Add block_storage default storage

bench/bench.cpp

@@ -114,7 +114,11 @@ public:
         int repeat) const override
     {
         while(repeat--)
-            json::parse(s);
+        {
+            auto sp = json::make_storage<
+                json::block_storage>();
+            json::parse(s, sp);
+        }
     }
 
     void

include/boost/json.hpp

@@ -14,6 +14,7 @@
 #include <boost/json/assign_string.hpp>
 #include <boost/json/assign_vector.hpp>
 #include <boost/json/basic_parser.hpp>
+#include <boost/json/block_storage.hpp>
 #include <boost/json/error.hpp>
 #include <boost/json/fixed_storage.hpp>
 #include <boost/json/ieee_decimal.hpp>

include/boost/json/block_storage.hpp

@@ -0,0 +1,141 @@
+//
+// Copyright (c) 2018-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// Official repository: https://github.com/vinniefalco/json
+//
+
+#ifndef BOOST_JSON_BLOCK_STORAGE_HPP
+#define BOOST_JSON_BLOCK_STORAGE_HPP
+
+#include <boost/json/detail/config.hpp>
+#include <boost/json/detail/assert.hpp>
+#include <boost/json/storage.hpp>
+#include <cstddef>
+#include <memory>
+#include <stdexcept>
+
+namespace boost {
+namespace json {
+
+/** A storage which uses a multiple fixed size blocks
+*/
+class block_storage : public storage
+{
+    struct block
+    {
+        std::size_t const size;
+        std::size_t used;
+        block* next;
+
+        char*
+        begin() noexcept
+        {
+            return reinterpret_cast<
+                char*>(this+1);
+        }
+
+        char*
+        end() noexcept
+        {
+            return begin() + size;
+        }
+    };
+
+    std::size_t const block_size_;
+    std::size_t refs_ = 0;
+    block* head_ = nullptr;
+
+public:
+    ~block_storage()
+    {
+        std::allocator<block> a;
+        auto b = head_;
+        while(b)
+        {
+            auto next = b->next;
+            a.deallocate(b,
+                sizeof(*b) + b->size);
+            b = next;
+        }
+    }
+
+    explicit
+    block_storage(
+        std::size_t block_size = 256 * 1024)
+        : block_size_(block_size)
+    {
+    }
+
+private:
+    block&
+    alloc_block(std::size_t size)
+    {
+        std::allocator<block> a;
+        auto const n = (
+            size + sizeof(block) - 1) /
+            sizeof(block);
+        auto& b = *::new(
+            a.allocate(n + 1)) block{
+                n * sizeof(block),
+                0,
+                head_};
+        head_ = &b;
+        return b;
+    }
+
+    void*
+    do_allocate(
+        std::size_t n,
+        std::size_t align) override
+    {
+        (void)align;
+        // must be power of 2
+        BOOST_JSON_ASSERT(
+            (align & (align - 1)) == 0);
+        // cannot exceed max alignment
+        BOOST_JSON_ASSERT(
+            align <= sizeof(std::max_align_t));
+        auto const needed =
+            [&]
+            {
+                if(n < block_size_)
+                    return block_size_;
+                return n + sizeof(block);
+            };
+        if(head_)
+        {
+            auto const avail =
+                head_->size - head_->used;
+            if(avail < n)
+                alloc_block(needed());
+        }
+        else
+        {
+            alloc_block(needed());
+        }
+        ++refs_;
+        auto p =
+            head_->begin() + head_->used;
+        head_->used += n;
+        return p;
+    }
+
+    void
+    do_deallocate(
+        void*,
+        std::size_t,
+        std::size_t) noexcept override
+    {
+        if(--refs_ > 0)
+            return;
+        //clear();
+    }
+};
+
+} // json
+} // boost
+
+#endif

include/boost/json/fixed_storage.hpp

@@ -11,7 +11,10 @@
 #define BOOST_JSON_FIXED_STORAGE_HPP
 
 #include <boost/json/detail/config.hpp>
+#include <boost/json/detail/assert.hpp>
 #include <boost/json/storage.hpp>
+#include <cstddef>
+#include <memory>
 #include <stdexcept>
 
 namespace boost {
@@ -21,22 +24,32 @@ namespace json {
 */
 class fixed_storage : public storage
 {
-    char* const base_;
     std::size_t const size_;
+    char* const base_;
     std::size_t used_ = 0;
     std::size_t refs_ = 0;
 
 public:
     ~fixed_storage()
     {
-        delete[] base_;
+        std::allocator<
+            char>{}.deallocate(base_, size_);
     }
 
     explicit
     fixed_storage(
         std::size_t bytes)
-        : base_(new char[bytes])
-        , size_(bytes)
+        : size_(
+            [bytes]
+            {
+                auto const align =
+                    sizeof(std::max_align_t) - 1;
+                if(bytes & align)
+                    return bytes | align;
+                return bytes;
+            }())
+        , base_(std::allocator<
+            char>{}.allocate(size_))
     {
     }
 
@@ -46,6 +59,7 @@ protected:
         std::size_t n,
         std::size_t align) override
     {
+        (void)align;
         // must be power of 2
         BOOST_JSON_ASSERT(
             (align & (align - 1)) == 0);

include/boost/json/impl/parser.ipp

@@ -12,6 +12,7 @@
 
 #include <boost/json/parser.hpp>
 #include <boost/json/error.hpp>
+#include <boost/json/block_storage.hpp>
 #include <boost/json/detail/assert.hpp>
 #include <stdexcept>
 #include <utility>
@@ -54,6 +55,8 @@ parser::
 
 parser::
 parser()
+    : jv_(make_storage<
+        block_storage>())
 {
 }
 

include/boost/json/parser.hpp

@@ -14,7 +14,6 @@
 #include <boost/json/basic_parser.hpp>
 #include <boost/json/storage.hpp>
 #include <boost/json/value.hpp>
-#include <boost/json/storage.hpp>
 #include <boost/json/detail/string.hpp>
 #include <new>
 #include <string>

test/CMakeLists.txt

@@ -34,7 +34,9 @@ add_executable (json-tests
     assign_string.cpp
     assign_vector.cpp
     basic_parser.cpp
+    block_storage.cpp
     error.cpp
+    fixed_storage.cpp
     ieee_decimal.cpp
     json.cpp
     kind.cpp

test/Jamfile

@@ -30,7 +30,9 @@ local SOURCES =
     assign_string.cpp
     assign_vector.cpp
     basic_parser.cpp
+    block_storage.cpp
     error.cpp
+    fixed_storage.cpp
     ieee_decimal.cpp
     json.cpp
     kind.cpp

test/block_storage.cpp

@@ -0,0 +1,31 @@
+//
+// Copyright (c) 2018-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// Official repository: https://github.com/vinniefalco/json
+//
+
+// Test that header file is self-contained.
+#include <boost/json/block_storage.hpp>
+
+#include <boost/beast/_experimental/unit_test/suite.hpp>
+
+namespace boost {
+namespace json {
+
+class block_storage_test : public beast::unit_test::suite
+{
+public:
+    void run() override
+    {
+        make_storage<block_storage>();
+        pass();
+    }
+};
+
+BEAST_DEFINE_TESTSUITE(boost,json,block_storage);
+
+} // json
+} // boost

test/fixed_storage.cpp

@@ -0,0 +1,31 @@
+//
+// Copyright (c) 2018-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// Official repository: https://github.com/vinniefalco/json
+//
+
+// Test that header file is self-contained.
+#include <boost/json/fixed_storage.hpp>
+
+#include <boost/beast/_experimental/unit_test/suite.hpp>
+
+namespace boost {
+namespace json {
+
+class fixed_storage_test : public beast::unit_test::suite
+{
+public:
+    void run() override
+    {
+        make_storage<fixed_storage>(65536);
+        pass();
+    }
+};
+
+BEAST_DEFINE_TESTSUITE(boost,json,fixed_storage);
+
+} // json
+} // boost