NEW JKQTPDataCache class template to generate a (possibly thread-safe) key-value cache

lib/jkqtcommon/CMakeLists.txt

@@ -27,6 +27,7 @@ set(SOURCES
   ${CMAKE_CURRENT_LIST_DIR}/jkqtpcodestructuring.cpp
   ${CMAKE_CURRENT_LIST_DIR}/jkqtpbasicimagetools.cpp
   ${CMAKE_CURRENT_LIST_DIR}/jkqtpconcurrencytools.cpp
+  ${CMAKE_CURRENT_LIST_DIR}/jkqtpcachingtools.cpp
   ${CMAKE_CURRENT_LIST_DIR}/jkqtpgeometrytools.cpp
   ${CMAKE_CURRENT_LIST_DIR}/jkqtpdrawingtools.cpp
   ${CMAKE_CURRENT_LIST_DIR}/jkqtpenhancedpainter.cpp
@@ -62,6 +63,8 @@ set(HEADERS
   $<INSTALL_INTERFACE:jkqtpgeometrytools.h>
   $<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/jkqtpconcurrencytools.h>
   $<INSTALL_INTERFACE:jkqtpconcurrencytools.h>
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/jkqtpcachingtools.h>
+  $<INSTALL_INTERFACE:jkqtpcachingtools.h>
 )
 
 include(CMakePackageConfigHelpers)
@@ -80,6 +83,10 @@ function(JKQtCommon_setDefaultLibOptions TARGETNAME)
       target_compile_options(${TARGETNAME} PUBLIC /EHsc)
       target_compile_definitions(${TARGETNAME} PUBLIC NOMINMAX)
     endif()
+    if(JKQtPlotter_BUILD_WITH_TIMING_INFO_OUTPUT)
+        target_compile_definitions(${TARGETNAME} PRIVATE JKQTBP_AUTOTIMER)
+    endif()
+
     target_include_directories(${TARGETNAME} PUBLIC
         $<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/../>
         $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>

lib/jkqtcommon/jkqtpcachingtools.cpp

@@ -0,0 +1,22 @@
+/*
+    Copyright (c) 2008-2024 Jan W. Krieger (<jan@jkrieger.de>)
+
+    last modification: $LastChangedDate$  (revision $Rev$)
+
+    This software is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License (LGPL) as published by
+    the Free Software Foundation, either version 2.1 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License (LGPL) for more details.
+
+    You should have received a copy of the GNU Lesser General Public License (LGPL)
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+
+
+#include "jkqtpcachingtools.h"

lib/jkqtcommon/jkqtpcachingtools.h

@@ -0,0 +1,95 @@
+/*
+    Copyright (c) 2008-2024 Jan W. Krieger (<jan@jkrieger.de>)
+
+    last modification: $LastChangedDate$  (revision $Rev$)
+
+    This software is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License (LGPL) as published by
+    the Free Software Foundation, either version 2.1 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License (LGPL) for more details.
+
+    You should have received a copy of the GNU Lesser General Public License (LGPL)
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+
+
+
+
+#ifndef JKQTPCACHINGTOOLS_H
+#define JKQTPCACHINGTOOLS_H
+
+#include "jkqtcommon/jkqtcommon_imexport.h"
+#include <QReadWriteLock>
+#include <QReadLocker>
+#include <QWriteLocker>
+#include <functional>
+
+/** \brief this class can be used to implement a general cache for values
+ *  \ingroup jkqtptools_concurrency
+ *
+ *  It is typically used to generate a static (ThreadSafe=true) of thread_local (ThreadSafe=false) cache inside a function.
+ *
+ *  The class is parametrized by a key (TKeay) and value (TData) data type and receives (in the constructor) a functor that
+ *  calculates the data for a key. An additional template parameter ThreadSafe indicates (true|false) whether the class
+ *  is implemented in a thread-safe way (for static instances) or not (then it should be used as thread_local instances in a
+ *  multi-threaded environment or in a single-thread environment).
+ *
+ *  The class member function get(key) returns a value for a given key, which is either taken from the internal cache,
+ *  or generated using the functor provided to the constructor. In the latter case the generated value is stored in the internal cache.
+ *
+ *  Internally the cache maps TKey to TData, but the signature of the get()-function and the generator functor actually uses TKeyInSignature,
+ *  which may differ from TKey. The only limitation is that TKeyInSignature can be converted/assigned to a TKey
+ */
+template <class TData, class TKey, bool ThreadSafe=true, class TKeyInSignature=TKey>
+struct JKQTPDataCache {
+    template <typename FF>
+    inline JKQTPDataCache(FF generateData):
+        m_generateData(std::forward<FF>(generateData))
+    {
+
+    }
+
+    template<class... Args>
+    inline TData get_inline(Args... args) {
+        return get(TKeyInSignature(args...));
+    }
+
+    template <bool TSS=ThreadSafe>
+    inline TData get(const typename std::enable_if<TSS, TKeyInSignature>::type& key) {
+        const TKey cacheKey=key;
+
+        QReadLocker lockR(&m_mutex);
+        if (m_cache.contains(cacheKey)) return m_cache[cacheKey];
+        lockR.unlock();
+
+        QWriteLocker lockW(&m_mutex);
+        if (m_cache.contains(cacheKey)) return m_cache[cacheKey];
+
+        const auto newData=m_generateData(key);
+        m_cache[cacheKey]=newData;
+        return newData;
+    }
+
+    template <bool TSS=ThreadSafe>
+    inline TData get(const typename std::enable_if<!TSS, TKeyInSignature>::type& key) {
+        const TKey cacheKey=key;
+
+        if (m_cache.contains(cacheKey)) return m_cache[cacheKey];
+        const auto newData=m_generateData(key);
+        m_cache[cacheKey]=newData;
+        return newData;
+    }
+private:
+    QHash<TKey, TData> m_cache;
+    mutable typename std::enable_if<ThreadSafe, QReadWriteLock>::type m_mutex;
+    const std::function<TData(TKeyInSignature)> m_generateData;
+    Q_DISABLE_COPY(JKQTPDataCache)
+};
+
+#endif // JKQTPCACHINGTOOLS_H