dashboard, p2p, vendor: visualize peers (#19247)

* dashboard, p2p: visualize peers

* dashboard: change scale to green to red

vendor/github.com/oschwald/maxminddb-golang/mmap_windows.go

@@ -0,0 +1,85 @@
+// +build windows,!appengine
+
+package maxminddb
+
+// Windows support largely borrowed from mmap-go.
+//
+// Copyright 2011 Evan Shaw. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+import (
+	"errors"
+	"os"
+	"reflect"
+	"sync"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+type memoryMap []byte
+
+// Windows
+var handleLock sync.Mutex
+var handleMap = map[uintptr]windows.Handle{}
+
+func mmap(fd int, length int) (data []byte, err error) {
+	h, errno := windows.CreateFileMapping(windows.Handle(fd), nil,
+		uint32(windows.PAGE_READONLY), 0, uint32(length), nil)
+	if h == 0 {
+		return nil, os.NewSyscallError("CreateFileMapping", errno)
+	}
+
+	addr, errno := windows.MapViewOfFile(h, uint32(windows.FILE_MAP_READ), 0,
+		0, uintptr(length))
+	if addr == 0 {
+		return nil, os.NewSyscallError("MapViewOfFile", errno)
+	}
+	handleLock.Lock()
+	handleMap[addr] = h
+	handleLock.Unlock()
+
+	m := memoryMap{}
+	dh := m.header()
+	dh.Data = addr
+	dh.Len = length
+	dh.Cap = dh.Len
+
+	return m, nil
+}
+
+func (m *memoryMap) header() *reflect.SliceHeader {
+	return (*reflect.SliceHeader)(unsafe.Pointer(m))
+}
+
+func flush(addr, len uintptr) error {
+	errno := windows.FlushViewOfFile(addr, len)
+	return os.NewSyscallError("FlushViewOfFile", errno)
+}
+
+func munmap(b []byte) (err error) {
+	m := memoryMap(b)
+	dh := m.header()
+
+	addr := dh.Data
+	length := uintptr(dh.Len)
+
+	flush(addr, length)
+	err = windows.UnmapViewOfFile(addr)
+	if err != nil {
+		return err
+	}
+
+	handleLock.Lock()
+	defer handleLock.Unlock()
+	handle, ok := handleMap[addr]
+	if !ok {
+		// should be impossible; we would've errored above
+		return errors.New("unknown base address")
+	}
+	delete(handleMap, addr)
+
+	e := windows.CloseHandle(windows.Handle(handle))
+	return os.NewSyscallError("CloseHandle", e)
+}