[FileCollector] Move interface into FileCollectorBase (NFC)

For the reproducers in LLDB we want to switch to an "immediate mode"
FileCollector that writes every file encountered straight to disk so we
can generate the actual mapping out-of-process. This patch moves the
interface into a separate base class.

Differential revision: https://reviews.llvm.org/D89742

Author: JDevlieghere

llvm/include/llvm/Support/FileCollector.h

@@ -20,6 +20,35 @@ namespace llvm {
 class FileCollectorFileSystem;
 class Twine;
 
+class FileCollectorBase {
+public:
+  FileCollectorBase();
+  virtual ~FileCollectorBase();
+
+  void addFile(const Twine &file);
+  void addDirectory(const Twine &Dir);
+
+protected:
+  bool markAsSeen(StringRef Path) {
+    if (Path.empty())
+      return false;
+    return Seen.insert(Path).second;
+  }
+
+  virtual void addFileImpl(StringRef SrcPath) = 0;
+
+  virtual llvm::vfs::directory_iterator
+  addDirectoryImpl(const llvm::Twine &Dir,
+                   IntrusiveRefCntPtr<vfs::FileSystem> FS,
+                   std::error_code &EC) = 0;
+
+  /// Synchronizes access to internal data structures.
+  std::mutex Mutex;
+
+  /// Tracks already seen files so they can be skipped.
+  StringSet<> Seen;
+};
+
 /// Captures file system interaction and generates data to be later replayed
 /// with the RedirectingFileSystem.
 ///
@@ -38,16 +67,13 @@ class Twine;
 ///
 /// In order to preserve the relative topology of files we use their real paths
 /// as relative paths inside of the Root.
-class FileCollector {
+class FileCollector : public FileCollectorBase {
 public:
   /// \p Root is the directory where collected files are will be stored.
   /// \p OverlayRoot is VFS mapping root.
   /// \p Root directory gets created in copyFiles unless it already exists.
   FileCollector(std::string Root, std::string OverlayRoot);
 
-  void addFile(const Twine &file);
-  void addDirectory(const Twine &Dir);
-
   /// Write the yaml mapping (for the VFS) to the given file.
   std::error_code writeMapping(StringRef MappingFile);
 
@@ -67,12 +93,6 @@ class FileCollector {
 private:
   friend FileCollectorFileSystem;
 
-  bool markAsSeen(StringRef Path) {
-    if (Path.empty())
-      return false;
-    return Seen.insert(Path).second;
-  }
-
   bool getRealPath(StringRef SrcPath, SmallVectorImpl<char> &Result);
 
   void addFileToMapping(StringRef VirtualPath, StringRef RealPath) {
@@ -83,24 +103,19 @@ class FileCollector {
   }
 
 protected:
-  void addFileImpl(StringRef SrcPath);
+  void addFileImpl(StringRef SrcPath) override;
 
   llvm::vfs::directory_iterator
   addDirectoryImpl(const llvm::Twine &Dir,
-                   IntrusiveRefCntPtr<vfs::FileSystem> FS, std::error_code &EC);
-
-  /// Synchronizes access to Seen, VFSWriter and SymlinkMap.
-  std::mutex Mutex;
+                   IntrusiveRefCntPtr<vfs::FileSystem> FS,
+                   std::error_code &EC) override;
 
   /// The directory where collected files are copied to in copyFiles().
   const std::string Root;
 
   /// The root directory where the VFS overlay lives.
   const std::string OverlayRoot;
 
-  /// Tracks already seen files so they can be skipped.
-  StringSet<> Seen;
-
   /// The yaml mapping writer.
   vfs::YAMLVFSWriter VFSWriter;
 

llvm/lib/Support/FileCollector.cpp

@@ -15,6 +15,22 @@
 
 using namespace llvm;
 
+FileCollectorBase::FileCollectorBase() = default;
+FileCollectorBase::~FileCollectorBase() = default;
+
+void FileCollectorBase::addFile(const Twine &File) {
+  std::lock_guard<std::mutex> lock(Mutex);
+  std::string FileStr = File.str();
+  if (markAsSeen(FileStr))
+    addFileImpl(FileStr);
+}
+
+void FileCollectorBase::addDirectory(const Twine &Dir) {
+  assert(sys::fs::is_directory(Dir));
+  std::error_code EC;
+  addDirectoryImpl(Dir, vfs::getRealFileSystem(), EC);
+}
+
 static bool isCaseSensitivePath(StringRef Path) {
   SmallString<256> TmpDest = Path, UpperDest, RealDest;
 
@@ -61,19 +77,6 @@ bool FileCollector::getRealPath(StringRef SrcPath,
   return true;
 }
 
-void FileCollector::addFile(const Twine &File) {
-  std::lock_guard<std::mutex> lock(Mutex);
-  std::string FileStr = File.str();
-  if (markAsSeen(FileStr))
-    addFileImpl(FileStr);
-}
-
-void FileCollector::addDirectory(const Twine &Dir) {
-  assert(sys::fs::is_directory(Dir));
-  std::error_code EC;
-  addDirectoryImpl(Dir, vfs::getRealFileSystem(), EC);
-}
-
 void FileCollector::addFileImpl(StringRef SrcPath) {
   // We need an absolute src path to append to the root.
   SmallString<256> AbsoluteSrc = SrcPath;