Params: faster atomic clearAll (#21973)

* faster clearAll

* use unlink

* fsync_dir if removed > 0

* remove macro ERR_NO_VALUE

* always fsync

* keep call to unlink

Co-authored-by: Willem Melching <willem.melching@gmail.com>
old-commit-hash: 383ff35790

selfdrive/common/params.cc

@@ -270,9 +270,8 @@ int Params::remove(const char *key) {
   std::lock_guard<FileLock> lk(file_lock);
   // Delete value.
   std::string path = params_path + "/d/" + key;
-  int result = ::remove(path.c_str());
+  int result = unlink(path.c_str());
   if (result != 0) {
-    result = ERR_NO_VALUE;
     return result;
   }
   // fsync parent directory
@@ -313,9 +312,18 @@ std::map<std::string, std::string> Params::readAll() {
 }
 
 void Params::clearAll(ParamKeyType key_type) {
+  FileLock file_lock(params_path + "/.lock", LOCK_EX);
+  std::lock_guard<FileLock> lk(file_lock);
+
+  std::string path;
   for (auto &[key, type] : keys) {
     if (type & key_type) {
-      remove(key);
+      path = params_path + "/d/" + key;
+      unlink(path.c_str());
     }
   }
+
+  // fsync parent directory
+  path = params_path + "/d";
+  fsync_dir(path.c_str());
 }

selfdrive/common/params.h

@@ -4,8 +4,6 @@
 #include <sstream>
 #include <string>
 
-#define ERR_NO_VALUE -33
-
 enum ParamKeyType {
   PERSISTENT = 0x02,
   CLEAR_ON_MANAGER_START = 0x04,