[lmi-commits] (no subject)

[Greg Chicares]

branch: master
commit c363b00e4cf4a7536e65ff0851656a2e3068bd77
Author: Gregory W. Chicares <address@hidden>
Date:   Sat Jul 30 23:05:04 2016 +0000

    Add unit test for class-instance caching
    
    The speed test shows little benefit from caching. That is not
    astonishing because the class it tests merely reads a file, without
    the costly processing that motivated caching in the first place.
    However, if this line:
            std::time_t const write_time = fs::last_write_time(filename);
    in the caching implementation is experimentally replaced with
            std::time_t const write_time = 0;
    then caching improves the speed by several orders of magnitude.
---
 Makefile.am               |    9 ++++
 cache_file_reads_test.cpp |  121 +++++++++++++++++++++++++++++++++++++++++++++
 objects.make              |    7 +++
 3 files changed, 137 insertions(+)

diff --git a/Makefile.am b/Makefile.am
index 42d9b1c..2c35293 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -89,6 +89,7 @@ TESTS = \
     test_any_member \
     test_assert_lmi \
     test_authenticity \
+    test_cache_file_reads \
     test_calendar_date \
     test_callback \
     test_comma_punct \
@@ -576,6 +577,14 @@ test_authenticity_CXXFLAGS = $(AM_CXXFLAGS)
 test_authenticity_LDADD = \
   $(BOOST_LIBS)
 
+test_cache_file_reads_SOURCES = \
+  $(common_test_objects) \
+  cache_file_reads_test.cpp \
+  timer.cpp
+test_cache_file_reads_CXXFLAGS = $(AM_CXXFLAGS)
+test_cache_file_reads_LDADD = \
+  $(BOOST_LIBS)
+
 test_calendar_date_SOURCES = \
   $(common_test_objects) \
   calendar_date.cpp \
diff --git a/cache_file_reads_test.cpp b/cache_file_reads_test.cpp
new file mode 100755
index 0000000..33817ce
--- /dev/null
+++ b/cache_file_reads_test.cpp
@@ -0,0 +1,121 @@
+// Cache class instances constructed from files--unit test.
+//
+// Copyright (C) 2016 Gregory W. Chicares.
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License version 2 as
+// published by the Free Software Foundation.
+//
+// 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 General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software Foundation,
+// Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+//
+// http://savannah.nongnu.org/projects/lmi
+// email: <address@hidden>
+// snail: Chicares, 186 Belle Woods Drive, Glastonbury CT 06033, USA
+
+#include "pchfile.hpp"
+
+#include "cache_file_reads.hpp"
+
+#include "istream_to_string.hpp"
+#include "miscellany.hpp"               // ios_in_binary()
+#include "test_tools.hpp"
+#include "timer.hpp"
+
+#include <boost/filesystem/exception.hpp>
+
+#include <fstream>
+
+class X
+    :public cache_file_reads<X>
+{
+  public:
+    X()
+        {}
+    X(std::string const& filename)
+        {
+        std::ifstream ifs(filename, ios_in_binary());
+        istream_to_string(ifs, s_);
+        }
+
+    std::string const& s() const
+        {
+        return s_;
+        }
+
+  private:
+    std::string s_;
+};
+
+class cache_file_reads_test
+{
+  public:
+    static void test()
+        {
+        test_preconditions();
+        assay_speed();
+        }
+
+  private:
+    static void test_preconditions();
+    static void assay_speed();
+
+    static void mete_uncached();
+    static void mete_cached  ();
+};
+
+void cache_file_reads_test::test_preconditions()
+{
+    // X() and X(filename) are required.
+    X x0;
+    X x1("sample.ill");
+
+    // The cache is accessible with or without an object.
+    BOOST_TEST_EQUAL
+        (x0.read_from_cache("sample.ill")->s()
+        ,X::read_from_cache("sample.ill")->s()
+        );
+
+    // The file must exist.
+    BOOST_TEST_THROW
+        (X::read_from_cache("no_such_file")
+        ,boost::filesystem::filesystem_error
+        ,lmi_test::what_regex("no_such_file.*cannot find the file specified")
+        );
+}
+
+void cache_file_reads_test::assay_speed()
+{
+    std::cout
+        << "\n  Speed tests..."
+        << "\n  Uncached: " << TimeAnAliquot(mete_uncached)
+        << "\n  Cached  : " << TimeAnAliquot(mete_cached  )
+        << std::endl
+        ;
+}
+
+void cache_file_reads_test::mete_uncached()
+{
+    X const x("sample.ill");
+    volatile std::string::size_type z = x.s().size();
+}
+
+void cache_file_reads_test::mete_cached()
+{
+    X const& x(*X::read_from_cache("sample.ill"));
+    volatile std::string::size_type z = x.s().size();
+}
+
+int test_main(int, char*[])
+{
+    cache_file_reads_test::test();
+
+    return EXIT_SUCCESS;
+}
+
diff --git a/objects.make b/objects.make
index b806edc..54f785b 100644
--- a/objects.make
+++ b/objects.make
@@ -398,6 +398,7 @@ unit_test_targets := \
   any_member_test \
   assert_lmi_test \
   authenticity_test \
+  cache_file_reads_test \
   calendar_date_test \
   callback_test \
   comma_punct_test \
@@ -515,6 +516,12 @@ authenticity_test$(EXEEXT): \
   system_command.o \
   system_command_non_wx.o \
 
+cache_file_reads_test$(EXEEXT): \
+  $(boost_filesystem_objects) \
+  $(common_test_objects) \
+  cache_file_reads_test.o \
+  timer.o \
+
 calendar_date_test$(EXEEXT): \
   $(common_test_objects) \
   calendar_date.o \