Add IoMuxer to toolbox

1 files changed, 101 insertions, 0 deletions

diff --git a/io_muxer.c b/io_muxer.c
new file mode 100644
index 0000000..31ebc53
--- /dev/null
+++ b/io_muxer.c
@@ -0,0 +1,101 @@
+/*
+ * Copyright (C) 2022 Mikhail Burakov. This file is part of toolbox.
+ *
+ * toolbox 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 3 of the License, or
+ * (at your option) any later version.
+ *
+ * toolbox 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 toolbox.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "io_muxer.h"
+
+#include <poll.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct IoMuxer_Closure {
+  void (*callback)(void*);
+  void* user;
+};
+
+static _Bool AppendRecord(struct IoMuxer* io_muxer) {
+  if (io_muxer->size < io_muxer->alloc) return 1;
+  size_t alloc = io_muxer->alloc + 1;
+  struct pollfd* pfds = realloc(io_muxer->pfds, alloc * sizeof(struct pollfd));
+  if (!pfds) return 0;
+  io_muxer->pfds = pfds;
+  struct IoMuxer_Closure* closures =
+      realloc(io_muxer->closures, alloc * sizeof(struct IoMuxer_Closure));
+  if (!closures) return 0;
+  io_muxer->closures = closures;
+  io_muxer->alloc = alloc;
+  return 1;
+}
+
+static void CompressRecords(struct IoMuxer* io_muxer) {
+  for (size_t forward = 0, reverse = io_muxer->size - 1; io_muxer->size;) {
+    while (forward < reverse && !io_muxer->pfds[forward].revents) forward++;
+    while (forward < reverse && io_muxer->pfds[reverse].revents) reverse--;
+    if (forward == reverse) {
+      if (!io_muxer->pfds[forward].revents) forward++;
+      io_muxer->size = forward;
+      return;
+    }
+    struct pollfd pfd = io_muxer->pfds[forward];
+    io_muxer->pfds[forward] = io_muxer->pfds[reverse];
+    io_muxer->pfds[reverse] = pfd;
+    struct IoMuxer_Closure closure = io_muxer->closures[forward];
+    io_muxer->closures[forward] = io_muxer->closures[reverse];
+    io_muxer->closures[reverse] = closure;
+  }
+}
+
+void IoMuxer_Create(struct IoMuxer* io_muxer) {
+  memset(io_muxer, 0, sizeof(struct IoMuxer));
+}
+
+int IoMuxer_OnRead(struct IoMuxer* io_muxer, int fd,
+                   void (*read_callback)(void*), void* user) {
+  if (!AppendRecord(io_muxer)) return -1;
+  struct pollfd pfd = {.fd = fd, .events = POLLIN};
+  struct IoMuxer_Closure closure = {.callback = read_callback, .user = user};
+  io_muxer->pfds[io_muxer->size] = pfd;
+  io_muxer->closures[io_muxer->size] = closure;
+  io_muxer->size++;
+  return 0;
+}
+
+int IoMuxer_OnWrite(struct IoMuxer* io_muxer, int fd,
+                    void (*write_callback)(void*), void* user) {
+  if (!AppendRecord(io_muxer)) return -1;
+  struct pollfd pfd = {.fd = fd, .events = POLLOUT};
+  struct IoMuxer_Closure closure = {.callback = write_callback, .user = user};
+  io_muxer->pfds[io_muxer->size] = pfd;
+  io_muxer->closures[io_muxer->size] = closure;
+  return 0;
+}
+
+int IoMuxer_Iterate(struct IoMuxer* io_muxer) {
+  CompressRecords(io_muxer);
+  int result = poll(io_muxer->pfds, io_muxer->size, -1);
+  if (result <= 0) return -1;
+  for (size_t i = 0; i < io_muxer->size; i++) {
+    if (io_muxer->pfds[i].revents)
+      io_muxer->closures[i].callback(io_muxer->closures[i].user);
+  }
+  return 0;
+}
+
+void IoMuxer_Destroy(struct IoMuxer* io_muxer) {
+  free(io_muxer->pfds);
+  free(io_muxer->closures);
+}