[LyX/master] Make static counters atomic

[Guillaume Munch]

commit 46d8dfc6c2fe3c75687bee773933a9fc7aec95c2
Author: Guillaume Munch <g...@lyx.org>
Date:   Sun Jul 10 16:50:19 2016 +0100

    Make static counters atomic
    
    This ensures thread-safety
    
    (requires: gcc >= 4.6, MSVC >= 2015)
---
 src/Paragraph.cpp              |   34 +++++++++++++++++++---------------
 src/graphics/PreviewLoader.cpp |    4 ++--
 src/sgml.cpp                   |    7 +++----
 3 files changed, 24 insertions(+), 21 deletions(-)

diff --git a/src/Paragraph.cpp b/src/Paragraph.cpp
index d1faa43..f9d942e 100644
--- a/src/Paragraph.cpp
+++ b/src/Paragraph.cpp
@@ -61,6 +61,7 @@
 #include "support/lstrings.h"
 #include "support/textutils.h"
 
+#include <atomic>
 #include <sstream>
 #include <vector>
 
@@ -283,10 +284,11 @@ private:
 
 class Paragraph::Private
 {
-       // Enforce our own "copy" constructor by declaring the standard one and
-       // the assignment operator private without implementing them.
-       Private(Private const &);
-       Private & operator=(Private const &);
+       // Enforce our own "copy" constructor
+       Private(Private const &) = delete;
+       Private & operator=(Private const &) = delete;
+       // Unique ID generator
+       static int make_id();
 public:
        ///
        Private(Paragraph * owner, Layout const & layout);
@@ -506,35 +508,37 @@ Paragraph::Private::Private(Paragraph * owner, Layout 
const & layout)
 }
 
 
-// Initialization of the counter for the paragraph id's,
-//
-// FIXME: There should be a more intelligent way to generate and use the
-// paragraph ids per buffer instead a global static counter for all InsetText
-// in the running program.
-// However, this per-session id is used in LFUN_PARAGRAPH_GOTO to
-// switch to a different buffer, as used in the outliner for instance.
-static int paragraph_id = -1;
+//static
+int Paragraph::Private::make_id()
+{
+       // The id is unique per session across buffers because it is used in
+       // LFUN_PARAGRAPH_GOTO to switch to a different buffer, for instance in 
the
+       // outliner.
+       // (thread-safe)
+       static atomic_uint next_id(0);
+       return next_id++;
+}
+
 
 Paragraph::Private::Private(Private const & p, Paragraph * owner)
        : owner_(owner), inset_owner_(p.inset_owner_), fontlist_(p.fontlist_),
+         id_(make_id()),
          params_(p.params_), changes_(p.changes_), insetlist_(p.insetlist_),
          begin_of_body_(p.begin_of_body_), text_(p.text_), words_(p.words_),
          layout_(p.layout_)
 {
-       id_ = ++paragraph_id;
        requestSpellCheck(p.text_.size());
 }
 
 
 Paragraph::Private::Private(Private const & p, Paragraph * owner,
        pos_type beg, pos_type end)
-       : owner_(owner), inset_owner_(p.inset_owner_),
+       : owner_(owner), inset_owner_(p.inset_owner_), id_(make_id()),
          params_(p.params_), changes_(p.changes_),
          insetlist_(p.insetlist_, beg, end),
          begin_of_body_(p.begin_of_body_), words_(p.words_),
          layout_(p.layout_)
 {
-       id_ = ++paragraph_id;
        if (beg >= pos_type(p.text_.size()))
                return;
        text_ = p.text_.substr(beg, end - beg);
diff --git a/src/graphics/PreviewLoader.cpp b/src/graphics/PreviewLoader.cpp
index 1f78d77..1240771 100644
--- a/src/graphics/PreviewLoader.cpp
+++ b/src/graphics/PreviewLoader.cpp
@@ -41,6 +41,7 @@
 #include "support/bind.h"
 #include "support/TempFile.h"
 
+#include <atomic>
 #include <fstream>
 #include <iomanip>
 #include <memory>
@@ -728,8 +729,7 @@ void PreviewLoader::Impl::startLoading(bool wait)
        if (wait) {
                ForkedCall call(buffer_.filePath(), buffer_.layoutPos());
                int ret = call.startScript(ForkedProcess::Wait, command);
-               // FIXME THREAD
-               static int fake = (2^20) + 1;
+               static atomic_int fake((2^20) + 1);
                int pid = fake++;
                inprogress.pid = pid;
                inprogress.command = command;
diff --git a/src/sgml.cpp b/src/sgml.cpp
index 75802c2..2facb3e 100644
--- a/src/sgml.cpp
+++ b/src/sgml.cpp
@@ -27,6 +27,7 @@
 #include "support/lstrings.h"
 #include "support/textutils.h"
 
+#include <atomic>
 #include <map>
 #include <QThreadStorage>
 
@@ -105,10 +106,8 @@ docstring sgml::escapeString(docstring const & raw)
 
 docstring const sgml::uniqueID(docstring const & label)
 {
-       // FIXME THREAD
-       // It seems unlikely there could be a problem here,
-       // but we could have concurrent access, in principle.
-       static unsigned int seed = 1000;
+       // thread-safe
+       static atomic_uint seed(1000);
        return label + convert<docstring>(++seed);
 }