From c00d5fb305abff370f869dec0e9404f8a4a5646b Mon Sep 17 00:00:00 2001
From: Christian Mollekopf <chrigi_1@fastmail.fm>
Date: Tue, 7 Apr 2015 12:50:07 +0200
Subject: Use memcpy to copy tables into vectors.

Ideally we wouldn't be copying at all, and somehow cast the table to a vector.
Unfortunately I haven't figured out how to do that, and this solution at least
gets us from 0.065 ms to 0.028 ms in testCreateCommand.
---
 common/entitybuffer.cpp | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

(limited to 'common/entitybuffer.cpp')

diff --git a/common/entitybuffer.cpp b/common/entitybuffer.cpp
index 5ba4afe..b555ac3 100644
--- a/common/entitybuffer.cpp
+++ b/common/entitybuffer.cpp
@@ -56,17 +56,24 @@ void EntityBuffer::extractResourceBuffer(void *dataValue, int dataSize, const st
     }
 }
 
-void EntityBuffer::assembleEntityBuffer(flatbuffers::FlatBufferBuilder &fbb, void const *metadataData, size_t metadataSize, void const *resourceData, size_t resourceSize, void const *localData, size_t localSize)
+flatbuffers::Offset<flatbuffers::Vector<uint8_t> > EntityBuffer::appendAsVector(flatbuffers::FlatBufferBuilder &fbb, void const *data, size_t size)
 {
-    auto metadata = fbb.CreateVector<uint8_t>(static_cast<uint8_t const*>(metadataData), metadataSize);
-    auto resource = fbb.CreateVector<uint8_t>(static_cast<uint8_t const*>(resourceData), resourceSize);
-    auto local = fbb.CreateVector<uint8_t>(static_cast<uint8_t const*>(localData), localSize);
-    auto builder = Akonadi2::EntityBuilder(fbb);
-    builder.add_metadata(metadata);
-    builder.add_resource(resource);
-    builder.add_local(local);
+    //Since we do memcpy trickery, this will only work on little endian
+    assert(FLATBUFFERS_LITTLEENDIAN);
+    auto metadata = fbb.CreateUninitializedVector<uint8_t>(size);
+    {
+        auto ptr = reinterpret_cast<flatbuffers::Vector<uint8_t> *>(fbb.GetBufferPointer())->Data();
+        std::memcpy((void*)ptr, data, size);
+    }
+    return metadata;
+}
 
-    auto buffer = builder.Finish();
-    Akonadi2::FinishEntityBuffer(fbb, buffer);
+void EntityBuffer::assembleEntityBuffer(flatbuffers::FlatBufferBuilder &fbb, void const *metadataData, size_t metadataSize, void const *resourceData, size_t resourceSize, void const *localData, size_t localSize)
+{
+    auto metadata = appendAsVector(fbb, metadataData, metadataSize);
+    auto resource = appendAsVector(fbb, resourceData, resourceSize);
+    auto local = appendAsVector(fbb, localData, localSize);
+    auto entity = Akonadi2::CreateEntity(fbb, metadata, resource, local);
+    Akonadi2::FinishEntityBuffer(fbb, entity);
 }
 
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