Interface update (#5)

* Query Interface Adjustments/Refactoring

Began the process of adjusting the query interface (and also the shard
interface, to a lesser degree) to better accommodate the user. In
particular the following changes have been made,

    1. The number of necessary template arguments for the query type
       has been drastically reduced, while also removing the void pointers
       and manual delete functions from the interface.

       This was accomplished by requiring many of the sub-types associated
       with a query (parameters, etc.) to be nested inside the main query
       class, and by forcing the SHARD type to expose its associated
       record type.

    2. User-defined query return types are now supported.

       Queries no longer are required to return strictly sets of records.
       Instead, the query now has LocalResultType and ResultType
       template parameters (which can be defaulted using a typedef in
       the Query type itself), allowing much more flexibility.

       Note that, at least for the short term, the LocalResultType must
       still expose the same is_deleted/is_tombstone interface as a
       Wrapped<R> used to, as this is currently needed for delete
       filtering. A better approach to this is, hopefully, forthcoming.

    3. Updated the ISAMTree.h shard and rangequery.h query to use the
       new interfaces, and adjusted the associated unit tests as well.

    4. Dropped the unnecessary "get_data()" function from the ShardInterface
       concept.

    5. Dropped the need to specify a record type in the ShardInterface
       concept. This is now handled using a required Shard::RECORD
       member of the Shard class itself, which should expose the name
       of the record type.

* Updates to framework to support new Query/Shard interfaces

Pretty extensive adjustments to the framework, particularly to the
templates themselves, along with some type-renaming work, to support
the new query and shard interfaces.

Adjusted the external query interface to take an rvalue reference, rather
than a pointer, to the query parameters.

* Removed framework-level delete filtering

This was causing some issues with the new query interface, and should
probably be reworked anyway, so I'm temporarily (TM) removing the
feature.

* Updated benchmarks + remaining code for new interface

1 files changed, 46 insertions, 43 deletions

diff --git a/include/util/Cursor.h b/include/util/Cursor.h
index e8ba53d..e7963b1 100644
--- a/include/util/Cursor.h
+++ b/include/util/Cursor.h
@@ -1,8 +1,8 @@
 /*
  * include/util/Cursor.h
  *
- * Copyright (C) 2023 Douglas B. Rumbaugh <drumbaugh@psu.edu> 
- *                    Dong Xie <dongx@psu.edu>
+ * Copyright (C) 2023-2024 Douglas B. Rumbaugh <drumbaugh@psu.edu>
+ *                         Dong Xie <dongx@psu.edu>
  *
  * Distributed under the Modified BSD License.
  *
@@ -21,16 +21,15 @@
 #include <vector>
 
 namespace de {
-template<typename R>
-struct Cursor {
-    R *ptr;
-    R *end;
-    size_t cur_rec_idx;
-    size_t rec_cnt;
+template <typename R> struct Cursor {
+  const R *ptr;
+  const R *end;
+  size_t cur_rec_idx;
+  size_t rec_cnt;
 
-    friend bool operator==(const Cursor &a, const Cursor &b) {
-        return a.ptr == b.ptr && a.end == b.end;
-    }
+  friend bool operator==(const Cursor &a, const Cursor &b) {
+    return a.ptr == b.ptr && a.end == b.end;
+  }
 };
 
 /*
@@ -43,51 +42,55 @@ struct Cursor {
  * be updated to be equal to end, and false will be returned. Iterators will
  * not be closed.
  */
-template<typename R>
-inline static bool advance_cursor(Cursor<R> &cur) {
-    cur.ptr++;
-    cur.cur_rec_idx++;
+template <typename R> inline static bool advance_cursor(Cursor<R> &cur) {
+  cur.ptr++;
+  cur.cur_rec_idx++;
 
-    if (cur.cur_rec_idx >= cur.rec_cnt) return false;
+  if (cur.cur_rec_idx >= cur.rec_cnt)
+    return false;
 
-    if (cur.ptr >= cur.end) {
-        return false;
-    }
-    return true;
+  if (cur.ptr >= cur.end) {
+    return false;
+  }
+  return true;
 }
 
 /*
  *   Process the list of cursors to return the cursor containing the next
  *   largest element. Does not advance any of the cursors. If current is
- *   specified, then skip the current head of that cursor during checking. 
- *   This allows for "peaking" at the next largest element after the current 
+ *   specified, then skip the current head of that cursor during checking.
+ *   This allows for "peaking" at the next largest element after the current
  *   largest is processed.
  */
 template <typename R>
-inline static Cursor<R> *get_next(std::vector<Cursor<R>> &cursors, Cursor<R> *current=nullptr) {
-    const R *min_rec = nullptr;
-    Cursor<R> *result = nullptr;
-    // FIXME: for large cursor vectors, it may be worth it to use a
-    //        PriorityQueue here instead of scanning.
-    for (size_t i=0; i< cursors.size(); i++) {
-        if (cursors[i] == (Cursor<R>) {0} ) continue;
-
-        const R *rec = (&cursors[i] == current) ? cursors[i].ptr + 1 : cursors[i].ptr;
-        if (rec >= cursors[i].end) continue;
+inline static Cursor<R> *get_next(std::vector<Cursor<R>> &cursors,
+                                  Cursor<R> *current = nullptr) {
+  const R *min_rec = nullptr;
+  Cursor<R> *result = nullptr;
+  // FIXME: for large cursor vectors, it may be worth it to use a
+  //        PriorityQueue here instead of scanning.
+  for (size_t i = 0; i < cursors.size(); i++) {
+    if (cursors[i] == (Cursor<R>){0})
+      continue;
 
-        if (min_rec == nullptr) {
-            result = &cursors[i];
-            min_rec = rec;
-            continue;
-        }
+    const R *rec =
+        (&cursors[i] == current) ? cursors[i].ptr + 1 : cursors[i].ptr;
+    if (rec >= cursors[i].end)
+      continue;
 
-        if (*rec < *min_rec) {
-            result = &cursors[i];
-            min_rec = rec;
-        }
+    if (min_rec == nullptr) {
+      result = &cursors[i];
+      min_rec = rec;
+      continue;
     }
 
-    return result;
-} 
+    if (*rec < *min_rec) {
+      result = &cursors[i];
+      min_rec = rec;
+    }
+  }
 
+  return result;
 }
+
+} // namespace de