fix crash on second call to sourceCpp

- Revert previous code which attempted to avoid calling dyn.load on libraries already loaded (which in turn had triggered an R bug that corrupts the load table when this occurs). That code's logic was not correct.

- Generate unique shared object paths using a simple static counter rather than a call to sample. The previous issue must have been triggered by sample returning the same integer twice, which in turn may have been triggered by some maniplation of the rng state by expm?.

Author: jjallaire

ChangeLog

@@ -1,3 +1,7 @@
+2015-07-14  JJ Allaire <[email protected]>
+
+        * src/attributes.cpp: fix crash on second call to sourceCpp
+
 2015-07-07  Matt P. Dziubinski  <[email protected]>
 
         * inst/include/Rcpp/sugar/functions/var.h: Variance -- changed from

inst/NEWS.Rd

@@ -17,8 +17,8 @@
     }
     \item Changes in Rcpp Attributes:
     \itemize{
-      \item Don't load \code{sourceCpp} dynamic library if it's already 
-      been loaded.
+      \item Use more robust method of ensuring unique paths for generated shared
+      libraries.
       \item The \code{evalCpp} function now also supports the \code{plugins}
       argument.
     }

src/attributes.cpp

@@ -2813,7 +2813,7 @@ namespace {
             dircreate(buildDirectory_);
 
             // generate a random context id
-            contextId_ = "sourceCpp_" + createRandomizer();
+            contextId_ = "sourceCpp_" + uniqueToken();
 
             // regenerate the source code
             regenerateSource();
@@ -2847,7 +2847,7 @@ namespace {
 
             // create new dynlib filename
             previousDynlibFilename_ = dynlibFilename_;
-            dynlibFilename_ = "sourceCpp_" + createRandomizer() + dynlibExt_;
+            dynlibFilename_ = "sourceCpp_" + uniqueToken() + dynlibExt_;
 
             // copy the source file to the build dir
             Rcpp::Function filecopy = Rcpp::Environment::base_env()["file.copy"];
@@ -2877,15 +2877,17 @@ namespace {
                 throw Rcpp::file_io_error(generatedRSourcePath());
 
             // DLLInfo - hide using . and ensure uniqueness using contextId
-            std::string dllInfoName = "." + contextId_ + "_DLLInfo";
-            std::string dllInfo = "`" + dllInfoName + "`";
-            rOfs << "if (!exists('" << dllInfoName << "', inherits = FALSE))" << std::endl;
-            rOfs << "   " << dllInfo << " <- dyn.load('" << dynlibPath() << "')"
+            std::string dllInfo = "`." + contextId_ + "_DLLInfo`";
+            rOfs << dllInfo << " <- dyn.load('" << dynlibPath() << "')"
                  << std::endl << std::endl;
 
             // Generate R functions
             generateR(rOfs, sourceAttributes, dllInfo);
 
+            // remove the DLLInfo
+            rOfs << std::endl << "rm(" << dllInfo << ")"
+                 << std::endl;
+
             rOfs.close();
 
             // discover exported functions and dependencies
@@ -3035,10 +3037,9 @@ namespace {
 
         }
 
-        std::string createRandomizer() {
-            Rcpp::Function sample = Rcpp::Environment::base_env()["sample"];
+        std::string uniqueToken() {
             std::ostringstream ostr;
-            ostr << Rcpp::as<int>(sample(100000, 1));
+            ostr << s_nextUniqueToken++;
             return ostr.str();
         }
 
@@ -3058,8 +3059,12 @@ namespace {
         std::vector<std::string> plugins_;
         std::vector<std::string> embeddedR_;
         std::vector<FileInfo> sourceDependencies_;
+        static int s_nextUniqueToken;
     };
 
+    // initialize next unique token
+    int SourceCppDynlib::s_nextUniqueToken = 0;
+
     // Dynlib cache that allows lookup by either file path or code contents
     class SourceCppDynlibCache {