From 5617bed5257506d3dfda8537b16f44b3e40f1b42 Mon Sep 17 00:00:00 2001
From: "Douglas B. Rumbaugh" <doug@douglasrumbaugh.com>
Date: Sun, 22 Dec 2024 13:00:19 -0500
Subject: Began overhauling reconstruction mechanism

---
 include/framework/reconstruction/BSMPolicy.h | 83 ++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 include/framework/reconstruction/BSMPolicy.h

(limited to 'include/framework/reconstruction/BSMPolicy.h')

diff --git a/include/framework/reconstruction/BSMPolicy.h b/include/framework/reconstruction/BSMPolicy.h
new file mode 100644
index 0000000..9138bd1
--- /dev/null
+++ b/include/framework/reconstruction/BSMPolicy.h
@@ -0,0 +1,83 @@
+/*
+ * include/framework/reconstruction/LevelingPolicy.h
+ *
+ * Copyright (C) 2023-2024 Douglas B. Rumbaugh <drumbaugh@psu.edu>
+ *                         Dong Xie <dongx@psu.edu>
+ *
+ * Distributed under the Modified BSD License.
+ *
+ */
+#pragma once
+#include <cmath>
+
+#include "framework/reconstruction/ReconstructionPolicy.h"
+#include "framework/scheduling/Epoch.h"
+#include "util/types.h"
+
+namespace de {
+template <ShardInterface ShardType, QueryInterface<ShardType> QueryType>
+class BSMPolicy : ReconstructionPolicy<ShardType, QueryType> {
+  typedef std::vector<std::shared_ptr<InternalLevel<ShardType, QueryType>>>
+      LevelVector;
+
+public:
+  BSMPolicy(size_t scale_factor, size_t buffer_size)
+      : m_scale_factor(scale_factor), m_buffer_size(buffer_size) {}
+
+  ReconstructionVector
+  get_reconstruction_tasks(Epoch<ShardType, QueryType> *epoch,
+                           size_t incoming_reccnt) override {
+    ReconstructionVector reconstructions;
+    auto levels = epoch->get_structure()->get_level_vector();
+
+    level_index target_level = find_reconstruction_target(levels);
+    assert(target_level != -1);
+    level_index source_level = 0;
+
+    if (target_level == invalid_level_idx) {
+      /* grow */
+      target_level = levels.size();
+    }
+
+    ReconstructionTask task;
+    task.target = target_level;
+    task.type = ReconstructionType::Merge;
+
+    for (level_index i = target_level; i > source_level; i--) {
+      if (i < levels.size()) {
+        task.add_shard({i, all_shards_idx}, levels[i]->get_record_count());
+      }
+    }
+
+    reconstructions.add_reconstruction(task);
+    return reconstructions;
+  }
+
+  ReconstructionTask
+  get_flush_task(Epoch<ShardType, QueryType> *epoch) override {
+    return ReconstructionTask{
+        {{buffer_shid}}, 0, m_buffer_size, ReconstructionType::Flush};
+  }
+
+private:
+  level_index find_reconstruction_target(LevelVector &levels) {
+    level_index target_level = 0;
+
+    for (size_t i = 0; i < (level_index)levels.size(); i++) {
+      if (levels[i].get_record_count() + 1 <= capacity(i)) {
+        target_level = i;
+        break;
+      }
+    }
+
+    return target_level;
+  }
+
+  inline size_t capacity(level_index level) {
+    return m_buffer_size * pow(m_scale_factor, level + 1);
+  }
+
+  size_t m_scale_factor;
+  size_t m_buffer_size;
+};
+} // namespace de
-- 
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