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cmFileSet: Fix poor performance of large file sets with export() on Windows

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Exporting targets having large FILE_SETs with install(EXPORT) or export(EXPORT)
currently performs poorly on Windows compared to Unix-like systems,
because cmFileSet::EvaluateDirectoryEntries calls SystemTools::SameFile on every
pair of parent directories in the file set. SystemTools::SameFile opens and closes
two read-only filesystem handles. This causes a significant performance drop
on Windows for FILE_SETs with even a couple of dozens of files.

Use the recently added SystemTools::GetFileId function in kwsys
(https://gitlab.kitware.com/utils/kwsys/-/merge_requests/298) instead of SameFile
to cache the identity of a directory in cmFileSet::EvaluateDirectoryEntries.
This means only one filesystem handle is needed per distinct directory path,
instead of two per (even if they're equal) directory pair.
This commit is contained in:
Jochem van Boxtel
2024-06-01 16:07:23 +02:00
committed by Brad King
parent fdf671fcc5
commit c598a4609c
1 changed files with 31 additions and 5 deletions
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36
Source/cmFileSet.cxx
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@@ -4,9 +4,11 @@
#include <sstream> #include <sstream>
#include <string> #include <string>
#include <unordered_map>
#include <utility> #include <utility>
#include <vector> #include <vector>
#include <cm/optional>
#include <cmext/algorithm> #include <cmext/algorithm>
#include <cmext/string_view> #include <cmext/string_view>
@@ -158,6 +160,13 @@ std::vector<std::string> cmFileSet::EvaluateDirectoryEntries(
const cmGeneratorTarget* target, const cmGeneratorTarget* target,
cmGeneratorExpressionDAGChecker* dagChecker) const cmGeneratorExpressionDAGChecker* dagChecker) const
{ {
struct DirCacheEntry
{
std::string collapsedDir;
cm::optional<cmSystemTools::FileId> fileId;
};
std::unordered_map<std::string, DirCacheEntry> dirCache;
std::vector<std::string> result; std::vector<std::string> result;
for (auto const& cge : cges) { for (auto const& cge : cges) {
auto entry = cge->Evaluate(lg, config, target, dagChecker); auto entry = cge->Evaluate(lg, config, target, dagChecker);
@@ -166,12 +175,29 @@ std::vector<std::string> cmFileSet::EvaluateDirectoryEntries(
if (!cmSystemTools::FileIsFullPath(dir)) { if (!cmSystemTools::FileIsFullPath(dir)) {
dir = cmStrCat(lg->GetCurrentSourceDirectory(), '/', dir); dir = cmStrCat(lg->GetCurrentSourceDirectory(), '/', dir);
} }
auto collapsedDir = cmSystemTools::CollapseFullPath(dir);
auto dirCacheResult = dirCache.emplace(dir, DirCacheEntry());
auto& dirCacheEntry = dirCacheResult.first->second;
const auto isNewCacheEntry = dirCacheResult.second;
if (isNewCacheEntry) {
cmSystemTools::FileId fileId;
auto isFileIdValid = cmSystemTools::GetFileId(dir, fileId);
dirCacheEntry.collapsedDir = cmSystemTools::CollapseFullPath(dir);
dirCacheEntry.fileId =
isFileIdValid ? cm::optional<decltype(fileId)>(fileId) : cm::nullopt;
}
for (auto const& priorDir : result) { for (auto const& priorDir : result) {
auto collapsedPriorDir = cmSystemTools::CollapseFullPath(priorDir); auto priorDirCacheEntry = dirCache.at(priorDir);
if (!cmSystemTools::SameFile(collapsedDir, collapsedPriorDir) && bool sameFile = dirCacheEntry.fileId.has_value() &&
(cmSystemTools::IsSubDirectory(collapsedDir, collapsedPriorDir) || priorDirCacheEntry.fileId.has_value() &&
cmSystemTools::IsSubDirectory(collapsedPriorDir, collapsedDir))) { (*dirCacheEntry.fileId == *priorDirCacheEntry.fileId);
if (!sameFile &&
(cmSystemTools::IsSubDirectory(dirCacheEntry.collapsedDir,
priorDirCacheEntry.collapsedDir) ||
cmSystemTools::IsSubDirectory(priorDirCacheEntry.collapsedDir,
dirCacheEntry.collapsedDir))) {
lg->GetCMakeInstance()->IssueMessage( lg->GetCMakeInstance()->IssueMessage(
MessageType::FATAL_ERROR, MessageType::FATAL_ERROR,
cmStrCat( cmStrCat(