feat(append): add append-only writer, compact task and coordinator (#112)

Author: lucasfang

include/paimon/append/append_compact_coordinator.h

@@ -0,0 +1,65 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <map>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "paimon/result.h"
+
+namespace paimon {
+
+class CommitMessage;
+class FileSystem;
+class MemoryPool;
+
+/// Compact coordinator for append-only unaware-bucket tables.
+///
+/// This coordinator scans the latest snapshot for small files, groups them by partition,
+/// and generates compaction tasks using a bin-packing algorithm. It then synchronously
+/// executes all tasks and returns the resulting commit messages.
+///
+/// @note This implementation does not support deletion vectors or streaming mode.
+///       It only scans the current latest snapshot (batch mode).
+class PAIMON_EXPORT AppendCompactCoordinator {
+ public:
+    AppendCompactCoordinator() = delete;
+    ~AppendCompactCoordinator() = delete;
+    /// Run the compaction coordinator.
+    ///
+    /// Scans the latest snapshot for small files across the specified partitions,
+    /// generates compact tasks via bin-packing, executes them synchronously,
+    /// and returns the resulting commit messages.
+    ///
+    /// @param table_path The root path of the table.
+    /// @param options User-defined options (will be merged with schema options).
+    /// @param partitions Partition filters; each element is a partition spec as key-value pairs.
+    ///                   Empty vector means all partitions.
+    /// @param file_system The file system to use. If nullptr, will be created from options.
+    /// @param pool The memory pool to use. If nullptr, will use default pool.
+    /// @return Result containing a vector of commit messages from compaction tasks.
+    static Result<std::vector<std::shared_ptr<CommitMessage>>> Run(
+        const std::string& table_path, const std::map<std::string, std::string>& options,
+        const std::vector<std::map<std::string, std::string>>& partitions,
+        const std::shared_ptr<FileSystem>& file_system, const std::shared_ptr<MemoryPool>& pool);
+};
+
+}  // namespace paimon