"Fixing CI Build for darwin amd_64 #1"

This reverts commit 0046ccd.

common/mmf_linux.go

@@ -0,0 +1,88 @@
+// +build linux darwin
+
+// Copyright © 2017 Microsoft <wastore@microsoft.com>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package common
+
+import (
+	"os"
+	"sync"
+	"syscall"
+)
+
+type MMF struct {
+	// slice represents the actual memory mapped buffer
+	slice []byte
+	// defines whether source has been mapped or not
+	isMapped bool
+	// This lock exists to fix a bug in Go's Http Client. Because the http
+	// client executes some operations asynchronously (via goroutines), it
+	// sometimes attempts to read from the http request stream AFTER the MMF
+	// is unmapped. This lock guards against the access violation panic.
+	// When the MMF is created, all readers can take the shared (read) access
+	// on this lock. When the MMF is no longer needed, exclusive (write) access
+	// it requested and once obtained, the MMF is unmapped. If the http client
+	// attempts to read again the request body again, our pacer code sees that
+	// isMapped is false and gracefully fails the http request (avoiding the
+	// access violation panic).
+	lock sync.RWMutex
+}
+
+func NewMMF(file *os.File, writable bool, offset int64, length int64) (*MMF, error) {
+	prot, flags := syscall.PROT_READ, syscall.MAP_SHARED // Assume read-only
+	if writable {
+		prot, flags = syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_SHARED
+	}
+	addr, err := syscall.Mmap(int(file.Fd()), offset, int(length), prot, flags)
+	syscall.Madvise(addr, syscall.MADV_SEQUENTIAL|syscall.MADV_WILLNEED)
+	return &MMF{slice: (addr), isMapped: true, lock: sync.RWMutex{}}, err
+}
+
+// To unmap, we need exclusive (write) access to the MMF and
+// then we set isMapped to false so that future readers know
+// the MMF is unusable.
+func (m *MMF) Unmap() {
+	m.lock.Lock()
+	err := syscall.Munmap(m.slice)
+	m.slice = nil
+	PanicIfErr(err)
+	m.isMapped = false
+	m.lock.Unlock()
+}
+
+func (m *MMF) UseMMF() bool {
+	m.lock.RLock()
+	if !m.isMapped {
+		m.lock.RUnlock()
+		return false
+	}
+	return true
+}
+
+// RUnlock unlocks the held lock
+func (m *MMF) UnuseMMF() {
+	m.lock.RUnlock()
+}
+
+// Slice() returns the memory mapped byte slice
+func (m *MMF) Slice() []byte {
+	return m.slice
+}

common/mmf_unix.go

@@ -52,7 +52,8 @@ func NewMMF(file *os.File, writable bool, offset int64, length int64) (*MMF, err
 		prot, flags = syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_SHARED
 	}
 	addr, err := syscall.Mmap(int(file.Fd()), offset, int(length), prot, flags)
-	syscall.Madvise(addr, syscall.MADV_SEQUENTIAL|syscall.MADV_WILLNEED)
+	//TODO: Prefetch api for darwin x64 is different than the one for linux.
+	//syscall.Madvise(addr, syscall.MADV_SEQUENTIAL|syscall.MADV_WILLNEED)
 	return &MMF{slice: (addr), isMapped: true, lock: sync.RWMutex{}}, err
 }