# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1629664675 -7200
# Node ID 40dc1cbd5356a31d28e76a4b8eb3b848c142d5eb
# Parent  9205a25c62d617e09c9c524e07b3b21eaeea5b97
Replaced per-thread notifiers with local notifiers, also changing the API to
employ explicit notifiers for waiting operations.

diff -r 9205a25c62d6 -r 40dc1cbd5356 libfsclient/include/fsclient/client.h
--- a/libfsclient/include/fsclient/client.h	Sat Aug 21 19:28:08 2021 +0200
+++ b/libfsclient/include/fsclient/client.h	Sun Aug 22 22:37:55 2021 +0200
@@ -72,10 +72,17 @@
 /* Notification operations. */
 
 long client_set_blocking(file_t *file, notify_flags_t flags);
-long client_subscribe(file_t *file, notify_flags_t flags, notifier_t notifier_type);
-long client_unsubscribe(file_t *file, notifier_t notifier_type);
-long client_wait_file(file_t *file);
-long client_wait_files(file_t **file);
+
+/* More advanced notification operations. */
+
+void client_notifier_close(file_notifier_t *notifier);
+file_notifier_t *client_notifier_local(void);
+file_notifier_t *client_notifier_task(void);
+
+long client_subscribe(file_t *file, notify_flags_t flags, file_notifier_t *notifier);
+long client_unsubscribe(file_t *file, file_notifier_t *notifier);
+long client_wait_file(file_t *file, file_notifier_t *notifier);
+long client_wait_files(file_t **file, file_notifier_t *notifier);
 
 EXTERN_C_END
 
diff -r 9205a25c62d6 -r 40dc1cbd5356 libfsclient/include/fsclient/file.h
--- a/libfsclient/include/fsclient/file.h	Sat Aug 21 19:28:08 2021 +0200
+++ b/libfsclient/include/fsclient/file.h	Sun Aug 22 22:37:55 2021 +0200
@@ -28,6 +28,14 @@
 
 
 
+/* C compatibility types (defined in the implementation). */
+
+struct file_notifier;
+
+typedef struct file_notifier file_notifier_t;
+
+
+
 EXTERN_C_BEGIN
 
 /* File access abstraction. */
@@ -68,17 +76,6 @@
 
 
 
-/* Notifier types. */
-
-typedef enum
-{
-    NOTIFIER_TASK = 0,
-    NOTIFIER_THREAD = 1,
-
-} notifier_t;
-
-
-
 /* Filesystem operations. */
 
 long file_open_for_user(user_t user, l4_cap_idx_t server, l4_cap_idx_t *opener);
@@ -125,10 +122,14 @@
 
 /* Notification functions. */
 
-long file_notify_subscribe(file_t *file, notify_flags_t flags, notifier_t notifier_type);
-long file_notify_unsubscribe(file_t *file, notifier_t notifier_type);
-long file_notify_wait_file(file_t *file);
-long file_notify_wait_files(file_t **file);
+void file_notify_close(file_notifier_t *notifier);
+file_notifier_t *file_notify_local(void);
+file_notifier_t *file_notify_task(void);
+
+long file_notify_subscribe(file_t *file, notify_flags_t flags, file_notifier_t *notifier);
+long file_notify_unsubscribe(file_t *file, file_notifier_t *notifier);
+long file_notify_wait_file(file_t *file, file_notifier_t *notifier);
+long file_notify_wait_files(file_t **file, file_notifier_t *notifier);
 
 
 
diff -r 9205a25c62d6 -r 40dc1cbd5356 libfsclient/include/fsclient/notifier.h
--- a/libfsclient/include/fsclient/notifier.h	Sat Aug 21 19:28:08 2021 +0200
+++ b/libfsclient/include/fsclient/notifier.h	Sun Aug 22 22:37:55 2021 +0200
@@ -96,6 +96,8 @@
     virtual void _unsubscribe(FileNotificationState &state, file_t *file);
 
 public:
+    virtual ~FileNotifier();
+
     /* Local operations. */
 
     virtual long start();
@@ -160,10 +162,8 @@
 
 /* Helper functions. */
 
-FileNotifier *get_notifier(notifier_t notifier_type);
+SpecificFileNotifier *notifier_get_task_notifier();
 
-SpecificFileNotifier *get_task_notifier();
-
-GeneralFileNotifier *get_thread_notifier();
+GeneralFileNotifier *notifier_get_local_notifier();
 
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r 9205a25c62d6 -r 40dc1cbd5356 libfsclient/lib/src/client.cc
--- a/libfsclient/lib/src/client.cc	Sat Aug 21 19:28:08 2021 +0200
+++ b/libfsclient/lib/src/client.cc	Sun Aug 22 22:37:55 2021 +0200
@@ -138,7 +138,7 @@
 
     /* Handle an inability to access by blocking, exiting if waiting failed. */
 
-    if (client_wait_file(file))
+    if (client_wait_file(file, client_notifier_task()))
       return 0;
   }
 
@@ -369,6 +369,29 @@
 
 
 
+/* Close a notifier object. */
+
+void client_notifier_close(file_notifier_t *notifier)
+{
+  file_notify_close(notifier);
+}
+
+/* Obtain a local notifier object. */
+
+file_notifier_t *client_notifier_local()
+{
+  return file_notify_local();
+}
+
+/* Obtain a task-wide notifier object. */
+
+file_notifier_t *client_notifier_task()
+{
+  return file_notify_task();
+}
+
+
+
 /* Read a directory entry. This must be freed by the caller after use. */
 
 struct dirent *client_readdir(file_t *file)
@@ -557,10 +580,12 @@
   /* Since blocking access is used with specific file notifications, the
      per-task notifier is used. */
 
+  file_notifier_t *notifier = client_notifier_task();
+
   if (flags)
-    err = client_subscribe(file, flags, NOTIFIER_TASK);
+    err = client_subscribe(file, flags, notifier);
   else
-    err = client_unsubscribe(file, NOTIFIER_TASK);
+    err = client_unsubscribe(file, notifier);
 
   if (err)
     return err;
@@ -573,12 +598,12 @@
 
 /* Subscribe from events concerning a file. */
 
-long client_subscribe(file_t *file, notify_flags_t flags, notifier_t notifier_type)
+long client_subscribe(file_t *file, notify_flags_t flags, file_notifier_t *notifier)
 {
   if (file == NULL)
     return -L4_EINVAL;
 
-  return file_notify_subscribe(file, flags, notifier_type);
+  return file_notify_subscribe(file, flags, notifier);
 }
 
 
@@ -597,32 +622,32 @@
 
 /* Unsubscribe from events concerning a file. */
 
-long client_unsubscribe(file_t *file, notifier_t notifier_type)
+long client_unsubscribe(file_t *file, file_notifier_t *notifier)
 {
   if (file == NULL)
     return -L4_EINVAL;
 
-  return file_notify_unsubscribe(file, notifier_type);
+  return file_notify_unsubscribe(file, notifier);
 }
 
 
 
 /* Wait for events involving a specific file. */
 
-long client_wait_file(file_t *file)
+long client_wait_file(file_t *file, file_notifier_t *notifier)
 {
   if (file == NULL)
     return -L4_EINVAL;
 
-  return file_notify_wait_file(file);
+  return file_notify_wait_file(file, notifier);
 }
 
 /* Wait for events concerning files, referencing a file object if an event is
    delivered. */
 
-long client_wait_files(file_t **file)
+long client_wait_files(file_t **file, file_notifier_t *notifier)
 {
-  return file_notify_wait_files(file);
+  return file_notify_wait_files(file, notifier);
 }
 
 
diff -r 9205a25c62d6 -r 40dc1cbd5356 libfsclient/lib/src/file.cc
--- a/libfsclient/lib/src/file.cc	Sat Aug 21 19:28:08 2021 +0200
+++ b/libfsclient/lib/src/file.cc	Sun Aug 22 22:37:55 2021 +0200
@@ -102,7 +102,7 @@
      here. */
 
   if (l4_is_valid_cap(file->ref))
-    get_task_notifier()->unsubscribe(file);
+    notifier_get_task_notifier()->unsubscribe(file);
 
   if (file->memory != NULL)
     ipc_detach_dataspace(file->memory);
@@ -386,50 +386,83 @@
 
 
 
+/* Opaque notifier type for file_notifier_t. */
+
+struct file_notifier
+{
+  FileNotifier *obj;
+};
+
+
+
+/* Close a notifier object. */
+
+void file_notify_close(file_notifier_t *notifier)
+{
+  delete notifier->obj;
+  delete notifier;
+}
+
+/* Obtain a local notifier object. */
+
+file_notifier_t *file_notify_local()
+{
+  file_notifier_t *notifier = new file_notifier_t;
+
+  notifier->obj = notifier_get_local_notifier();
+  return notifier;
+}
+
+/* Obtain the task-wide notifier object. */
+
+file_notifier_t *file_notify_task()
+{
+  file_notifier_t *notifier = new file_notifier_t;
+
+  notifier->obj = notifier_get_task_notifier();
+  return notifier;
+}
+
 /* Subscribe to notification events on a file. */
 
-long file_notify_subscribe(file_t *file, notify_flags_t flags, notifier_t notifier_type)
+long file_notify_subscribe(file_t *file, notify_flags_t flags, file_notifier_t *notifier)
 {
-  FileNotifier *notifier = get_notifier(notifier_type);
-
-  return notifier->subscribe(file, flags);
+  return notifier->obj->subscribe(file, flags);
 }
 
 /* Unsubscribe from notification events on a file. */
 
-long file_notify_unsubscribe(file_t *file, notifier_t notifier_type)
+long file_notify_unsubscribe(file_t *file, file_notifier_t *notifier)
 {
-  FileNotifier *notifier = get_notifier(notifier_type);
-
-  return notifier->unsubscribe(file);
+  return notifier->obj->unsubscribe(file);
 }
 
 /* Wait for a notification event on a file. */
 
-long file_notify_wait_file(file_t *file)
+long file_notify_wait_file(file_t *file, file_notifier_t *notifier)
 {
-  SpecificFileNotifier *notifier = get_task_notifier();
-  long err = notifier->wait_file(file);
+  SpecificFileNotifier *specific_notifier = dynamic_cast<SpecificFileNotifier *>(notifier->obj);
+  long err = specific_notifier->wait_file(file);
 
   /* Unsubscribe if a closure notification has been received. */
 
   if (!err && (file->notifications & NOTIFY_PEER_CLOSED))
-    file_notify_unsubscribe(file, NOTIFIER_TASK);
+    file_notify_unsubscribe(file, notifier);
 
   return err;
 }
 
 /* Wait for notification events on files. */
 
-long file_notify_wait_files(file_t **file)
+long file_notify_wait_files(file_t **file, file_notifier_t *notifier)
 {
-  GeneralFileNotifier *notifier = get_thread_notifier();
-  long err = notifier->wait(file);
+  GeneralFileNotifier *general_notifier = dynamic_cast<GeneralFileNotifier *>(notifier->obj);
+  long err = general_notifier->wait(file);
 
   /* Unsubscribe if a closure notification has been received. */
 
   if (!err && ((*file)->notifications & NOTIFY_PEER_CLOSED))
-    file_notify_unsubscribe(*file, NOTIFIER_THREAD);
+    file_notify_unsubscribe(*file, notifier);
 
   return err;
 }
diff -r 9205a25c62d6 -r 40dc1cbd5356 libfsclient/lib/src/notifier.cc
--- a/libfsclient/lib/src/notifier.cc	Sat Aug 21 19:28:08 2021 +0200
+++ b/libfsclient/lib/src/notifier.cc	Sun Aug 22 22:37:55 2021 +0200
@@ -47,17 +47,11 @@
 
 static SpecificFileNotifier *_notifier = NULL;
 
-/* Per-thread storage for "open" waiting operations.
-   (This workaround for thread-local storage maps thread capabilities to
-   notifiers). */
-
-static std::map<l4_cap_idx_t, GeneralFileNotifier *> _notifiers;
-
 
 
 /* Return the per-task notifier for file-specific waiting operations. */
 
-SpecificFileNotifier *get_task_notifier()
+SpecificFileNotifier *notifier_get_task_notifier()
 {
   std::lock_guard<std::mutex> guard(_lock);
 
@@ -72,37 +66,14 @@
   return _notifier;
 }
 
-/* Return the per-thread notifier for general file waiting operations. */
-
-GeneralFileNotifier *get_thread_notifier()
-{
-  std::lock_guard<std::mutex> guard(_lock);
-
-  l4_cap_idx_t thread = pthread_l4_cap(pthread_self());
-  GeneralFileNotifier *notifier = _notifiers[thread];
-
-  /* Start any new notifier. */
+/* Return a local notifier for general file waiting operations. */
 
-  if (notifier == NULL)
-  {
-    notifier = new GeneralFileNotifier;
-    _notifiers[thread] = notifier;
-    notifier->start();
-  }
-
-  return notifier;
-}
+GeneralFileNotifier *notifier_get_local_notifier()
+{
+  GeneralFileNotifier *notifier = new GeneralFileNotifier;
 
-/* Helper function to obtain the appropriate notifier. */
-
-FileNotifier *get_notifier(notifier_t notifier_type)
-{
-  switch (notifier_type)
-  {
-    case NOTIFIER_TASK: return get_task_notifier();
-    case NOTIFIER_THREAD: return get_thread_notifier();
-    default: return NULL;
-  }
+  notifier->start();
+  return notifier;
 }
 
 
@@ -117,6 +88,14 @@
   return 0;
 }
 
+
+
+/* Virtual destructor required for base class instance reference deletion. */
+
+FileNotifier::~FileNotifier()
+{
+}
+
 /* Listen for notifications. */
 
 void FileNotifier::mainloop()
diff -r 9205a25c62d6 -r 40dc1cbd5356 tests/dstest_file_client.cc
--- a/tests/dstest_file_client.cc	Sat Aug 21 19:28:08 2021 +0200
+++ b/tests/dstest_file_client.cc	Sun Aug 22 22:37:55 2021 +0200
@@ -61,7 +61,7 @@
 
   /* Register for notifications. */
 
-  if ((err = client_subscribe(file, NOTIFY_CONTENT_AVAILABLE | NOTIFY_PEER_CLOSED, NOTIFIER_TASK)))
+  if ((err = client_subscribe(file, NOTIFY_CONTENT_AVAILABLE | NOTIFY_PEER_CLOSED, client_notifier_task())))
   {
     printf("Could not subscribe to notifications: %s\n", l4sys_errtostr(err));
     return;
@@ -85,7 +85,7 @@
 
     /* Wait for notification of content. */
 
-    err = client_wait_file(file);
+    err = client_wait_file(file, client_notifier_task());
 
     if (err)
     {
diff -r 9205a25c62d6 -r 40dc1cbd5356 tests/dstest_pipe_client.cc
--- a/tests/dstest_pipe_client.cc	Sat Aug 21 19:28:08 2021 +0200
+++ b/tests/dstest_pipe_client.cc	Sun Aug 22 22:37:55 2021 +0200
@@ -78,10 +78,14 @@
   long err;
   file_t *reader;
 
+  /* Use a local notifier to wait for pipe events. */
+
+  file_notifier_t *notifier = client_notifier_local();
+
   /* Register the readers for notification. */
 
-  if ((err = client_subscribe(reader1, NOTIFY_CONTENT_AVAILABLE | NOTIFY_PEER_CLOSED, NOTIFIER_THREAD)) ||
-      (err = client_subscribe(reader2, NOTIFY_CONTENT_AVAILABLE | NOTIFY_PEER_CLOSED, NOTIFIER_THREAD)))
+  if ((err = client_subscribe(reader1, NOTIFY_CONTENT_AVAILABLE | NOTIFY_PEER_CLOSED, notifier)) ||
+      (err = client_subscribe(reader2, NOTIFY_CONTENT_AVAILABLE | NOTIFY_PEER_CLOSED, notifier)))
   {
     printf("Could not subscribe to notifications: %s\n", l4sys_errtostr(err));
     return;
@@ -94,11 +98,12 @@
 
     /* Wait for notification of content. */
 
-    err = client_wait_files(&reader);
+    err = client_wait_files(&reader, notifier);
 
     if (err)
     {
       printf("Error waiting for notifications: %s\n", l4sys_errtostr(err));
+      client_notifier_close(notifier);
       return;
     }
 
@@ -143,6 +148,7 @@
 
   client_close(reader1);
   client_close(reader2);
+  client_notifier_close(notifier);
 
   printf("Data shown.\n");
 }