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ENH: Improved speed of cmake::CheckBuildSystem when checking build system outputs versus dependencies. Instead of doing an O(m*n) comparison of every pair, just locate the oldest output and the newest input and compare them which is now O(m+n).

This commit is contained in:
Brad King 2007-12-19 11:51:30 -05:00
parent 07db9b83a7
commit 9ccba7c391
1 changed files with 72 additions and 22 deletions
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94
Source/cmake.cxx
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@ -2556,9 +2556,16 @@ int cmake::CheckBuildSystem()
}
// Get the set of dependencies and outputs.
std::vector<std::string> depends;
std::vector<std::string> outputs;
const char* dependsStr = mf->GetDefinition("CMAKE_MAKEFILE_DEPENDS");
const char* outputsStr = mf->GetDefinition("CMAKE_MAKEFILE_OUTPUTS");
if(!dependsStr || !outputsStr)
if(dependsStr && outputsStr)
{
cmSystemTools::ExpandListArgument(dependsStr, depends);
cmSystemTools::ExpandListArgument(outputsStr, outputs);
}
if(depends.empty() || outputs.empty())
{
// Not enough information was provided to do the test. Just rerun.
if(verbose)
@ -2570,35 +2577,78 @@ int cmake::CheckBuildSystem()
}
return 1;
}
std::vector<std::string> depends;
std::vector<std::string> outputs;
cmSystemTools::ExpandListArgument(dependsStr, depends);
cmSystemTools::ExpandListArgument(outputsStr, outputs);
// If any output is older than any dependency then rerun.
for(std::vector<std::string>::iterator dep = depends.begin();
dep != depends.end(); ++dep)
// Find find the newest dependency.
std::vector<std::string>::iterator dep = depends.begin();
std::string dep_newest = *dep++;
for(;dep != depends.end(); ++dep)
{
for(std::vector<std::string>::iterator out = outputs.begin();
out != outputs.end(); ++out)
int result = 0;
if(this->FileComparison->FileTimeCompare(dep_newest.c_str(),
dep->c_str(), &result))
{
int result = 0;
if(!this->FileComparison->FileTimeCompare(out->c_str(),
dep->c_str(), &result) ||
result < 0)
if(result < 0)
{
if(verbose)
{
cmOStringStream msg;
msg << "Re-run cmake file: " << out->c_str()
<< " older than: " << dep->c_str() << "\n";
cmSystemTools::Stdout(msg.str().c_str());
}
return 1;
dep_newest = *dep;
}
}
else
{
if(verbose)
{
cmOStringStream msg;
msg << "Re-run cmake: build system dependency is missing\n";
cmSystemTools::Stdout(msg.str().c_str());
}
return 1;
}
}
// Find find the oldest output.
std::vector<std::string>::iterator out = outputs.begin();
std::string out_oldest = *out++;
for(;out != outputs.end(); ++out)
{
int result = 0;
if(this->FileComparison->FileTimeCompare(out_oldest.c_str(),
out->c_str(), &result))
{
if(result > 0)
{
out_oldest = *out;
}
}
else
{
if(verbose)
{
cmOStringStream msg;
msg << "Re-run cmake: build system output is missing\n";
cmSystemTools::Stdout(msg.str().c_str());
}
return 1;
}
}
// If any output is older than any dependency then rerun.
{
int result = 0;
if(!this->FileComparison->FileTimeCompare(out_oldest.c_str(),
dep_newest.c_str(),
&result) ||
result < 0)
{
if(verbose)
{
cmOStringStream msg;
msg << "Re-run cmake file: " << out_oldest.c_str()
<< " older than: " << dep_newest.c_str() << "\n";
cmSystemTools::Stdout(msg.str().c_str());
}
return 1;
}
}
// No need to rerun.
return 0;
}