# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1626388764 -7200
# Node ID 83c79809b8530bb654e3a11284bbb73176bfe99f
# Parent  b0f34fc8d4d8192d634a803db7bec8567ce4e661
Added support for notifications when accessing files.

diff -r b0f34fc8d4d8 -r 83c79809b853 conf/dstest_file.cfg
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/conf/dstest_file.cfg	Fri Jul 16 00:39:24 2021 +0200
@@ -0,0 +1,23 @@
+-- vim:set ft=lua:
+
+local L4 = require("L4");
+
+local l = L4.default_loader;
+
+local server = l:new_channel();
+
+l:startv({
+    caps = {
+      server = server:svr(),
+    },
+    log = { "server", "r" },
+  },
+  "rom/dstest_block_server", "10");
+
+l:startv({
+    caps = {
+      server = server,
+    },
+    log = { "client", "g" },
+  },
+  "rom/dstest_file_client", "rom/dstest_file.cfg");
diff -r b0f34fc8d4d8 -r 83c79809b853 conf/dstest_file.list
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/conf/dstest_file.list	Fri Jul 16 00:39:24 2021 +0200
@@ -0,0 +1,25 @@
+entry dstest_file
+roottask moe rom/dstest_file.cfg
+module dstest_file.cfg
+module l4re
+module ned
+module dstest_file_client
+module dstest_block_server
+module lib4re-c.so
+module lib4re-c-util.so
+module lib4re.so
+module lib4re-util.so
+module libc_be_l4refile.so
+module libc_be_l4re.so
+module libc_be_socket_noop.so
+module libc_support_misc.so
+module libdl.so
+module libipc.so
+module libl4sys-direct.so
+module libl4sys.so
+module libl4util.so
+module libld-l4.so
+module libpthread.so
+module libstdc++.so
+module libsupc++.so
+module libuc_c.so
diff -r b0f34fc8d4d8 -r 83c79809b853 libfsserver/include/fsserver/file_pager.h
--- a/libfsserver/include/fsserver/file_pager.h	Fri Jul 16 00:38:55 2021 +0200
+++ b/libfsserver/include/fsserver/file_pager.h	Fri Jul 16 00:39:24 2021 +0200
@@ -34,6 +34,14 @@
 protected:
     FilePaging *_paging;
 
+    /* Notification endpoint for event subscription. */
+
+    unsigned int _endpoint;
+
+    /* Resize flag for notification. */
+
+    bool _resized = false;
+
 public:
     fileid_t fileid;
 
@@ -64,6 +72,12 @@
 
     virtual long mmap(offset_t position, offset_t length, offset_t *start_pos,
                       offset_t *end_pos, offset_t *size);
+
+    /* Notification methods. */
+
+    virtual long subscribe(l4_cap_idx_t notifier, notify_flags_t flags);
+
+    virtual long unsubscribe(l4_cap_idx_t notifier);
 };
 
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r b0f34fc8d4d8 -r 83c79809b853 libfsserver/include/fsserver/file_paging.h
--- a/libfsserver/include/fsserver/file_paging.h	Fri Jul 16 00:38:55 2021 +0200
+++ b/libfsserver/include/fsserver/file_paging.h	Fri Jul 16 00:39:24 2021 +0200
@@ -25,6 +25,7 @@
 #include <mutex>
 
 #include <fsserver/accessor.h>
+#include <fsserver/notification.h>
 #include <fsserver/pager.h>
 #include <fsserver/page_mapper.h>
 
@@ -39,7 +40,7 @@
 
 /* A registry of mappers for accessors. */
 
-class FilePaging
+class FilePaging : public NotificationSupport
 {
 protected:
     Pages *_pages;
@@ -55,9 +56,11 @@
 
     /* Configurable methods. */
 
-    virtual fileid_t get_fileid(const char *path) = 0;
+    virtual map_flags_t get_flags(flags_t flags);
 
-    virtual map_flags_t get_flags(flags_t flags);
+    /* Configurable methods requiring implementation. */
+
+    virtual fileid_t get_fileid(const char *path) = 0;
 
     virtual Accessor *make_accessor(const char *path, fileid_t fileid) = 0;
 
@@ -72,8 +75,6 @@
 public:
     explicit FilePaging(Pages *pages);
 
-    virtual ~FilePaging();
-
     /* Methods for the pager. */
 
     void detach_pager(fileid_t fileid, PageMapper *mapper);
diff -r b0f34fc8d4d8 -r 83c79809b853 libfsserver/lib/Makefile
--- a/libfsserver/lib/Makefile	Fri Jul 16 00:38:55 2021 +0200
+++ b/libfsserver/lib/Makefile	Fri Jul 16 00:39:24 2021 +0200
@@ -16,7 +16,7 @@
 # Compound interfaces.
 
 mapped_file_object_NAME			= MappedFileObject
-mapped_file_object_INTERFACES		= dataspace file flush mapped_file
+mapped_file_object_INTERFACES		= dataspace file flush mapped_file notification
 
 opener_context_object_NAME		= OpenerContextObject
 opener_context_object_INTERFACES	= dataspace opener_context
diff -r b0f34fc8d4d8 -r 83c79809b853 libfsserver/lib/files/file_pager.cc
--- a/libfsserver/lib/files/file_pager.cc	Fri Jul 16 00:38:55 2021 +0200
+++ b/libfsserver/lib/files/file_pager.cc	Fri Jul 16 00:39:24 2021 +0200
@@ -51,6 +51,10 @@
 void FilePager::close()
 {
     _paging->detach_pager(fileid, _mapper);
+
+    /* Notify other users of the file. */
+
+    _paging->notify_others(_endpoint, NOTIFY_PEER_CLOSED);
 }
 
 
@@ -59,12 +63,29 @@
 
 long FilePager::flush(offset_t populated_size, offset_t *size)
 {
-    return Pager::flush(populated_size, size);
+    long err = Pager::flush(populated_size, size);
+
+    if (_resized)
+    {
+        _paging->notify_others(_endpoint, NOTIFY_CONTENT_AVAILABLE);
+        _resized = false;
+    }
+
+    return err;
 }
 
 long FilePager::resize(offset_t *size)
 {
-    return Pager::resize(size);
+    offset_t old_size = get_data_size();
+    long err = Pager::resize(size);
+
+    /* If the size has changed, notify other users, but only after data has been
+       flushed. */
+
+    if (old_size < get_data_size())
+        _resized = true;
+
+    return err;
 }
 
 long FilePager::mmap(offset_t position, offset_t length, offset_t *start_pos,
@@ -84,4 +105,23 @@
     return Pager::map(offset, hot_spot, flags, region);
 }
 
+
+
+/* Subscribe to notifications. */
+
+long FilePager::subscribe(l4_cap_idx_t notifier, notify_flags_t flags)
+{
+    /* Readers can subscribe to new data (at end), and pipe closed events.
+       Writers can subscribe to new space and pipe closed events. */
+
+    _endpoint = _paging->subscribe(notifier, flags);
+    return L4_EOK;
+}
+
+long FilePager::unsubscribe(l4_cap_idx_t notifier)
+{
+    _paging->unsubscribe(_endpoint, notifier);
+    return L4_EOK;
+}
+
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r b0f34fc8d4d8 -r 83c79809b853 libfsserver/lib/files/file_paging.cc
--- a/libfsserver/lib/files/file_paging.cc	Fri Jul 16 00:38:55 2021 +0200
+++ b/libfsserver/lib/files/file_paging.cc	Fri Jul 16 00:39:24 2021 +0200
@@ -27,11 +27,7 @@
 
 
 FilePaging::FilePaging(Pages *pages)
-: _pages(pages)
-{
-}
-
-FilePaging::~FilePaging()
+: NotificationSupport(), _pages(pages)
 {
 }
 
diff -r b0f34fc8d4d8 -r 83c79809b853 tests/Makefile
--- a/tests/Makefile	Fri Jul 16 00:38:55 2021 +0200
+++ b/tests/Makefile	Fri Jul 16 00:39:24 2021 +0200
@@ -4,6 +4,7 @@
 TARGET		= \
 		dstest_block_client dstest_block_client_simple \
 		dstest_ext2fs_client \
+		dstest_file_client \
 		dstest_host_client \
 		dstest_pipe_client \
 		dstest_test_client \
@@ -16,6 +17,8 @@
 
 SRC_CC_dstest_ext2fs_client		= dstest_ext2fs_client.cc
 
+SRC_CC_dstest_file_client		= dstest_file_client.cc
+
 SRC_CC_dstest_host_client		= dstest_host_client.cc
 
 SRC_CC_dstest_pipe_client		= dstest_pipe_client.cc
diff -r b0f34fc8d4d8 -r 83c79809b853 tests/dstest_file_client.cc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/dstest_file_client.cc	Fri Jul 16 00:39:24 2021 +0200
@@ -0,0 +1,168 @@
+/*
+ * Test file operations.
+ *
+ * Copyright (C) 2020, 2021 Paul Boddie <paul@boddie.org.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA  02110-1301, USA
+ */
+
+#include <l4/re/env.h>
+#include <l4/sys/err.h>
+
+#include <thread>
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+#include <fsclient/client.h>
+#include <systypes/fcntl.h>
+
+
+
+/* Write data to the file. */
+
+static void write_data(file_t *file, int region)
+{
+  offset_t size = 600;
+  char buffer[size];
+
+  memset(buffer, (int) 'a' + region, size);
+
+  offset_t nwritten = client_write(file, buffer, size);
+
+  printf("Written %ld/%ld in #%d to file with first %c, last %c...\n", nwritten, size, region, *buffer, *(buffer + nwritten - 1));
+
+  /* Flush to make the output available. */
+
+  client_flush(file);
+}
+
+/* Read and write data to the file. */
+
+static void read_and_write(file_t *file, bool creator)
+{
+  offset_t size = 600, total = 0;
+  long err;
+  int region = 0;
+
+  /* Register for notifications. */
+
+  if ((err = client_subscribe(file, NOTIFY_CONTENT_AVAILABLE | NOTIFY_PEER_CLOSED)))
+  {
+    printf("Could not subscribe to notifications: %s\n", l4sys_errtostr(err));
+    return;
+  }
+
+  /* Seek to the end of the file, if this is not actually a new file. */
+
+  client_seek(file, 0, SEEK_END);
+
+  printf("File %s at position %ld...\n", creator ? "creator" : "follower", client_tell(file));
+
+  /* Write initial data as the file's creator. */
+
+  if (creator)
+    write_data(file, region++);
+
+  while (region < 26)
+  {
+    char buffer[size];
+    offset_t nread;
+
+    /* Wait for notification of content. */
+
+    err = client_wait_file(file);
+
+    if (err)
+    {
+      printf("Error waiting for notifications: %s\n", l4sys_errtostr(err));
+      return;
+    }
+
+    printf("File %s notified with conditions:%s%s\n", creator ? "creator" : "follower",
+                                                      file->notifications & NOTIFY_PEER_CLOSED ? " closed" : "",
+                                                      file->notifications & NOTIFY_CONTENT_AVAILABLE ? " content" : "");
+
+    /* Attempt to read. */
+
+    nread = client_read(file, buffer, size);
+
+    while (nread)
+    {
+      total += nread;
+
+      printf("Read as %s %ld/%ld, total %ld, first %c, last %c, from file...\n", creator ? "creator" : "follower",
+             nread, size, total, *buffer, *(buffer + nread - 1));
+
+      if (!(*(buffer + nread - 1)))
+        printf("Warning: length before zero region is %ld\n", strlen(buffer));
+
+#if 0
+      for (offset_t i = 0; i < nread; i += 60)
+      {
+        fwrite(buffer + i, sizeof(char), nread - i > 60 ? 60 : nread - i, stdout);
+        fputs("\n", stdout);
+      }
+#endif
+      nread = client_read(file, buffer, size);
+    }
+
+    /* Without any more content, a peer closed event should terminate reading
+       from the pipe. */
+
+    if (file->notifications & NOTIFY_PEER_CLOSED)
+      break;
+
+    write_data(file, region++);
+  }
+
+  printf("Data shown.\n");
+}
+
+int main(int argc, char *argv[])
+{
+  if (argc < 2)
+  {
+    printf("Need a filename.\n");
+    return 1;
+  }
+
+  char *filename = argv[1];
+
+  /* Invoke the open function to receive each file reference. */
+
+  file_t *file1 = client_open(filename, O_RDWR); // | O_CREAT
+  file_t *file2 = client_open(filename, O_RDWR);
+
+  if ((file1 == NULL) || (file2 == NULL))
+  {
+    printf("Could not obtain files.\n");
+    return 1;
+  }
+
+  /* Schedule threads. */
+
+  std::thread *activities[2];
+
+  activities[0] = new std::thread(read_and_write, file1, true);
+  activities[1] = new std::thread(read_and_write, file2, false);
+
+  for (int i = 0; i < 2; i++)
+    activities[i]->join();
+}
+
+// vim: tabstop=2 expandtab shiftwidth=2