From b03816bbb8947e365791bd69542979800ab35242 Mon Sep 17 00:00:00 2001
From: mrbald <mail@bobah.net>
Date: Tue, 17 Dec 2024 17:00:19 +0100
Subject: [PATCH] thread-unsafe memory type with seq-fit algorithm

---
 rtb/datacache/entity_cache.hpp |  8 ++++++-
 rtb/datacache/memory_types.hpp | 44 +++++++++++++++++++++++++++++++---
 2 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/rtb/datacache/entity_cache.hpp b/rtb/datacache/entity_cache.hpp
index f6229db..3eec15d 100644
--- a/rtb/datacache/entity_cache.hpp
+++ b/rtb/datacache/entity_cache.hpp
@@ -38,9 +38,11 @@
 #include "rtb/core/core.hpp"
 #include "rtb/common/concepts.hpp"
 
-#include <boost/throw_exception.hpp>
+#include <boost/chrono/duration.hpp>
 #include <boost/exception/info.hpp>
 #include <boost/stacktrace.hpp>
+#include <boost/thread/lock_options.hpp>
+#include <boost/throw_exception.hpp>
 #include <stdexcept>
 
 // Define an error_info tag for stacktrace
@@ -139,6 +141,10 @@ class entity_cache
         // TODO: add to ctor to switch between mmap and shm
         // TODO: maybe needs bip::scoped_lock to lock for other processes calling  grow_memory
         std::string data_base_dir = "/tmp/CACHE";
+
+        auto guard = bip::scoped_lock{_named_mutex, bip::defer_lock};
+        VAV_REQUIRE(guard.try_lock_for(boost::chrono::seconds(10)));
+
         _store_name = Memory::convert_base_dir(data_base_dir) + _cache_name;
         _segment_ptr.reset(Memory::open_or_create_segment(_store_name.c_str(), memory_size));
         _container_ptr = _segment_ptr->template find_or_construct<Container_t>(_cache_name.c_str())(
diff --git a/rtb/datacache/memory_types.hpp b/rtb/datacache/memory_types.hpp
index 8b62727..1dc133f 100644
--- a/rtb/datacache/memory_types.hpp
+++ b/rtb/datacache/memory_types.hpp
@@ -23,12 +23,50 @@
 #include <boost/interprocess/managed_mapped_file.hpp> //Variant-II , open(), mmap()
 #include <boost/interprocess/managed_heap_memory.hpp> // Variant III for heap
 #include <boost/interprocess/creation_tags.hpp>
-
+#include <boost/interprocess/mem_algo/simple_seq_fit.hpp>
 #include <boost/thread/locks.hpp>
 #include <boost/thread/shared_mutex.hpp>
 
 namespace mpclmi::ipc {
-   
+
+/** A variation of the Shared:
+ * - simpler memory allocation algorithm suitable for segments storing a single node-based cotainer
+ * - memory allocation is not thread safe, relying on external synchronization typical for entity_cache-based containers
+ */
+struct SharedVL {
+    using char_type = char;
+    using mutex_family_type = boost::interprocess::null_mutex_family;
+    using memory_algorithm_type = boost::interprocess::simple_seq_fit<mutex_family_type>;
+    template <typename T> using index_type = boost::interprocess::iset_index<T>;
+    using segment_t = boost::interprocess::basic_managed_shared_memory<char_type, memory_algorithm_type, index_type>;
+    using segment_manager_t = boost::interprocess::segment_manager<char, memory_algorithm_type, index_type>;
+
+    static segment_t * open_or_create_segment (const std::string &path, size_t size) {
+        return new segment_t(boost::interprocess::open_or_create, path.c_str(), size) ;
+    }
+    static segment_t * open_segment (const std::string &path) {
+        return new segment_t(boost::interprocess::open_only, path.c_str()) ;
+    }
+    static segment_t * create_segment (const std::string &path, size_t size) {
+        return new segment_t(boost::interprocess::create_only, path.c_str(), size) ;
+    }
+    template <typename MemPtr>
+    static void grow(MemPtr &mem_ptr , const std::string &path, size_t size) {
+        mem_ptr.reset() ;
+        segment_t::grow(path.c_str(), size) ;
+        mem_ptr.reset(open_segment(path)) ;
+    }
+    static std::string convert_base_dir([[maybe_unused]] const std::string &base_dir) {
+        return "" ;
+    }
+
+    template<typename Function>
+    static void attach( Function && f ) {
+        f() ;
+    }
+};
+
+
 struct Shared {
     typedef boost::interprocess::managed_shared_memory   segment_t;
     typedef boost::interprocess::managed_shared_memory::segment_manager  segment_manager_t;
@@ -36,7 +74,7 @@ struct Shared {
     typedef boost::unique_lock<lock_t>  scoped_exclusive_locker_t;
     typedef boost::shared_lock<lock_t>  scoped_shared_locker_t;
     static segment_t * open_or_create_segment (const std::string &path, size_t size) {
-        return new segment_t(boost::interprocess::open_or_create, path.c_str(), size) ; 
+        return new segment_t(boost::interprocess::open_or_create, path.c_str(), size) ;
     }
     static segment_t * open_segment (const std::string &path) {
         return new segment_t(boost::interprocess::open_only, path.c_str()) ;