fix(memdb): expire semantics + Boost 1.83 portability + backlog & test harness

- expire 改为 update+refresh_ttl：键不存在返回 false，与 del/update 约定一致
- _require_string 适配 Boost 1.83（boost::json::string 已非 std::string）
- 新增 --backlog（默认 128，libmsg 默认 10 短连接突刺易丢连接）
- Makefile 补 HOST/PORT 默认值，test-memdb 用 PID 文件替代失效的 kill %1
- 补测试：复制构造/源销毁后副本有效/refresh 延长 TTL/expire 不存在键

memdb/.gitignore

@@ -69,4 +69,7 @@ Testing/
 .cache/
 
 # Databases
-*.db*
+*.db*
+# unit test binary
+test_libmemdb
+.memdb.pid

memdb/Makefile

@@ -8,6 +8,9 @@ BUILD    = build
 TARGET   = $(BUILD)/memdb
 SRC      = src/memdb.cpp
 
+HOST    ?= 127.0.0.1
+PORT    ?= 8011
+
 all: $(TARGET)
 
 $(BUILD):
@@ -37,13 +40,12 @@ test-libmemdb: $(TEST_LIBMEMDB)
 
 test-memdb: $(TARGET)
 	@echo "Starting memdb server..."
-	./$(TARGET) --host $(HOST) --port $(PORT) --workers 2 --max-time 10 &
+	@./$(TARGET) --host $(HOST) --port $(PORT) --workers 2 --max-time 10 >/dev/null 2>&1 & echo $$! > .memdb.pid
 	@sleep 1
-	-python3 test_memdb.py $(HOST) $(PORT); EXIT=$$?
-	@kill %1 2>/dev/null; wait %1 2>/dev/null
-	@exit $$EXIT
+	@python3 test_memdb.py $(HOST) $(PORT); EXIT=$$?; \
+	kill $$(cat .memdb.pid) 2>/dev/null; rm -f .memdb.pid; exit $$EXIT
 
 clean:
-	rm -f $(TARGET) $(TEST_LIBMEMDB)
+	rm -f $(TARGET) $(TEST_LIBMEMDB) .memdb.pid
 
 .PHONY: all clean test test-libmemdb test-memdb

memdb/README.md

@@ -21,7 +21,7 @@ Memdb<std::string, std::string>        (libmemdb 模板：LRU 链表 + 哈希索
 | `update` | `key`, `value`, `refresh_ttl?` | `true/false` | 更新值，可选刷新 TTL |
 | `exists` | `key` | `true/false` | 键是否存在 |
 | `size` | — | `int` | 当前条目数 |
-| `expire` | `key`, `value` | `true/false` | 更新值并重置 TTL（del + set） |
+| `expire` | `key`, `value` | `true/false` | 更新已有键的值并重置 TTL（键不存在返回 false） |
 | `show` | — | `[{key,value},...]` | 导出所有条目 |
 
 ## 配置
@@ -34,6 +34,7 @@ Memdb<std::string, std::string>        (libmemdb 模板：LRU 链表 + 哈希索
 | `listen_port` | `8011` | 监听端口 |
 | `workers` | `4` | 线程池大小 |
 | `max_time` | `600` | 默认 TTL（秒），10 分钟 |
+| `backlog` | `128` | listen() backlog（libmsg 默认 10，短连接突刺易丢连接） |
 
 ## 构建与运行
 

memdb/src/memdb.cpp

@@ -20,6 +20,7 @@ struct ServerConfig {
     int         listen_port = 8011;
     int         workers     = 4;
     int         max_time    = 600;   // 默认 TTL 10 分钟
+    int         backlog     = 128;   // 短连接并发突刺时防丢连接（libmsg 默认仅 10）
 };
 
 static std::atomic<bool> g_running{true};
@@ -35,7 +36,7 @@ private:
     pmc::net::RpcServer __rpc;
     std::mutex __mtx;
 
-    static const std::string& _require_string(const json::object& req, const std::string& field) {
+    static std::string _require_string(const json::object& req, const std::string& field) {
         auto it = req.find(field);
         if (it == req.end()) {
             throw std::runtime_error("missing required field: " + field);
@@ -43,7 +44,8 @@ private:
         if (!it->value().is_string()) {
             throw std::runtime_error("field '" + field + "' must be a string");
         }
-        return it->value().as_string();
+        const auto& s = it->value().as_string();
+        return std::string(s.data(), s.size());
     }
 
 public:
@@ -51,7 +53,7 @@ public:
         : __cfg(cfg)
         , __db(cfg.max_time)
         , __rpc(cfg.listen_host, cfg.listen_port,
-                {.workers = cfg.workers})
+                {.workers = cfg.workers, .listen_backlog = cfg.backlog})
     {
         _register_routes();
     }
@@ -130,13 +132,12 @@ private:
             return result;
         });
 
-        // ---- expire: 更新值并重置 TTL（等价于 del + set）----
+        // ---- expire: 更新值并重置 TTL（仅已有键；等价于 update + refresh_ttl）----
         __rpc.add_route("expire", [this](const json::object& req) -> json::value {
             const auto& key = _require_string(req, "key");
             const auto& val = _require_string(req, "value");
             std::lock_guard<std::mutex> lock(__mtx);
-            __db.remove(key);
-            return __db.insert(key, val);
+            return __db.update(key, val, true);
         });
     }
 };
@@ -156,7 +157,8 @@ int main(int argc, char** argv) {
         ("host",      po::value<std::string>()->default_value("127.0.0.1"), "listen host")
         ("port",      po::value<int>()->default_value(8011), "listen port")
         ("workers",   po::value<int>()->default_value(4),    "worker threads")
-        ("max-time",  po::value<int>()->default_value(600),  "default TTL (seconds)");
+        ("max-time",  po::value<int>()->default_value(600),  "default TTL (seconds)")
+        ("backlog",   po::value<int>()->default_value(128),  "listen() backlog");
 
     po::variables_map vm;
     po::store(po::parse_command_line(argc, argv, desc), vm);
@@ -171,6 +173,7 @@ int main(int argc, char** argv) {
     cfg.listen_port = vm["port"].as<int>();
     cfg.workers     = vm["workers"].as<int>();
     cfg.max_time    = vm["max-time"].as<int>();
+    cfg.backlog     = vm["backlog"].as<int>();
 
     auto instance  = vm["instance"].as<std::string>();
     auto log_level = vm["log-level"].as<std::string>();

memdb/test_libmemdb.cpp

@@ -10,6 +10,7 @@
 #include <cassert>
 #include <chrono>
 #include <iostream>
+#include <optional>
 #include <string>
 #include <thread>
 #include <vector>
@@ -266,19 +267,57 @@ static void test_get_time_touch() {
     PASS();
 }
 
-// ── copy assignment ─────────────────────────────────────────────────────
+// ── copy semantics ──────────────────────────────────────────────────────
 
 static void test_copy_assignment() {
     TEST("copy assignment");
-    Memdb<std::string, std::string> db1;
-    db1.insert("a", "1");
     Memdb<std::string, std::string> db2;
-    db2 = db1;
-    CHECK(db2.search("a").value() == "1", "copied db should have same data");
-    // verify independence
-    db2.insert("b", "2");
-    CHECK(db1.size() == 1, "original should be unchanged");
-    CHECK(db2.size() == 2, "copy should be independent");
+    {
+        Memdb<std::string, std::string> db1;
+        db1.insert("a", "1");
+        db2 = db1;
+        CHECK(db2.search("a").value() == "1", "copied db should have same data");
+        // verify independence
+        db2.insert("b", "2");
+        CHECK(db1.size() == 1, "original should be unchanged");
+        CHECK(db2.size() == 2, "copy should be independent");
+    }
+    // db1 destroyed — db2 must still work (indices must not dangle)
+    CHECK(db2.search("a").value() == "1", "copy must survive source destruction");
+    CHECK(db2.remove("a"), "copy remove should work after source destroyed");
+    CHECK(db2.size() == 1, "copy size after remove");
+    PASS();
+}
+
+static void test_copy_constructor() {
+    TEST("copy constructor");
+    std::optional<Memdb<std::string, std::string>> cpy;
+    {
+        Memdb<std::string, std::string> src;
+        src.insert("a", "1");
+        src.insert("b", "2");
+        cpy.emplace(src);  // copy constructor
+        CHECK(cpy->size() == 2, "copy should have 2 entries");
+        CHECK(src.size() == 2, "source unchanged");
+    }
+    CHECK(cpy->search("a").value() == "1", "copy value a after source destroyed");
+    CHECK(cpy->search("b").value() == "2", "copy value b after source destroyed");
+    cpy->remove("a");
+    CHECK(cpy->size() == 1, "copy mutation after source destroyed");
+    // flush on copy must not touch freed memory
+    CHECK(cpy->search("b").value() == "2", "flush path safe on copy");
+    PASS();
+}
+
+static void test_update_refresh_extends_ttl() {
+    TEST("update with refresh extends TTL");
+    Memdb<std::string, std::string> db(1);
+    db.insert("a", "1");
+    std::this_thread::sleep_for(std::chrono::milliseconds(700));
+    CHECK(db.update("a", "2", true), "update with refresh should succeed");
+    std::this_thread::sleep_for(std::chrono::milliseconds(600));
+    CHECK(db.search("a").value() == "2",
+          "entry alive past original TTL thanks to refresh");
     PASS();
 }
 
@@ -344,6 +383,8 @@ int main() {
     test_get_keys();
     test_get_time_touch();
     test_copy_assignment();
+    test_copy_constructor();
+    test_update_refresh_extends_ttl();
     test_large_number_of_keys();
     test_reinsert_after_remove();
     test_update_without_refresh_keeps_old_ttl();

memdb/test_memdb.py

@@ -197,6 +197,12 @@ def test_expire(c, cnt):
     ok, data = c.call("get", key="test:exp")
     cnt.check(ok and data == "new", "value after expire", f"got {data}")
 
+    ok, data = c.call("expire", key="test:exp:nonexistent", value="x")
+    cnt.check(ok and data is False, "expire nonexistent key returns false", f"got {data}")
+
+    ok, data = c.call("get", key="test:exp:nonexistent")
+    cnt.check(ok and data is None, "expire nonexistent does not insert", f"got {data}")
+
 
 def test_missing_params(c, cnt):
     ok, data = c.call("set", key="only_key")