[Feat] Implementation of BufferManager and KvProtocol.

## Purpose
Implement BufferManager for slot-based memory management with IndexPool,
and unify SQE packing/CQE unpacking into a single KvProtocol abstraction
with comprehensive request validation and full integration testing.

## Modifications
1. Add BufferManager with IndexPool-based slot allocation, supporting
   HOST (malloc), HOST_PINNED (aclrtMallocHost + aclrtHostRegister),
   and ASCEND_DEVICE (aclrtMalloc) memory types via AscendBuffer.
2. Unify Sqe/Cqe into KvProtocol base class with PackSqe/UnpackCqe
   interfaces, replacing separate SqeManager and CqeManager.
3. Add ValidateRequest to check Request fields before packing, including
   bit-field overflow, alignment, key length, and batch number validation
   with actual values in error messages and [[unlikely]] hints.
4. Add ProtocolManager to manage send_buffer and flag_buffer instances,
   with PackRequest, UnpackResponse, and PollResponseCid interfaces.
5. Use protocol-specific max batch numbers per SSU spec: BatchStore/
   BatchRetrieve=110, Delete=254, Exist=256.
6. Rename link_proto to link_protocol for naming consistency.
7. Remove old sqe.h/cpp files, replaced by kv_protocol.h/cpp.
8. Move ScatterGatherEntry from types.h to buffer_manager.h.

## Test
BufferManagerTest (19 cases), KvProtocolPackTest (38 cases), and
ProtocolManagerTest (13 integration cases) all passed. Total: 70 tests.

Author: yumingyue624

ucm/transport/kv/asu/CMakeLists.txt

@@ -10,6 +10,11 @@ target_include_directories(asu_transport
 )
 target_link_libraries(asu_transport PUBLIC infra_logger pthread)
 
+if(RUNTIME_ENVIRONMENT STREQUAL "ascend")
+    target_compile_definitions(asu_transport PRIVATE ASCEND_ENABLED)
+    target_link_libraries(asu_transport PRIVATE trans)
+endif()
+
 file(GLOB ASU_CLIENT_SOURCES CONFIGURE_DEPENDS client/src/*.cpp)
 add_library(asu_client SHARED ${ASU_CLIENT_SOURCES})
 target_include_directories(asu_client

ucm/transport/kv/asu/test/case/buffer_manager_test.cc

@@ -0,0 +1,330 @@
+/**
+ * MIT License
+ *
+ * Copyright (c) 2026 Huawei Technologies Co., Ltd. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ * */
+#include "buffer_manager.h"
+#include <cstring>
+#include <gtest/gtest.h>
+#include <thread>
+#include <vector>
+
+namespace UC::ASU {
+namespace {
+
+class BufferManagerTest : public ::testing::Test {
+protected:
+    void SetUp() override {}
+    void TearDown() override {}
+};
+
+TEST_F(BufferManagerTest, InitAndDestroy)
+{
+    BufferManager mgr;
+    auto status = mgr.Init("test_buffer", MemoryType::HOST, 1024, 100);
+    ASSERT_TRUE(status.ok()) << status.message;
+}
+
+TEST_F(BufferManagerTest, InitWithZeroSlotSize)
+{
+    BufferManager mgr;
+    auto status = mgr.Init("test_buffer", MemoryType::HOST, 0, 100);
+    ASSERT_FALSE(status.ok());
+    ASSERT_EQ(status.code, StatusCode::INVALID_ARGUMENT);
+}
+
+TEST_F(BufferManagerTest, InitWithZeroSlotNum)
+{
+    BufferManager mgr;
+    auto status = mgr.Init("test_buffer", MemoryType::HOST, 1024, 0);
+    ASSERT_FALSE(status.ok());
+    ASSERT_EQ(status.code, StatusCode::INVALID_ARGUMENT);
+}
+
+TEST_F(BufferManagerTest, DoubleInit)
+{
+    BufferManager mgr;
+    auto status = mgr.Init("test_buffer", MemoryType::HOST, 1024, 100);
+    ASSERT_TRUE(status.ok());
+    status = mgr.Init("test_buffer", MemoryType::HOST, 1024, 100);
+    ASSERT_FALSE(status.ok());
+    ASSERT_EQ(status.code, StatusCode::INVALID_ARGUMENT);
+}
+
+TEST_F(BufferManagerTest, AllocateWithoutInit)
+{
+    BufferManager mgr;
+    ScatterGatherEntry sge;
+    auto status = mgr.Allocate(64, sge);
+    ASSERT_FALSE(status.ok());
+    ASSERT_EQ(status.code, StatusCode::NOT_INITIALIZED);
+}
+
+TEST_F(BufferManagerTest, AllocateZeroSize)
+{
+    BufferManager mgr;
+    auto status = mgr.Init("test_buffer", MemoryType::HOST, 1024, 100);
+    ASSERT_TRUE(status.ok());
+
+    ScatterGatherEntry sge;
+    status = mgr.Allocate(0, sge);
+    ASSERT_FALSE(status.ok());
+    ASSERT_EQ(status.code, StatusCode::INVALID_ARGUMENT);
+}
+
+TEST_F(BufferManagerTest, AllocateExceedsSlotSize)
+{
+    BufferManager mgr;
+    auto status = mgr.Init("test_buffer", MemoryType::HOST, 1024, 100);
+    ASSERT_TRUE(status.ok());
+
+    ScatterGatherEntry sge;
+    status = mgr.Allocate(2048, sge);
+    ASSERT_FALSE(status.ok());
+    ASSERT_EQ(status.code, StatusCode::INVALID_ARGUMENT);
+}
+
+TEST_F(BufferManagerTest, SingleAllocateAndFree)
+{
+    BufferManager mgr;
+    auto status = mgr.Init("test_buffer", MemoryType::HOST, 1024, 100);
+    ASSERT_TRUE(status.ok());
+
+    ScatterGatherEntry sge;
+    status = mgr.Allocate(64, sge);
+    ASSERT_TRUE(status.ok()) << status.message;
+    ASSERT_NE(sge.addr, 0);
+    ASSERT_EQ(sge.length, 64);
+    ASSERT_EQ(sge.lkey, 0);
+
+    auto* ptr = reinterpret_cast<void*>(sge.addr);
+    std::memset(ptr, 0xAB, 64);
+
+    status = mgr.Free(ptr);
+    ASSERT_TRUE(status.ok()) << status.message;
+}
+
+TEST_F(BufferManagerTest, MultipleAllocatesAndFrees)
+{
+    BufferManager mgr;
+    auto status = mgr.Init("test_buffer", MemoryType::HOST, 1024, 100);
+    ASSERT_TRUE(status.ok());
+
+    constexpr int kCount = 50;
+    std::vector<ScatterGatherEntry> sges(kCount);
+
+    for (int i = 0; i < kCount; ++i) {
+        status = mgr.Allocate(128, sges[i]);
+        ASSERT_TRUE(status.ok()) << "Failed at i=" << i << ": " << status.message;
+        ASSERT_NE(sges[i].addr, 0);
+        std::memset(reinterpret_cast<void*>(sges[i].addr), i, 128);
+    }
+
+    for (int i = 0; i < kCount; ++i) {
+        auto* data = reinterpret_cast<unsigned char*>(sges[i].addr);
+        for (int j = 0; j < 128; ++j) {
+            ASSERT_EQ(data[j], static_cast<unsigned char>(i));
+        }
+    }
+
+    for (int i = 0; i < kCount; ++i) {
+        status = mgr.Free(reinterpret_cast<void*>(sges[i].addr));
+        ASSERT_TRUE(status.ok()) << status.message;
+    }
+}
+
+TEST_F(BufferManagerTest, FreeNullPointer)
+{
+    BufferManager mgr;
+    auto status = mgr.Init("test_buffer", MemoryType::HOST, 1024, 100);
+    ASSERT_TRUE(status.ok());
+
+    status = mgr.Free(nullptr);
+    ASSERT_FALSE(status.ok());
+    ASSERT_EQ(status.code, StatusCode::INVALID_ARGUMENT);
+}
+
+TEST_F(BufferManagerTest, FreeWithoutInit)
+{
+    BufferManager mgr;
+    int dummy = 0;
+    auto status = mgr.Free(&dummy);
+    ASSERT_FALSE(status.ok());
+    ASSERT_EQ(status.code, StatusCode::NOT_INITIALIZED);
+}
+
+TEST_F(BufferManagerTest, FreeOutOfRangePointer)
+{
+    BufferManager mgr;
+    auto status = mgr.Init("test_buffer", MemoryType::HOST, 1024, 100);
+    ASSERT_TRUE(status.ok());
+
+    int dummy = 0;
+    status = mgr.Free(&dummy);
+    ASSERT_FALSE(status.ok());
+    ASSERT_EQ(status.code, StatusCode::INVALID_ARGUMENT);
+}
+
+TEST_F(BufferManagerTest, FreeUnalignedPointer)
+{
+    BufferManager mgr;
+    auto status = mgr.Init("test_buffer", MemoryType::HOST, 1024, 100);
+    ASSERT_TRUE(status.ok());
+
+    ScatterGatherEntry sge;
+    status = mgr.Allocate(64, sge);
+    ASSERT_TRUE(status.ok());
+
+    auto* ptr = reinterpret_cast<char*>(sge.addr) + 1;
+    status = mgr.Free(ptr);
+    ASSERT_FALSE(status.ok());
+    ASSERT_EQ(status.code, StatusCode::INVALID_ARGUMENT);
+
+    mgr.Free(reinterpret_cast<void*>(sge.addr));
+}
+
+TEST_F(BufferManagerTest, AllocateFullSlotSize)
+{
+    BufferManager mgr;
+    auto status = mgr.Init("test_buffer", MemoryType::HOST, 1024, 10);
+    ASSERT_TRUE(status.ok());
+
+    ScatterGatherEntry sge;
+    status = mgr.Allocate(1024, sge);
+    ASSERT_TRUE(status.ok()) << status.message;
+    ASSERT_EQ(sge.length, 1024);
+
+    std::memset(reinterpret_cast<void*>(sge.addr), 0xFF, 1024);
+
+    mgr.Free(reinterpret_cast<void*>(sge.addr));
+}
+
+TEST_F(BufferManagerTest, ReuseAfterFree)
+{
+    BufferManager mgr;
+    auto status = mgr.Init("test_buffer", MemoryType::HOST, 1024, 1);
+    ASSERT_TRUE(status.ok());
+
+    ScatterGatherEntry sge1;
+    status = mgr.Allocate(64, sge1);
+    ASSERT_TRUE(status.ok());
+
+    auto* ptr = reinterpret_cast<void*>(sge1.addr);
+    mgr.Free(ptr);
+
+    ScatterGatherEntry sge2;
+    status = mgr.Allocate(64, sge2);
+    ASSERT_TRUE(status.ok());
+    ASSERT_EQ(sge2.addr, sge1.addr);
+
+    mgr.Free(reinterpret_cast<void*>(sge2.addr));
+}
+
+TEST_F(BufferManagerTest, ConcurrentAllocateAndFree)
+{
+    BufferManager mgr;
+    auto status = mgr.Init("test_buffer", MemoryType::HOST, 1024, 100);
+    ASSERT_TRUE(status.ok());
+
+    constexpr int kThreadCount = 4;
+    constexpr int kOpsPerThread = 500;
+
+    auto worker = [&mgr](int thread_id) {
+        for (int i = 0; i < kOpsPerThread; ++i) {
+            ScatterGatherEntry sge;
+            auto s = mgr.Allocate(64, sge);
+            ASSERT_TRUE(s.ok()) << "Thread " << thread_id << " op " << i << ": " << s.message;
+
+            std::memset(reinterpret_cast<void*>(sge.addr), thread_id, 64);
+
+            s = mgr.Free(reinterpret_cast<void*>(sge.addr));
+            ASSERT_TRUE(s.ok()) << s.message;
+        }
+    };
+
+    std::vector<std::thread> threads;
+    for (int i = 0; i < kThreadCount; ++i) { threads.emplace_back(worker, i); }
+    for (auto& t : threads) { t.join(); }
+}
+
+TEST_F(BufferManagerTest, ConcurrentStressTest)
+{
+    BufferManager mgr;
+    auto status = mgr.Init("test_buffer", MemoryType::HOST, 256, 16);
+    ASSERT_TRUE(status.ok());
+
+    constexpr int kThreadCount = 4;
+    constexpr int kOpsPerThread = 1000;
+
+    auto worker = [&mgr](int thread_id) {
+        for (int i = 0; i < kOpsPerThread; ++i) {
+            ScatterGatherEntry sge;
+            auto s = mgr.Allocate(128, sge);
+            ASSERT_TRUE(s.ok());
+
+            std::memset(reinterpret_cast<void*>(sge.addr), thread_id, 128);
+
+            for (int j = 0; j < 128; ++j) {
+                ASSERT_EQ(reinterpret_cast<unsigned char*>(sge.addr)[j], thread_id);
+            }
+
+            s = mgr.Free(reinterpret_cast<void*>(sge.addr));
+            ASSERT_TRUE(s.ok());
+        }
+    };
+
+    std::vector<std::thread> threads;
+    for (int i = 0; i < kThreadCount; ++i) { threads.emplace_back(worker, i); }
+    for (auto& t : threads) { t.join(); }
+}
+
+TEST_F(BufferManagerTest, AllocateZeroedReturnsZeroedMemory)
+{
+    BufferManager mgr;
+    auto status = mgr.Init("test", MemoryType::HOST, 1024, 10);
+    ASSERT_TRUE(status.ok());
+
+    ScatterGatherEntry sge;
+    status = mgr.AllocateZeroed(512, sge);
+    ASSERT_TRUE(status.ok());
+
+    auto* ptr = reinterpret_cast<uint8_t*>(sge.addr);
+    for (size_t i = 0; i < 1024; ++i) {
+        ASSERT_EQ(ptr[i], 0) << "byte " << i << " not zeroed";
+    }
+
+    mgr.Free(reinterpret_cast<void*>(sge.addr));
+}
+
+TEST_F(BufferManagerTest, AllocateZeroedRejectsZeroSize)
+{
+    BufferManager mgr;
+    auto status = mgr.Init("test", MemoryType::HOST, 1024, 10);
+    ASSERT_TRUE(status.ok());
+
+    ScatterGatherEntry sge;
+    status = mgr.AllocateZeroed(0, sge);
+    ASSERT_FALSE(status.ok());
+    ASSERT_EQ(status.code, StatusCode::INVALID_ARGUMENT);
+}
+
+}  // namespace
+}  // namespace UC::ASU