From 711769574e647839677739192698e400529efe75 Mon Sep 17 00:00:00 2001
From: Douglas Rumbaugh <dbr4@psu.edu>
Date: Thu, 8 Feb 2024 16:38:44 -0500
Subject: Updated VPTree to new shard/query interfaces

---
 include/query/knn.h | 159 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 159 insertions(+)
 create mode 100644 include/query/knn.h

(limited to 'include/query/knn.h')

diff --git a/include/query/knn.h b/include/query/knn.h
new file mode 100644
index 0000000..19dcf5c
--- /dev/null
+++ b/include/query/knn.h
@@ -0,0 +1,159 @@
+/*
+ * include/query/knn.h
+ *
+ * Copyright (C) 2023 Douglas B. Rumbaugh <drumbaugh@psu.edu>
+ *
+ * Distributed under the Modified BSD License.
+ *
+ * A query class for k-NN queries, designed for use with the VPTree
+ * shard. 
+ *
+ * FIXME: no support for tombstone deletes just yet. This would require a
+ * query resumption mechanism, most likely.
+ */
+#pragma once
+
+#include "framework/QueryRequirements.h"
+#include "psu-ds/PriorityQueue.h"
+
+namespace de { namespace knn {
+
+using psudb::PriorityQueue;
+
+template <NDRecordInterface R>
+struct Parms {
+    R point;
+    size_t k;
+};
+
+template <NDRecordInterface R>
+struct State {
+    size_t k;
+};
+
+template <NDRecordInterface R>
+struct BufferState {
+    BufferView<R> *buffer;
+
+    BufferState(BufferView<R> *buffer) 
+        : buffer(buffer) {}
+};
+
+template <NDRecordInterface R, ShardInterface<R> S>
+class Query {
+public:
+    constexpr static bool EARLY_ABORT=false;
+    constexpr static bool SKIP_DELETE_FILTER=true;
+
+    static void *get_query_state(S *shard, void *parms) {
+        return nullptr;
+    }
+
+    static void* get_buffer_query_state(BufferView<R> *buffer, void *parms) {
+        return new BufferState<R>(buffer);
+    }
+
+    static void process_query_states(void *query_parms, std::vector<void*> &shard_states, void* buffer_state) {
+        return;
+    }
+
+    static std::vector<Wrapped<R>> query(S *shard, void *q_state, void *parms) {
+        std::vector<Wrapped<R>> results;
+        Parms<R> *p = (Parms<R> *) parms;
+        Wrapped<R> wrec;
+        wrec.rec = p->point;
+        wrec.header = 0;
+
+        PriorityQueue<Wrapped<R>, DistCmpMax<Wrapped<R>>> pq(p->k, &wrec);
+
+        shard->search(p->point, p->k, pq);
+
+        while (pq.size() > 0) {
+            results.emplace_back(*pq.peek().data);
+            pq.pop();
+        }
+
+        return results;
+    }
+
+    static std::vector<Wrapped<R>> buffer_query(void *state, void *parms) {
+        Parms<R> *p = (Parms<R> *) parms;
+        BufferState<R> *s = (BufferState<R> *) state;
+        Wrapped<R> wrec;
+        wrec.rec = p->point;
+        wrec.header = 0;
+
+        size_t k = p->k;
+
+        PriorityQueue<Wrapped<R>, DistCmpMax<Wrapped<R>>> pq(k, &wrec);
+        for (size_t i=0; i<s->buffer->get_record_count(); i++) {
+            // Skip over deleted records (under tagging)
+            if (s->buffer->get(i)->is_deleted()) {
+                continue;
+            }
+
+            if (pq.size() < k) {
+                pq.push(s->buffer->get(i));
+            } else {
+                double head_dist = pq.peek().data->rec.calc_distance(wrec.rec);
+                double cur_dist = (s->buffer->get(i))->rec.calc_distance(wrec.rec);
+
+                if (cur_dist < head_dist) {
+                    pq.pop();
+                    pq.push(s->buffer->get(i));
+                }
+            }
+        }
+
+        std::vector<Wrapped<R>> results;
+        while (pq.size() > 0) {
+            results.emplace_back(*(pq.peek().data));
+            pq.pop();
+        }
+
+        return results;
+    }
+
+    static std::vector<R> merge(std::vector<std::vector<Wrapped<R>>> &results, void *parms) {
+        Parms<R> *p = (Parms<R> *) parms;
+        R rec = p->point;
+        size_t k = p->k;
+
+        PriorityQueue<R, DistCmpMax<R>> pq(k, &rec);
+        for (size_t i=0; i<results.size(); i++) {
+            for (size_t j=0; j<results[i].size(); j++) {
+                if (pq.size() < k) {
+                    pq.push(&results[i][j].rec);
+                } else {
+                    double head_dist = pq.peek().data->calc_distance(rec);
+                    double cur_dist = results[i][j].rec.calc_distance(rec);
+
+                    if (cur_dist < head_dist) {
+                        pq.pop();
+                        pq.push(&results[i][j].rec);
+                    }
+                }
+            }
+        }
+
+        std::vector<R> output;
+        while (pq.size() > 0) {
+            output.emplace_back(*pq.peek().data);
+            pq.pop();
+        }
+
+        return output;
+    }
+
+    static void delete_query_state(void *state) {
+        auto s = (State<R> *) state;
+        delete s;
+    }
+
+    static void delete_buffer_query_state(void *state) {
+        auto s = (BufferState<R> *) state;
+        delete s;
+    }
+};
+
+}}
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