fdtrack: temporary hack for tracking file descriptor usage

Package fdtrack logs statistics about open file descriptors.
This should help identify the source of #1549.

1 files changed, 72 insertions, 0 deletions

diff --git a/fdtrack/fdusage_darwin.go b/fdtrack/fdusage_darwin.go
new file mode 100644
index 000000000..04a3a9baf
--- /dev/null
+++ b/fdtrack/fdusage_darwin.go
@@ -0,0 +1,72 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library 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 Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// +build darwin
+
+package fdtrack
+
+import (
+	"os"
+	"syscall"
+	"unsafe"
+)
+
+// #cgo CFLAGS: -lproc
+// #include <libproc.h>
+// #include <stdlib.h>
+import "C"
+
+func fdlimit() int {
+	var nofile syscall.Rlimit
+	if err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &nofile); err != nil {
+		return 0
+	}
+	return int(nofile.Cur)
+}
+
+func fdusage() (int, error) {
+	pid := C.int(os.Getpid())
+	// Query for a rough estimate on the amout of data that
+	// proc_pidinfo will return.
+	rlen, err := C.proc_pidinfo(pid, C.PROC_PIDLISTFDS, 0, nil, 0)
+	if rlen <= 0 {
+		return 0, err
+	}
+	// Load the list of file descriptors. We don't actually care about
+	// the content, only about the size. Since the number of fds can
+	// change while we're reading them, the loop enlarges the buffer
+	// until proc_pidinfo says the result fitted.
+	var buf unsafe.Pointer
+	defer func() {
+		if buf != nil {
+			C.free(buf)
+		}
+	}()
+	for buflen := rlen; ; buflen *= 2 {
+		buf, err = C.reallocf(buf, C.size_t(buflen))
+		if buf == nil {
+			return 0, err
+		}
+		rlen, err = C.proc_pidinfo(pid, C.PROC_PIDLISTFDS, 0, buf, buflen)
+		if rlen <= 0 {
+			return 0, err
+		} else if rlen == buflen {
+			continue
+		}
+		return int(rlen / C.PROC_PIDLISTFD_SIZE), nil
+	}
+	panic("unreachable")
+}