huishou/node_modules/nodegit/include/lock_master.h

#ifndef LOCK_MASTER_H
#define LOCK_MASTER_H

#include <git2.h>

class LockMasterImpl;

class LockMaster {
public:
  enum Status {
    Disabled = 0,
    EnabledForAsyncOnly,
    Enabled
  };

private:
  static Status status;

  LockMasterImpl *impl;

  template<typename T>
  void AddLocks(const T *t) {
    // by default, don't lock anything
  }

  // base case for variadic template unwinding
  void AddParameters() {
  }

  // processes a single parameter, then calls recursively on the rest
  template<typename T, typename... Types>
  void AddParameters(const T *t, const Types*... args) {
    if(t) {
      AddLocks(t);
    }
    AddParameters(args...);
  }

  void ConstructorImpl();
  void DestructorImpl();
  void ObjectToLock(const void *);
  void ObjectsToLockAdded();
public:

  // we lock on construction
  template<typename ...Types> LockMaster(bool asyncAction, const Types*... types) {
    if((status == Disabled) || ((status == EnabledForAsyncOnly) && !asyncAction)) {
      impl = NULL;
      return;
    }

    ConstructorImpl();
    AddParameters(types...);
    ObjectsToLockAdded();
  }

  // and unlock on destruction
  ~LockMaster() {
    if(!impl) {
      return;
    }
    DestructorImpl();
  }

  // TemporaryUnlock unlocks the LockMaster currently registered on the thread,
  // and re-locks it on destruction.
  class TemporaryUnlock {
    LockMasterImpl *impl;

    void ConstructorImpl();
    void DestructorImpl();
  public:
    TemporaryUnlock() {
      // We can't return here if disabled
      // It's possible that a LockMaster was fully constructed and registered
      // before the thread safety was disabled.
      // So we rely on ConstructorImpl to abort if there is no registered LockMaster
      ConstructorImpl();
    }
    ~TemporaryUnlock() {
      if(!impl) {
        return;
      }
      DestructorImpl();
    }
  };

  static void Initialize();

  // Enables the thread safety system
  static void Enable() {
    status = Enabled;
  }

  static void SetStatus(Status status) {
    LockMaster::status = status;
  }

  static void Disable() {
    status = Disabled;
  }

  static Status GetStatus() {
    return status;
  }

  // Diagnostic information that can be provided to the JavaScript layer
  // for a minimal level of testing
  struct Diagnostics {
    // this counts all stored mutexes - even if they are unlocked:
    int storedMutexesCount;
  };

  static Diagnostics GetDiagnostics();
};


template<> inline void LockMaster::AddLocks(const git_repository *repo) {
  // when using a repo, lock the repo
  ObjectToLock(repo);
}

template<> inline void LockMaster::AddLocks(const git_index *index) {
  // when using an index, lock the repo, or if there isn't one lock the index
  const void *owner = git_index_owner(index);
  if(!owner) {
    owner = index;
  }
  ObjectToLock(owner);
}

template<> inline void LockMaster::AddLocks(const git_commit *commit) {
  // when using a commit, lock the repo
  const void *owner = git_commit_owner(commit);
  ObjectToLock(owner);
}

// ... more locking rules would go here.  According to an analysis of idefs.json,
// the following types are passed as non-const * and may require locking
// (some likely, some probably not):
// 'git_annotated_commit',
// 'git_blame_options',
// 'git_blob',
// 'git_buf',
// 'git_checkout_options',
// 'git_cherrypick_options',
// 'git_clone_options',
// 'git_commit',
// 'git_config',
// 'git_diff',
// 'git_diff_perfdata',
// 'git_error',
// 'git_fetch_options',
// 'git_fetch_options',
// 'git_filter',
// 'git_filter_list',
// 'git_hashsig',
// 'git_index',
// 'git_merge_file_input',
// 'git_merge_options',
// 'git_merge_options',
// 'git_note',
// 'git_note_iterator',
// 'git_object',
// 'git_odb',
// 'git_odb_object',
// 'git_oid',
// 'git_oidarray',
// 'git_packbuilder',
// 'git_patch',
// 'git_pathspec',
// 'git_push_options',
// 'git_rebase',
// 'git_rebase_options',
// 'git_refdb',
// 'git_reference',
// 'git_reflog',
// 'git_remote',
// 'git_remote_callbacks',
// 'git_remote_callbacks',
// 'git_repository',
// 'git_repository_init_options',
// 'git_revwalk',
// 'git_signature',
// 'git_stash_apply_options',
// 'git_status_list',
// 'git_strarray',
// 'git_submodule',
// 'git_submodule_update_options',
// 'git_tag',
// 'git_transfer_progress',
// 'git_transport',
// 'git_tree',
// 'git_treebuilder',
// 'git_writestream'
//
// Other types are always passed as const * and perhaps don't require locking
// (it's not a guarantee though)


#endif