From e78d41ca393820e5b611b78dfc8323399f7a7306 Mon Sep 17 00:00:00 2001
From: Tor Egge <Tor.Egge@online.no>
Date: Tue, 7 Mar 2023 12:33:13 +0100
Subject: Move portions of TensorBufferTypeMapper to ArrayStoreTypeMapper.

---
 .../src/vespa/vespalib/datastore/CMakeLists.txt    |  1 +
 .../vespalib/datastore/array_store_type_mapper.cpp | 41 ++++++++++++++++++++++
 .../vespalib/datastore/array_store_type_mapper.h   | 31 ++++++++++++++++
 3 files changed, 73 insertions(+)
 create mode 100644 vespalib/src/vespa/vespalib/datastore/array_store_type_mapper.cpp
 create mode 100644 vespalib/src/vespa/vespalib/datastore/array_store_type_mapper.h

(limited to 'vespalib')

diff --git a/vespalib/src/vespa/vespalib/datastore/CMakeLists.txt b/vespalib/src/vespa/vespalib/datastore/CMakeLists.txt
index f11004363f8..1c3b9112dda 100644
--- a/vespalib/src/vespa/vespalib/datastore/CMakeLists.txt
+++ b/vespalib/src/vespa/vespalib/datastore/CMakeLists.txt
@@ -3,6 +3,7 @@ vespa_add_library(vespalib_vespalib_datastore OBJECT
     SOURCES
     array_store.cpp
     array_store_config.cpp
+    array_store_type_mapper.cpp
     atomic_entry_ref.cpp
     buffer_free_list.cpp
     buffer_stats.cpp
diff --git a/vespalib/src/vespa/vespalib/datastore/array_store_type_mapper.cpp b/vespalib/src/vespa/vespalib/datastore/array_store_type_mapper.cpp
new file mode 100644
index 00000000000..ff514f5a00b
--- /dev/null
+++ b/vespalib/src/vespa/vespalib/datastore/array_store_type_mapper.cpp
@@ -0,0 +1,41 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#include "array_store_type_mapper.h"
+#include <algorithm>
+#include <cassert>
+
+namespace vespalib::datastore {
+
+ArrayStoreTypeMapper::ArrayStoreTypeMapper()
+    : _array_sizes()
+{
+}
+
+ArrayStoreTypeMapper::~ArrayStoreTypeMapper() = default;
+
+uint32_t
+ArrayStoreTypeMapper::get_type_id(size_t array_size) const
+{
+    assert(!_array_sizes.empty());
+    auto result = std::lower_bound(_array_sizes.begin() + 1, _array_sizes.end(), array_size);
+    if (result == _array_sizes.end()) {
+        return 0; // type id 0 uses buffer type for large arrays
+    }
+    return result - _array_sizes.begin();
+}
+
+size_t
+ArrayStoreTypeMapper::get_array_size(uint32_t type_id) const
+{
+    assert(type_id > 0 && type_id < _array_sizes.size());
+    return _array_sizes[type_id];
+}
+
+uint32_t
+ArrayStoreTypeMapper::get_max_small_array_type_id(uint32_t max_small_array_type_id) const noexcept
+{
+    auto clamp_type_id = _array_sizes.size() - 1;
+    return (clamp_type_id < max_small_array_type_id) ? clamp_type_id : max_small_array_type_id;
+}
+
+}
diff --git a/vespalib/src/vespa/vespalib/datastore/array_store_type_mapper.h b/vespalib/src/vespa/vespalib/datastore/array_store_type_mapper.h
new file mode 100644
index 00000000000..e707627de19
--- /dev/null
+++ b/vespalib/src/vespa/vespalib/datastore/array_store_type_mapper.h
@@ -0,0 +1,31 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#pragma once
+
+#include <cstddef>
+#include <cstdint>
+#include <vector>
+
+namespace vespalib::datastore {
+
+/*
+ * This class provides mapping between type ids and array sizes needed for
+ * storing a value with size smaller than or equal to the array size.
+ *
+ * The array sizes vector is a monotic increasing sequence that might end
+ * with exponential growth.
+ */
+class ArrayStoreTypeMapper
+{
+protected:
+    std::vector<size_t> _array_sizes;
+public:
+    ArrayStoreTypeMapper();
+    ~ArrayStoreTypeMapper();
+
+    uint32_t get_type_id(size_t array_size) const;
+    size_t get_array_size(uint32_t type_id) const;
+    uint32_t get_max_small_array_type_id(uint32_t max_small_array_type_id) const noexcept;
+};
+
+}
-- 
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