ENH: Improve performance of check build system by creating another file that is simpler to parse and therefore much faster overall

1 files changed, 102 insertions, 7 deletions

diff --git a/Source/cmDepends.cxx b/Source/cmDepends.cxx
index 01c6e11..d66efb4 100644
--- a/Source/cmDepends.cxx
+++ b/Source/cmDepends.cxx
@@ -18,28 +18,34 @@
 
 #include "cmGeneratedFileStream.h"
 #include "cmSystemTools.h"
+#include "cmFileTimeComparison.h"
 
 #include <assert.h>
 
 //----------------------------------------------------------------------------
-cmDepends::cmDepends()
+cmDepends::cmDepends(): m_Verbose(false), m_FileComparison(0),
+  m_MaxPath(cmSystemTools::GetMaximumFilePathLength()),
+  m_Dependee(new char[m_MaxPath]),
+  m_Depender(new char[m_MaxPath])
 {
-  m_Verbose = false;
 }
 
 //----------------------------------------------------------------------------
 cmDepends::~cmDepends()
 {
+  delete [] m_Dependee;
+  delete [] m_Depender;
 }
 
 //----------------------------------------------------------------------------
-bool cmDepends::Write(const char *src, const char *obj, std::ostream &fout)
+bool cmDepends::Write(const char *src, const char *obj,
+  std::ostream &makeDepends, std::ostream &internalDepends)
 {
-  return this->WriteDependencies(src, obj, fout);
+  return this->WriteDependencies(src, obj, makeDepends, internalDepends);
 }
 
 //----------------------------------------------------------------------------
-void cmDepends::Check(const char *file)
+void cmDepends::Check(const char *makeFile, const char *internalFile)
 {
   // Dependency checks must be done in proper working directory.
   std::string oldcwd = ".";
@@ -52,11 +58,12 @@ void cmDepends::Check(const char *file)
     }
 
   // Check whether dependencies must be regenerated.
-  std::ifstream fin(file);
+  std::ifstream fin(internalFile);
   if(!(fin && this->CheckDependencies(fin)))
     {
     // Clear all dependencies so they will be regenerated.
-    this->Clear(file);
+    this->Clear(makeFile);
+    this->Clear(internalFile);
     }
 
   // Restore working directory.
@@ -82,6 +89,7 @@ void cmDepends::Clear(const char *file)
   std::string markFile = file;
   markFile += ".mark";
   cmSystemTools::RemoveFile(markFile.c_str());
+  std::cout << "Remove mark file: " << markFile.c_str() << std::endl;
   
   // Write an empty dependency file.
   cmGeneratedFileStream depFileStream(file);
@@ -90,3 +98,90 @@ void cmDepends::Clear(const char *file)
     << "# This may be replaced when dependencies are built." << std::endl;
 }
 
+//----------------------------------------------------------------------------
+bool cmDepends::CheckDependencies(std::istream& internalDepends)
+{
+  // Parse dependencies from the stream.  If any dependee is missing
+  // or newer than the depender then dependencies should be
+  // regenerated.
+  bool okay = true;
+  while(internalDepends.getline(m_Dependee, m_MaxPath))
+    {
+    if ( m_Dependee[0] == 0 || m_Dependee[0] == '#' || m_Dependee[0] == '\r' )
+      {
+      continue;
+      }
+    size_t len = internalDepends.gcount()-1;
+    if ( m_Dependee[len-1] == '\r' )
+      {
+      len --;
+      m_Dependee[len] = 0;
+      }
+    if ( m_Dependee[0] != ' ' )
+      {
+      memcpy(m_Depender, m_Dependee, len+1);
+      continue;
+      }
+    /*
+    // Parse the dependency line.
+    if(!this->ParseDependency(line.c_str()))
+      {
+      continue;
+      }
+      */
+
+    // Dependencies must be regenerated if the dependee does not exist
+    // or if the depender exists and is older than the dependee.
+    bool regenerate = false;
+    const char* dependee = m_Dependee+1;
+    const char* depender = m_Depender;
+    if(!cmSystemTools::FileExists(dependee))
+      {
+      // The dependee does not exist.
+      regenerate = true;
+
+      // Print verbose output.
+      if(m_Verbose)
+        {
+        cmOStringStream msg;
+        msg << "Dependee \"" << dependee
+            << "\" does not exist for depender \""
+            << depender << "\"." << std::endl;
+        cmSystemTools::Stdout(msg.str().c_str());
+        }
+      }
+    else if(cmSystemTools::FileExists(depender))
+      {
+      // The dependee and depender both exist.  Compare file times.
+      int result = 0;
+      if((!m_FileComparison->FileTimeCompare(depender, dependee,
+                                             &result) || result < 0))
+        {
+        // The depender is older than the dependee.
+        regenerate = true;
+
+        // Print verbose output.
+        if(m_Verbose)
+          {
+          cmOStringStream msg;
+          msg << "Dependee \"" << dependee
+              << "\" is newer than depender \""
+              << depender << "\"." << std::endl;
+          cmSystemTools::Stdout(msg.str().c_str());
+          }
+        }
+      }
+    if(regenerate)
+      {
+      // Dependencies must be regenerated.
+      okay = false;
+
+      // Remove the depender to be sure it is rebuilt.
+      cmSystemTools::RemoveFile(depender);
+      }
+    }
+
+  return okay;
+}
+
+