Update ReArchive.cpp

busy-wait in the event of a thread collision.

src/ReArchive.cpp

@@ -1,5 +1,5 @@
 #include <ReArchive/ReArchive.h>
-
+#include <unordered_set>
 #include <ReArchive/types/Header.h>
 #include <ReArchive/types/FileTable.h>
 #include <ReArchive/types/FileEntry.h>
@@ -9,6 +9,8 @@ using ReArchive::Header;
 using ReArchive::FileTable;
 using ReArchive::FileEntry;
 
+std::unordered_set<std::filesystem::path> locked {};
+
 Header GetHeader(const unsigned char* archive) {
     ReArchive::Header h = ReArchive::Header::DeSerialize(archive);
     return h;
@@ -72,6 +74,11 @@ bool ReArchive::CreateArchive(const std::filesystem::path& filesystem_path, bool
     if (std::filesystem::exists(filesystem_path))
         return false;
 
+    if (locked.contains(filesystem_path))
+        return false;
+
+    locked.insert(filesystem_path);
+
     std::ofstream file(filesystem_path, std::ios::binary);
     if (!file)
         return false;
@@ -86,6 +93,12 @@ bool ReArchive::CreateArchive(const std::filesystem::path& filesystem_path, bool
 
     if (running_tally)
         *running_tally = file_table;
+
+    // Remove lock.
+    auto position = locked.find(filesystem_path);
+    if (position != locked.end())
+        locked.erase(position);
+
     return true;
 }
 
@@ -93,6 +106,10 @@ bool ReArchive::WriteFile(const std::filesystem::path& archive, const std::files
     if (!std::filesystem::exists(archive))
         return false;
 
+    // Busy-wait.
+    while (locked.contains(archive)) {}
+    locked.insert(archive);
+
     std::ifstream in(archive, std::ios::binary);
     if (!in)
         return false;
@@ -133,8 +150,14 @@ bool ReArchive::WriteFile(const std::filesystem::path& archive, const std::files
     out.write(reinterpret_cast<const char *>(new_header.data()), (int64_t) new_header.size());
     out.close();
 
+    // Remove lock.
+    auto position = locked.find(archive);
+    if (position != locked.end())
+        locked.erase(position);
+
     if (running_tally)
         *running_tally = file_table;
+
     return true;
 }
 
@@ -142,6 +165,10 @@ bool ReArchive::OverwriteFile(const std::filesystem::path& archive, const std::f
     if (!std::filesystem::exists(archive))
         return false;
 
+    // Busy-wait.
+    while (locked.contains(archive)) {}
+    locked.insert(archive);
+
     std::ifstream in(archive, std::ios::binary);
     if (!in)
         return false;
@@ -179,6 +206,11 @@ bool ReArchive::OverwriteFile(const std::filesystem::path& archive, const std::f
     out.write(reinterpret_cast<const char *>(file_data), byte_count);
     out.close();
 
+    // Remove lock.
+    auto position = locked.find(archive);
+    if (position != locked.end())
+        locked.erase(position);
+
     return true;
 }
 
@@ -224,6 +256,10 @@ bool ReArchive::EraseFile(const std::filesystem::path& archive, const std::files
     if (!std::filesystem::exists(archive))
         return false;
 
+    // Busy-wait.
+    while (locked.contains(archive)) {}
+    locked.insert(archive);
+
     std::ifstream in(archive, std::ios::binary);
     if (!in)
         return false;
@@ -266,5 +302,10 @@ bool ReArchive::EraseFile(const std::filesystem::path& archive, const std::files
     if (running_tally)
         *running_tally = current_file_table;
 
+    // Remove lock.
+    auto position = locked.find(archive);
+    if (position != locked.end())
+        locked.erase(position);
+
     return true;
 }