test(rpc_client): add RpcClient unit tests

CMakeLists.txt

@@ -151,6 +151,7 @@ if(BUILD_TESTS)
     add_cloudsql_test(btree_index_tests tests/btree_index_tests.cpp)
     add_cloudsql_test(storage_manager_tests tests/storage_manager_tests.cpp)
     add_cloudsql_test(rpc_server_tests tests/rpc_server_tests.cpp)
+    add_cloudsql_test(rpc_client_tests tests/rpc_client_tests.cpp)
     add_cloudsql_test(operator_tests tests/operator_tests.cpp)
     add_cloudsql_test(query_executor_tests tests/query_executor_tests.cpp)
     add_cloudsql_test(distributed_executor_tests tests/distributed_executor_tests.cpp)

tests/operator_tests.cpp

@@ -800,9 +800,9 @@ TEST_F(OperatorTests, AggregateMultipleAggregates) {
 
     Tuple tuple;
     EXPECT_TRUE(agg->next(tuple));
-    EXPECT_EQ(tuple.get(0).to_int64(), 60);    // SUM
-    EXPECT_EQ(tuple.get(1).to_int64(), 3);     // COUNT
-    EXPECT_EQ(tuple.get(2).to_float64(), 20.0); // AVG
+    EXPECT_EQ(tuple.get(0).to_int64(), 60);      // SUM
+    EXPECT_EQ(tuple.get(1).to_int64(), 3);       // COUNT
+    EXPECT_EQ(tuple.get(2).to_float64(), 20.0);  // AVG
     EXPECT_FALSE(agg->next(tuple));
     agg->close();
 }
@@ -905,7 +905,8 @@ TEST_F(OperatorTests, HashJoinRightOuter) {
     // RIGHT join output: matched rows + unmatched right rows with NULLs
     // Matched: (2, 2)
     // Unmatched right: (NULL, 3), (NULL, 4)
-    std::vector<std::pair<int64_t, int64_t>> results;  // (left_value, right_value); use INT64_MIN as sentinel for NULL
+    std::vector<std::pair<int64_t, int64_t>>
+        results;  // (left_value, right_value); use INT64_MIN as sentinel for NULL
     Tuple tuple;
     while (join->next(tuple)) {
         int64_t left_val = tuple.get(0).is_null() ? INT64_MIN : tuple.get(0).to_int64();
@@ -991,11 +992,11 @@ TEST_F(OperatorTests, HashJoinNullKeys) {
     Schema left_schema = make_schema({{"id", common::ValueType::TYPE_INT64}});
     std::vector<Tuple> left_data;
     left_data.push_back(make_tuple({common::Value::make_int64(1)}));  // matches 1
-    left_data.push_back(make_tuple({common::Value()}));                        // NULL - currently matches NULL
+    left_data.push_back(make_tuple({common::Value()}));  // NULL - currently matches NULL
 
     Schema right_schema = make_schema({{"id", common::ValueType::TYPE_INT64}});
     std::vector<Tuple> right_data;
-    right_data.push_back(make_tuple({common::Value()}));                        // NULL - currently matches
+    right_data.push_back(make_tuple({common::Value()}));               // NULL - currently matches
     right_data.push_back(make_tuple({common::Value::make_int64(1)}));  // matches 1
 
     auto left_scan = make_buffer_scan("left_table", left_data, left_schema);

tests/rpc_client_tests.cpp

@@ -0,0 +1,229 @@
+/**
+ * @file rpc_client_tests.cpp
+ * @brief Unit tests for RpcClient - internal RPC client for node-to-node communication
+ */
+
+#include <gtest/gtest.h>
+
+#include <atomic>
+#include <csignal>
+#include <cstdint>
+#include <cstring>
+#include <memory>
+#include <thread>
+#include <vector>
+
+#include "network/rpc_client.hpp"
+#include "network/rpc_message.hpp"
+#include "network/rpc_server.hpp"
+
+using namespace cloudsql::network;
+
+namespace {
+
+// Ignore SIGPIPE to prevent crashes when writing to closed sockets
+struct SigpipeGuard {
+    SigpipeGuard() { std::signal(SIGPIPE, SIG_IGN); }
+};
+SigpipeGuard g_sigpipe;
+
+class RpcClientTests : public ::testing::Test {
+   protected:
+    void SetUp() override {
+        port_ = TEST_PORT_BASE_ + next_port_++;
+        server_ = std::make_unique<RpcServer>(port_);
+        handler_called_ = false;
+    }
+
+    void TearDown() override {
+        if (server_) {
+            server_->stop();
+        }
+        std::this_thread::sleep_for(std::chrono::milliseconds(10));
+    }
+
+    static constexpr uint16_t TEST_PORT_BASE_ = 6400;
+    static std::atomic<uint16_t> next_port_;
+    uint16_t port_;
+    std::unique_ptr<RpcServer> server_;
+    std::atomic<bool> handler_called_{false};
+};
+
+std::atomic<uint16_t> RpcClientTests::next_port_{0};
+
+TEST_F(RpcClientTests, ConnectAndDisconnect) {
+    server_->start();
+
+    RpcClient client("127.0.0.1", port_);
+    EXPECT_TRUE(client.connect());
+    EXPECT_TRUE(client.is_connected());
+
+    client.disconnect();
+    EXPECT_FALSE(client.is_connected());
+}
+
+TEST_F(RpcClientTests, ConnectRefused) {
+    // No server started - connection should fail
+    RpcClient client("127.0.0.1", port_);
+    EXPECT_FALSE(client.connect());
+    EXPECT_FALSE(client.is_connected());
+}
+
+TEST_F(RpcClientTests, ConnectInvalidAddress) {
+    // Use an address that nothing is listening on
+    RpcClient client("127.0.0.1", port_);
+    // Port not in use, but connection refused happens at TCP level
+    EXPECT_FALSE(client.connect());
+}
+
+TEST_F(RpcClientTests, CallAfterServerStop) {
+    server_->start();
+
+    // Set a handler that responds immediately
+    server_->set_handler(RpcType::Heartbeat,
+                         [](const RpcHeader&, const std::vector<uint8_t>&, int fd) {
+                             RpcHeader resp_h;
+                             resp_h.type = RpcType::Heartbeat;
+                             resp_h.payload_len = 0;
+                             char h_buf[RpcHeader::HEADER_SIZE];
+                             resp_h.encode(h_buf);
+                             send(fd, h_buf, RpcHeader::HEADER_SIZE, 0);
+                         });
+
+    RpcClient client("127.0.0.1", port_);
+    ASSERT_TRUE(client.connect());
+    ASSERT_TRUE(client.is_connected());
+
+    // Stop the server
+    server_->stop();
+    std::this_thread::sleep_for(std::chrono::milliseconds(50));
+
+    // Call after server stop should fail (connection refused/reset)
+    // Note: is_connected() returns true because it only checks if fd_ >= 0,
+    // not whether the server is still connected
+    std::vector<uint8_t> response;
+    EXPECT_FALSE(client.call(RpcType::Heartbeat, {}, response, 0));
+}
+
+TEST_F(RpcClientTests, FullRoundTrip) {
+    server_->start();
+
+    server_->set_handler(RpcType::QueryResults,
+                         [](const RpcHeader& h, const std::vector<uint8_t>& p, int fd) {
+                             // Echo back the payload
+                             RpcHeader resp_h;
+                             resp_h.type = RpcType::QueryResults;
+                             resp_h.payload_len = static_cast<uint16_t>(p.size());
+                             char h_buf[RpcHeader::HEADER_SIZE];
+                             resp_h.encode(h_buf);
+                             send(fd, h_buf, RpcHeader::HEADER_SIZE, 0);
+                             if (!p.empty()) {
+                                 send(fd, p.data(), p.size(), 0);
+                             }
+                         });
+
+    RpcClient client("127.0.0.1", port_);
+    ASSERT_TRUE(client.connect());
+
+    std::vector<uint8_t> payload = {1, 2, 3, 4, 5};
+    std::vector<uint8_t> response;
+    ASSERT_TRUE(client.call(RpcType::QueryResults, payload, response, 0));
+
+    EXPECT_EQ(response.size(), 5U);
+    EXPECT_EQ(response[0], 1);
+    EXPECT_EQ(response[4], 5);
+}
+
+TEST_F(RpcClientTests, ConcurrentCalls) {
+    server_->start();
+
+    std::atomic<int> call_count{0};
+    server_->set_handler(RpcType::QueryResults,
+                         [&](const RpcHeader& h, const std::vector<uint8_t>& p, int fd) {
+                             call_count++;
+                             RpcHeader resp_h;
+                             resp_h.type = RpcType::QueryResults;
+                             resp_h.payload_len = static_cast<uint16_t>(p.size());
+                             char h_buf[RpcHeader::HEADER_SIZE];
+                             resp_h.encode(h_buf);
+                             send(fd, h_buf, RpcHeader::HEADER_SIZE, 0);
+                             if (!p.empty()) {
+                                 send(fd, p.data(), p.size(), 0);
+                             }
+                         });
+
+    RpcClient client("127.0.0.1", port_);
+    ASSERT_TRUE(client.connect());
+
+    // Make 5 concurrent calls - RpcClient is single-threaded so they serialize
+    for (int i = 0; i < 5; i++) {
+        std::vector<uint8_t> payload = {static_cast<uint8_t>(i)};
+        std::vector<uint8_t> response;
+        ASSERT_TRUE(client.call(RpcType::QueryResults, payload, response, 0));
+        EXPECT_EQ(response.size(), 1U);
+        EXPECT_EQ(response[0], static_cast<uint8_t>(i));
+    }
+
+    EXPECT_EQ(call_count, 5);
+}
+
+TEST_F(RpcClientTests, ReconnectAfterServerRestart) {
+    // Use a different port to avoid conflicts with other tests
+    constexpr uint16_t reconnect_port = TEST_PORT_BASE_ + 100;
+    auto reconnect_server = std::make_unique<RpcServer>(reconnect_port);
+    reconnect_server->start();
+
+    server_->set_handler(RpcType::QueryResults,
+                         [](const RpcHeader& h, const std::vector<uint8_t>& p, int fd) {
+                             RpcHeader resp_h;
+                             resp_h.type = RpcType::QueryResults;
+                             resp_h.payload_len = static_cast<uint16_t>(p.size());
+                             char h_buf[RpcHeader::HEADER_SIZE];
+                             resp_h.encode(h_buf);
+                             send(fd, h_buf, RpcHeader::HEADER_SIZE, 0);
+                             if (!p.empty()) {
+                                 send(fd, p.data(), p.size(), 0);
+                             }
+                         });
+
+    RpcClient client("127.0.0.1", reconnect_port);
+    ASSERT_TRUE(client.connect());
+
+    std::vector<uint8_t> response;
+    ASSERT_TRUE(client.call(RpcType::QueryResults, {}, response, 0));
+
+    // Stop server
+    reconnect_server->stop();
+    std::this_thread::sleep_for(std::chrono::milliseconds(50));
+
+    // Start server again on same port
+    reconnect_server = std::make_unique<RpcServer>(reconnect_port);
+    reconnect_server->start();
+
+    // Reconnect
+    ASSERT_TRUE(client.connect());
+    ASSERT_TRUE(client.is_connected());
+    ASSERT_TRUE(client.call(RpcType::QueryResults, {}, response, 0));
+
+    reconnect_server->stop();
+}
+
+TEST_F(RpcClientTests, SendOnlyWithoutResponse) {
+    server_->start();
+
+    std::atomic<int> call_count{0};
+    server_->set_handler(RpcType::Heartbeat, [&](const RpcHeader& h, const std::vector<uint8_t>& p,
+                                                 int fd) { call_count++; });
+
+    RpcClient client("127.0.0.1", port_);
+    ASSERT_TRUE(client.connect());
+
+    // send_only doesn't wait for response
+    ASSERT_TRUE(client.send_only(RpcType::Heartbeat, {}, 0));
+
+    // Give server time to process
+    std::this_thread::sleep_for(std::chrono::milliseconds(50));
+    EXPECT_EQ(call_count, 1);
+}
+
+}  // namespace