Adding classes, functions, and utilities for common LMDB operations.

1 files changed, 74 insertions, 0 deletions

diff --git a/src/lmdb/value_stream.cpp b/src/lmdb/value_stream.cpp
new file mode 100644
index 000000000..1024deb06
--- /dev/null
+++ b/src/lmdb/value_stream.cpp
@@ -0,0 +1,74 @@
+// Copyright (c) 2018, The Monero Project
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#include "value_stream.h"
+
+#include <stdexcept>
+
+#include "common/expect.h"
+#include "lmdb/error.h"
+#include "lmdb/util.h"
+
+namespace lmdb
+{
+    namespace stream
+    {
+        std::size_t count(MDB_cursor* cur)
+        {
+            std::size_t out = 0;
+            if (cur)
+            {
+                const int rc = mdb_cursor_count(cur, &out);
+                if (rc)
+                    MONERO_THROW(lmdb::error(rc), "mdb_cursor_count");
+            }
+            return out;
+        }
+
+        std::pair<epee::span<const std::uint8_t>, epee::span<const std::uint8_t>>
+        get(MDB_cursor& cur, MDB_cursor_op op, std::size_t key, std::size_t value)
+        {
+            MDB_val key_bytes{};
+            MDB_val value_bytes{};
+            const int rc = mdb_cursor_get(&cur, &key_bytes, &value_bytes, op);
+            if (rc)
+            {
+                if (rc == MDB_NOTFOUND)
+                    return {};
+                MONERO_THROW(lmdb::error(rc), "mdb_cursor_get");
+            }
+
+            if (key && key != key_bytes.mv_size)
+                MONERO_THROW(lmdb::error(MDB_BAD_VALSIZE), "mdb_cursor_get key");
+
+            if (value && (value_bytes.mv_size % value != 0 || value_bytes.mv_size == 0))
+                MONERO_THROW(lmdb::error(MDB_BAD_VALSIZE), "mdb_cursor_get value");
+
+            return {lmdb::to_byte_span(key_bytes), lmdb::to_byte_span(value_bytes)};
+        }
+    }
+}
+