From c1b91c8f5f644b614277732b90d2059e2b29d52a Mon Sep 17 00:00:00 2001
From: "Adam C. Emerson" <aemerson@redhat.com>
Date: Tue, 27 Dec 2016 21:26:25 -0500
Subject: [PATCH] denc: Support boost::optional

Signed-off-by: Adam C. Emerson <aemerson@redhat.com>
---
 src/include/denc.h      | 101 ++++++++++++++++++++++++++++++++++++++++
 src/test/CMakeLists.txt |   1 +
 src/test/test_denc.cc   |  38 +++++++++++++++
 3 files changed, 140 insertions(+)

diff --git a/src/include/denc.h b/src/include/denc.h
index 29adc2e2970f1d..01eddd7e48b2fd 100644
--- a/src/include/denc.h
+++ b/src/include/denc.h
@@ -35,6 +35,7 @@
 #include <boost/container/flat_map.hpp>
 #include <boost/container/flat_set.hpp>
 #include <boost/intrusive/set.hpp>
+#include <boost/optional.hpp>
 
 #include "include/intarith.h"
 #include "include/int_types.h"
@@ -231,6 +232,7 @@ WRITE_INT_DENC(uint32_t, __le32);
 WRITE_INT_DENC(int32_t, __le32);
 WRITE_INT_DENC(uint64_t, __le64);
 WRITE_INT_DENC(int64_t, __le64);
+WRITE_INT_DENC(bool, uint8_t);
 
 
 // varint
@@ -1134,6 +1136,105 @@ struct denc_traits<
   }
 };
 
+//
+// boost::optional<T>
+//
+template<typename T>
+struct denc_traits<
+  boost::optional<T>,
+  typename std::enable_if<denc_traits<T>::supported != 0>::type> {
+  using traits = denc_traits<T>;
+
+  enum { supported = true };
+  enum { featured = traits::featured };
+  enum { bounded = false };
+
+  template<typename U = T>
+  static typename std::enable_if<sizeof(U) && !featured>::type
+  bound_encode(const boost::optional<T>& v, size_t& p) {
+    denc(*(bool *)nullptr, p);
+    if (v)
+      denc(*v, p);
+  }
+  template<typename U = T>
+  static typename std::enable_if<sizeof(U) && featured>::type
+  bound_encode(const boost::optional<T>& v, size_t& p, uint64_t f) {
+    denc(*(bool *)nullptr, p);
+    if (v)
+      denc(*v, p);
+  }
+
+  template<typename U = T>
+  static typename std::enable_if<sizeof(U) && !featured>::type
+  encode(const boost::optional<T>& v, bufferlist::contiguous_appender& p) {
+    denc((bool)v, p);
+    if (v)
+      denc(*v, p);
+  }
+  template<typename U = T>
+  static typename std::enable_if<sizeof(U) && featured>::type
+  encode(const boost::optional<T>& v, bufferlist::contiguous_appender& p,
+	 uint64_t f) {
+    denc((bool)v, p, f);
+    if (v)
+      denc(*v, p, f);
+  }
+
+  static void decode(boost::optional<T>& v, buffer::ptr::iterator& p,
+		     uint64_t f = 0) {
+    bool x;
+    denc(x, p, f);
+    if (x) {
+      v = T{};
+      denc(*v, p, f);
+    } else {
+      v = boost::none;
+    }
+  }
+
+  template<typename U = T>
+  static typename std::enable_if<sizeof(U) && !featured>::type
+  encode_nohead(const boost::optional<T>& v,
+		bufferlist::contiguous_appender& p) {
+    if (v)
+      denc(*v, p);
+  }
+  template<typename U = T>
+  static typename std::enable_if<sizeof(U) && featured>::type
+  encode_nohead(const boost::optional<T>& v,
+		bufferlist::contiguous_appender& p,
+		uint64_t f) {
+    if (v)
+      denc(*v, p, f);
+  }
+
+  static void decode_nohead(bool num, boost::optional<T>& v,
+			    buffer::ptr::iterator& p, uint64_t f = 0) {
+    if (num) {
+      v = T();
+      denc(*v, p, f);
+    } else {
+      v = boost::none;
+    }
+  }
+};
+
+template<>
+struct denc_traits<boost::none_t> {
+  enum { supported = true };
+  enum { featured = false };
+  enum { bounded = true };
+
+  static void bound_encode(const boost::none_t& v, size_t& p) {
+    denc(*(bool *)nullptr, p);
+  }
+
+  static void encode(const boost::none_t& v,
+		     bufferlist::contiguous_appender& p) {
+    denc(false, p);
+  }
+};
+
 // ----------------------------------------------------------------------
 // class helpers
 
diff --git a/src/test/CMakeLists.txt b/src/test/CMakeLists.txt
index a5719da30206ae..4e1ab2482c39f5 100644
--- a/src/test/CMakeLists.txt
+++ b/src/test/CMakeLists.txt
@@ -878,6 +878,7 @@ target_link_libraries(unittest_subprocess global)
 # unittest_pageset
 add_executable(unittest_pageset test_pageset.cc)
 add_ceph_unittest(unittest_pageset ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/unittest_pageset)
+target_link_libraries(unittest_pageset global)
 
 #make check ends here
 
diff --git a/src/test/test_denc.cc b/src/test/test_denc.cc
index 83edd9191023f4..152088146bf7bd 100644
--- a/src/test/test_denc.cc
+++ b/src/test/test_denc.cc
@@ -539,3 +539,41 @@ TEST(denc, tuple)
     test_denc(s);
   }
 }
+
+TEST(denc, optional)
+{
+  {
+    cout << "boost::optional<uint64_t>" << std::endl;
+    boost::optional<uint64_t> s = 97, t = boost::none;
+    counts.reset();
+    test_denc(s);
+    test_denc(t);
+  }
+  {
+    cout << "boost::optional<std::string>" << std::endl;
+    boost::optional<std::string> s = std::string("Meow"), t = boost::none;
+    counts.reset();
+    test_denc(s);
+    test_denc(t);
+  }
+  {
+    size_t s = 0;
+    denc(boost::none, s);
+    ASSERT_NE(s, 0u);
+
+    // encode
+    bufferlist bl;
+    {
+      auto a = bl.get_contiguous_appender(s);
+      denc(boost::none, a);
+    }
+    ASSERT_LE(bl.length(), s);
+
+    bl.rebuild();
+    boost::optional<uint32_t> out = 5;
+    auto bpi = bl.front().begin();
+    denc(out, bpi);
+    ASSERT_FALSE(!!out);
+    ASSERT_EQ(bpi.get_pos(), bl.c_str() + bl.length());
+  }
+}