path), "%u %s", pathLen, path);
+        LOG_ALWAYS_FATAL_IF(pathLen > sizeof(mAddr.sun_path), "Socket path is too long: %u %s",
+                            pathLen, path);
         memcpy(mAddr.sun_path, path, pathLen);
     }
     virtual ~UnixSocketAddress() {}
diff --git a/libs/binder/tests/Android.bp b/libs/binder/tests/Android.bp
index afc4b1b..e39408c 100644
--- a/libs/binder/tests/Android.bp
+++ b/libs/binder/tests/Android.bp
@@ -151,6 +151,22 @@
     require_root: true,
 }
 
+cc_benchmark {
+    name: "binderRpcBenchmark",
+    defaults: ["binder_test_defaults"],
+    host_supported: true,
+    srcs: [
+        "binderRpcBenchmark.cpp",
+        "IBinderRpcBenchmark.aidl",
+    ],
+    shared_libs: [
+        "libbase",
+        "libbinder",
+        "liblog",
+        "libutils",
+    ],
+}
+
 cc_test {
     name: "binderThroughputTest",
     defaults: ["binder_test_defaults"],
diff --git a/libs/binder/tests/IBinderRpcBenchmark.aidl b/libs/binder/tests/IBinderRpcBenchmark.aidl
new file mode 100644
index 0000000..1457422
--- /dev/null
+++ b/libs/binder/tests/IBinderRpcBenchmark.aidl
@@ -0,0 +1,20 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * 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.
+ */
+
+interface IBinderRpcBenchmark {
+    @utf8InCpp String repeatString(@utf8InCpp String str);
+    IBinder repeatBinder(IBinder binder);
+}
diff --git a/libs/binder/tests/binderRpcBenchmark.cpp b/libs/binder/tests/binderRpcBenchmark.cpp
new file mode 100644
index 0000000..7c82226
--- /dev/null
+++ b/libs/binder/tests/binderRpcBenchmark.cpp
@@ -0,0 +1,141 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include <BnBinderRpcBenchmark.h>
+#include <android-base/logging.h>
+#include <benchmark/benchmark.h>
+#include <binder/Binder.h>
+#include <binder/RpcConnection.h>
+#include <binder/RpcServer.h>
+
+#include <thread>
+
+#include <sys/types.h>
+#include <unistd.h>
+
+using android::BBinder;
+using android::IBinder;
+using android::interface_cast;
+using android::OK;
+using android::RpcConnection;
+using android::RpcServer;
+using android::sp;
+using android::binder::Status;
+
+class MyBinderRpcBenchmark : public BnBinderRpcBenchmark {
+    Status repeatString(const std::string& str, std::string* out) override {
+        *out = str;
+        return Status::ok();
+    }
+    Status repeatBinder(const sp<IBinder>& str, sp<IBinder>* out) override {
+        *out = str;
+        return Status::ok();
+    }
+};
+
+static sp<RpcConnection> gConnection = RpcConnection::make();
+
+void BM_getRootObject(benchmark::State& state) {
+    while (state.KeepRunning()) {
+        CHECK(gConnection->getRootObject() != nullptr);
+    }
+}
+BENCHMARK(BM_getRootObject);
+
+void BM_pingTransaction(benchmark::State& state) {
+    sp<IBinder> binder = gConnection->getRootObject();
+    CHECK(binder != nullptr);
+
+    while (state.KeepRunning()) {
+        CHECK_EQ(OK, binder->pingBinder());
+    }
+}
+BENCHMARK(BM_pingTransaction);
+
+void BM_repeatString(benchmark::State& state) {
+    sp<IBinder> binder = gConnection->getRootObject();
+    CHECK(binder != nullptr);
+    sp<IBinderRpcBenchmark> iface = interface_cast<IBinderRpcBenchmark>(binder);
+    CHECK(iface != nullptr);
+
+    // Googlers might see go/another-look-at-aidl-hidl-perf
+    //
+    // When I checked in July 2019, 99.5% of AIDL transactions and 99.99% of HIDL
+    // transactions were less than one page in size (system wide during a test
+    // involving media and camera). This is why this diverges from
+    // binderThroughputTest and hwbinderThroughputTest. Future consideration - get
+    // this data on continuous integration. Here we are testing sending a
+    // transaction of twice this size. In other cases, we should focus on
+    // benchmarks of particular usecases. If individual binder transactions like
+    // the ones tested here are fast, then Android performance will be dominated
+    // by how many binder calls work together (and by factors like the scheduler,
+    // thermal throttling, core choice, etc..).
+    std::string str = std::string(getpagesize() * 2, 'a');
+    CHECK_EQ(str.size(), getpagesize() * 2);
+
+    while (state.KeepRunning()) {
+        std::string out;
+        Status ret = iface->repeatString(str, &out);
+        CHECK(ret.isOk()) << ret;
+    }
+}
+BENCHMARK(BM_repeatString);
+
+void BM_repeatBinder(benchmark::State& state) {
+    sp<IBinder> binder = gConnection->getRootObject();
+    CHECK(binder != nullptr);
+    sp<IBinderRpcBenchmark> iface = interface_cast<IBinderRpcBenchmark>(binder);
+    CHECK(iface != nullptr);
+
+    while (state.KeepRunning()) {
+        // force creation of a new address
+        sp<IBinder> binder = sp<BBinder>::make();
+
+        sp<IBinder> out;
+        Status ret = iface->repeatBinder(binder, &out);
+        CHECK(ret.isOk()) << ret;
+    }
+}
+BENCHMARK(BM_repeatBinder);
+
+int main(int argc, char** argv) {
+    ::benchmark::Initialize(&argc, argv);
+    if (::benchmark::ReportUnrecognizedArguments(argc, argv)) return 1;
+
+    std::string addr = std::string(getenv("TMPDIR") ?: "/tmp") + "/binderRpcBenchmark";
+    (void)unlink(addr.c_str());
+
+    std::thread([addr]() {
+        sp<RpcServer> server = RpcServer::make();
+        server->setRootObject(sp<MyBinderRpcBenchmark>::make());
+
+        server->iUnderstandThisCodeIsExperimentalAndIWillNotUseItInProduction();
+
+        sp<RpcConnection> connection = server->addClientConnection();
+        CHECK(connection->setupUnixDomainServer(addr.c_str()));
+
+        connection->join();
+    }).detach();
+
+    for (size_t tries = 0; tries < 5; tries++) {
+        usleep(10000);
+        if (gConnection->addUnixDomainClient(addr.c_str())) goto success;
+    }
+    LOG(FATAL) << "Could not connect.";
+success:
+
+    ::benchmark::RunSpecifiedBenchmarks();
+}