Add byte_stream for zero-copy serialization, and add support in ZMQ-JSON.

1 files changed, 93 insertions, 0 deletions

diff --git a/contrib/epee/src/byte_stream.cpp b/contrib/epee/src/byte_stream.cpp
new file mode 100644
index 000000000..e87d9f0bc
--- /dev/null
+++ b/contrib/epee/src/byte_stream.cpp
@@ -0,0 +1,93 @@
+// Copyright (c) 2020, 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 "byte_stream.h"
+
+#include <algorithm>
+#include <limits>
+#include <utility>
+
+#include <iostream>
+
+namespace epee
+{
+  void byte_stream::overflow(const std::size_t requested)
+  {
+    // Recalculating `need` bytes removes at least one instruction from every
+    // inlined `put` call in header
+
+    assert(available() < requested);
+    const std::size_t need = requested - available();
+
+    const std::size_t len = size();
+    const std::size_t cap = capacity();
+    const std::size_t increase = std::max(need, increase_size());
+
+    next_write_ = nullptr;
+    end_ = nullptr;
+
+    buffer_ = byte_buffer_increase(std::move(buffer_), cap, increase);
+    if (!buffer_)
+      throw std::bad_alloc{};
+
+    next_write_ = buffer_.get() + len;
+    end_ = buffer_.get() + cap + increase;
+  }
+
+  byte_stream::byte_stream(byte_stream&& rhs) noexcept
+    : buffer_(std::move(rhs.buffer_)),
+      next_write_(rhs.next_write_),
+      end_(rhs.end_),
+      increase_size_(rhs.increase_size_)
+  {
+    rhs.next_write_ = nullptr;
+    rhs.end_ = nullptr;
+  }
+
+  byte_stream& byte_stream::operator=(byte_stream&& rhs) noexcept
+  {
+    if (this != std::addressof(rhs))
+    {
+      buffer_ = std::move(rhs.buffer_);
+      next_write_ = rhs.next_write_;
+      end_ = rhs.end_;
+      increase_size_ = rhs.increase_size_;
+      rhs.next_write_ = nullptr;
+      rhs.end_ = nullptr;
+    }
+    return *this;
+  }
+
+  byte_buffer byte_stream::take_buffer() noexcept
+  {
+    byte_buffer out{std::move(buffer_)};
+    next_write_ = nullptr;
+    end_ = nullptr;
+    return out;
+  }
+}