Add async message processing

libfuse/lib/fuse_msgbuf.cpp

@@ -0,0 +1,123 @@
+/*
+  ISC License
+
+  Copyright (c) 2022, Antonio SJ Musumeci <trapexit@spawn.link>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#include "fuse_msgbuf.h"
+
+#include <assert.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <mutex>
+#include <stack>
+
+
+static std::size_t g_BUFSIZE = (1024 * 1024 * 2);
+
+static std::mutex g_MUTEX;
+static std::stack<fuse_msgbuf_t*> g_MSGBUF_STACK;
+
+static
+__attribute__((destructor))
+void
+msgbuf_destroy()
+{
+  // TODO: cleanup?
+}
+
+std::size_t
+msgbuf_bufsize()
+{
+  return g_BUFSIZE;
+}
+
+void
+msgbuf_bufsize(const std::size_t size_)
+{
+  g_BUFSIZE = size_;
+}
+
+fuse_msgbuf_t*
+msgbuf_alloc()
+{
+  int rv;
+  fuse_msgbuf_t *msgbuf;
+
+  g_MUTEX.lock();
+  if(g_MSGBUF_STACK.empty())
+    {
+      g_MUTEX.unlock();
+
+      msgbuf = (fuse_msgbuf_t*)malloc(sizeof(fuse_msgbuf_t));
+      if(msgbuf == NULL)
+        return NULL;
+
+      rv = pipe(msgbuf->pipefd);
+      assert(rv == 0);
+      rv = fcntl(msgbuf->pipefd[0],F_SETPIPE_SZ,g_BUFSIZE);
+      assert(rv > 0);
+      msgbuf->mem  = (char*)malloc(rv);
+      msgbuf->size = rv;
+      msgbuf->used = 0;
+    }
+  else
+    {
+      msgbuf = g_MSGBUF_STACK.top();
+      g_MSGBUF_STACK.pop();
+      g_MUTEX.unlock();
+    }
+
+  return msgbuf;
+}
+
+fuse_msgbuf_t*
+msgbuf_alloc_memonly()
+{
+  fuse_msgbuf_t *msgbuf;
+
+  g_MUTEX.lock();
+  if(g_MSGBUF_STACK.empty())
+    {
+      g_MUTEX.unlock();
+
+      msgbuf = (fuse_msgbuf_t*)malloc(sizeof(fuse_msgbuf_t));
+      if(msgbuf == NULL)
+        return NULL;
+
+      msgbuf->pipefd[0] = -1;
+      msgbuf->pipefd[1] = -1;
+      msgbuf->mem  = (char*)malloc(g_BUFSIZE);
+      msgbuf->size = g_BUFSIZE;
+      msgbuf->used = 0;
+    }
+  else
+    {
+      msgbuf = g_MSGBUF_STACK.top();
+      g_MSGBUF_STACK.pop();
+      g_MUTEX.unlock();
+    }
+
+  return msgbuf;
+}
+
+void
+msgbuf_free(fuse_msgbuf_t *msgbuf_)
+{
+  std::lock_guard<std::mutex> lck(g_MUTEX);
+
+  g_MSGBUF_STACK.push(msgbuf_);
+}