Re: [lmi] PDF generation performance

[Vadim Zeitlin]

On Wed, 7 Feb 2018 21:40:46 +0100 I wrote:

Me>  I think it should be possible to obtain much more than microscopic
Me> refinements.

 Just FYI, applying this simple and still not really optimal (because
operator<<() is very slow on its own) patch:

---------------------------------- >8 --------------------------------------
diff --git a/ledger_text_formats.cpp b/ledger_text_formats.cpp
index 9e5a7ef6d..952b98d13 100644
--- a/ledger_text_formats.cpp
+++ b/ledger_text_formats.cpp
@@ -1227,11 +1227,22 @@ void FlatTextLedgerPrinter::PrintTabularDetail() const
     ,std::pair<int,oenum_format_style> f
     )
 {
-    std::stringstream interpreter;
-    std::locale loc;
-    std::locale new_loc(loc, new comma_punct);
-    interpreter.imbue(new_loc);
-    interpreter.setf(std::ios_base::fixed, std::ios_base::floatfield);
+    static std::stringstream interpreter;
+    static bool initialized = false;
+    if(!initialized)
+        {
+        initialized = true;
+        std::locale loc;
+        std::locale new_loc(loc, new comma_punct);
+        interpreter.imbue(new_loc);
+        interpreter.setf(std::ios_base::fixed, std::ios_base::floatfield);
+        }
+    else
+        {
+        interpreter.str(std::string{});
+        interpreter.clear();
+        }
+
     interpreter.precision(f.first);
     std::string s;
     if(f.second)
---------------------------------- >8 --------------------------------------

speeds the code by 50% for me, i.e. makes it exactly twice faster (status
bar shows ~6800ms instead of ~13700ms for me) without any non-trivial
change in the generated output files (they're still different solely
because the "CreationDate" field in the generated PDFs changes -- I think
it would be nice to have some way to call wxPdfDocument::SetCreationDate()
with some fixed date for testing to allow checking for the changes in
output just using diff, instead of having to use diffpdf as I do now).

 I don't necessarily advocate applying the patch above (although neither do
I see anything really wrong with doing this), but IMO this definitely
proves my quoted statement in the beginning of this email.

 Regards,
VZ