Write with parallel

cpp/CMakeLists.txt

@@ -150,6 +150,13 @@ if (ENABLE_ZLIB)
     add_definitions(-DENABLE_GZIP)
 endif()
 
+option(ENABLE_THREADS "Enable multi-threaded read/write (requires pthreads)" ON)
+message("cmake using: ENABLE_THREADS=${ENABLE_THREADS}")
+
+if (ENABLE_THREADS)
+    add_definitions(-DENABLE_THREADS)
+endif()
+
 option(ENABLE_SIMDE "Enable SIMDe (SIMD Everywhere)" OFF)
 message("cmake using: ENABLE_SIMDE=${ENABLE_SIMDE}")
 

cpp/src/common/config/config.h

@@ -46,6 +46,8 @@ typedef struct ConfigValue {
     TSEncoding double_encoding_type_;
     TSEncoding string_encoding_type_;
     CompressionType default_compression_type_;
+    bool parallel_write_enabled_;
+    int32_t write_thread_count_;
     // When true, aligned writer enforces page size limit strictly by
     // interleaving time/value writes and sealing pages together when any side
     // becomes full.

cpp/src/common/global.cc

@@ -54,12 +54,15 @@ void init_config_value() {
     g_config_value_.int64_encoding_type_ = TS_2DIFF;
     g_config_value_.float_encoding_type_ = GORILLA;
     g_config_value_.double_encoding_type_ = GORILLA;
+    g_config_value_.string_encoding_type_ = PLAIN;
     // Default compression type is LZ4
 #ifdef ENABLE_LZ4
     g_config_value_.default_compression_type_ = LZ4;
 #else
     g_config_value_.default_compression_type_ = UNCOMPRESSED;
 #endif
+    g_config_value_.parallel_write_enabled_ = true;
+    g_config_value_.write_thread_count_ = 6;
     // Enforce aligned page size limits strictly by default.
     g_config_value_.strict_page_size_ = true;
 }

cpp/src/common/global.h

@@ -163,6 +163,20 @@ FORCE_INLINE uint8_t get_global_compression() {
     return static_cast<uint8_t>(g_config_value_.default_compression_type_);
 }
 
+FORCE_INLINE void set_parallel_write_enabled(bool enabled) {
+    g_config_value_.parallel_write_enabled_ = enabled;
+}
+
+FORCE_INLINE bool get_parallel_write_enabled() {
+    return g_config_value_.parallel_write_enabled_;
+}
+
+FORCE_INLINE int set_write_thread_count(int32_t count) {
+    if (count < 1 || count > 64) return E_INVALID_ARG;
+    g_config_value_.write_thread_count_ = count;
+    return E_OK;
+}
+
 extern int init_common();
 extern bool is_timestamp_column_name(const char* time_col_name);
 extern void cols_to_json(ByteStream* byte_stream,

cpp/src/common/tablet.h

@@ -46,6 +46,7 @@ class TabletColIterator;
  * with their associated metadata such as column names and types.
  */
 class Tablet {
+   public:
     // Arrow-style string column: offsets + contiguous buffer.
     // string[i] = buffer + offsets[i], len = offsets[i+1] - offsets[i]
     struct StringColumn {
@@ -235,6 +236,12 @@ class Tablet {
     }
     size_t get_column_count() const { return schema_vec_->size(); }
     uint32_t get_cur_row_size() const { return cur_row_size_; }
+    int64_t get_timestamp(uint32_t row_index) const {
+        return timestamps_[row_index];
+    }
+    bool is_null(uint32_t row_index, uint32_t col_index) const {
+        return bitmaps_[col_index].test(row_index);
+    }
 
     /**
      * @brief Adds a timestamp to the specified row.

cpp/src/common/thread_pool.h

@@ -0,0 +1,122 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 COMMON_THREAD_POOL_H
+#define COMMON_THREAD_POOL_H
+
+#ifdef ENABLE_THREADS
+
+#include <condition_variable>
+#include <functional>
+#include <future>
+#include <mutex>
+#include <queue>
+#include <thread>
+#include <vector>
+
+namespace common {
+
+// Unified fixed-size thread pool supporting both fire-and-forget tasks
+// (submit void + wait_all) and future-returning tasks (submit<F>).
+// Used by both write path (column-parallel encoding) and read path
+// (column-parallel decoding).
+class ThreadPool {
+   public:
+    explicit ThreadPool(size_t num_threads) : stop_(false), active_(0) {
+        for (size_t i = 0; i < num_threads; i++) {
+            workers_.emplace_back([this] { worker_loop(); });
+        }
+    }
+
+    ~ThreadPool() {
+        {
+            std::lock_guard<std::mutex> lk(mu_);
+            stop_ = true;
+        }
+        cv_work_.notify_all();
+        for (auto& w : workers_) {
+            if (w.joinable()) w.join();
+        }
+    }
+
+    // Submit a fire-and-forget task (no return value).
+    void submit(std::function<void()> task) {
+        {
+            std::lock_guard<std::mutex> lk(mu_);
+            tasks_.push(std::move(task));
+            active_++;
+        }
+        cv_work_.notify_one();
+    }
+
+    // Submit a task that returns a value via std::future.
+    template <typename F>
+    std::future<typename std::result_of<F()>::type> submit(F&& f) {
+        using RetType = typename std::result_of<F()>::type;
+        auto task =
+            std::make_shared<std::packaged_task<RetType()>>(std::forward<F>(f));
+        std::future<RetType> result = task->get_future();
+        {
+            std::lock_guard<std::mutex> lk(mu_);
+            tasks_.emplace([task]() { (*task)(); });
+            active_++;
+        }
+        cv_work_.notify_one();
+        return result;
+    }
+
+    // Block until all submitted tasks have completed.
+    void wait_all() {
+        std::unique_lock<std::mutex> lk(mu_);
+        cv_done_.wait(lk, [this] { return active_ == 0 && tasks_.empty(); });
+    }
+
+   private:
+    void worker_loop() {
+        while (true) {
+            std::function<void()> task;
+            {
+                std::unique_lock<std::mutex> lk(mu_);
+                cv_work_.wait(lk, [this] { return stop_ || !tasks_.empty(); });
+                if (stop_ && tasks_.empty()) return;
+                task = std::move(tasks_.front());
+                tasks_.pop();
+            }
+            task();
+            {
+                std::lock_guard<std::mutex> lk(mu_);
+                active_--;
+            }
+            cv_done_.notify_one();
+        }
+    }
+
+    std::vector<std::thread> workers_;
+    std::queue<std::function<void()>> tasks_;
+    std::mutex mu_;
+    std::condition_variable cv_work_;
+    std::condition_variable cv_done_;
+    bool stop_;
+    int active_;
+};
+
+}  // namespace common
+
+#endif  // ENABLE_THREADS
+
+#endif  // COMMON_THREAD_POOL_H