Add pushover notifications, this should be a super basic MVP

vendor/github.com/dgraph-io/ristretto/z/mmap_darwin.go

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2019 Dgraph Labs, Inc. and Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package z
+
+import (
+	"os"
+	"syscall"
+	"unsafe"
+
+	"golang.org/x/sys/unix"
+)
+
+// Mmap uses the mmap system call to memory-map a file. If writable is true,
+// memory protection of the pages is set so that they may be written to as well.
+func mmap(fd *os.File, writable bool, size int64) ([]byte, error) {
+	mtype := unix.PROT_READ
+	if writable {
+		mtype |= unix.PROT_WRITE
+	}
+	return unix.Mmap(int(fd.Fd()), 0, int(size), mtype, unix.MAP_SHARED)
+}
+
+// Munmap unmaps a previously mapped slice.
+func munmap(b []byte) error {
+	return unix.Munmap(b)
+}
+
+// This is required because the unix package does not support the madvise system call on OS X.
+func madvise(b []byte, readahead bool) error {
+	advice := unix.MADV_NORMAL
+	if !readahead {
+		advice = unix.MADV_RANDOM
+	}
+
+	_, _, e1 := syscall.Syscall(syscall.SYS_MADVISE, uintptr(unsafe.Pointer(&b[0])),
+		uintptr(len(b)), uintptr(advice))
+	if e1 != 0 {
+		return e1
+	}
+	return nil
+}
+
+func msync(b []byte) error {
+	return unix.Msync(b, unix.MS_SYNC)
+}